Patient support apparatus including an auxiliary drive system

Abstract

A patient support apparatus includes a support structure and an auxiliary drive system including a drive member and a motor coupled to the drive member. The patient support apparatus may include a sensing system for generating data representing load acting on the support structure in one or more directions. A controller may be configured to operate the auxiliary drive system to counteract deviations in a trajectory of the patient support apparatus along the floor surface occurring due to the direction of the load acting on the support structure. The controller may additionally or alternatively be configured to operate the auxiliary drive system in a two-handed mode based on user engagement with both of a first and second user input control, and to operate in a one-handed mode based on user engagement with a single one of the first and second user input control.

Description

Docket No. 060252.01136PATIENT SUPPORT APPARATUS INCLUDING AN AUXILIARY DRIVE SYSTEMCROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] The subject patent application claims priority to and all the benefits of U.S. Provisional Patent Application No. 63 / 680,127 filed on August 7, 2024, the disclosure of which is hereby incorporated by reference in its entirety.BACKGROUND

[0002] There are a number of challenges associated with equipping patient support apparatuses with auxiliary drive systems. For example, a patient support apparatus including an auxiliary drive system may veer from an intended trajectory along a floor surface due to the magnitude and / or direction of a load acting on the support structure of the patient support apparatus (e.g., where a heavy patient or heavy medical equipment is placed on the patient support apparatus such that the load is off-center from the middle of the patient support apparatus). Furthermore, there are additional challenges associated with controlling operation of the auxiliary drive system where more than one user input control is arranged for user engagement to operate the auxiliary drive system. Consequently, there is an unmet need in the field for a patient support apparatus including an auxiliary drive system that solves one or more of the aforementioned challenges.SUMMARY

[0003] One general aspect of the present disclosure is directed to a patient support apparatus including a support structure. The support structure includes a base arranged for movement about a floor surface and a litter operatively attached to the base and defining a patient support surface for supporting a patient. The patient support apparatus also includes a sensing system coupled to the support structure to generate data representing load acting on the support structure in one or more directions. The patient support apparatus further includes an auxiliary drive system operatively attached to the support structure. The auxiliary drive system includes a drive member configured to influence motion of the patient support apparatus over the floor surface and a motor coupled to the drive member for providing motive power to the drive member. The patient support apparatus also includes a controller in communication with the auxiliary drive system and the sensing system. The controller is configured to operate the auxiliary drive system to counteract deviations in a trajectory of the patient support apparatus along the floor surface occurring due to the direction of the load acting on the support structure based on the data generated by the sensing system.

[0004] Another general aspect of the present disclosure is directed to a patient support apparatus including a support structure. The support structure includes a base arranged for movement about a floor surface and a litter operatively attached to the base and defining a patient support surface for supporting a patient. The patient support apparatus also includes a sensing system coupled to the support structure to generate data representing load acting on the support structure in one or more directions. The patient support apparatus further includes an auxiliary drive system operatively attached to the support structure. The auxiliary drive system includes a first drive member configured to influence motion of the patient support apparatus over the floorDocket No. 060252.01136 surface, a first motor coupled to the first drive member for providing motive power to the first drive member, a second drive member configured to influence motion of the patient support apparatus over the floor surface, and a second motor coupled to the second drive member for providing motive power to the second drive member. The patient support apparatus also includes a controller in communication with the auxiliary drive system and the sensing system. The controller is configured to operate the auxiliary drive system to counteract deviations in a trajectory of the patient support apparatus along the floor surface occurring due to the direction of the load acting on the support structure based on the data generated by the sensing system.

[0005] Yet another general aspect of the present disclosure is directed to a patient support apparatus including a support structure. The support structure includes a base arranged for movement about a floor surface and a litter operatively attached to the base and defining a patient support surface for supporting a patient. The patient support apparatus also includes an auxiliary drive system operatively attached to the support structure. The auxiliary drive system includes a drive member configured to influence motion of the patient support apparatus over the floor surface, and a motor coupled to the drive member for providing motive power to the drive member. The patient support apparatus further includes a first user input control operatively attached to the support structure and arranged for user engagement and a second user input control operatively attached to the support structure and arranged for user engagement. The patient support apparatus additionally includes a controller in communication with the auxiliary drive system, the first user input control, and the second user input control. The controller is configured to operate the auxiliary drive system based on user engagement with at least one of the first user input control and the second user input control, operate the auxiliary drive system in a two-handed mode based on user engagement with both of the first user input control and the second user input control, and operate the auxiliary drive system in a one-handed mode based on user engagement with a single one of the first user input control and the second user input control.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Other advantages of the present disclosure will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

[0007] Figure 1 is a perspective view of a patient support apparatus including a support structure and an auxiliary drive system according to the present disclosure.

[0008] Figure 2 schematically illustrates a controller of the patient support apparatus in communication with various aspects of the patient support apparatus to effect operation of various functions of the patient support apparatus.

[0009] Figure 3 A is a schematic side view of the patient support apparatus of Figure 1, shown with each of the side rails arranged in a raised position.

[0010] Figure 3B is another schematic side view of the patient support apparatus of Figure 3A, shown with the first side rail arranged in a lowered position.Docket No. 060252.01136

[0011] Figure 4A is another schematic side view of the patient support apparatus of Figures 3A and 3B, shown with two of the side rails removed for illustrative purpose, and with the lift mechanism supporting the litter in a raised configuration.

[0012] Figure 4B is another schematic side view of the patient support apparatus of Figure 4A, shown with the lift mechanism supporting the litter in a lowered configuration.

[0013] Figure 5 A is another schematic side view of the patient support apparatus of Figures 3A-4B, shown with the patient support deck having a back section arranged in a fowler’s position with the second side rail coupled to the back section.

[0014] Figure 5B is another schematic side view of the patient support apparatus of Figure 5A, shown with the lift mechanism supporting the litter in an inclined configuration.

[0015] Figure 6 is a schematic front view of one configuration of an auxiliary drive system coupled to a support structure of the patient support apparatus with a single drive member arranged to influence motion of the patient support apparatus over the floor surface.

[0016] Figure 7 is a schematic front view of another configuration of an auxiliary drive system with a single drive member arranged to influence motion of the patient support apparatus over the floor surface and a second motor configured to alter the orientation of the drive member about a vertical axis.

[0017] Figure 8 A is a schematic side view of the patient support apparatus of Figure 1, shown with a drive member of the auxiliary drive system in a stowed state.

[0018] Figure 8B is another schematic side view of the patient support apparatus of Figure 8A, shown with a drive member of the auxiliary drive system in a deployed state.

[0019] Figure 9 is a schematic representation of an exemplary configuration of the auxiliary drive system including a motor control circuit.

[0020] Figure 10A is a schematic top view of the patient support apparatus of Figure 1, shown depicting a sensing system coupled to the support structure to generate data representing load acting on the support structure in one or more directions and including an indicia indicating the direction of load acting on the support structure.

[0021] Figure 10B is another schematic top view of the patient support apparatus of Figure 10A, shown with the load indicia having moved laterally relative to a longitudinal axis of the patient support apparatus.

[0022] Figure 11A is a schematic side view of the patient support apparatus of Figure 1, shown with load cell assemblies of the sensing system interposed between the lift mechanism and the base of the patient support apparatus.

[0023] Figure 1 IB is a schematic side view of the patient support apparatus of Figure 1, shown with load cell assemblies of the sensing system interposed between the lift mechanism and the litter of the patient support apparatus.

[0024] Figure 11C is a schematic side view of the patient support apparatus of Figure 1, shown with load cell assemblies of the sensing system interposed between the base and the support wheels of the patient support apparatus.Docket No. 060252.01136

[0025] Figure 12 is a flowchart illustrating operation of the controller to operate the auxiliary drive system to counteract deviations in a trajectory of the patient support apparatus along the floor surface occurring due to the direction of the load acting on the support structure as determined by the sensing system.

[0026] Figure 13 is a schematic top view of the patient support apparatus of Figure 1, shown depicting operation of the auxiliary drive system to counteract deviations in a trajectory of the patient support apparatus along the floor surface occurring due to the direction of the load acting on the support structure as determined by the sensing system.

[0027] Figure 14 is a flowchart illustrating operation of the controller to operate the auxiliary drive system to adjust the commanded torque value of the motor(s) where there is a difference between an expected speed of the patient support apparatus along the floor surface and the actual speed of the patient support apparatus along the floor surface.

[0028] Figure 15A is a schematic front view of the patient support apparatus of Figure 1, shown with a first user input control implemented as a first throttle arranged for user engagement to operate the auxiliary drive system.

[0029] Figure 15B is a partial top perspective view of the patient support apparatus illustrated in Figure 15 A.

[0030] Figure 16 illustrates a graph of a throttle map for use by the controller to determine the commanded torque value of the motor(s) based on the magnitude of movement of the first throttle.

[0031] Figure 17 is a partial top perspective view of the patient support apparatus of Figure 1, shown with a first user input control implemented as a first force sensor and a first input member arranged for user engagement to operate the auxiliary drive system.

[0032] Figure 18A is a schematic front view of the patient support apparatus of Figure 1, shown with a first user input control implemented as a joystick arranged for user engagement to operate the auxiliary drive system.

[0033] Figure 18B is a partial top view of the patient support apparatus illustrated in Figure 18A.

[0034] Figure 19A is a schematic front view of the patient support apparatus of Figure 1, shown with a second user input control implemented as a second presence sensor to operate the auxiliary drive system.

[0035] Figure 19B is a partial top perspective view of the patient support apparatus illustrated in Figure 19 A.

[0036] Figure 20 is a perspective view of a patient support apparatus including a support structure and an auxiliary drive system including a first drive member, a first motor, a second drive member, and a second motor.

[0037] Figure 21 is a schematic front view of one configuration of an auxiliary drive system coupled to a support structure of the patient support apparatus and including a first drive member, a first motor, a second drive member, and a second motor.Docket No. 060252.01136

[0038] Figure 22 is a schematic top view of the patient support apparatus of Figure 20, shown depicting operation of the auxiliary drive system to counteract deviations in a trajectory of the patient support apparatus along the floor surface occurring due to the direction of the load acting on the support structure as determined by the sensing system.

[0039] Figures 23A through 25B are each schematic top views of the patient support apparatus of Figure 20, shown depicting various scenarios of the controller permitting a rotational speed differential between the first drive member and the second drive member in response to a caretaker exerting force on the support structure of the patient support apparatus.

[0040] Figures 26A through 27B are each schematic top views of the patient support apparatus of Figure 20, shown depicting various scenarios of the controller operating the first motor at a first torque in response to a first magnitude and direction of user engagement with the first user input control and operating the second motor at a second torque in response to a second magnitude and direction of user engagement with the second user input control.

[0041] Figure 28 is a schematic top view of the patient support apparatus of Figure 20 showing a configuration where the controller is configured to operate the auxiliary drive system in a forward and / or reverse direction based on user engagement with the first user input control and to operate the auxiliary drive system to differentially turn the patient support apparatus relative to the floor surface based on user engagement with the second user input control.

[0042] Figure 29A is a schematic front view of the patient support apparatus of Figure 20, shown with a first user input control implemented as a first throttle arranged for user engagement to operate the auxiliary drive system and a second user input control implemented as a second throttle arranged for user engagement to operate the auxiliary drive system.

[0043] Figure 29B is a partial top perspective view of the patient support apparatus illustrated in Figure 29A.

[0044] Figure 30A is a schematic front view of the patient support appar atus of Figure 20, shown with a first user input control implemented as a first throttle arranged for user engagement to operate the auxiliary drive system and a second user input control implemented as a second force sensor and a second input member arranged for user engagement to operate the auxiliary drive system.

[0045] Figure 30B is a partial top perspective view of the patient support apparatus illustrated in Figure 30A.

[0046] Figure 31A is a schematic front view of the patient support apparatus of Figure 20, shown with a first user input control implemented as a first force sensor and a first input member arranged for user engagement to operate the auxiliary drive system and a second user input control implemented as a second throttle arranged for user engagement to operate the auxiliary drive system.

[0047] Figure 3 IB is a partial top perspective view of the patient support apparatus illustrated in Figure 31 A.

[0048] Figure 32A is a schematic front view of the patient support apparatus of Figure 20, shown with a first user input control implemented as a first force sensor and a first input memberDocket No. 060252.01136 arranged for user engagement to operate the auxiliary drive system and a second user input control implemented as a second force sensor and a second input member arranged for user engagement to operate the auxiliary drive system.

[0049] Figure 32B is a partial top perspective view of the patient support apparatus illustrated in Figure 32A.

[0050] Figure 33A is a schematic front view of a patient support apparatus according to the present disclosure, shown with a user engaging one of a first user input control and a second user input control such that a controller operates an auxiliary drive system in a one-handed mode.

[0051] Figure 33B is a schematic front view of a patient support apparatus according to the present disclosure, shown with a user engaging both of the first user input control and the second user input control such that a controller operates an auxiliary drive system in a two-handed mode.

[0052] Figure 34 is a flowchart illustrating one example of the controller operating the auxiliary drive system in the two-handed mode.DETAILED DESCRIPTION

[0053] Referring to Figure 1, a patient support apparatus 100 is shown for supporting a patient in a health care setting. The patient support apparatus 100 illustrated throughout the drawings is realized as a hospital bed. In other configurations, however, the patient support apparatus 100 may be a stretcher, a cot, a table, a wheelchair, a chair, or a similar apparatus utilized in the care of a patient and / or to transport the patient between locations.

[0054] A support structure 102 provides support for the patient. The support structure 102 includes a base 104 and a litter 106. In one exemplary configuration, the litter 106 comprises an intermediate frame 108 and a patient support deck 110 spaced above the base 104. Here, the patient support deck 110 typically includes at least one deck section 112 arranged for movement relative to the intermediate frame 108. The deck sections 112 may define a patient support surface 114 upon which the patient is supported. In the illustrated configurations, the patient support deck 110 has four deck sections 112 which cooperate to define the patient support surface 114. More specifically, the patient support deck 110 illustrated herein includes a back section 1 16, a seat section 118, a leg section 120, and a foot section 122 (best shown in Figures 4A-5B). Other configurations of the litter 106 and components thereof are contemplated, and it will be appreciated that different arrangements of deck sections 112 are also contemplated.

[0055] A mattress, although not shown, may be disposed on the patient support deck 110. The mattress may define a secondary patient support surface upon which the patient is supported. The base 104 and litter 106 each have a head end HE and a foot end FE corresponding to designated placement of the patient’ s head and feet on the patient support apparatus 100. The construction of the support structure 102 may take on any known or conventional design and is not limited to that specifically set forth above. In addition, the mattress may be omitted in certain embodiments, such that the patient rests directly on the patient support surface 114.

[0056] The patient support apparatus 100 may also include side rails 124, 126, 128, 130 supported by the support structure. A first side rail 124 may be positioned at a right head end ofDocket No. 060252.01136 the intermediate frame 108. A second side rail 126 may be positioned at a right foot end of the intermediate frame 108. A third side rail 128 may be positioned at a left head end of the intermediate frame 108. A fourth side rail 130 may be positioned at a left foot end of the intermediate frame 108. Where the patient support apparatus 100 is realized as a stretcher, there may be fewer side rails. The side rails 124, 126, 128, 130 are typically movable between a raised position in which they block ingress and egress into and out of the patient support apparatus 100, and a lowered position in which they are not an obstacle to such ingress and egress. The side rails 124, 126, 128, 130 may also be movable to one or more intermediate positions between the raised position and the lowered position. In still other configurations, the patient support apparatus 100 may not comprise any side rails.

[0057] In the illustrated configurations, a headboard 132 and a footboard 134 are coupled to the intermediate frame 108. In other embodiments, when the headboard 132 and footboard 134 are provided, the headboard 132 and footboard 134 may be coupled to other locations of the support structure 102, such as the base 104. In still other embodiments, the patient support apparatus 100 does not comprise the headboard 132 and / or the footboard 134. The side rails 124, 126, 128, 130 headboard 132, and footboard 134, or other components of the support structure 102 may also include manual operator interfaces 136, such as handles or the like to facilitate manual movement of the patient support apparatus 100 over the floor surfaces FS.

[0058] Support wheels 138 may be coupled to the base 104 to support the base 104 on a floor surface FS such as a hospital floor. The support wheels 138 allow the patient support apparatus 100 to move in any direction along the floor surface FS by swiveling to assume a trailing orientation relative to a desired direction of movement. In the illustrated configurations, the support wheels 138 comprise four support wheels 138 each arranged in comers of the base 104. The support wheels 138 shown are caster wheels able to rotate and swivel about respective vertical swivel axes during transport. Each of the support wheels 138 may form part of a caster assembly 140. Each caster assembly 140 is typically mounted to the base 104. It should be understood that various configurations of the caster assemblies 140 are contemplated.

[0059] The support structure 102 may include a lift mechanism 142 interposed between the base 104 and the litter 106 to move the litter 106 relative to the base 104 between a plurality of vertical configurations, such as to the raised vertical configuration 142A depicted in Figures 3A-4A, the lowered vertical configuration 142B depicted in Figures 4B-5A, or to any desired vertical configuration therebetween including various inclined configurations 1421 such as depicted in Figure 5B. To this end, the lift mechanism 142 may include a head end lift member 144 and a foot end lift member 146 which are each arranged to facilitate movement of the litter 106 with respect to the base 104 using one or more lift actuators 148. The lift actuators 148 may be realized as lineal’ actuators, rotary actuators, or other types of actuators, and may be electrically operated and / or may be hydraulic. It is contemplated that, in some configurations, only one lift member and one associated lift actuator may be employed, e.g., one central lift actuator to raise and lower the litter 106. The construction of the lift mechanism 142, the head end lift member 144, and / or the foot end lift member 146 may take on any known or conventional design and isDocket No. 060252.01136 not limited to that specifically illustrated. By way of non-limiting example, the lift mechanism 142 could comprise a “scissor” linkage arranged between the base 104 and the litter 106 with one or more actuators configured to facilitate vertical movement of the patient support deck 110.

[0060] One or more deck actuators 152 may be interposed between the deck section(s) 112 and the intermediate frame 108 to move the deck section(s) 112. In the representative embodiments illustrated herein, the deck actuator(s) 150 are realized as linear actuator(s) disposed in force-translating relationship between the deck section 112 and the intermediate frame 108. For example, Figure 5A illustrates the back section 116 elevated relative to the intermediate frame 108 via a deck actuator 152 interposed between the intermediate frame and the back section 116. Those having ordinary skill in the art will appreciate that the patient support apparatus 100 could employ any suitable number of deck actuators 150 of any suitable type or configuration sufficient to effect selective movement of one or more of the deck sections 112 relative to the litter 106 or other components of the support structure 102. By way of non-limiting example, the deck actuator 150 could be a linear actuator or one or more rotary actuators driven electronically and / or hydraulically, and / or controlled or driven in any suitable way. Moreover, the deck actuator 150 could be mounted, secured, coupled, or otherwise operatively attached to the intermediate frame 108 and to one of the deck sections 112, either directly or indirectly, in any suitable way. In addition, one or more of the deck actuators 150 could be omitted for certain applications.

[0061] The patient support apparatus 100 employs a controller, generally indicated at 156, to effect operation of various functions of the patient support apparatus 100, as described in greater detail below. The controller 156 may be disposed in communication with one or more user interfaces 158 adapted for user engagement by the patient and / or the caregiver to facilitate operation of one or more functions of the patient support apparatus 100. For example, the controller 156 may be disposed in communication with the lift actuators 150, the deck actuators 152, and additional components described in greater detail below to effect operation of these various components. The controller 156 may also be in communication with one or more sensors S for monitoring the status of various aspects of the patient support apparatus 100. The implementation of the one or more sensors S is not particularly limited for the purposes of this disclosure and may include motion sensor(s) for monitoring motion of the patient, brake sensor(s) for monitoring whether the support wheels 138 arc in a brakes state, lift sensor(s) for monitoring the operational state of the lift mechanism 142, deck sensor(s) for monitoring the operational state of the section(s) of the patient support deck 110, barrier sensor(s) for monitoring the operational state of the side rail(s), a mattress sensor for monitoring the presence of / the operational state of the mattress, etc. The controller 156 has been omitted from certain drawings for the purposes of clarity and consistency.

[0062] It will be appreciated that the controller 156 can be configured or otherwise arranged in a number of different ways. The controller 156 may comprise one or more microprocessors for processing instructions or for processing algorithms stored in memory to control operation of the various functions of the patient support apparatus 100, as described in greater detail below. Additionally or alternatively, the controller 156 may comprise one or moreDocket No. 060252.01136 microcontrollers, field programmable gate arrays, systems on a chip, discrete circuitry, and / or other suitable hardware, software, or firmware that is capable of carrying out the various functions and operations described herein. The controller 156 may be carried on-board the patient support apparatus 100, such as on the base 104, the litter 106, or may be remotely located. The controller 156 may comprise one or more subcontrollers configured to control certain functions of the patient support apparatus 100. The controller 156 may communicate with the various components of the patient support apparatus 100 via wired or wireless connections.

[0063] In the representative configuration illustrated in Figures 1 and 2, the patient support apparatus 100 comprises a plurality of user interfaces 158 which may be accessible by the patient, the caregiver, or by both the caregiver and the patient. Each user interface 158 of the patient support apparatus 100 generally comprises an input device 160 configured to generate an input signal in response to activation by a user which, in turn, is communicated to the controller 156. The controller 156, in turn, is responsive to the input signal and can control or otherwise carry out one or more functions of the patient support apparatus 100 in response to receiving the input signal. Put differently, the controller 156 is configured to perform a function of the patient support apparatus 100 in response to receiving the input from the input device(s) 160. By way of nonlimiting example, the input device 160 could be realized as a “lift bed” button, activation of which causes the controller 156 to drive the lift actuators 150 to move the litter 106 from the lowered configuration 106B (see Figure 4B) vertically away from the base 104 towards the raised configuration 106A (see Figure 4A). Moreover, in some embodiments, the controller 156 may be configured to facilitate navigation of visual content of the user interface 158 in response to receiving the input signal from the input device 160. Thus, it will be appreciated that the user interface 158 could be configured in a number of different ways sufficient to generate the input signal. Moreover, it will be appreciated that the user interfaces 158 could be of a number of different styles, shapes, configurations, and the like. By way of non-limiting example, one or more of the user interfaces 158 may comprise buttons, indicators, screens, graphical user interfaces, and the like. Other configurations are contemplated.

[0064] As shown throughout the Figures, the patient support apparatus 100 also includes an auxiliary drive system 162 operatively attached to the support structure 102. As illustrated schematically in Figure 6, the auxiliary drive system 162 includes a drive member 164 configured to influence motion of the patient support apparatus 100 over the floor surface FS, and a motor 166 coupled to the drive member 164 for providing motive power to the drive member 164. The drive member 164 may be realized as a wheel or the like for contacting the floor surface FS. The motor 166 is in communication with the controller 156 such that the controller 156 is configured to operate the motor 166 to rotate the drive member 164 to move the patient support apparatus 100 relative to the floor surface FS. The motor 166 may be realized as an electric motor operatively attached to the drive member 164 (e.g., via a reduction gearset or directly).

[0065] In some examples, the auxiliary drive system 162 may be steerable. In one example, referring to Figure 7, the motor 166 A may be defined as a first motor 166 A and the auxiliary drive system 162 may further include a second motor 166B configured to alter theDocket No. 060252.01136 orientation of the drive member 164 about a vertical axis VA. In these examples, the drive member 164 and first motor 166 A may be supported relative to the support structure 102 by an attachment member 167 operatively coupled to the support structure 102 for rotation about the vertical axis VA. Here, the second motor 166B is operatively attached to the attachment member 167 and in communication with the controller 156 such that the controller 156 may be configured to operate the second motor 166B to alter the orientation of the drive member 164 about the vertical axis VA to steer the patient support apparatus relative to the floor surface FS as the first motor 166 A provides motive power to the drive member 164 to move the patient support apparatus 100 along the floor surface FS. The configuration of Figure 7 is merely one example of an auxiliary drive system 162 that steerable, other configurations are contemplated.

[0066] As best shown in Figures 1 and 8A-8B, in some configurations, the auxiliary drive system 162 may include an auxiliary drive actuator 168 operatively attached to the support structure 102 and operable to move at least the drive member 164 relative to the support structure 102 between a deployed state 164D (shown in Figure 8B) where the drive member 164 contacts the floor surface FS to influence motion of the patient support apparatus 100 over the floor surface FS, and a stowed state 164S (shown in Figure 8A) where the drive member 164 is spaced from the floor surface FS. The auxiliary drive actuator 168 may be realized as an electric actuator in communication with the controller 156 such that the controller 156 is configured to operate the auxiliary drive system 162 between the deployed state and the stowed state. One exemplary configuration of a deploy able auxiliary drive system 162 is disclosed in U.S. Patent No. 10,799,403, which is hereby incorporated by reference in its entirety. Other configurations of the auxiliary drive system 162 are contemplated.

[0067] In some examples, the auxiliary drive system 162 includes a first drive member 164A configured to influence motion of the patient support apparatus 100 over the floor surface FS, as well as a second drive member 164B configured to influence motion of the patient support apparatus 100 over the floor surface FS. In some examples, such as illustrated in Figures 20 and 21, the first drive member 164A is configured to rotate about a first axis 170A and the second drive member 164B is configured to rotate about a second axis 170B, and the first axis 170A and second axis 170B are aligned (e.g., coaxial or substantially coaxial). However, other configurations where the first axis 170A and second axis 170B are not aligned are contemplated. Each of the first drive member 164A and the second drive member 164B may be implemented similar to as described above in the context of the singular drive member 164.

[0068] In some configurations, the first drive member 164A and the second drive member 164B may be coupled to a single motor 166 via a differential. The differential may be an open differential, but in some examples the differential may be a limited slip differential or even an electronic differential operable to selectively allocate power between the first drive member 164A and the second drive member 164B (e.g., configured to send all power from the motor 166 to one of the first drive member 164A and the second drive member 164B, or incrementally split power from the motor 166 between the first drive member 164 A and the second drive member 164B).Docket No. 060252.01136

[0069] In other configurations, such as illustrated in Figures 20 and 21 , the auxiliary drive system 162 may include a first motor 166A coupled to the first drive member 164A for providing motive power to the first drive member 164A, and a second motor 166B coupled to the second drive member 164B for providing motive power to the second drive member 164B. In these configurations, each of the first motor 166A and the second motor 166B may be individually operated by the controller 156 (discussed in further detail below). Each of the first motor 166A and the second motor 166B may be implemented similar to as described above in the context of the singular motor 166. It is also contemplated that the auxiliary drive system 162 may include additional drive member(s), as well as additional motor(s) for providing motive power to the additional drive member(s) for moving the patient support apparatus 100 relative to the floor surface FS.

[0070] Figure 9 is a schematic diagram depicting an exemplary configuration of the auxiliary drive system 162. As illustrated in Figure 9, the auxiliary drive system 162 may include a motor control circuit 169 configured to transmit control and / or power signals to the motor(s) 166. The motor control circuit 169 is typically in communication with the controller 156 to operate the auxiliary drive system 162 based on signals received from the controller 156 (e.g., in response to user engagement with a first user input control 184 and / or a second user input control 196, as described below). The motor control circuit 169 is typically coupled to a power source (illustrated schematically as batteries in Figure 9) to provide power from the power source to energize the motor(s) 166. The motor(s) 166 are configured to convert electrical power from the power source to the drive member(s) 164 to rotate the drive member(s) 164. The motor control circuit 169 may also include speed sensor(s) configured to sense a rotational speed of the drive member(s) 164. In some examples, the speed sensor(s) may include one or more hall effect devices that are configured to sense rotation of the motor(s) 166 but other configurations, such as an optical encoder, are contemplated.

[0071] In some examples, the controller 156 may be programmed to operate the auxiliary drive system 162 in a plurality of operating modes. For example, the controller 156 may be programmed to operate the auxiliary drive system 162 in a drive mode, a free wheel mode, a coast mode, a free wheel speed limiting mode, and a drag mode. The controller 156 may also be programmed to quickly turn the modes on / off and quickly toggle between modes in certain scenarios. For example, the controller 156 may quickly toggle between the free wheel mode (e.g., used for manually pushing in certain situations) and the drag mode (e.g., used for braking in certain situations). The controller 156 may also quickly toggle between the drive mode (e.g., used for active driving) and the coast mode (e.g., used to come to a gradual stop). The controller 156 may quickly toggle between any two or more of the various modes.

[0072] When operating the auxiliary drive system 162 in the drive mode, the controller 156 may be programmed to operate the auxiliary drive system 162 to rotate the drive member(s) 164 based on the commanded torque and rotational direction (e.g. in response to user engagement with the first user input control 184 and / or the second user input control 196). For example, the controller 156 may be programmed to operate the motor control circuit 169 to generate one orDocket No. 060252.01136 more pulse-width modulated (PWM) signals that are transmitted to the motor(s) 166 for operating a plurality of switches to control the torque output and direction of the motor(s) 166. Other variable motor control methods are also contemplated, including those based on output signals other than PWM signals.

[0073] When operating the auxiliary drive system 162 in the free wheel mode, the controller 156 may be programmed to operate the motor control circuit 169 to enable the drive member(s) 164 to rotate relatively freely (non-driving mode). The free wheel mode may be available upon start-up (e.g., initially after the drive member(s) 164 is / are at least partially deployed or fully deployed and before operating in the drive mode) and after ceasing operation in the drive mode and detecting that the drive member(s) 164 is / are no longer rotating at or above a threshold rotational speed for at least a predetermined duration. The free wheel mode may also be available in response to user input (e.g. in response to user engagement with the first user input control 184 and / or the second user input control 196) or anytime the controller 156 determines that the user wishes to manually push the patient support apparatus 100 vs. actively drive the patient support apparatus 100. In the free wheel mode, for example, the controller 156 may operate the motor control circuit 169 to disconnect the motor(s) 166 from the power source. In some examples, the controller 156 may operate the motor control circuit 169 to transmit a zero PWM signal to the switches of the motor(s) 166. Other configurations of operating the motor control circuit 169 to effectuate free rotation of the drive member(s) 164 are contemplated.

[0074] The coast mode may occur after the user has released user engagement with the first user input control 184 and / or the second user input control 196 thereby ceasing the drive mode but has maintained contact with the first user input control 184 and / or the second user input control 196 (e.g., as indicated by a presence sensor). In the coast mode, the controller 156 is programmed to operate the motor control circuit 169 to enable the drive member(s) 164 to rotate relatively freely and allow the drive member(s) 164 to come to rest by virtue of the inertia of the patient support apparatus 100, e.g., without any controlled deceleration or dynamic braking of the drive mcmbcr(s) 164 and / or the motor(s) 166. In some examples, the coast mode, unlike the free wheel mode, may be triggered by releasing of the user engagement, whereas the free wheel mode may be unavailable until the controller 156 first brakes the drive member(s) 164 in the drag mode (described in further detail below) and then determines that the drive member(s) 164 is / are no longer moving at or above a threshold rotational speed for a predetermined duration to ensure that the patient support apparatus 100 is not located on a slope (incline / decline). Other configurations of a coast mode are contemplated.

[0075] The controller 156 may also be programmed to operate the auxiliary drive system 162 in the free wheel speed limiting mode to limit the rotational speed of the drive member(s) 164. For example, the controller 156 may be programmed to monitor the current rotational speed of the drive member(s) (e.g. based on the speed sensor) with the auxiliary drive system 162 being operated in the free wheel mode, and change operation of the auxiliary drive system 162 to the free wheel speed limiting mode upon determining the current rotational speed is greater than a predefined rotational speed (e.g., to keep the speed at or below a maximum limit). When operatingDocket No. 060252.01136 in the free wheel speed limiting mode, the controller 156 may be programmed to operate the motor control circuit 169 to generate and transmit PWM signals to the motor(s) 166 to limit the maximum rotational speed of the drive member(s) 164. In some versions this can be accomplished by active speed control in which the PWM signal is selected to effectively decelerate the patient support apparatus 100. The free wheel speed limiting mode is particularly helpful when the user is pushing the patient support apparatus 100 manually in the free wheel mode and encounters a slope / ramp and expects the auxiliary drive system 162 to assist with braking in the event the patient support apparatus 100 begins to travel too fast. Otherwise, the patient support apparatus 100 may roll down the slope / ramp more quickly than the user is expecting. By capping the maximum speed during the free wheel mode, the auxiliary drive system 162 provides for a controlled descent down the slope / ramp. In some versions, controlled deceleration in the free wheel speed limiting mode can be accomplished by disconnecting the motor(s) 166 from the power supply and / or by operating the switches of the motor(s) 166 to limit the maximum rotational speed of drive member(s) 164, e.g., by dynamic braking or reverse braking. Other configurations for limiting the speed of the drive member(s) in the free wheel mode are contemplated.

[0076] The controller 156 may also programmed to operate the auxiliary drive system 162 in the drag mode to limit rotation of the drive member(s) 164. When operating the auxiliary drive system 162 in the drag mode, the controller 156 may be programmed to operate motor control circuit 169 to cause dynamic braking or reverse braking of the motor(s) 166 to resist rotation of the drive member(s) 164. This may be useful, for example, when the patient support apparatus 100 is located on a slope / ramp and the user releases engagement with the first user input control 184 and / or the second user input control 196. The drag mode could provide for a controlled descent down the slope / ramp. In some examples, the motor control circuit 169 may utilize back EMF on the motor(s) 166 to operate the auxiliary drive system 162 in the drag mode. In other examples, the motor control circuit 169 may short the leads of the motor(s) to effectuate operation in the drag mode. Other configurations for effectuating operation in the drag mode arc contemplated.

[0077] It should be appreciated that the plurality of operating modes of the auxiliary drive system 162 described above are merely one exemplary implementation of the auxiliary drive system 162 and approaches for operating the same. Additional configurations and details of controlling operation of an auxiliary drive system 162 are described in U.S. Patent App. Pub. No. 2021 / 0196533, which is hereby incorporated by reference in its entirety. Other configurations are contemplated.

[0078] Referring to Figures 10A-11C, in some configurations, the patient support apparatus 100 includes a sensing system 172. The sensing system 172 is coupled to the support structure 102 and is configured to generate data representing load (indicated by reference symbol L) acting on the support structure 102 in one or more directions. For example, referring to Figures 10A and 10B, the patient support apparatus 100 may define a longitudinal axis LA extending between the head end HE and the foot end FE of the patient support apparatus 100 such that the longitudinal axis LA bisects the patient support apparatus 100 longitudinally. Here, the controllerDocket No. 060252.01136156 is in communication with the sensing system 172 and may be configured to determine the magnitude and direction of the load L acting on the support structure 102 based on the data generated by the sensing system 172. In one example, the controller 156 may be configured to determine a center of gravity of the load L acting on the support structure 102 based on the data generated by the sensing system 172. Where the direction of the load L acting on the support structure 102 deviates from along the longitudinal axis LA, as shown in Figure 10B, the load L acting on the support structure 102 may cause the patient support apparatus 100 to veer from an intended trajectory along the floor surface FS. Accordingly, as described in further detail below, the controller 156 may be configured to operate the auxiliary drive system 162 to counteract deviations in a trajectory of the patient support apparatus 100 along the floor surface FS occurring due to the direction of the load L acting on the support structure 102 based on the data generated by the sensing system 172.

[0079] Referring to Figures 11A-11C, in one configuration, the sensing system 172 includes one or more load cell assemblies 174 operatively attached to the support structure 102, with each of the one or more load cell assemblies 174 being configured to generate a respective output signal representing the load L acting on the support structure 102. In these configurations, the controller 156 is in communication with the one or more load cell assemblies 174 and is configured to determine the load L acting on the support structure 102 based on the output signals of each of the one or more load cell assemblies 174. In some examples, referring to Figures 11 A and 11B, the one or more load cell assemblies 174 are interposed between the base 104 and the litter 106. For example, as shown schematically in Figure HA, the one or more load cell assemblies 174 may be interposed between the lift mechanism 142 and the base 104 to generate output signal(s) representing the load L acting therebetween. In the configuration illustrated schematically in Figure 1 IB, the one or more load cell assemblies 174 are interposed between the litter 106 and the lift mechanism 142 to generate output signal(s) representing the load L acting therebetween. In the configuration illustrated schematically in Figure 11C, the one or more load cell assemblies 174 are interposed between the base 104 and one or more of the support wheels 138 to generate output signal(s) representing the load L acting therebetween. In some configurations the one or more load cell assemblies 174 includes four load cell assemblies each configured to generate a respective output signal representing the load L acting on a quadrant the support structure 102. One exemplary configuration of a sensing system 172 including the one or more load cell assemblies 174 are disclosed in U.S. Patent App. Pub. No. 2023 / 0346615, which is hereby incorporated by reference in its entirety. Other configuration of the sensing system 172 are contemplated.

[0080] Referring to Figures 12 and 13, the controller 156 may be configured to operate the auxiliary drive system 162 to counteract deviations in a trajectory of the patient support apparatus 100 along the floor surface FS occurring due to the direction of the load L acting on the support structure 102 based on the data generated by the sensing system 172. Referring to the flowchart of Figure 12, the controller 156 may be configured to determine a commanded torque value for the motor(s) 166 (e.g., based on user input, as further described below) and adjust the commandedDocket No. 060252.01136 torque value for the motor(s) 166 based on the direction of the load L acting on the support structure 102 to counteract deviations in a trajectory of the patient support apparatus 100 along the floor surface FS due to the load L acting on the support structure 102. In some examples, to counteract the deviations in the trajectory of the patient support apparatus 100 along the floor surface FS due to the load L acting on the support structure 102, the controller 156 may be configured to determine a gain value based on the load L acting on the support structure 102 and scale the commanded torque value for the motor(s) 166 by the gain value. As used herein, the term “scale” may include increasing or decreasing the commanded torque value for the motor(s) 166. Stated differently, the gain value may be greater than 1 or less than 1.

[0081] In one example, referring to Figure 13, the patient support apparatus 100 may have an intended trajectory (indicated by arrow 176) along the floor surface FS. However, as indicated by arrow 178, the patient support apparatus 100 may veer from the intended trajectory 176 along the floor surface FS due to the load L acting on the support structure 102. In these circumstances, the controller 156 may be configured to adjust the commanded torque value for the motor(s) 166 to counteract the deviations in the trajectory of the patient support apparatus 100 along the floor surface FS (indicated by arrow 180). Accordingly, the commanded torque value applied to the motor(s) 166 to counteract the deviations in the trajectory will cancel out the veering of the patient support apparatus 100 from the intended trajectory 176 such that the patient support apparatus 100 moves along the floor surface FS along the intended trajectory 176.

[0082] It is also contemplated that the controller 156 may adjust the commanded torque value for the motor(s) 166 based on other conditions. For example, as depicted schematically in Figure 2, the patient support apparatus 100 may further include an angle sensor 182 operatively attached to the support structure 102 for measuring an angle of the support structure 102 relative to gravity. Here, the controller 156 may be configured to adjust to the commanded torque value for the motor(s) 166 based on the angle of the support structure 102 relative to gravity (e.g., such that the patient support apparatus 100 maintains an expected speed relative to the floor surface FS even when going up or down a ramp). Additionally or alternatively, the controller 156 may adjust the commanded torque value for the motor(s) 166 where the commanded torque of the motor(s) 166 does not result in an expected speed of the patient support apparatus 100 along the floor surface FS.

[0083] Referring to the flowchart of Figure 14, the controller 156 may be configured to determine an expected speed of the patient support apparatus 100 along the floor surface FS based on the commanded torque value for the motor(s) 166. The specific approach to determining the expected speed of the patient support apparatus 100 along the floor surface FS is not particularly limited for the purposes of this disclosure. In one example, the expected speed of the patient support apparatus 100 along the floor surface FS may be determined based on a lookup table expected speed values corresponding to the commanded torque of the motor(s) 166. In another example, the expected speed of the patient support apparatus 100 along the floor surface FS may be calculated dynamically based on a number of additional factors (e.g., the magnitude of the load L acting on the support structure 102, the angle of the support structure 102 relative to gravity,Docket No. 060252.01136 etc.). Other approaches for determining the expected speed of the patient support apparatus 100 along the floor surface FS are contemplated. With continued reference to Figure 14, the controller 156 may also be configured to determine an actual speed of the patient support apparatus 100 along the floor surface FS (e.g., based on the speed of the motor(s) 166 or via a speed sensor). Here, the controller 156 is configured to determine a difference between the actual speed of the patient support apparatus 100 along the floor surface FS and the expected speed of the patient support apparatus 100 along the floor surface FS and, based on the difference, scale the commanded torque value for the motor(s) 166 by a compensation value where the difference between the actual speed and the expected speed exceeds a predetermined threshold (e.g., a difference of greater than 0.5 miles per hour). Here, the compensation value may be greater than 1 (e.g., where actual speed is less than the expected speed) or less than 1 (e.g., where actual speed is greater than the expected speed).

[0084] As alluded to above, the controller 156 may be configured to determine a commanded torque value for the motor(s) 166 based on user input. Referring to Figures 15A-19B, the patient support apparatus 100 may further include a first user input control 184 arranged for user engagement. For example, in the configurations shown in Figures 15A-19B, the first user input control 184 as arranged on one of the headboard 132 and the footboard 134 of the patient support apparatus 100 for user engagement, but other locations are contemplated. As illustrated schematically in Figures 15A-19B, the first user input control 184 is in communication with the controller 156 such that the controller 156 is configured to operate the auxiliary drive system 162 based on user engagement with the first user input control 184. More specifically, the first user input control 184 may be configured to provide a first user input signal to the controller 156 in response to user engagement with the first user input control 184 and the controller 156 may be configured to determine a commanded torque value for the motor(s) 166 based on the first user input signal. In some examples, the controller 156 may be configured to operate the auxiliary drive system 162 in a forward direction in response to user engagement of the first user input control 184 in a first direction DI, and may be further configured to operate the auxiliary drive system 162 in a reverse direction in response to user engagement of the first user input control 184 in a second direction D2, opposite the first direction DI.

[0085] Referring to Figures 15A-15B and 17-19B, the first user input control 184 may be arranged for modulation based on user engagement to adjust the first user input signal between a plurality of first user input signal magnitudes. In these examples, the controller 156 is configured determine a commanded torque value of the motor(s) 166 based on the first user input signal magnitude. In one example, referring to Figures 15A and 15B, the first user input control 184 is realized as a first throttle 186 in communication with the controller 156 and arranged for movement in response to user engagement. Here, the first user input control 184 is configured to generate the first user input signal in response to user engagement with the first throttle 186, with the first user input signal pertaining to a magnitude of movement of the first throttle 186. Referring to Figure 16, in these examples, the controller 156 may include a memory with a throttle map 188,Docket No. 060252.01136 and the controller 156 is configured to refer to the throttle map 188 to determine the commanded torque value of the motor(s) 166 based on the magnitude of movement of the first throttle 186.

[0086] As illustrated in Figure 16, the throttle map 188 may define the commanded torque value of the motor(s) (shown on the vertical axis) as a function of the magnitude of movement of the first throttle 186 (shown on the horizontal axis). In some examples, such as shown in Figure 16, the throttle map 188 may be non-linear. For example, as shown in Figure 16, where the first user input signal pertaining to a magnitude of movement of the first throttle 186 is 50%, the commanded torque value of the motor(s) 166 is 25%, and where the first user input signal pertaining to a magnitude of movement of the first throttle 186 is 100%, the commanded torque value of the motor(s) 166 is 100%, representing a non-linear correlation of the commanded torque value of the motor(s) as a function of the magnitude of movement of the first throttle 186. As also illustrated in Figure 16, in some examples, the controller 156 may be configured to operate the auxiliary drive system 162 in a forward direction in response to user engagement of the first throttle 186 in a first direction DI, and may be further configured to operate the auxiliary drive system 162 in a reverse direction in response to user engagement of the first throttle 186 in a second direction D2, opposite the first direction DI. Here, the throttle map 188 is non-linear for both the forward direction and the reverse direction. Other configurations of the throttle map 188 are contemplated. It is also contemplated that a throttle map-like correlation of input magnitude to commanded torque may be implemented in other configurations of the first user input control 184.

[0087] Referring to Figure 17, in another example, the first user input control 184 is realized as a first force sensor 190 in communication with the controller 156 and operatively attached to a first input member 192 arranged for user engagement. In these examples, the first force sensor 190 is configured to generate the first user input signal in response to user engagement with the first input member 192, with the first user input signal pertaining to a magnitude of force experienced by the first force sensor 190 in response to user engagement with the first input member 192. As described above, the controller 156 is configured determine a commanded torque value of the motor(s) 166 based on the first user input signal magnitude. For example, referring to Figure 17, in some examples, the controller 156 may be configured to operate the auxiliary drive system 162 in a forward direction in response to user engagement of the first input member 192 in a first direction DI, and may be further configured to operate the auxiliary drive system 162 in a reverse direction in response to user engagement of the first input member 192 in a second direction D2, opposite the first direction D 1.

[0088] In configurations where the auxiliary drive system 162 is steerable, the controller 156 may also be configured to operate the auxiliary drive system 162 to the steer the patient support apparatus 100 in a first lateral direction in response to user engagement of the first input member 192 in a third direction D3, orthogonal to directions DI and D2, and may be further configured to operate the auxiliary drive system 162 to the steer the patient support apparatus 100 in a second lateral direction, opposite the first lateral direction, in response to user engagement of the first input member 192 in a fourth direction D4, opposite the third direction D3. It should be appreciated that user engagement of the first input member 192 may be in multiple directions (e.g.,Docket No. 060252.01136 the forward direction DI and the first lateral direction D3). In these examples, the controller 156 may be configured to operate the auxiliary drive system 162 to move the patient support apparatus 100 along the floor surface FS in the commanded direction (e.g., DI or D2) as well as steer the patient support apparatus 100 in the commanded direction (e.g. the first lateral direction or the second lateral direction).

[0089] Referring to Figures 18A and 18B, in another example, the first user input control 184 is realized as a joystick 194 in communication with the controller 156 and arranged for user engagement. In these examples, the joystick 194 is configured to generate the first user input signal in response to user engagement with the joystick 194, with the first user input signal pertaining to a magnitude of displacement of the joystick 194 from a disengaged position in response to user engagement with the joystick 194. As described above, the controller 156 is configured determine a commanded torque value of the motor(s) 166 based on the first user input signal magnitude. For example, referring to Figure 18B, in some examples, the controller 156 may be configured to operate the auxiliary drive system 162 in a forward direction in response to user engagement of the joystick 194 in a first direction DI, and may be further configured to operate the auxiliary drive system 162 in a reverse direction in response to user engagement of the joystick 194 in a second direction D2, opposite the first direction DI.

[0090] In configurations where the auxiliary drive system 162 is steerable, the controller 156 may also be configured to operate the auxiliary drive system 162 to the steer the patient support apparatus 100 in a first lateral direction in response to user engagement of the joystick 194 in a third direction D3, orthogonal to directions DI and D2, and may be further configured to operate the auxiliary drive system 162 to the steer the patient support apparatus 100 in a second lateral direction, opposite the first lateral direction, in response to user engagement of the joystick 194 in a fourth direction D4, opposite the third direction D3. Similar to as described above, it should be appreciated that user engagement of the joystick 194 may be in multiple directions (e.g., the forward direction DI and the first lateral direction D3). In these examples, the controller 156 may be configured to operate the auxiliary drive system 162 to move the patient support apparatus 100 along the floor surface FS in the commanded direction (e.g., DI or D2) as well as steer the patient support apparatus 100 in the commanded direction (e.g. the first lateral direction or the second lateral direction).

[0091] It should be appreciated that the configurations of the first user input control 184 described above in the context of Figures 15A-18B are merely illustrate exemplary configurations of implementing the first user input control 184 to generate the first user input signal for the controller 156 to determine a commanded torque value of the motor(s) based on the first user input signal. Other configurations of implementing the first user input control 184 are contemplated. It should also be appreciated that regardless of the specific implementation of the first user input control 184, the controller 156 is also typically configured to further adjust the commanded torque value for the motor(s) 166 (e.g., after determining commanded torque value for the motor(s) 166 based on the first user input signal) based on the load L acting on the support structure determinedDocket No. 060252.01136 to counteract deviations in the trajectory of the patient support apparatus 100 along the floor surface FS, as described above.

[0092] The patient support apparatus 100 may further include a second user input control 196 in communication with the controller 156 and arranged for user engagement. The second user input control 196 is configured to provide a second user input signal to the controller 156 in response to user engagement with the second user input control 196. As described in further detail below, where the patient support apparatus 100 includes the second user input control 196, the controller 156 is configured to operate the auxiliary drive system 162 based on user engagement with at least one of the first user input control 184 and the second user input control 196 (e.g., based on the first user input signal and / or the second user input signal).

[0093] In one example, referring to Figures 19A and 19B, the second user input control 196 is realized as a second presence sensor 198 configured to generate the second user input signal in response to the presence of user engagement with the second user input control 196. For example, the second presence sensor 198 may be implemented as a capacitive touch sensor, but other configurations are contemplated. In these examples, the controller 156 may be configured to inhibit operation of the auxiliary drive system 162 in response to a lack of user engagement with the second user input control 196. Other configurations of implementing the second user input control 196 are contemplated, with additional examples of employing the second user input control 196 described in further detail below.

[0094] In the configuration illustrated in Figures 19A and 19B, the first user input control 184 is spaced from the second user input control 196. For example, in the illustrated configuration, the first user input control 184 is arranged on a first lateral side of the patient support apparatus 100 (e.g., on one side of the longitudinal axis LA), and the second user input control 196 is arranged on a second lateral side of the patient support apparatus 100 (e.g., on the other side of the longitudinal axis LA), opposite the first lateral side. However, it should be appreciated that in some configurations the first user input control 184 and the second user input control 196 may be arranged on the same side of the patient support apparatus 100. For example, the second user input control 196 may be arranged on a member which supports the first user input control 184 such that the second user input control 196 is configured to sense engagement with the member such that the controller 156 is configured to operate the auxiliary drive system 162 in response to user engagement with both the second user input control 196 (e.g., to sense presence) and the first user input control 184 (e.g., to determine the commanded torque for the motor(s) 166 based on user engagement with the first user input control 184). Other arrangements of arranging the second user input control 196 relative to the first user input control 184 are contemplated.

[0095] Referring to Figures 20 and 21, as described above, in some examples, the auxiliary drive system 162 includes a first drive member 164A and a second drive member 164B each configured to influence motion of the patient support apparatus 100 over the floor surface FS. In the example illustrated in Figures 20 and 21, the auxiliary drive system 162 includes a first motor 166 A coupled to the first drive member 164 A for providing motive power to the first drive member 164A, and a second motor 166B coupled to the second drive member 164B for providing motiveDocket No. 060252.01136 power to the second drive member 164B. In these configurations, each of the first motor 166A and the second motor 166B may be individually operated by the controller 156.

[0096] Referring to Figure 22, similar to as described above in the context of Figure 13, the patient support apparatus 100 may have an intended trajectory (indicated by arrow 176) along the floor surface FS. However, as indicated by arrow 178, the patient support apparatus 100 may veer from the intended trajectory 176 along the floor surface FS due to the load L acting on the support structure 102. Accordingly, the controller 156 may be configured to adjust a commanded torque value for at least one of the first motor 166 A and the second motor 166B based on the load L acting on the support structure 102 to counteract deviations in a trajectory of the patient support apparatus 100 along the floor surface FS (indicated by arrow 180). For example, as illustrated in Figure 22, the controller 156 may be configured to determine at least one of a first gain value (indicated by arrow 200 A) and a second gain value (indicated by arrow 200B) based on the load L acting on the support structure and scale the commanded torque value for at least one of the first motor 166A by the first gain value 200A and the second motor 166B by the second gain value 200B. In the scenario illustrated schematically in Figure 22, for example, the first gain value 200A of the first motor 166 A is greater than the second gain value 200B of the second motor 166B to counteract the load L acting on the support structure 102.

[0097] Referring to Figures 23A-25B, in some configurations, the controller 156 may be configured to permit a rotational speed differential between the first drive member 164A and the second drive member 164B in response to a caretaker exerting force (indicated by arrow 202) on the support structure 102 to alter the trajectory of the patient support apparatus 100 along the floor surface FS. In other words, the controller 156 may permit the first drive member 164A to rotate at a first speed (indicated by arrow 204A) and the second drive member 164B to rotate at a second speed (indicated by arrow 204B) based on the magnitude and / or direction of the force exerted on the support structure 102 by the caretaker.

[0098] Figures 23A-25B schematically depict various scenarios of the controller 156 permitting a rotational speed differential between the first drive member 164A and the second drive member 164B in response to a caretaker exerting force (indicated by arrow 202) on the support structure 102 to alter the trajectory of the patient support apparatus 100 along the floor surface FS. Referring first to Figures 23 A and 23B, in some examples, a caretaker may exert a pushing force 202 on the support structure 102 that is substantially parallel to the longitudinal axis LA and laterally spaced from the longitudinal axis LA. As shown in Figure 23A, where the pushing force 202 is exerted on the support structure 102 on the same side of longitudinal axis LA as the first drive member 164A, the controller 156 is configured to permit the first speed 204A of the first drive member 164A to be greater than the second speed 204B of the second drive member 164B such that the force exerted on the support structure 102 by the caretaker alters the trajectory (indicated by arrow 206) of the patient support apparatus 100 along the floor surface FS. Conversely, in the scenario depicted in Figure 23B, where the pushing force 202 is exerted on the support structure 102 on the same side of longitudinal axis LA as the second drive member 164B, the controller 156 is configured to permit the second speed 204B of the second drive member 164BDocket No. 060252.01136 to be greater than the first speed 204A of the first drive member 164A such that the force exerted on the support structure 102 by the caretaker alters the trajectory (indicated by arrow 206) of the patient support apparatus 100 along the floor surface FS.

[0099] Referring next to the scenarios depicted in Figures 24A and 24B, in some examples, a caretaker may exert a pushing force 202 on the support structure that is substantially transverse to the longitudinal axis LA. As shown in Figure 24A, where the transverse pushing force 202 is exerted on the support structure 102 on the same side of the longitudinal axis LA as the second drive member 164B, the controller 156 is configured to permit the first speed 204A of the first drive member 164A to be greater than the second speed 204B of the second drive member 164B such that the force exerted on the support structure 102 by the caretaker alters the trajectory (indicated by arrow 206) of the patient support apparatus 100 along the floor surface FS. Conversely, in the scenario depicted in Figure 24B, where the transverse pushing force 202 is exerted on the support structure 102 on the same side of longitudinal axis LA as the first drive member 164A, the controller 156 is configured to permit the second speed 204B of the second drive member 164B to be greater than the first speed 204A of the first drive member 164A such that the force exerted on the support structure 102 by the caretaker alters the trajectory (indicated by arrow 206) of the patient support apparatus 100 along the floor surface FS.

[0100] Referring next to the scenarios depicted in Figures 25A and 25B, in some examples, a caretaker may exert a pulling force 202 on the support structure 102 that is substantially parallel to the longitudinal axis LA and laterally spaced from the longitudinal axis LA. As shown in Figure 25A, where the pulling force 202 is exerted on the support structure 102 on the same side of longitudinal axis LA as the second drive member 164B, the controller 156 is configured to permit the first speed 204A of the first drive member 164A to be greater than the second speed 204B of the second drive member 164B such that the force exerted on the support structure 102 by the caretaker alters the trajectory (indicated by arrow 206) of the patient support apparatus 100 along the floor surface FS. Conversely, in the scenario depicted in Figure 25B, where the pushing force 202 is exerted on the support structure 102 on the same side of longitudinal axis LA as the first drive member 164A, the controller 156 is configured to permit the second speed 204B of the second drive member 164B to be greater than the first speed 204 A of the first drive member 164A such that the force exerted on the support structure 102 by the caretaker alters the trajectory (indicated by arrow 206) of the patient support apparatus 100 along the floor surface FS.

[0101] It should be appreciated that the scenarios depicted and described in the context of Figures 23A-25B are intended to illustrate exemplary scenarios of a caretaker exerting force on the support structure 102. As shown in the Figures, the location and direction of the force exerted on the support structure 102 by the caretaker will determine which of the first drive member 164A and the second drive member 164B rotates at a greater speed. Stated differently, the force exerted on the support structure 102 by the caretaker will act as a moment for rotating the patient support apparatus 100 about a central vertical axis CVA. Whichever of the first drive member 164A and the second drive member 164B is on the outside radius of the turn commanded by the force exerted on the support structure 102 by the caretaker will rotate at a greater speed. It is contemplated thatDocket No. 060252.01136 the force exerted on the support structure 102 by the caretaker may be applied at any location on the support structure and from any direction (e.g., pulling or pushing).

[0102] In some examples, the controller 156 may be configured to operate the first motor 166A and / or the second motor 166B to provide assistive torque to alter the trajectory of the patient support apparatus 100 along the floor surface FS based on the force exerted on the support structure 102 by the caretaker. However, in other configurations, the controller 156 may not operate the motor(s) to provide an assistive force such that solely the force exerted by the caretaker on the support structure 102 alters the trajectory of the patient support apparatus 100 along the floor surface FS.

[0103] In some examples, commanded torque value for the first motor 166A and the second motor 166B may be fixed such that the first motor 166 A and the second motor 166B are configured to increase or decrease speed until the commanded torque is reached. In other examples, the controller 156 may be configured to adjust the commanded torque value for at least one of the first motor 166A and the second motor 166B in response to the rotational speed differential between the first drive member 164A and the second drive member 164B exceeding a threshold value. Stated differently, in some configurations, the controller 156 may be configured to operate the first motor 166 A and the second motor 166B in a manner that simulates a limited slip differential to adjust the commanded torque value for at least one of the first motor 166A and the second motor 166B in response to the rotational speed differential between the first drive member 164A and the second drive member 164B exceeding a threshold value to prevent scenarios where one of the first motor 166 A and the second motor 166B is rotating at a high speed than the other but not providing meaningful motive power to move the patient support apparatus 100 along the floor surface FS (e.g., where the patient support apparatus 100 is on a ramp and one of the first drive member 164A and the second drive member 164B is not contacting the floor surface FS). The threshold value may be defined as a predetermined rotational speed difference (e.g., 10 RPM, 20 RPM, 30 RPM, etc.) or the controller 156 may be configured to determine a threshold value based on other parameters in real time.

[0104] As described above, the patient support apparatus 100 may include a first user input control 184 arranged for user engagement and in communication with the controller 156 such that the controller 156 is configured to operate the auxiliary drive system 162 based on user engagement with the first user input control 184 (e.g., based on the first user input signal). In examples where the auxiliary drive system 162 includes the first motor 166A and the second motor 166B, the controller 156 may be configured to determine a commanded torque value for the first motor 166 A and the second motor 166B based on the first user input signal generated in response to user engagement with the first user input control 184. Stated differently, in some configurations, the controller 156 may be configured to operate both the first motor 166 A and the second motor 166B based on one user input control (i.e., the first user input control 184). For example, as described above in the context of Figures 15A-15B and 17-19B, the first user input control 184 may be arranged for modulation based on user engagement to adjust the first user input signal between a plurality of first user input signal magnitudes. In these examples, the controller 156 isDocket No. 060252.01136 configured determine a commanded torque value of the first motor 166A and the second motor 166B based on the first user input signal magnitude. It should be appreciated that in examples where the auxiliary drive system 162 includes the first motor 166A and the second motor 166B, the first user input control may be implemented similar' to as described above in the context of Figures 15A-15B and 17-19B (e.g., comprising a first throttle 186 or a first force sensor 190) but other configurations are contemplated.

[0105] In examples where the auxiliary drive system 162 includes the first motor 166 A and the second motor 166B, the patient support apparatus 100 may further include a second user input control 196 configured to provide a second user input signal to the controller in response to user engagement with the second user input control 196. In these configurations, the controller 156 may be configured to operate the auxiliary drive system 162 based on user engagement with at least one of the first user input control 184 and the second user input control 196. In one example, similar to as described above in the context of Figures 19A and 19B, the second user input control 196 may be realized as a second presence sensor 198 configured to generate the second user input signal in response to the presence of user engagement with the second user input control 196. In these examples, the controller 156 may be configured to inhibit operation of the auxiliary drive system 162 in response to a lack of user engagement with the second user input control 196.

[0106] In other examples, the second user input control 196 may be arranged for modulation based on user engagement to adjust the second user input signal between a plurality of second user input signal magnitudes. In one example, similar to the user input control 184 described above in the context of Figures 15A and 15B, the second user input control 196 may be realized as a second throttle 208 in communication with the controller 156 and arranged for movement in response to user engagement. Here, the second user input control 196 is configured to generate the second user input signal in response to user engagement with the second throttle 208, with the second user input signal pertaining to a magnitude of movement of the second throttle 208. In other examples, similar to the user input control 184 described above in the context of Figure 17, the second user input control 196 may be realized as a second force sensor 210 in communication with the controller 156 and operatively attached to a second input member 212 arranged for user engagement. In these examples, the second force sensor 210 is configured to generate the second user input signal in response to user engagement with the second input member 212, with the second user input signal pertaining to a magnitude of force experienced by the second force sensor 210 in response to user engagement with the second input member 212. Other configurations of the second user input control 196 are contemplated (e.g., similar to the joystick 194 describe above in the context of Figures 18A and 18B).

[0107] Where the patient support apparatus 100 includes the second user input control 196, the controller 156 may be configured to determine a commanded torque value for the first motor 166 A based on the first user input signal generated by the first user input control 184 and determine a commanded torque value for the second motor 166B based on the second user input signal generated by the second user input control 196. For example, the controller 156 may be configuredDocket No. 060252.01136 to determine the commanded torque value of the first motor 166A based on the first user input signal magnitude and to determine the commanded torque value of the second motor 166B based on the second user input signal magnitude. For example, referring to Figures 26A-27B, a user may engage the first user input control 184 such that the first user input signal corresponds to a first user input signal magnitude (indicated by arrow Ml) and engage the second user input control such the second user input signal corresponds to a second input signal magnitude (indicated by arrow M2). Stated differently, the controller 156 may be configured to determine a first commanded torque (indicated by arrow Tl) for the first motor 166 A and a second commanded torque (indicated by arrow T2) for the second motor 166B, with the first commanded torque Tl corresponding to the first user input signal magnitude Ml and the second commanded torque T2 corresponding to the second user input signal magnitude M2.

[0108] In the scenario illustrated in Figure 26 A, the first user input signal magnitude Ml is greater than second input signal magnitude M2. Accordingly, as shown schematically in Figure 26 A, the first commanded torque Tl of the first motor 166 A is greater than the second commanded torque T2 of the second motor 166B such that the first motor 166 A and the second motor 166B rotate at different speeds to turn the patient support apparatus 100 relative to the floor surface FS (indicated by arrow 214) in a direction where the second drive member 164B is at the inside of the turning radius of the patient support apparatus 100 relative to the floor surface FS. Conversely, in the scenario illustrated in Figure 26B, the second user input signal magnitude M2 is greater than first input signal magnitude Ml. Accordingly, as shown schematically in Figure 26B, the second commanded torque T2 of the second motor 166B is greater than the first commanded torque Tl of the first motor 166 A such that the first motor 166 A and the second motor 166B rotate at different speeds to turn the patient support apparatus 100 relative to the floor surface FS (indicated by arrow 214) in a direction where the first drive member 164A is at the inside of the turning radius of the patient support apparatus 100 relative to the floor surface FS.

[0109] Referring to Figures 27A and 27B, similar to as described above, in some examples, the first user input control 184 may be configured to generate a first user input signal magnitude M 1 that is either positive or negative depending on the direction of the user engagement with the first user input control 184. Likewise, the second user input control 196 may be configured to generate a second user input signal magnitude M2 that is either positive or negative depending on the direction of the user engagement with the second user input control 196. In these examples, where the first user input signal magnitude Ml and / or the second user input signal magnitude M2 are negative, the controller 156 may be configured to determine the first commanded torque Tl of the first motor 166 A and / or the second commanded torque of the second motor 166B to be negative (i.e., applied in an opposite direction to forward operation) such that the first drive member 164A and / or the second drive member 164B may be rotated in reverse. In some examples, this configuration may allow the patient support apparatus 100 to be moved relative to the floor surface FS in both a forward direction and a reverse direction. Furthermore, in additional examples, such as illustrated in Figures 27A and 27B, the auxiliary drive system 162 may be configured for operation such that one of the first drive member 164A and second drive member 164B rotates inDocket No. 060252.01136 the forward direction and the other of the first drive member 164A and second drive member 164B rotates in the reverse direction to rotate the patient support apparatus 100 relative to the floor surface FS about a central vertical axis CVA.

[0110] For example, referring to Figure 27 A, in the illustrated example, the first user input signal magnitude Ml is positive (i.e., in the forward direction) and the second user input signal magnitude M2 is negative (i.e., in the reverse direction). Accordingly, as illustrated schematically in Figure 27A, in this scenario, the controller 156 is configured to define the first commanded torque T1 of the first motor 166A as positive and the second commanded torque of the second motor 166B as negative such that the patient support apparatus 100 rotates counterclockwise relative to the floor surface FS about a central vertical axis CVA (indicated by arrows 216). Conversely, referring to Figure 27B, in the illustrated example, the first user input signal magnitude Ml is negative (i.e., in the reverse direction) and the second user input signal magnitude M2 is positive (i.e., in the forward direction). Accordingly, as illustrated schematically in Figure 27B, in this scenario, the controller 156 is configured to define the first commanded torque T1 of the first motor 166 A as negative and the second commanded torque of the second motor 166B as positive such that the patient support apparatus 100 rotates clockwise relative to the floor surface FS about a central vertical axis CVA (indicated by arrows 216).

[0111] In some examples, to effectuate rotation of the patient support apparatus 100 relative to the floor surface FS about the central vertical axis CVA, the first commanded torque T 1 and the second commanded torque T2 may be substantially equal but in opposite directions (i.e., the absolute value of the first commanded torque T1 may be substantially equal to the absolute value of the second commanded torque T2). However, in other configurations, it is contemplated that the magnitude of the first commanded torque T1 and the second commanded torque T2 may not be substantially equal (e.g., where more torque is required from the first motor 166A than the second motor 166B to rotate the patient support apparatus 100 relative to the floor surface FS about the central vertical axis CVA due to the direction of the load L acting on the support structure 102).

[0112] In other configurations, the controller 156 may be configured to determine a commanded torque value for the first motor 166A and the second motor 166B based on the first user input signal generated by the first user input control 184, and the controller 156 may be further configured to determine a rotational speed differential value between the first drive member 164A and the second drive member 164B based on the second user input signal generated by the second user input control 196. Based on the determined rotational speed differential value, in these examples the controller 156 is operate the first motor 166 A and the second motor 166B at the rotational speed differential value to differentially turn the patient support apparatus 100 about the floor surface FS. For example, as depicted schematically in Figure 28, the first user input control 184 may be configured to generate the first user input signal corresponding to desired operation of the auxiliary drive system 162 in the forward and / or reverse direction (indicated by arrow 218) and the second user input control 196 may be configured to generate the second user input control signal corresponding the desired direction of the auxiliary drive system 162 to differentially turnDocket No. 060252.01136(i.e., steer) the patient support apparatus 100 relative to the floor surface FS, such as left or right (indicated by arrow 220).

[0113] Other configurations of operating the auxiliary drive system 162 to propel and / or steer the patient support apparatus 100 relative to the floor surface FS based on the first user input signal and the second user input signal are contemplated. For example, where the auxiliary drive system 162 is steerable such as the configuration depicted in Figure 7, the first user input signal may pertain to operation of the first motor 166A to propel the patient transport apparatus in the forward or reverse direction, and the second user input signal may pertain to operation of the second motor 166B to alter the orientation of the drive member 164 to alter the direction of the patient support apparatus 100 relative to the floor surface.

[0114] Figures 29A-32B illustrate various exemplary combinations of modalities of the first user input control 184 and the second user input control 196. In one example, referring to Figures 29A and 29B, the first user input control 184 is implemented as a first throttle 186 (as described above) and the second user input control 196 is implemented as a second throttle 208 (as also described above). In some examples, the controller 156 may be configured to determine a commanded torque value for the first motor 166 A and the second motor 166B based on the first user input signal generated by the first throttle 186 in response to user engagement, and the controller 156 may be further configured to determine a rotational speed differential value between the first drive member 164A and the second drive member 164B based on the second user input signal generated by the second throttle 208 and operate the first motor 166 A and the second motor 166B at the rotational speed differential value to differentially turn the patient support apparatus 100 about the floor surface FS. In other configurations, the controller 156 may be configured determine the commanded torque value of the first motor 166 A based on the first user input signal generated by the first throttle 186 in response to user engagement and to determine the commanded torque value of the second motor 166B based on the second user input signal generated by the second throttle 208 in response to user engagement. Other configurations of operating the auxiliary drive system 162 based on user engagement with the first throttle 186 and the second throttle 208 are contemplated.

[0115] In another example, referring to Figures 30A and 30B, the first user input control 184 is implemented as a first throttle 186 (as described above) and the second user input control 196 is implemented as a second force sensor 210 operatively attached to a second input member 212 arranged for user engagement (as also described above). In some examples, the controller 156 may be configured to determine a commanded torque value for the first motor 166 A and the second motor 166B based on the first user input signal generated by the first throttle 186 in response to user engagement, and the controller 156 may be further configured to determine a rotational speed differential value between the first drive member 164A and the second drive member 164B based on the second user input signal generated by the second force sensor 210 and operate the first motor 166 A and the second motor 166B at the rotational speed differential value to differentially turn the patient support apparatus 100 about the floor surface FS. In other configurations, the controller 156 may be configured determine the commanded torque value of the first motor 166ADocket No. 060252.01136 based on the first user input signal generated by the first throttle 186 in response to user engagement and to determine the commanded torque value of the second motor 166B based on the second user input signal generated by the second force sensor 210 in response to user engagement. Other configurations of operating the auxiliary drive system 162 based on user engagement with the first throttle 186 and the second force sensor 210 are contemplated.

[0116] In yet another example, referring to Figures 31A and 31B, the first user input control 184 is implemented as a first force sensor 190 operatively attached to a first input member 192 arranged for user engagement (as described above) and the second user input control 196 is implemented as a second throttle 208 (as also described above). In some examples, the controller 156 may be configured to determine a commanded torque value for the first motor 166A and the second motor 166B based on the first user input signal generated by the first force sensor 190 in response to user engagement with the first input member 192, and the controller 156 may be further configured to determine a rotational speed differential value between the first drive member 16 A and the second drive member 164B based on the second user input signal generated by the second throttle 208 and operate the first motor 166 A and the second motor 166B at the rotational speed differential value to differentially turn the patient support apparatus 100 about the floor surface FS. In other configurations, the controller 156 may be configured determine the commanded torque value of the first motor 166 A based on the first user input signal generated by the first force sensor 190 in response to user engagement with the first input member 192, and to determine the commanded torque value of the second motor 166B based on the second user input signal generated by the second throttle 208 in response to user engagement. Other configurations of operating the auxiliary drive system 162 based on user engagement with the first force sensor 190 and the second throttle 208 are contemplated.

[0117] In the examples of Figures 32A and 32B, the first user input control 184 is implemented as a first force sensor 190 operatively attached to a first input member 192 arranged for user engagement (as described above) and the second user input control 196 is implemented as a second force sensor 210 operatively attached to a second input member 212 arranged for user engagement (as also described above). In some examples, the controller 156 may be configured to determine a commanded torque value for the first motor 166 A and the second motor 166B based on the first user input signal generated by the first force sensor 190 in response to user engagement with the first input member 192, and the controller 156 may be further configured to determine a rotational speed differential value between the first drive member 164A and the second drive member 164B based on the second user input signal generated by the second force sensor 210 and operate the first motor 166A and the second motor 166B at the rotational speed differential value to differentially turn the patient support apparatus 100 about the floor surface FS. In other configurations, the controller 156 may be configured determine the commanded torque value of the first motor 166 A based on the first user input signal generated by the first force sensor 190 in response to user engagement with the first input member 192, and to determine the commanded torque value of the second motor 166B based on the second user input signal generated by the second force sensor 210 in response to user engagement. Other configurations of operating theDocket No. 060252.01136 auxiliary drive system 162 based on user engagement with the first force sensor 190 and the second force sensor 210 are contemplated.

[0118] It should be appreciated that the examples illustrated in Figures 29A-32B are merely intended to be exemplary combinations of different implementations of the first user input control 184 and the second user input control 196. Additional implementations and combinations of implementations of the first user input control 184 and the second user input control 196 as described herein are contemplated.

[0119] Referring to Figures 33A-34, in configurations where the patient support apparatus 100 includes the first user input control 184 and the second user input control 196, the controller 156 may be configured to operate the auxiliary drive system 162 in a two-handed mode based on user engagement with both of the first user input control 184 and the second user input control 196 (shown in Figure 33B) and to operate the auxiliary drive system 162 in a one-handed mode based on user engagement with a single one of the first user input control 184 and the second user input control 196 (shown in Figure 33 A). It should be appreciated that in these configurations, the first user input control 184 and the second user input control 196 may be implemented in any manner described above.

[0120] Referring to Figure 34, in one configuration of the two-handed mode (i.e., where the controller 156 senses user engagement with the second user input control 196), the controller 156 may be further configured to determine a rotational speed differential value between the first drive member 164A and the second drive member 164B based on the second user input signal, and to operate the first motor 166 A and the second motor 166B at the rotational speed differential value to differentially turn the patient support apparatus 100 about the floor surface FS, similar to as described above in Figure 28. On other examples of the two-handed mode, the controller 156 may be configured to determine a commanded torque value for the first motor 166 A based on the first user input signal generated by the first user input control 184 and determine a commanded torque value for the second motor 166B based on the second user input signal generated by the second user input control 196, and to pennit that the first motor 166 A and the second motor 166B rotate at different speeds to turn the patient support apparatus 100 relative to the floor surface FS, as described above in the context of Figures 26A-27B. Stated differently, in some examples, the controller 156 may only be configured to operate the first motor 166 A and the second motor 166B at the rotational speed differential value to differentially turn the patient support apparatus 100 where the controller 156 senses user engagement with the both the first user input control 184 and second user input control 196 such that the controller 156 operates the auxiliary drive system 162 in the two-handed mode.

[0121] In the one-handed mode, on the other hand, the controller 156 may inhibit operation of the auxiliary drive system 162 to differentially turn the patient support apparatus 100 about the floor surface FS. For example, in some configurations, in the one-handed mode, the controller 156 may be configured to determine a commanded torque value for the first motor 166A and the second motor 166B based on one of the first user input signal generated in response to user engagement with the first user input control 184 and the second user input signal generated inDocket No. 060252.01136 response to user engagement with the second user input control 196. Here, the controller 156 may inhibit the auxiliary drive system 162 from operating in a manner that allows the first drive member 164A and the second drive member 164B to rotate at different speeds. Rather, the controller may operate the auxiliary drive system 162 such that the first drive member 164A and the second drive member 164B rotate at substantially the same speed to maintain the trajectory of the patient support apparatus 100 along the floor surface FS. Of course, it is contemplated that during operation in either or both of the one-handed mode and the two-handed mode, the controller 156 may be configured to adjust the commanded torque value for at least one of the first motor 166A and the second motor 166B based on the direction of the load L acting on the support structure 102 to counteract deviations in a trajectory of the patient support apparatus 100 along the floor surface FS due to the load L acting on the support structure 102, as described above.

[0122] The controller 156 may be configured to switch from the one-handed mode to the two-handed mode in response to user engagement with both of the first user input control 184 and the second user input control 196 persisting for a predetermined time period. For example, the controller 156 may be configured to switch from the one-handed mode to the two-handed mode in response to user engagement with both of the first user input control 184 and the second user input control 196 persisting for 0.5 seconds, 1 second, 2 seconds, 5 seconds, etc. In other examples, the controller 156 may be configured to switch from the one-handed mode to the two-handed mode as soon as the controller 156 detects user engagement with both of the first user input control 184 and the second user input control 196. Likewise, the controller 156 may be configured to switch from the two-handed mode to the one-handed mode is response to a lack of user engagement with one of the first user input control 184 and the second user input control 196 persisting for a predetermined time period. For example, controller 156 may be configured to switch from the two-handed mode to the one-handed mode is response to a lack of user engagement with one of the first user input control 184 and the second user input control 196 persisting for 0.5 seconds, 1 second, 2 seconds, 5 seconds, etc. In other examples, the controller 156 may be configured to switch from the two-handed mode to the one-handed mode as soon as the controller 156 detects a lack of user engagement with one of the first user input control 184 and the second user input control 196. In additional examples, the controller 156 may be configured to inhibit switching between the one-handed mode and the two-handed mode where a speed of the patient support apparatus 100 along the floor surface FS (e.g., as measured by the speed sensor or the speed of the motor(s) 166) exceeds a predetermined threshold. For example, the controller 156 may be configured to inhibit switching between the one-handed mode and the two-handed mode where a speed of the patient support apparatus 100 along the floor surface FS exceeds 0.5 mph, 1.0 mph, 2.0 mph, etc.

[0123] Several configurations have been discussed in the foregoing description. However, the configurations discussed herein are not intended to be exhaustive or limit the invention to any particular form. The terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations are possible in light of the above teachings and the invention may be practiced otherwise than as specifically described.Docket No. 060252.01136

[0124] The present disclosure also comprises the following clauses, with specific features laid out in dependent clauses, that may specifically be implemented as described in greater detail with reference to the configurations and drawings above.CLAUSESI. A patient support apparatus comprising: a support structure including: a base arranged for movement about a floor surface; a litter operatively attached to the base and defining a patient support surface for supporting a patient; a sensing system coupled to the support structure to generate data representing load acting on the support structure in one or more directions; an auxiliary drive system operatively attached to the support structure and including: a drive member configured to influence motion of the patient support apparatus over the floor surface, and a motor coupled to the drive member for providing motive power to the drive member; and a controller in communication with the auxiliary drive system and the sensing system, the controller configured to operate the auxiliary drive system to counteract deviations in a trajectory of the patient support apparatus along the floor surface occurring due to the direction of the load acting on the support structure based on the data generated by the sensing system.II. The patient support apparatus according to clause I, wherein the sensing system includes one or more load cell assemblies operatively attached to the support structure, with each of the one or more load cell assemblies being configured to generate a respective output signal representing the load acting on the support structure; and wherein the controller is configured to determine the load acting on the support structure based on the output signals of each of the one or more load cell assemblies.III. The patient support apparatus according to any one of clauses I or II, further comprising a first user input control in communication with the controller and arranged for user engagement, wherein the first user input control is configured to provide a first user input signal to the controller in response to user engagement with the first user input control.IV. The patient support apparatus according to clause III, wherein the controller is configured to determine a commanded torque value for the motor based on the first user input signal.V. The patient support apparatus according to clause IV, wherein the controller is configured to adjust the commanded torque value for the motor based on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.VI. The patient support apparatus according to clause V, wherein the controller is configured to determine a gain value based on the load acting on the support structure and scale the commanded torque value for the motor by the gain value.Docket No. 060252.01136VII. The patient support apparatus according to any one of clauses IV to VI, wherein the controller is configured to determine an expected speed of the patient support apparatus along the floor surface based on the commanded torque value for the motor, wherein the controller is configured to determine an actual speed of the patient support apparatus along the floor surface based on the speed of the motor, and wherein controller is configured to determine a difference between the actual speed and the expected speed, and scale the commanded torque value for the motor by a compensation value where the difference between the actual speed and the expected speed exceeds a predetermined threshold.VIII. The patient support apparatus according to any one of clauses IV to VII, further comprising an angle sensor operatively attached to the support structure for measuring an angle of the support structure relative to gravity, wherein the controller is configured to adjust to the commanded torque value for the motor based on the angle of the support structure relative to gravity.IX. The patient support apparatus according to any one of clauses II to VIII, wherein the one or more load cell assemblies are interposed between the base and the litter.X. The patient support apparatus according to any one of clauses II to VIII, wherein the one or more load cell assemblies are interposed between the base and one or more support wheels operatively attached to the base for supporting the base for movement relative to the floor surface.XI. The patient support apparatus according to any one of clauses II to VIII, further comprising a lift mechanism interposed between the base and the litter to move the litter relative to the base between a plurality of vertical configurations.XII. The patient support apparatus according to clause XI, wherein the one or more load cell assemblies are interposed between the base and the lift mechanism.XIII. The patient support apparatus according to clause XI, wherein the one or more load cell assemblies are interposed between the litter and the lift mechanism.XIV. The patient support apparatus according to any one of clauses II to XIII, wherein the one or more load cell assemblies includes four load cell assemblies.XV. The patient support apparatus according to any one of clauses IV to XIV, wherein the controller is configured to determine a gain value based on the load acting on the support structure and scale the commanded torque value for the motor by the gain value.XVI. The patient support apparatus according to any one of clauses III to XV, wherein the first user input control is arranged for modulation based on user engagement to adjust the first user input signal between a plurality of first user input signal magnitudes.XVII. The patient support apparatus according to clause XVI, wherein the controller is configured to determine a commanded torque value of the motor based on the first user input signal magnitude. XVIII. The patient support apparatus according to clause XVII, wherein the first user input control comprises a first throttle arranged for movement in response to user engagement; and wherein the first user input control is configured to generate the first user input signal in response to user engagement with the first throttle, the first user input signal pertaining to a magnitude of movement of the first throttle.Docket No. 060252.01136XIX. The patient support apparatus according to clause XVIII, wherein the controller includes a memory with a throttle map, and wherein the controller is configured to refer to the throttle map to determine the commanded torque value of the motor based on the magnitude of movement of the first throttle.XX. The patient support apparatus according to clause XIX, wherein the throttle map defines the commanded torque value of the motor as a function of the magnitude of movement of the first throttle.XXI. The patient support apparatus according to clause XX, wherein the throttle map is nonlinear’.XXII. The patient support apparatus according to clause XVII, wherein the first user input control comprises a first force sensor operatively attached to a first input member arranged for user engagement, and wherein the first force sensor is configured to generate the first user input signal in response to user engagement with the first input member, the first user input signal pertaining to a magnitude of force experienced by the first force sensor in response to user engagement with the first input member.XXIII. The patient support apparatus according to any one of clauses III to XXII, further comprising a second user input control in communication with the controller and arranged for user engagement, wherein the controller is configured to operate the auxiliary drive system based on user engagement with at least one of the first user input control and the second user input control.XXIV. The patient support apparatus according to clause XXIII, wherein the first user input control is spaced from the second user input control.XXV. The patient support apparatus according to clause XXIV, wherein the first user input control is arranged on a first lateral side of the patient support apparatus, and wherein the second user input control is arranged on a second lateral side of the patient support apparatus, opposite the first lateral side.XXVI. The patient support apparatus according to any one of clauses XXIII to XXV, wherein the second user input control is configured to provide a second user input signal to the controller in response to user engagement with the second user input control.XXVII. The patient support apparatus according to any one of clauses XXIII to XXVI, wherein the second user input control comprises a second presence sensor configured to generate the second user input signal in response to the presence of user engagement with the second user input control. XXVIII. The patient support apparatus according to clause XXVII, wherein the controller is configured to inhibit operation of the auxiliary drive system in response to a lack of user engagement with the second user input control.XXIX. The patient support apparatus according to any one of clauses I to XXVIII, wherein the drive member is further defined as a first drive member, and the motor is further defined as a first motor, and wherein the auxiliary drive system further includes: a second drive member configured to influence motion of the patient support apparatus over the floor surface, andDocket No. 060252.01136 a second motor coupled to the second drive member for providing motive power to the second drive member.XXX. The patient support apparatus according to clause XXIX, wherein the first drive member is configured to rotate about a first axis and the second drive member is configured to rotate about a second axis, and wherein the first axis and second axis are aligned.XXXI. The patient support apparatus according to any one of clauses XXIX or XXX, wherein the controller is configured to adjust a commanded torque value for at least one of the first motor and the second motor based on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.XXXII. The patient support apparatus according to clause XXXI, wherein the controller is configured to determine at least one of a first gain value and a second gain value based on the load acting on the support structure and scale the commanded torque value for at least one of the first motor and the second motor by the first gain value and the second gain value, respectively.XXXIII. The patient support apparatus according to any one of clauses XXIX to XXXII, wherein the controller is configured to permit a rotational speed differential between the first drive member and the second drive member in response to a caretaker exerting force on the support structure to alter the trajectory of the patient support apparatus along the floor surface.XXXIV. The patient support apparatus according to clause XXX111, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor in response to the rotational speed differential between the first drive member and the second drive member exceeding a threshold value.XXXV. The patient support apparatus according to clause XXXIV, further comprising a first user input control in communication with the controller and arranged for user engagement, wherein the controller is configured to operate the auxiliary drive system based on user engagement with the first user input control.XXXVI. The patient support apparatus according to clause XXXV, wherein the first user input control is configured to provide a first user input signal to the controller in response to user engagement with the first user input control.XXXVII. The patient support apparatus according to clause XXXVI, wherein the controller is configured to determine a commanded torque value for the first motor and the second motor based on the first user input signal.XXXVIII. The patient support apparatus according to any one of clauses XXXVI or XXXVII, wherein the first user input control is arranged for modulation based on user engagement to adjust the first user input signal between a plurality of first user input signal magnitudes.XXXIX. The patient support apparatus according to clause XXXVIII, wherein the controller is configured to determine the commanded torque value of the first motor and the second motor based on the first user input signal magnitude.XL. The patient support apparatus according to clause XXXIX, wherein the first user input control comprises a first throttle arranged for movement in response to user engagement; andDocket No. 060252.01136 wherein the first user input control is configured to generate the first user input signal in response to user engagement with the first throttle, the first user input signal pertaining to a magnitude of movement of the first throttle.XLI. The patient support apparatus according to clause XXXIX, wherein the first user input control comprises a first force sensor operatively attached to a first input member arranged for user engagement, and wherein the first force sensor is configured to generate the first user input signal in response to user engagement with the first input member, the first user input signal pertaining to a magnitude of force experienced by the first force sensor in response to user engagement with the first input member.XLII. The patient support apparatus according to any one of clauses XXXV to XLI, further comprising a second user input control in communication with the controller and arranged for user engagement, wherein the controller is configured to operate the auxiliary drive system based on user engagement with at least one of the first user input control and the second user input control. XLIII. The patient support apparatus according to clause XLII, wherein the second user input control is configured to provide a second user input signal to the controller in response to user engagement with the second user input control.XL1V. The patient support apparatus according to clause XL111, wherein the second user input control comprises a second presence sensor configured to generate the second user input signal in response to the presence of user engagement with the second user input control.XLV. The patient support apparatus according to clause XLIV, wherein the controller is configured to inhibit operation of the auxiliary drive system in response to a lack of user engagement with the second user input control.XLVI. The patient support apparatus according to any one of clauses XLII to XLV, wherein the controller is configured to operate the auxiliary drive system in a one-handed mode based on user engagement with one of the first user input control and the second user input control, and wherein the controller is configured to operate the auxiliary drive system in a two-handed mode based on user engagement with both of the first user input control and the second user input control.XLVII. The patient support apparatus according to clause XLVI, wherein, in the two-handed mode, the controller is configured to determine a commanded torque value for the first motor and the second motor based on the first user input signal; and wherein the controller is configured to determine a rotational speed differential value between the first drive member and the second drive member based on the second user input signal and operate the first motor and the second motor at the rotational speed differential value to differentially turn the patient support apparatus about the floor surface.XLVIII. The patient support apparatus according to clause XLVI, wherein, in the two-handed mode, the controller is configured to determine a commanded torque value for the first motor based on the first user input signal and determine a commanded torque value for the second motor based on the second user input signal; andDocket No. 060252.01136 wherein the controller is configured to determine a rotational speed differential value between the first drive member and the second drive member based on the first user input signal and the second user input signal and operate the first motor and the second motor at the rotational speed differential value to differentially turn the patient support apparatus about the floor surface. XLIX. The patient support apparatus according to any one of clauses XLVI to XLVIII, wherein the controller is configured to switch from the one-handed mode to the two-handed mode in response to user engagement with both of the first user input control and the second user input control persisting for a predetermined time period.L. The patient support apparatus according to any one of clauses XLVI to XLIX, wherein the controller is configured to switch from the two-handed mode to the one-handed mode is response to a lack of user engagement with one of the first user input control and the second user input control persisting for a predetermined time period.LI. The patient support apparatus according to any one of clauses XLVI to L, wherein the controller is configured to inhibit switching between the one-handed mode and the two-handed mode where a speed of the patient support apparatus along the floor surface exceeds a predetermined threshold.LIL The patient support apparatus according to any one of clauses XLIII to LI, wherein the controller is configured to determine a commanded torque value for the first motor based on the first user input signal; and wherein the controller is configured to determine a commanded torque value for the second motor based on the second user input signal.LIII. The patient support apparatus according to any one of clauses XLIII to LII, wherein the second user input control is arranged for modulation based on user engagement to adjust the second user input signal between a plurality of second user input signal magnitudes.LIV. The patient support apparatus according to clause LIII, wherein the controller is configured to determine the commanded torque value of the second motor based on the second user input signal magnitude.LV. The patient support apparatus according to clause LIV, wherein the second user input control comprises a second throttle arranged for movement in response to user engagement; and wherein the second user input control is configured to generate the second user input signal in response to user engagement with the second throttle, the second user input signal pertaining to a magnitude of movement of the second throttle.LVI. The patient support apparatus according to clause LIV, wherein the second user input control comprises a second force sensor operatively attached to a second input member arranged for user engagement, and wherein the second force sensor is configured to generate the second user input signal in response to user engagement with the second input member, the second user input signal pertaining to a magnitude of force experienced by the second force sensor in response to user engagement with the second input member.Docket No. 060252.01136LVII. The patient support apparatus according to any one of clauses XLIIT to LVI, wherein the controller is configured to determine a commanded torque value for the first motor and the second motor based on the first user input signal; and wherein the controller is configured to determine a rotational speed differential value between the first drive member and the second drive member based on the second user input signal and operate the first motor and the second motor at the rotational speed differential value to differentially turn the patient support apparatus about the floor surface.LVIII. The patient support apparatus according to clause LVII, wherein the controller is configured to determine the commanded torque value of the first motor and the second motor based on the first user input signal magnitude.LIX. The patient support apparatus according to any one of clauses LIII to LVIII, wherein the controller is configured to determine the rotational speed differential value between the first drive member and the second drive member based on the second user input signal magnitude.LX. A patient support apparatus comprising: a support structure including: a base arranged for movement about a floor surface; a litter operatively attached to the base and defining a patient support surface for supporting a patient; a sensing system coupled to the support structure to generate data representing load acting on the support structure in one or more directions; an auxiliary drive system operatively attached to the support structure and including: a first drive member configured to influence motion of the patient support apparatus over the floor surface, a first motor coupled to the first drive member for providing motive power to the first drive member, a second drive member configured to influence motion of the patient support apparatus over the floor surface, and a second motor coupled to the second drive member for providing motive power to the second drive member; and a controller in communication with the auxiliary drive system and the sensing system, the controller configured to operate the auxiliary drive system to counteract deviations in a trajectory of the patient support apparatus along the floor surface occurring due to the direction of the load acting on the support structure based on the data generated by the sensing system.LXI. The patient support apparatus according to clause LX, wherein the sensing system includes one or more load cell assemblies operatively attached to the support structure, with each of the one or more load cell assemblies being configured to generate a respective output signal representing the load acting on the support structure; and wherein the controller is configured to determine the load acting on the support structure based on the output signals of each of the one or more load cell assemblies.Docket No. 060252.01136LXII. The patient support apparatus according to any one of clauses LX or LXI, further comprising a first user input control in communication with the controller and arranged for user engagement, wherein the first user input control is configured to provide a first user input signal to the controller in response to user engagement with the first user input control.LXIII. The patient support apparatus according to clause LXII, wherein the controller is configured to determine a commanded torque value for the first motor and the second motor based on the first user input signal.LXIV. The patient support apparatus according to clause LXIII, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor based on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.LXV. The patient support apparatus according to clause LXIV, wherein the controller is configured to determine at least one of a first gain value and a second gain value based on the load acting on the support structure and scale the commanded torque value for at least one of the first motor and the second motor by the first gain value and the second gain value, respectively.LXVI. The patient support apparatus according to any one of clauses LXIII to LXV, wherein the controller is configured to permit a rotational speed differential between the first drive member and the second drive member in response to a caretaker exerting force on the support structure to alter the trajectory of the patient support apparatus along the floor surface.LXVII. The patient support apparatus according to clause LXVI, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor in response to the rotational speed differential between the first drive member and the second drive member exceeding a threshold value.LXVIII. The patient support apparatus according to any one of clauses LXIV to LXVII, wherein the controller is configured to determine an expected speed of the patient support appar atus along the floor surface based on the commanded torque value for the first motor and the second motor, wherein the controller is configured to determine an actual speed of the patient support apparatus along the floor surface based on the speed of the first motor and the second motor, and wherein controller is configured to determine a difference between the actual speed and the expected speed and scale the commanded torque value for the first motor and the second motor by a compensation value where the difference between the actual speed and the expected speed exceeds a predetermined threshold.LXIX. The patient support apparatus according to any one of clauses LXIV to LXVIII, further comprising an angle sensor operatively attached to the support structure for measuring an angle of the support structure relative to gravity, wherein the controller is configured to adjust to the commanded torque value for the first motor and the second motor based on the angle of the support structure relative to gravity.LXX. The patient support apparatus according to any one of clauses LXI to LXIX, wherein the one or more load cell assemblies are interposed between the base and one or more support wheels operatively attached to the base for supporting the base for movement relative to the floor surface.Docket No. 060252.01136LXXI. The patient support apparatus according to any one of clauses LXI to LXIX, wherein the one or more load cell assemblies are interposed between the base and the litter.LXXII. The patient support apparatus according to any one of clauses LXI to LXIX, further comprising a lift mechanism interposed between the base and the litter to move the litter relative to the base between a plurality of vertical configurations.LXXIII. The patient support apparatus according to clause LXXII, wherein the one or more load cell assemblies are interposed between the base and the lift mechanism.LXXIV. The patient support apparatus according to clause LXXII, wherein the one or more load cell assemblies are interposed between the litter and the lift mechanism.LXXV. The patient support apparatus according to any one of clauses LXI to LXXIV, wherein the one or more load cell assemblies includes four load cell assemblies.LXXVI. The patient support apparatus according to any one of clauses LXII to LXXV, wherein the first user input control is configured to provide a first user input signal to the controller in response to user engagement with the first user input control.LXXVII. The patient support apparatus according to clause LXXVI, wherein the controller is configured to determine a commanded torque value for the first motor and the second motor based on the first user input signal.LXXV111. The patient support apparatus according to any one of clauses LX11 to LXXVII, wherein the first user input control comprises a first presence sensor configured to generate the first user input signal in response to the presence of user engagement with the first user input control.LXXIX. The patient support apparatus according to clause LXXVIII, wherein the controller is configured to inhibit operation of the auxiliary drive system in response to a lack of user engagement with the first user input control.LXXX. The patient support apparatus according to any one of clauses LXII to LXXIX, wherein the first user input control is arranged for modulation based on user engagement to adjust the first user input signal between a plurality of first user input signal magnitudes.LXXXI. The patient support apparatus according to clause LXXX, wherein the controller is configured to determine a commanded torque value of the first motor and the second motor based on the first user input signal magnitude.LXXXII. The patient support apparatus according to clause LXXXI, wherein the first user input control comprises a throttle arranged for movement in response to user engagement; and wherein the first user input control is configured to generate the first user input signal in response to user engagement with the throttle, the first user input signal pertaining to a magnitude of movement of the throttle.LXXXIII. The patient support apparatus according to clause LXXXII, wherein the controller includes a memory with a throttle map, and wherein the controller is configured to refer to the throttle map to determine the commanded torque value of the first motor and the second motor based on the magnitude of movement of the throttle.Docket No. 060252.01136LXXXIV. The patient support apparatus according to clause LXXXIII, wherein the throttle map defines the commanded torque value of the first motor and the second motor as a function of the magnitude of movement of the throttle.LXXXV. The patient support apparatus according to clause LXXXIV, wherein the throttle map is non-linear.LXXXVI. The patient support apparatus according to any one of clauses LXII to LXXXV, further comprising a second user input control in communication with the controller and arranged for user engagement, wherein the controller is configured to operate the auxiliary drive system based on user engagement with the first user input control and the second user input control.LXXXVII. The patient support apparatus according to clause LXXXVI, wherein the first user input control is spaced from the second user input control.LXXXVIII. The patient support apparatus according to clause LXXXVII, wherein the first user input control is arranged on a first lateral side of the patient support apparatus, and wherein the second user input control is arranged on a second lateral side of the patient support apparatus, opposite the first lateral side.LXXXIX. The patient support apparatus according to any one of clauses LXXXVI to LXXXVIII, wherein the second user input control is configured to provide a second user input signal to the controller in response to user engagement with the second user input control.XC. The patient support apparatus according to clause LXXXIX, wherein the second user input control comprises a second presence sensor configured to generate the second user input signal in response to the presence of user engagement with the second user input control.XCI. The patient support apparatus according to clause XC, wherein the controller is configured to inhibit operation of the auxiliary drive system in response to a lack of user engagement with the second user input control.XCII. The patient support apparatus according to clause LXXXIX, wherein the controller is configured to determine a commanded torque value for the first motor and the second motor based on at least one of the first user input signal and the second user input signal.XCIII. The patient support apparatus according to any one of clauses LXXXVI to XCII, wherein the controller is configured to operate the auxiliary drive system in a one-handed mode based on user engagement with one of the first user input control and the second user input control, and wherein the controller is configured to operate the auxiliary drive system in a two-handed mode based on user engagement with both of the first user input control and the second user input control. XCIV. The patient support apparatus according to clause XCIII, wherein, in the two-handed mode, the controller is configured to determine a commanded torque value for the first motor and the second motor based on the first user input signal; and wherein the controller is configured to determine a rotational speed differential value between the first drive member and the second drive member based on the second user input signal and operate the first motor and the second motor at the rotational speed differential value to differentially turn the patient support apparatus about the floor surface.Docket No. 060252.01136XCV. The patient support apparatus according to clause XCIII, wherein, in the two-handed mode, the controller is configured to determine a commanded torque value for the first motor based on the first user input signal and determine a commanded torque value for the second motor based on the second user input signal; and wherein the controller is configured to determine a rotational speed differential value between the first drive member and the second drive member based on the first user input signal and the second user input signal and operate the first motor and the second motor at the rotational speed differential value to differentially turn the patient support apparatus about the floor surface. XCVI. The patient support apparatus according to any one of clauses XCIII to XCV, wherein the controller is configured to switch from the one-handed mode to the two-handed mode in response to user engagement with both of the first user input control and the second user input control persisting for a predetermined time period.XCVII. The patient support apparatus according to any one of clauses XCIII to XCVI, wherein the controller is configured to switch from the two-handed mode to the one-handed mode is response to a lack of user engagement with one of the first user input control and the second user input control persisting for a predetermined time period.XCVIII. The patient support apparatus according to any one of clauses XCIII to XCVII, wherein the controller is configured to inhibit switching between the one-handed mode and the two-handed mode where a speed of the patient support apparatus along the floor surface exceeds a predetermined threshold.XCIX. The patient support apparatus according to any one of clauses XCIII to XCVIII, wherein the controller is configured to determine a commanded torque value for the first motor based on the first user input signal; and wherein the controller is configured to determine a commanded torque value for the second motor based on the second user input signal.C. The patient support apparatus according to clause XCIX, wherein the controller is configured to determine the commanded torque value of the first motor based on the first user input signal magnitude.CI. The patient support apparatus according to any one of clauses LXXXIX to C, wherein the second user input control is arranged for modulation based on user engagement to adjust the second user input signal between a plurality of second user input signal magnitudes.CII. The patient support apparatus according to clause CI, wherein the controller is configured to determine the commanded torque value of the second motor based on the second user input signal magnitude.CIII. The patient support apparatus according to clause CII, wherein the second user input control comprises a second throttle arranged for movement in response to user engagement; and wherein the second user input control is configured to generate the second user input signal in response to user engagement with the second throttle, the second user input signal pertaining to a magnitude of movement of the second throttle.Docket No. 060252.01136CIV. The patient support apparatus according to clause CIII, wherein the second user input control comprises a second force sensor operatively attached to a second input member arranged for user engagement, and wherein the second force sensor is configured to generate the second user input signal in response to user engagement with the second input member, the second user input signal pertaining to a magnitude of force experienced by the second force sensor in response to user engagement with the second input member.CV. The patient support apparatus according to any one of clauses LXXXIX to CIV, wherein the controller is configured to determine a commanded torque value for the first motor and the second motor based on the first user input signal; and wherein the controller is configured to determine a rotational speed differential value between the first drive member and the second drive member based on the second user input signal and operate the first motor and the second motor at the rotational speed differential value to differentially turn the patient support apparatus about the floor surface.CVI. The patient support apparatus according to any one of clauses CII to CIV, wherein the controller is configured to determine the commanded torque value of the first motor and the second motor based on the first user input signal magnitude.CV11. The patient support apparatus according to any one of clauses Cll to CVI, wherein the controller is configured to determine the rotational speed differential value between the first drive member and the second drive member based on the second user input signal magnitude.CVIII. The patient support apparatus according to any one of clauses LX to CVII, wherein the first drive member is configured to rotate about a first axis and the second drive member is configured to rotate about a second axis, and wherein the first axis and second axis are aligned. CIX. A patient support apparatus comprising: a support structure including: a base arranged for movement about a floor surface; a litter operatively attached to the base and defining a patient support surface for supporting a patient; an auxiliary drive system operatively attached to the support structure and including: a drive member configured to influence motion of the patient support apparatus over the floor surface, and a motor coupled to the drive member for providing motive power to the drive member; a first user input control operatively attached to the support structure and arranged for user engagement; a second user input control operatively attached to the support structure and arranged for user engagement; and a controller in communication with the auxiliary drive system, the first user input control, and the second user input control, wherein the controller is configured to:Docket No. 060252.01136 operate the auxiliary drive system based on user engagement with at least one of the first user input control and the second user input control, and operate the auxiliary drive system in a two-handed mode based on user engagement with both of the first user input control and the second user input control, and wherein the controller is configured to operate the auxiliary drive system in a one-handed mode based on user engagement with a single one of the first user input control and the second user input control.CX. The patient support apparatus according to clause CIX, wherein the drive member is further defined as a first drive member, and the motor is further defined as a first motor, and wherein the auxiliary drive system further includes: a second drive member configured to influence motion of the patient support apparatus over the floor surface, and a second motor coupled to the second drive member for providing motive power to the second drive member.CXI. The patient support apparatus according to clause CX, wherein the first user input control is configured to provide a first user input signal to the controller in response to user engagement with the first user input control; wherein the second user input control is configured to provide a second user input signal to the controller in response to user engagement with the second user input control; and wherein the controller is configured to determine a commanded torque value for the first motor and the second motor based on at least one of the first user input signal and the second user input signal.CXII. The patient support apparatus according to any one of clauses CIX to CXI, wherein the first user input control is spaced from the second user input control.CXIII. The patient support apparatus according to clause CXII, wherein the first user input control is arranged on a first lateral side of the patient support apparatus, and wherein the second user input control is arranged on a second lateral side of the patient support apparatus, opposite the first lateral side.CXIV. The patient support apparatus according to any one of clauses CXI to CXIII, wherein the controller is configured to determine a commanded torque value for the first motor and the second motor based on the first user input signal; and wherein, in the two-handed mode, the controller is configured to determine a rotational speed differential value between the first drive member and the second drive member based on the second user input signal and operate the first motor and the second motor at the rotational speed differential value to differentially turn the patient support apparatus about the floor surface.CXV. The patient support apparatus according to any one of clauses CXI to CXIV, wherein, in the two-handed mode, the controller is configured to determine a commanded torque value for the first motor based on the first user input signal and determine a commanded torque value for the second motor based on the second user input signal; andDocket No. 060252.01136 wherein the controller is configured to determine a rotational speed differential value between the first drive member and the second drive member based on the first user input signal and the second user input signal and operate the first motor and the second motor at the rotational speed differential value to differentially turn the patient support apparatus about the floor surface. CXVI. The patient support apparatus according to any one of clauses CXI to CXV, wherein the first user input control is arranged for modulation based on user engagement to adjust the first user input signal between a plurality of first user input signal magnitudes.CXVII. The patient support apparatus according to clause CXVI, wherein the first user input control comprises a first throttle arranged for movement in response to user engagement; and wherein the first user input control is configured to generate the first user input signal in response to user engagement with the first throttle, the first user input signal pertaining to a magnitude of movement of the first throttle.CXVIII. The patient support apparatus according to clause CXVI, wherein the first user input control comprises a first force sensor operatively attached to a first input member arranged for user engagement, and wherein the first force sensor is configured to generate the first user input signal in response to user engagement with the first input member, the first user input signal pertaining to a magnitude of force experienced by the first force sensor in response to user engagement with the first input member.CXIX. The patient support apparatus according to any one of clauses CXI to CXVIII, wherein the second user input control is arranged for modulation based on user engagement to adjust the second user input signal between a plurality of second user input signal magnitudes.CXX. The patient support apparatus according to clause CXIX, wherein the second user input control comprises a second throttle arranged for movement in response to user engagement; and wherein the second user input control is configured to generate the second user input signal in response to user engagement with the second throttle, the second user input signal pertaining to a magnitude of movement of the second throttle.CXXI. The patient support apparatus according to clause CXIX, wherein the second user input control comprises a second force sensor operatively attached to a second input member arranged for user engagement, and wherein the second force sensor is configured to generate the second user input signal in response to user engagement with the second input member, the second user input signal pertaining to a magnitude of force experienced by the second force sensor in response to user engagement with the second input member.CXXII. The patient support apparatus according to any one of clauses CX to CXXI, further comprising a sensing system coupled to the support structure to generate data representing load acting on the support structure in one or more directions; and wherein the controller is configured to adjust a commanded torque value for at least one of the first motor and the second motor based on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.Docket No. 060252.01136CXXIII. The patient support apparatus according to clause CXXTI, wherein the controller is configured to determine at least one of a first gain value and a second gain value based on the load acting on the support structure and scale the commanded torque value for at least one of the first motor and the second motor by the first gain value and the second gain value, respectively.CXXIV. The patient support apparatus according to clause CXXIII, wherein the controller is configured to permit a rotational speed differential between the first drive member and the second drive member in response to a caretaker exerting force on the support structure to alter the trajectory of the patient support apparatus along the floor surface.CXXV. The patient support apparatus according to clause CXXIV, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor in response to the rotational speed differential between the first drive member and the second drive member exceeding a threshold value.CXXVI. The patient support apparatus according to any one of clauses CX to CXXV, wherein the first drive member is configured to rotate about a first axis and the second drive member is configured to rotate about a second axis, and wherein the first axis and second axis are aligned. CXXVII. The patient support apparatus according to any one of clauses CIX to CXXVI, wherein the controller is configured to switch from the one-handed mode to the two-handed mode in response to user engagement with both of the first user input control and the second user input control persisting for a predetermined time period.CXXVIII. The patient support apparatus according to any one of clauses CIX to CXXVII, wherein the controller is configured to switch from the two-handed mode to the one-handed mode is response to a lack of user engagement with one of the first user input control and the second user input control persisting for a predetermined time period.CXXIX. The patient support apparatus according to any one of clauses CIX to CXXVIII, wherein the controller is configured to inhibit switching between the one-handed mode and the two-handed mode where a speed of the patient support apparatus along the floor surface exceeds a predetermined threshold.CXXX. The patient support apparatus according to any one of clauses CIX to CXXIX, wherein the first user input control is configured to provide a first user input signal to the controller in response to user engagement with the first user input control; and wherein the second user input control is configured to provide a second user input signal to the controller in response to user engagement with the second user input control; and wherein the controller is configured to determine a commanded torque value for the motor based on at least one of the first user input signal and the second user input signal.CXXXI. The patient support apparatus according to clause CXXX, wherein the second user input control comprises a second presence sensor configured to generate the second user input signal in response to the presence of user engagement with the second user input control.CXXXII. The patient support apparatus according to clause CXXXI, wherein the controller is configured to inhibit operation of the auxiliary drive system in response to a lack of user engagement with the second user input control.Docket No. 060252.01136CXXXIII. The patient support apparatus according to clause CXXX, wherein the first user input control is arranged for modulation based on user engagement to adjust the first user input signal between a plurality of first user input signal magnitudes.CXXXIV. The patient support apparatus according to clause CXXXIII, wherein the first user input control comprises a first throttle arranged for movement in response to user engagement; and wherein the first user input control is configured to generate the first user input signal in response to user engagement with the first throttle, the first user input signal pertaining to a magnitude of movement of the first throttle.CXXXV. The patient support apparatus according to clause CXXXIII, wherein the first user input control comprises a first force sensor operatively attached to a first input member arranged for user engagement, and wherein the first force sensor is configured to generate the first user input signal in response to user engagement with the first input member, the first user input signal pertaining to a magnitude of force experienced by the first force sensor in response to user engagement with the first input member.CXXXVI. The patient support apparatus according to any one of clauses CXXX to CXXXV, wherein the second user input control is arranged for modulation based on user engagement to adjust the second user input signal between a plurality of second user input signal magnitudes. CXXXVII. The patient support apparatus according to clause CXXXVI, wherein the second user input control comprises a second throttle arranged for movement in response to user engagement; and wherein the second user input control is configured to generate the second user input signal in response to user engagement with the second throttle, the second user input signal pertaining to a magnitude of movement of the second throttle.CXXXVIII. The patient support apparatus according to clause CXXXVI, wherein the second user input control comprises a second force sensor operatively attached to a second input member arranged for user engagement, and wherein the second force sensor is configured to generate the second user input signal in response to user engagement with the second input member, the second user input signal pertaining to a magnitude of force experienced by the second force sensor in response to user engagement with the second input member.CXXXIX. The patient support apparatus according to any one of clauses CIX to CXXXVIII, further comprising a sensing system coupled to the support structure to generate data representing load acting on the support structure in one or more directions; and wherein the controller is configured to adjust a commanded torque value for the motor based on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.CXL. The patient support apparatus according to clause CXXXIX, wherein the sensing system includes one or more load cell assemblies operatively attached to the support structure, with eachDocket No. 060252.01136 of the one or more load cell assemblies being configured to generate a respective output signal representing the load acting on the support structure; and wherein the controller is configured to determine the load acting on the support structure based on the output signals of each of the one or more load cell assemblies.CXLI. The patient support apparatus according to clause CXL, wherein the one or more load cell assemblies are interposed between the base and one or more support wheels operatively attached to the base for supporting the base for movement relative to the floor surface.CXLII. The patient support apparatus according to clause CXL, wherein the one or more load cell assemblies are interposed between the base and the litter.CXLIII. The patient support apparatus according to clause CXL, further comprising a lift mechanism interposed between the base and the litter to move the litter relative to the base between a plurality of vertical configurations.CXLIV. The patient support apparatus according to clause CXLIII, wherein the one or more load cell assemblies are interposed between the base and the lift mechanism.CXLV. The patient support apparatus according to clause CXLIII, wherein the one or more load cell assemblies are interposed between the litter and the lift mechanism.CXL VI. The patient support apparatus according to any one of clauses CXL to CXLV, wherein the one or more load cell assemblies includes four load cell assemblies.

Claims

Docket No. 060252.01136CLAIMSWhat is claimed is:

1. A patient support apparatus comprising: a support structure including: a base arranged for movement about a floor surface; a litter operatively attached to the base and defining a patient support surface for supporting a patient; a sensing system coupled to the support structure to generate data representing load acting on the support structure in one or more directions; an auxiliary drive system operatively attached to the support structure and including: a drive member configured to influence motion of the patient support apparatus over the floor surface, and a motor coupled to the drive member for providing motive power to the drive member; and a controller in communication with the auxiliary drive system and the sensing system, the controller configured to operate the auxiliary drive system to counteract deviations in a trajectory of the patient support apparatus along the floor surface occurring due to the direction of the load acting on the support structure based on the data generated by the sensing system.

2. The patient support apparatus according to claim 1, wherein the sensing system includes one or more load cell assemblies operatively attached to the support structure, with each of the one or more load cell assemblies being configured to generate a respective output signal representing the load acting on the support structure; and wherein the controller is configured to determine the load acting on the support structure based on the output signals of each of the one or more load cell assemblies.

3. The patient support apparatus according to claim 2, further comprising a first user input control in communication with the controller and arranged for user engagement, wherein the first user input control is configured to provide a first user input signal to the controller in response to user engagement with the first user input control.

4. The patient support apparatus according to claim 3, wherein the controller is configured to determine a commanded torque value for the motor based on the first user input signal.

5. The patient support apparatus according to claim 4, wherein the controller is configured to adjust the commanded torque value for the motor based on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.

6. The patient support apparatus according to claim 5, wherein the controller is configured to determine a gain value based on the load acting on the support structure and scale the commanded torque value for the motor by the gain value.

7. The patient support apparatus according to claim 4, wherein the controller is configured to determine an expected speed of the patient support apparatus along the floor surface based on the commanded torque value for the motor,Docket No. 060252.01136 wherein the controller is configured to determine an actual speed of the patient support apparatus along the floor surface based on the speed of the motor, and wherein controller is configured to determine a difference between the actual speed and the expected speed, and scale the commanded torque value for the motor by a compensation value where the difference between the actual speed and the expected speed exceeds a predetermined threshold.

8. The patient support apparatus according to claim 4, further comprising an angle sensor operatively attached to the support structure for measuring an angle of the support structure relative to gravity, wherein the controller is configured to adjust to the commanded torque value for the motor based on the angle of the support structure relative to gravity.

9. The patient support apparatus according to claim 2, wherein the one or more load cell assemblies are interposed between the base and the litter.

10. The patient support apparatus according to claim 2, wherein the one or more load cell assemblies are interposed between the base and one or more support wheels operatively attached to the base for supporting the base for movement relative to the floor surface.

11. The patient support apparatus according to claim 2, further comprising a lift mechanism interposed between the base and the litter to move the litter relative to the base between a plurality of vertical configurations.

12. The patient support apparatus according to claim 11, wherein the one or more load cell assemblies are interposed between the base and the lift mechanism.

13. The patient support apparatus according to claim 11, wherein the one or more load cell assemblies are interposed between the litter and the lift mechanism.

14. The patient support apparatus according to claim 2, wherein the one or more load cell assemblies includes four load cell assemblies.

15. The patient support apparatus according to claim 1, further comprising a first user input control in communication with the controller and arranged for user engagement, wherein the controller is configured to operate the auxiliary drive system based on user engagement with the first user input control .

16. The patient support apparatus according to claim 15, wherein the first user input control is configured to provide a first user input signal to the controller in response to user engagement with the first user input control.

17. The patient support apparatus according to claim 16, wherein the controller is configured to determine a commanded torque value for the motor based on the first user input signal.

18. The patient support apparatus according to claim 17, wherein the controller is configured to adjust the commanded torque value for the motor based on the direction of the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.

19. The patient support apparatus according to claim 18, wherein the controller is configured to determine a gain value based on the load acting on the support structure and scale the commanded torque value for the motor by the gain value.Docket No. 060252.0113620. The patient support apparatus according to claim 17, wherein the controller is configured to determine an expected speed of the patient support apparatus along the floor surface based on the commanded torque value for the motor, wherein the controller is configured to determine an actual speed of the patient support apparatus along the floor surface based on the speed of the motor, and wherein controller is configured to determine a difference between the actual speed and the expected speed, and scale the commanded torque value for the motor by a compensation value where the difference between the actual speed and the expected speed exceeds a predetermined threshold.

21. The patient support apparatus according to claim 17, further comprising an angle sensor operatively attached to the support structure for measuring an angle of the support structure relative to gravity, wherein the controller is configured to adjust to the commanded torque value for the motor based on the angle of the support structure relative to gravity.

22. The patient support apparatus according to claim 16, wherein the first user input control is arranged for modulation based on user engagement to adjust the first user input signal between a plurality of first user input signal magnitudes.

23. The patient support apparatus according to claim 22, wherein the controller is configured to determine a commanded torque value of the motor based on the first user input signal magnitude.

24. The patient support apparatus according to claim 23, wherein the first user input control comprises a first throttle arranged for movement in response to user engagement; and wherein the first user input control is configured to generate the first user input signal in response to user engagement with the first throttle, the first user input signal pertaining to a magnitude of movement of the first throttle.

25. The patient support apparatus according to claim 24, wherein the controller includes a memory with a throttle map, and wherein the controller is configured to refer to the throttle map to determine the commanded torque value of the motor based on the magnitude of movement of the first throttle.

26. The patient support apparatus according to claim 25, wherein the throttle map defines the commanded torque value of the motor as a function of the magnitude of movement of the first throttle.

27. The patient support apparatus according to claim 26, wherein the throttle map is non-linear.

28. The patient support apparatus according to claim 23, wherein the first user input control comprises a first force sensor operatively attached to a first input member arranged for user engagement, and wherein the first force sensor is configured to generate the first user input signal in response to user engagement with the first input member, the first user input signal pertaining to a magnitude of force experienced by the first force sensor in response to user engagement with the first input member.

29. The patient support apparatus according to claim 23, wherein the controller is configured to adjust the commanded torque value for the motor based on the load acting on the support structureDocket No. 060252.01136 determined to counteract deviations in a trajectory of the patient support apparatus along the floor surface.

30. The patient support apparatus according to claim 23, further comprising a second user input control in communication with the controller and arranged for user engagement, wherein the controller is configured to operate the auxiliary drive system based on user engagement with at least one of the first user input control and the second user input control.

31. The patient support apparatus according to claim 30, wherein the first user input control is spaced from the second user input control.

32. The patient support apparatus according to claim 31, wherein the first user input control is arranged on a first lateral side of the patient support apparatus, and wherein the second user input control is arranged on a second lateral side of the patient support apparatus, opposite the first lateral side.

33. The patient support apparatus according to claim 30, wherein the second user input control is configured to provide a second user input signal to the controller in response to user engagement with the second user input control.

34. The patient support apparatus according to claim 33, wherein the second user input control comprises a second presence sensor configured to generate the second user input signal in response to the presence of user engagement with the second user input control.

35. The patient support apparatus according to claim 34, wherein the controller is configured to inhibit operation of the auxiliary drive system in response to a lack of user engagement with the second user input control.

36. The patient support apparatus according to claim 23, wherein the controller is configured to determine an expected speed of the patient support apparatus along the floor surface based on the commanded torque value for the motor, wherein the controller is configured to determine an actual speed of the patient support apparatus along the floor surface based on the speed of the motor, and wherein controller is configured to determine a difference between the actual speed and the expected speed, and scale the commanded torque value for the motor by a compensation value where the difference between the actual speed and the expected speed exceeds a predetermined threshold.

37. The patient support apparatus according to claim 23, further comprising an angle sensor operatively attached to the support structure for measuring an angle of the support structure relative to gravity, wherein the controller is configured to adjust the commanded torque value for the motor based on the angle of the support structure relative to gravity.

38. The patient support apparatus according to claim 1, wherein the drive member is further defined as a first drive member, and the motor is further defined as a first motor, and wherein the auxiliary drive system further includes: a second drive member configured to influence motion of the patient support apparatus over the floor surface, andDocket No. 060252.01136 a second motor coupled to the second drive member for providing motive power to the second drive member.

39. The patient support apparatus according to claim 38, wherein the first drive member is configured to rotate about a first axis and the second drive member is configured to rotate about a second axis, and wherein the first axis and second axis are aligned.

40. The patient support apparatus according to claim 38, wherein the controller is configured to adjust a commanded torque value for at least one of the first motor and the second motor based on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.

41. The patient support apparatus according to claim 40, wherein the controller is configured to determine at least one of a first gain value and a second gain value based on the load acting on the support structure and scale the commanded torque value for at least one of the first motor and the second motor by the first gain value and the second gain value, respectively.

42. The patient support apparatus according to claim 41, wherein the controller is configured to permit a rotational speed differential between the first drive member and the second drive member in response to a caretaker exerting force on the support structure to alter the trajectory of the patient support apparatus along the floor surface.

43. The patient support apparatus according to claim 42, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor in response to the rotational speed differential between the first drive member and the second drive member exceeding a threshold value.

44. The patient support apparatus according to claim 38, further comprising a first user input control in communication with the controller and arranged for user engagement, wherein the controller is configured to operate the auxiliary drive system based on user engagement with the first user input control.

45. The patient support apparatus according to claim 44, wherein the first user input control is configured to provide a first user input signal to the controller in response to user engagement with the first user input control.

46. The patient support apparatus according to claim 45, wherein the controller is configured to determine a commanded torque value for the first motor and the second motor based on the first user input signal.

47. The patient support apparatus according to claim 46, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor based on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.

48. The patient support apparatus according to claim 47, wherein the first user input control is arranged for modulation based on user engagement to adjust the first user input signal between a plurality of first user input signal magnitudes.Docket No. 060252.0113649. The patient support apparatus according to claim 48, wherein the controller is configured to determine the commanded torque value of the first motor and the second motor based on the first user input signal magnitude.

50. The patient support apparatus according to claim 49, wherein the first user input control comprises a first throttle arranged for movement in response to user engagement; and wherein the first user input control is configured to generate the first user input signal in response to user engagement with the first throttle, the first user input signal pertaining to a magnitude of movement of the first throttle.

51. The patient support apparatus according to claim 49, wherein the first user input control comprises a first force sensor operatively attached to a first input member arranged for user engagement, and wherein the first force sensor is configured to generate the first user input signal in response to user engagement with the first input member, the first user input signal pertaining to a magnitude of force experienced by the first force sensor in response to user engagement with the first input member.

52. The patient support apparatus according to claim 45, further comprising a second user input control in communication with the controller and arranged for user engagement, wherein the controller is configured to operate the auxiliary drive system based on user engagement with at least one of the first user input control and the second user input control.

53. The patient support apparatus according to claim 52, wherein the first user input control is spaced from the second user input control.

54. The patient support apparatus according to claim 53, wherein the first user input control is arranged on a first lateral side of the patient support apparatus, and wherein the second user input control is arranged on a second lateral side of the patient support apparatus, opposite the first lateral side.

55. The patient support apparatus according to claim 52, wherein the second user input control is configured to provide a second user input signal to the controller in response to user engagement with the second user input control.

56. The patient support apparatus according to claim 55, wherein the second user input control comprises a second presence sensor configured to generate the second user input signal in response to the presence of user engagement with the second user input control.

57. The patient support apparatus according to claim 56, wherein the controller is configured to inhibit operation of the auxiliary drive system in response to a lack of user engagement with the second user input control.

58. The patient support apparatus according to claim 55, wherein the controller is configured to determine a commanded torque value for the first motor and the second motor based on at least one of the first user input signal and the second user input signal.

59. The patient support apparatus according to claim 58, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor basedDocket No. 060252.01136 on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.

60. The patient support apparatus according to claim 55, wherein the controller is configured to operate the auxiliary drive system in a one-handed mode based on user engagement with one of the first user input control and the second user input control, and wherein the controller is configured to operate the auxiliary drive system in a two-handed mode based on user engagement with both of the first user input control and the second user input control.

61. The patient support apparatus according to claim 60, wherein, in the two-handed mode, the controller is configured to determine a commanded torque value for the first motor and the second motor based on the first user input signal; and wherein the controller is configured to determine a rotational speed differential value between the first drive member and the second drive member based on the second user input signal and operate the first motor and the second motor at the rotational speed differential value to differentially turn the patient support apparatus about the floor surface.

62. The patient support apparatus according to claim 60, wherein, in the two-handed mode, the controller is configured to determine a commanded torque value for the first motor based on the first user input signal and determine a commanded torque value for the second motor based on the second user input signal; and wherein the controller is configured to determine a rotational speed differential value between the first drive member and the second drive member based on the first user input signal and the second user input signal and operate the first motor and the second motor at the rotational speed differential value to differentially turn the patient support apparatus about the floor surface.

63. The patient support apparatus according to claim 60, wherein the controller is configured to switch from the one-handed mode to the two-handed mode in response to user engagement with both of the first user input control and the second user input control persisting for a predetermined time period.

64. The patient support apparatus according to claim 60, wherein the controller is configured to switch from the two-handed mode to the one-handed mode is response to a lack of user engagement with one of the first user input control and the second user input control persisting for a predeteimined time period.

65. The patient support apparatus according to claim 60, wherein the controller is configured to inhibit switching between the one-handed mode and the two-handed mode where a speed of the patient support apparatus along the floor surface exceeds a predetermined threshold.

66. The patient support apparatus according to claim 55, wherein the controller is configured to determine a commanded torque value for the first motor based on the first user input signal; and wherein the controller is configured to determine a commanded torque value for the second motor based on the second user input signal.

67. The patient support apparatus according to claim 66, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor basedDocket No. 060252.01136 on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.

68. The patient support apparatus according to claim 66, wherein the first user input control is arranged for modulation based on user engagement to adjust the first user input signal between a plurality of first user input signal magnitudes.

69. The patient support apparatus according to claim 68, wherein the controller is configured to determine the commanded torque value of the first motor based on the first user input signal magnitude.

70. The patient support apparatus according to claim 69, wherein the first user input control comprises a first throttle arranged for movement in response to user engagement; and wherein the first user input control is configured to generate the first user input signal in response to user engagement with the first throttle, the first user input signal pertaining to a magnitude of movement of the first throttle.

71. The patient support apparatus according to claim 69, wherein the first user input control comprises a first force sensor operatively attached to a first input member arranged for user engagement, and wherein the first force sensor is configured to generate the first user input signal in response to user engagement with the first input member, the first user input signal pertaining to a magnitude of force experienced by the first force sensor in response to user engagement with the first input member.

72. The patient support apparatus according to claim 66, wherein the second user input control is arranged for modulation based on user engagement to adjust the second user input signal between a plurality of second user input signal magnitudes.

73. The patient support apparatus according to claim 72, wherein the controller is configured to determine the commanded torque value of the second motor based on the second user input signal magnitude.

74. The patient support apparatus according to claim 73, wherein the second user input control comprises a second throttle arranged for movement in response to user engagement; and wherein the second user input control is configured to generate the second user input signal in response to user engagement with the second throttle, the second user input signal pertaining to a magnitude of movement of the second throttle.

75. The patient support apparatus according to claim 73, wherein the second user input control comprises a second force sensor operatively attached to a second input member arranged for user engagement, and wherein the second force sensor is configured to generate the second user input signal in response to user engagement with the second input member, the second user input signal pertaining to a magnitude of force experienced by the second force sensor in response to user engagement with the second input member.Docket No. 060252.0113676. The patient support apparatus according to claim 55, wherein the controller is configured to determine a commanded torque value for the first motor and the second motor based on the first user input signal; and wherein the controller is configured to determine a rotational speed differential value between the first drive member and the second drive member based on the second user input signal and operate the first motor and the second motor at the rotational speed differential value to differentially turn the patient support apparatus about the floor surface.

77. The patient support apparatus according to claim 76, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor based on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.

78. The patient support apparatus according to claim 76, wherein the first user input control is arranged for modulation based on user engagement to adjust the first user input signal between a plurality of first user input signal magnitudes.

79. The patient support apparatus according to claim 78, wherein the controller is configured to determine the commanded torque value of the first motor and the second motor based on the first user input signal magnitude.

80. The patient support apparatus according to claim 79, wherein the first user input control comprises a first throttle arranged for movement in response to user engagement; and wherein the first user input control is configured to generate the first user input signal in response to user engagement with the first throttle, the first user input signal pertaining to a magnitude of movement of the first throttle.

81. The patient support apparatus according to claim 79, wherein the first user input control comprises a first force sensor operatively attached to a first input member arranged for user engagement, and wherein the first force sensor is configured to generate the first user input signal in response to user engagement with the first input member, the first user input signal pertaining to a magnitude of force experienced by the first force sensor in response to user engagement with the first input member.

82. The patient support apparatus according to claim 76, wherein the second user input control is arranged for modulation based on user engagement to adjust the second user input signal between a plurality of second user input signal magnitudes.

83. The patient support apparatus according to claim 82, wherein the controller is configured to determine the rotational speed differential value between the first drive member and the second drive member based on the second user input signal magnitude.

84. The patient support apparatus according to claim 83, wherein the second user input control comprises a second throttle arranged for movement in response to user engagement; and wherein the second user input control is configured to generate the second user input signal in response to user engagement with the second throttle, the second user input signal pertaining to a magnitude of movement of the second throttle.Docket No. 060252.0113685. The patient support apparatus according to claim 83, wherein the second user input control comprises a second force sensor operatively attached to a second input member arranged for user engagement, and wherein the second force sensor is configured to generate the second user input signal in response to user engagement with the second input member, the second user input signal pertaining to a magnitude of force experienced by the second force sensor in response to user engagement with the second input member.

86. A patient support apparatus comprising: a support structure including: a base arranged for movement about a floor surface; a litter operatively attached to the base and defining a patient support surface for supporting a patient; a sensing system coupled to the support structure to generate data representing load acting on the support structure in one or more directions; an auxiliary drive system operatively attached to the support structure and including: a first drive member configured to influence motion of the patient support apparatus over the floor surface, a first motor coupled to the first drive member for providing motive power to the first drive member, a second drive member configured to influence motion of the patient support apparatus over the floor surface, and a second motor coupled to the second drive member for providing motive power to the second drive member; and a controller in communication with the auxiliary drive system and the sensing system, the controller configured to operate the auxiliary drive system to counteract deviations in a trajectory of the patient support apparatus along the floor surface occurring due to the direction of the load acting on the support structure based on the data generated by the sensing system.

87. The patient support apparatus according to claim 86, wherein the sensing system includes one or more load cell assemblies operatively attached to the support structure, with each of the one or more load cell assemblies being configured to generate a respective output signal representing the load acting on the support structure; and wherein the controller is configured to determine the load acting on the support structure based on the output signals of each of the one or more load cell assemblies.

88. The patient support apparatus according to claim 87, further comprising a first user input control in communication with the controller and arranged for user engagement, wherein the first user input control is configured to provide a first user input signal to the controller in response to user engagement with the first user input control.

89. The patient support apparatus according to claim 88, wherein the controller is configured to determine a commanded torque value for the first motor and the second motor based on the first user input signal.Docket No. 060252.0113690. The patient support apparatus according to claim 89, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor based on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.

91. The patient support apparatus according to claim 90, wherein the controller is configured to determine at least one of a first gain value and a second gain value based on the load acting on the support structure and scale the commanded torque value for at least one of the first motor and the second motor by the first gain value and the second gain value, respectively.

92. The patient support apparatus according to claim 89, wherein the controller is configured to permit a rotational speed differential between the first drive member and the second drive member in response to a caretaker exerting force on the support structure to alter the trajectory of the patient support apparatus along the floor surface.

93. The patient support apparatus according to claim 92, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor in response to the rotational speed differential between the first drive member and the second drive member exceeding a threshold value.

94. The patient support apparatus according to claim 89, wherein the controller is configured to determine an expected speed of the patient support apparatus along the floor surface based on the commanded torque value for the first motor and the second motor, wherein the controller is configured to determine an actual speed of the patient support apparatus along the floor surface based on the speed of the first motor and the second motor, and wherein controller is configured to determine a difference between the actual speed and the expected speed and scale the commanded torque value for the first motor and the second motor by a compensation value where the difference between the actual speed and the expected speed exceeds a predetermined threshold.

95. The patient support apparatus according to claim 89, further comprising an angle sensor operatively attached to the support structure for measuring an angle of the support structure relative to gravity, wherein the controller is configured to adjust to the commanded torque value for the first motor and the second motor based on the angle of the support structure relative to gravity.

96. The patient support apparatus according to claim 87, wherein the one or more load cell assemblies are interposed between the base and one or more support wheels operatively attached to the base for supporting the base for movement relative to the floor surface.

97. The patient support apparatus according to claim 87, wherein the one or more load cell assemblies are interposed between the base and the litter.

98. The patient support apparatus according to claim 87, further comprising a lift mechanism interposed between the base and the litter to move the litter relative to the base between a plurality of vertical configurations.

99. The patient support apparatus according to claim 98, wherein the one or more load cell assemblies are interposed between the base and the lift mechanism.Docket No. 060252.01136100. The patient support apparatus according to claim 98, wherein the one or more load cell assemblies are interposed between the litter and the lift mechanism.

101. The patient support apparatus according to claim 87, wherein the one or more load cell assemblies includes four load cell assemblies.

102. The patient support apparatus according to claim 86, further comprising a first user input control in communication with the controller and arranged for user engagement, wherein the controller is configured to operate the auxiliary drive system based on user engagement with the first user input control.

103. The patient support apparatus according to claim 102, wherein the first user input control is configured to provide a first user input signal to the controller in response to user engagement with the first user input control.

104. The patient support apparatus according to claim 103, wherein the controller is configured to determine a commanded torque value for the first motor and the second motor based on the first user input signal.

105. The patient support apparatus according to claim 104, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor based on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.

106. The patient support apparatus according to claim 105, wherein the controller is configured to determine at least one of a first gain value and a second gain value based on the load acting on the support structure and scale the commanded torque value for at least one of the first motor and the second motor by the first gain value and the second gain value, respectively.

107. The patient support apparatus according to claim 104, wherein the controller is configured to permit a rotational speed differential between the first drive member and the second drive member in response to a caretaker exerting force on the support structure to alter the trajectory of the patient support apparatus along the floor surface.

108. The patient support apparatus according to claim 107, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor in response to the rotational speed differential between the first drive member and the second drive member exceeding a threshold value.

109. The patient support apparatus according to claim 104, wherein the controller is configured to determine an expected speed of the patient support apparatus along the floor surface based on the commanded torque value for the first motor and the second motor, wherein the controller is configured to determine an actual speed of the patient support apparatus along the floor surface based on the speed of the first motor and the second motor, and wherein controller is configured to determine a difference between the actual speed and the expected speed and scale the commanded torque value for the first motor and the second motor by a compensation value where the difference between the actual speed and the expected speed exceeds a predetermined threshold.Docket No. 060252.01136110. The patient support apparatus according to claim 104, further comprising an angle sensor operatively attached to the support structure for measuring an angle of the support structure relative to gravity, wherein the controller is configured to adjust to the commanded torque value for the first motor and the second motor based on the angle of the support structure relative to gravity.

111. The patient support apparatus according to claim 103, wherein the first user input control comprises a first presence sensor configured to generate the first user input signal in response to the presence of user engagement with the first user input control.

112. The patient support apparatus according to claim 111, wherein the controller is configured to inhibit operation of the auxiliary drive system in response to a lack of user engagement with the first user input control.

113. The patient support apparatus according to claim 103, wherein the first user input control is arranged for modulation based on user engagement to adjust the first user input signal between a plurality of first user input signal magnitudes.

114. The patient support apparatus according to claim 113, wherein the controller is configured to determine a commanded torque value of the first motor and the second motor based on the first user input signal magnitude.

115. The patient support apparatus according to claim 114, wherein the first user input control comprises a throttle arranged for movement in response to user engagement; and wherein the first user input control is configured to generate the first user input signal in response to user engagement with the throttle, the first user input signal pertaining to a magnitude of movement of the throttle.

116. The patient support apparatus according to claim 115, wherein the controller includes a memory with a throttle map, and wherein the controller is configured to refer to the throttle map to determine the commanded torque value of the first motor and the second motor based on the magnitude of movement of the throttle.

117. The patient support apparatus according to claim 116, wherein the throttle map defines the commanded torque value of the first motor and the second motor as a function of the magnitude of movement of the throttle.

118. The patient support apparatus according to claim 117, wherein the throttle map is non-linear.

119. The patient support apparatus according to claim 116, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor based on the load acting on the support structure determined to counteract deviations in a trajectory of the patient support apparatus along the floor surface.

120. The patient support apparatus according to claim 119, wherein the controller is configured to determine at least one of a first gain value and a second gain value based on the load acting on the support structure and scale the commanded torque value for at least one of the first motor and the second motor by the gain value and the second gain value, respectively.

121. The patient support apparatus according to claim 116, wherein the controller is configured to permit a rotational speed differential between the first drive member and the second driveDocket No. 060252.01136 member in response to a caretaker exerting force on the support structure to alter the trajectory of the patient support apparatus along the floor surface.

122. The patient support apparatus according to claim 121, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor in response to the rotational speed differential between the first drive member and the second drive member exceeding a threshold value.

123. The patient support apparatus according to claim 116, wherein the controller is configured to determine an expected speed of the patient support apparatus along the floor surface based on the commanded torque value for the first motor and the second motor, wherein the controller is configured to determine an actual speed of the patient support apparatus along the floor surface based on the speed of the first motor and the second motor, and wherein controller is configured to determine a difference between the actual speed and the expected speed and scale the commanded torque value for the first motor and the second motor by a compensation value where the difference between the actual speed and the expected speed exceeds a predetermined threshold.

124. The patient support apparatus according to claim 116, further comprising an angle sensor operatively attached to the support structure for measuring an angle of the support structure relative to gravity, wherein the controller is configured to adjust the commanded torque value for the first motor and the second motor based on the angle of the support structure relative to gravity.

125. The patient support apparatus according to claim 102, further comprising a second user input control in communication with the controller and arranged for user engagement, wherein the controller is configured to operate the auxiliary drive system based on user engagement with the first user input control and the second user input control.

126. The patient support apparatus according to claim 125, wherein the first user input control is spaced from the second user input control.

127. The patient support apparatus according to claim 126, wherein the first user input control is arranged on a first lateral side of the patient support apparatus, and wherein the second user input control is arranged on a second lateral side of the patient support apparatus, opposite the first lateral side.

128. The patient support apparatus according to claim 125, wherein the second user input control is configured to provide a second user input signal to the controller in response to user engagement with the second user input control.

129. The patient support apparatus according to claim 128, wherein the second user input control comprises a second presence sensor configured to generate the second user input signal in response to the presence of user engagement with the second user input control.

130. The patient support apparatus according to claim 129, wherein the controller is configured to inhibit operation of the auxiliary drive system in response to a lack of user engagement with the second user input control.Docket No. 060252.01136131 . The patient support apparatus according to claim 128, wherein the controller is configured to determine a commanded torque value for the first motor and the second motor based on at least one of the first user input signal and the second user input signal.

132. The patient support apparatus according to claim 131, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor based on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.

133. The patient support apparatus according to claim 128, wherein the controller is configured to operate the auxiliary drive system in a one-handed mode based on user engagement with one of the first user input control and the second user input control, and wherein the controller is configured to operate the auxiliary drive system in a two-handed mode based on user engagement with both of the first user input control and the second user input control.

134. The patient support apparatus according to claim 133, wherein, in the two-handed mode, the controller is configured to determine a commanded torque value for the first motor and the second motor based on the first user input signal; and wherein the controller is configured to determine a rotational speed differential value between the first drive member and the second drive member based on the second user input signal and operate the first motor and the second motor at the rotational speed differential value to differentially turn the patient support apparatus about the floor surface.

135. The patient support apparatus according to claim 133, wherein, in the two-handed mode, the controller is configured to determine a commanded torque value for the first motor based on the first user input signal and determine a commanded torque value for the second motor based on the second user input signal; and wherein the controller is configured to determine a rotational speed differential value between the first drive member and the second drive member based on the first user input signal and the second user input signal and operate the first motor and the second motor at the rotational speed differential value to differentially turn the patient support apparatus about the floor surface.

136. The patient support apparatus according to claim 133, wherein the controller is configured to switch from the one-handed mode to the two-handed mode in response to user engagement with both of the first user input control and the second user input control persisting for a predetermined time period.

137. The patient support apparatus according to claim 133, wherein the controller is configured to switch from the two-handed mode to the one-handed mode is response to a lack of user engagement with one of the first user input control and the second user input control persisting for a predetermined time period.

138. The patient support apparatus according to claim 133, wherein the controller is configured to inhibit switching between the one-handed mode and the two-handed mode where a speed of the patient support apparatus along the floor surface exceeds a predetermined threshold.

139. The patient support apparatus according to claim 128, wherein the controller is configured to determine a commanded torque value for the first motor based on the first user input signal; andDocket No. 060252.01136 wherein the controller is configured to determine a commanded torque value for the second motor based on the second user input signal.

140. The patient support apparatus according to claim 139, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor based on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.

141. The patient support apparatus according to claim 139, wherein the first user input control is arranged for modulation based on user engagement to adjust the first user input signal between a plurality of first user input signal magnitudes.

142. The patient support apparatus according to claim 141, wherein the controller is configured to determine the commanded torque value of the first motor based on the first user input signal magnitude.

143. The patient support apparatus according to claim 142, wherein the first user input control comprises a first throttle arranged for movement in response to user engagement; and wherein the first user input control is configured to generate the first user input signal in response to user engagement with the first throttle, the first user input signal pertaining to a magnitude of movement of the first throttle.

144. The patient support apparatus according to claim 142, wherein the first user input control comprises a first force sensor operatively attached to a first input member arranged for user engagement, and wherein the first force sensor is configured to generate the first user input signal in response to user engagement with the first input member, the first user input signal pertaining to a magnitude of force experienced by the first force sensor in response to user engagement with the first input member.

145. The patient support apparatus according to claim 139, wherein the second user input control is arranged for modulation based on user engagement to adjust the second user input signal between a plurality of second user input signal magnitudes.

146. The patient support apparatus according to claim 145, wherein the controller is configured to determine the commanded torque value of the second motor based on the second user input signal magnitude.

147. The patient support apparatus according to claim 146, wherein the second user input control comprises a second throttle arranged for movement in response to user engagement; and wherein the second user input control is configured to generate the second user input signal in response to user engagement with the second throttle, the second user input signal pertaining to a magnitude of movement of the second throttle.

148. The patient support apparatus according to claim 146, wherein the second user input control comprises a second force sensor operatively attached to a second input member arranged for user engagement, and wherein the second force sensor is configured to generate the second user input signal in response to user engagement with the second input member, the second user input signal pertainingDocket No. 060252.01136 to a magnitude of force experienced by the second force sensor in response to user engagement with the second input member.

149. The patient support apparatus according to claim 128, wherein the controller is configured to determine a commanded torque value for the first motor and the second motor based on the first user input signal; and wherein the controller is configured to determine a rotational speed differential value between the first drive member and the second drive member based on the second user input signal and operate the first motor and the second motor at the rotational speed differential value to differentially turn the patient support apparatus about the floor surface.

150. The patient support apparatus according to claim 149, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor based on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.

151. The patient support apparatus according to claim 149, wherein the first user input control is arranged for modulation based on user engagement to adjust the first user input signal between a plurality of first user input signal magnitudes.

152. The patient support apparatus according to claim 151, wherein the controller is configured to determine the commanded torque value of the first motor and the second motor based on the first user input signal magnitude.

153. The patient support apparatus according to claim 152, wherein the first user input control comprises a first throttle arranged for movement in response to user engagement; and wherein the first user input control is configured to generate the first user input signal in response to user engagement with the first throttle, the first user input signal pertaining to a magnitude of movement of the first throttle.

154. The patient support apparatus according to claim 152, wherein the first user input control comprises a first force sensor operatively attached to a first input member arranged for user engagement, and wherein the first force sensor is configured to generate the first user input signal in response to user engagement with the first input member, the first user input signal pertaining to a magnitude of force experienced by the first force sensor in response to user engagement with the first input member.

155. The patient support apparatus according to claim 149, wherein the second user input control is arranged for modulation based on user engagement to adjust the second user input signal between a plurality of second user input signal magnitudes.

156. The patient support apparatus according to claim 155, wherein the controller is configured to determine the rotational speed differential value between the first drive member and the second drive member based on the second user input signal magnitude.

157. The patient support apparatus according to claim 156, wherein the second user input control comprises a second throttle arranged for movement in response to user engagement; andDocket No. 060252.01136 wherein the second user input control is configured to generate the second user input signal in response to user engagement with the second throttle, the second user input signal pertaining to a magnitude of movement of the second throttle.

158. The patient support apparatus according to claim 156, wherein the second user input control comprises a second force sensor operatively attached to a second input member arranged for user engagement, and wherein the second force sensor is configured to generate the second user input signal in response to user engagement with the second input member, the second user input signal pertaining to a magnitude of force experienced by the second force sensor in response to user engagement with the second input member.

159. The patient support apparatus according to claim 86, wherein the first drive member is configured to rotate about a first axis and the second drive member is configured to rotate about a second axis, and wherein the first axis and second axis are aligned.

160. A patient support apparatus comprising: a support structure including: a base arranged for movement about a floor surface; a litter operatively attached to the base and defining a patient support surface for supporting a patient; an auxiliary drive system operatively attached to the support structure and including: a drive member configured to influence motion of the patient support apparatus over the floor surface, and a motor coupled to the drive member for providing motive power to the drive member; a first user input control operatively attached to the support structure and arranged for user engagement; a second user input control operatively attached to the support structure and arranged for user engagement; and a controller in communication with the auxiliary drive system, the first user input control, and the second user input control, wherein the controller is configured to: operate the auxiliary drive system based on user engagement with at least one of the first user input control and the second user input control, and operate the auxiliary drive system in a two-handed mode based on user engagement with both of the first user input control and the second user input control, and wherein the controller is configured to operate the auxiliary drive system in a one-handed mode based on user engagement with a single one of the first user input control and the second user input control.

161. The patient support apparatus according to claim 160, wherein the drive member is further defined as a first drive member, and the motor is further defined as a first motor, and wherein the auxiliary drive system further includes:Docket No. 060252.01136 a second drive member configured to influence motion of the patient support apparatus over the floor surface, and a second motor coupled to the second drive member for providing motive power to the second drive member.

162. The patient support apparatus according to claim 161, wherein the first user input control is configured to provide a first user input signal to the controller in response to user engagement with the first user input control; wherein the second user input control is configured to provide a second user input signal to the controller in response to user engagement with the second user input control; and wherein the controller is configured to determine a commanded torque value for the first motor and the second motor based on at least one of the first user input signal and the second user input signal.

163. The patient support apparatus according to claim 162, wherein the first user input control is spaced from the second user input control.

164. The patient support apparatus according to claim 163, wherein the first user input control is arranged on a first lateral side of the patient support apparatus, and wherein the second user input control is arranged on a second lateral side of the patient support apparatus, opposite the first lateral side.

165. The patient support apparatus according to claim 162, wherein the controller is configured to determine a commanded torque value for the first motor and the second motor based on the first user input signal; and wherein, in the two-handed mode, the controller is configured to determine a rotational speed differential value between the first drive member and the second drive member based on the second user input signal and operate the first motor and the second motor at the rotational speed differential value to differentially turn the patient support apparatus about the floor surface.

166. The patient support apparatus according to claim 162, wherein, in the two-handed mode, the controller is configured to determine a commanded torque value for the first motor based on the first user input signal and determine a commanded torque value for the second motor based on the second user input signal; and wherein the controller is configured to determine a rotational speed differential value between the first drive member and the second drive member based on the first user input signal and the second user input signal and operate the first motor and the second motor at the rotational speed differential value to differentially turn the patient support apparatus about the floor surface.

167. The patient support apparatus according to claim 162, wherein the first user input control is arranged for modulation based on user engagement to adjust the first user input signal between a plurality of first user input signal magnitudes.

168. The patient support apparatus according to claim 167, wherein the first user input control comprises a first throttle arranged for movement in response to user engagement; andDocket No. 060252.01136 wherein the first user input control is configured to generate the first user input signal in response to user engagement with the first throttle, the first user input signal pertaining to a magnitude of movement of the first throttle.

169. The patient support apparatus according to claim 167, wherein the first user input control comprises a first force sensor operatively attached to a first input member arranged for user engagement, and wherein the first force sensor is configured to generate the first user input signal in response to user engagement with the first input member, the first user input signal pertaining to a magnitude of force experienced by the first force sensor in response to user engagement with the first input member.

170. The patient support apparatus according to claim 162, wherein the second user input control is arranged for modulation based on user engagement to adjust the second user input signal between a plurality of second user input signal magnitudes.

171. The patient support apparatus according to claim 170, wherein the second user input control comprises a second throttle arranged for movement in response to user engagement; and wherein the second user input control is configured to generate the second user input signal in response to user engagement with the second throttle, the second user input signal pertaining to a magnitude of movement of the second throttle.

172. The patient support apparatus according to claim 170, wherein the second user input control comprises a second force sensor operatively attached to a second input member arranged for user engagement, and wherein the second force sensor is configured to generate the second user input signal in response to user engagement with the second input member, the second user input signal pertaining to a magnitude of force experienced by the second force sensor in response to user engagement with the second input member.

173. The patient support apparatus according to claim 161, further comprising a sensing system coupled to the support structure to generate data representing load acting on the support structure in one or more directions; and wherein the controller is configured to adjust a commanded torque value for at least one of the first motor and the second motor based on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.

174. The patient support apparatus according to claim 173, wherein the controller is configured to determine at least one of a first gain value and a second gain value based on the load acting on the support structure and scale the commanded torque value for at least one of the first motor and the second motor by the first gain value and the second gain value, respectively.

175. The patient support apparatus according to claim 174, wherein the controller is configured to permit a rotational speed differential between the first drive member and the second drive member in response to a caretaker exerting force on the support structure to alter the trajectory of the patient support apparatus along the floor surface.Docket No. 060252.01136176. The patient support apparatus according to claim 175, wherein the controller is configured to adjust the commanded torque value for at least one of the first motor and the second motor in response to the rotational speed differential between the first drive member and the second drive member exceeding a threshold value.

177. The patient support apparatus according to claim 161, wherein the first drive member is configured to rotate about a first axis and the second drive member is configured to rotate about a second axis, and wherein the first axis and second axis are aligned.

178. The patient support apparatus according to claim 160, wherein the controller is configured to switch from the one-handed mode to the two-handed mode in response to user engagement with both of the first user input control and the second user input control persisting for a predetermined time period.

179. The patient support apparatus according to claim 160, wherein the controller is configured to switch from the two-handed mode to the one-handed mode is response to a lack of user engagement with one of the first user input control and the second user input control persisting for a predetermined time period.

180. The patient support apparatus according to claim 160, wherein the controller is configured to inhibit switching between the one-handed mode and the two-handed mode where a speed of the patient support apparatus along the floor surface exceeds a predetermined threshold.

181. The patient support apparatus according to claim 160, wherein the first user input control is configured to provide a first user input signal to the controller in response to user engagement with the first user input control; and wherein the second user input control is configured to provide a second user input signal to the controller in response to user engagement with the second user input control; and wherein the controller is configured to determine a commanded torque value for the motor based on at least one of the first user input signal and the second user input signal.

182. The patient support apparatus according to claim 181, wherein the second user input control comprises a second presence sensor configured to generate the second user input signal in response to the presence of user engagement with the second user input control.

183. The patient support apparatus according to claim 182, wherein the controller is configured to inhibit operation of the auxiliary drive system in response to a lack of user engagement with the second user input control.

184. The patient support apparatus according to claim 181, wherein the first user input control is arranged for modulation based on user engagement to adjust the first user input signal between a plurality of first user input signal magnitudes.

185. The patient support apparatus according to claim 184, wherein the first user input control comprises a first throttle arranged for movement in response to user engagement; and wherein the first user input control is configured to generate the first user input signal in response to user engagement with the first throttle, the first user input signal pertaining to a magnitude of movement of the first throttle.Docket No. 060252.01136186. The patient support apparatus according to claim 184, wherein the first user input control comprises a first force sensor operatively attached to a first input member arranged for user engagement, and wherein the first force sensor is configured to generate the first user input signal in response to user engagement with the first input member, the first user input signal pertaining to a magnitude of force experienced by the first force sensor in response to user engagement with the first input member.

187. The patient support apparatus according to claim 181, wherein the second user input control is arranged for modulation based on user engagement to adjust the second user input signal between a plurality of second user input signal magnitudes.

188. The patient support apparatus according to claim 187, wherein the second user input control comprises a second throttle arranged for movement in response to user engagement; and wherein the second user input control is configured to generate the second user input signal in response to user engagement with the second throttle, the second user input signal pertaining to a magnitude of movement of the second throttle.

189. The patient support apparatus according to claim 187, wherein the second user input control comprises a second force sensor operatively attached to a second input member arranged for user engagement, and wherein the second force sensor is configured to generate the second user input signal in response to user engagement with the second input member, the second user input signal pertaining to a magnitude of force experienced by the second force sensor in response to user engagement with the second input member.

190. The patient support apparatus according to claim 181, further comprising a sensing system coupled to the support structure to generate data representing load acting on the support structure in one or more directions; and wherein the controller is configured to adjust the commanded torque value for the motor based on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.

191. The patient support apparatus according to claim 190, wherein the controller is configured to determine a gain value based on the load acting on the support structure and scale the commanded torque value for the motor by the gain value.

192. The patient support apparatus according to claim 160, further comprising a sensing system coupled to the support structure to generate data representing load acting on the support structure in one or more directions; and wherein the controller is configured to adjust a commanded torque value for the motor based on the load acting on the support structure to counteract deviations in a trajectory of the patient support apparatus along the floor surface.

193. The patient support apparatus according to claim 192, wherein the sensing system includes one or more load cell assemblies operatively attached to the support structure, with each of the oneDocket No. 060252.01136 or more load cell assemblies being configured to generate a respective output signal representing the load acting on the support structure; and wherein the controller is configured to determine the load acting on the support structure based on the output signals of each of the one or more load cell assemblies.

194. The patient support apparatus according to claim 193, wherein the one or more load cell assemblies are interposed between the base and one or more support wheels operatively attached to the base for supporting the base for movement relative to the floor surface.

195. The patient support apparatus according to claim 193, wherein the one or more load cell assemblies are interposed between the base and the litter.

196. The patient support apparatus according to claim 193, further comprising a lift mechanism interposed between the base and the litter to move the litter relative to the base between a plurality of vertical configurations.

197. The patient support apparatus according to claim 196, wherein the one or more load cell assemblies are interposed between the base and the lift mechanism.

198. The patient support apparatus according to claim 196, wherein the one or more load cell assemblies are interposed between the litter and the lift mechanism.

199. The patient support apparatus according to claim 193, wherein the one or more load cell assemblies includes four load cell assemblies.

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