Exit detection system with obstacle response

Abstract

Human assist devices, such as beds, stretchers, cot, recliners, and the like, include an egress detection system having a plurality of force sensors that support the weight of a passenger positioned on a support surface and an obstacle detection system having one or more obstacle sensors.SOLUTION: The force sensor is part of an exit detection system that issues an alert when the occupant exits or is about to exit the human assist device. The bed exit system may be responsive to detection of an obstruction. The distribution of weight on the force sensors is used to determine whether the occupant is exiting the human assist device. Compensation is provided to the egress detection system for changes in weight distribution that are not due to occupant movement. Such changes may be due to movement of the human assistive device or components thereof, as well as due to obstacles encountered by the human assistive device or components thereof.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 085,523, filed September 30, 2020, entitled "Obstacle-Responsive Exit Detection System," by inventors Anish Paul et al., the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to human-assist devices such as beds, cots, stretchers, operating tables, recliners, etc. More specifically, the present disclosure relates to human-assist devices that include sensors for detecting obstacles and for detecting when an occupant of the human-assist device has exited or may be attempting to exit the human-assist device. Summary of the Invention [Problem to be solved by the invention]

[0003] Existing hospital beds and / or stretchers often have bed exit systems adapted to detect when a patient has exited the bed or when a patient may be attempting to exit. Typically, such beds have circuitry that provides an audio or visual alert when such an exit or pre-exit condition is detected. Often, the bed or stretcher has circuitry that sends a signal to a remote location, such as a nurse's station, so that appropriate caregivers are notified of the exit or pre-exit condition and can respond appropriately. Existing exit detection systems often rely on analyzing the outputs of multiple load cells. Some existing systems monitor the load cell outputs to calculate the occupant's position and issue an exit alert if the position moves outside a defined area. Other existing systems monitor the load cell outputs and calculate one or more ratios of the forces detected by one or more of the load cells. If one or more ratios change by more than a threshold value, an exit alert is issued. [Means for solving the problem]

[0004] According to various embodiments, the present disclosure provides an improved human-assist device having an exit detection system that responds to obstacle detection. The exit detection system can respond by compensating for the obstacle, disabling the bed exit system until the obstacle is removed, or issuing an exit alert. By taking one or more of these actions, the improved human-assist device can avoid situations in which the exit detection system may experience errors or generate unreliable assessments of the patient's position and / or movement due to an obstacle exerting a force on a force sensor of the exit detection system. That is, a force exerted by an obstacle on a force sensor may be interpreted as a force due to patient movement, potentially leading to a false exit alert being issued when such an alert would be inaccurate or a false no exit alert being issued when such an alert would be accurate. Thus, the improved human-assist device helps overcome issues with the reliability of exit detection systems when an obstacle is encountered.

[0005] In some embodiments, the exit detection system may be configured to automatically attempt to compensate for errors introduced into the force sensor readings from impact with an obstacle. In such embodiments, the compensation may include shifting the patient's calculated center of gravity by an amount equal to the shift caused by contact with the obstacle, and / or (in embodiments in which the exit detection system is configured to issue an alert if the calculated center of gravity falls outside one of the zones) modifying the size, shape, and / or position of one or more zones to account for contact with the obstacle.

[0006] According to one embodiment of the present disclosure, there is provided a human-assist device having a litter frame, a lift system, a support deck, an obstacle sensor, an exit detection system, and a controller. The lift system is adapted to raise and lower the height of the litter frame. The support deck is supported by the litter frame and adapted to support an occupant of the human-assist device. The obstacle sensor is adapted to detect when the litter frame contacts an obstacle during movement of the litter frame. The exit detection system is adapted to be in an equipped state and an unequipped state. When in the equipped state, the exit detection system is adapted to issue an exit alert in response to an occupant of the human-assist device moving in a direction toward exiting the human-assist device. When in the unequipped state, the exit detection system is adapted not to issue the exit alert in response to an occupant of the human-assist device moving in a direction toward exiting the human-assist device. The exit detection system includes a plurality of force sensors adapted to output a signal corresponding to a downward force acting on the litter frame. The controller is in communication with the plurality of force sensors, the exit detection system, and the obstacle sensor. The controller is further adapted to automatically switch the exit detection system from an armed state to a disarmed state in response to the obstacle sensor detecting contact with an obstacle.

[0007] According to another aspect of the present disclosure, the human assist device may be adapted to automatically send a notification to a remote server in response to detecting contact with an obstacle, the notification indicating that the controller has switched the exit detection system to a disarmed state.

[0008] In some embodiments, the controller is further adapted to automatically return the exit detection system from the unarmed state to the armed state in response to the obstacle sensor no longer detecting contact with the obstacle.

[0009] In some embodiments, the obstacle sensors are mounted on the underside.

[0010] In some embodiments, the exit detection system, when in the armed state, is adapted to calculate the occupant's center of gravity, compare the occupant's calculated center of gravity with the boundaries of the zones, and issue an exit alert if the calculated center of gravity is outside the boundaries of the zones. In such embodiments, the controller may be further adapted to modify at least one of the size, shape, or position of the zones in response to movement of a component of the human assist device.

[0011] In some embodiments, the human assistance device may further include a second obstacle sensor, wherein the controller is adapted to automatically switch the exit detection system from an armed state to a disarmed state in response to either the first obstacle sensor or the second obstacle sensor detecting contact with an obstacle.

[0012] According to another embodiment of the present disclosure, there is provided a human-assist device having a litter frame, a lift system, a support deck, an obstacle sensor, an exit detection system, and a controller. The lift system is adapted to raise and lower the height of the litter frame. The support deck is supported by the litter frame and adapted to support an occupant of the human-assist device. The obstacle sensor is adapted to detect when the litter frame contacts an obstacle during movement of the litter frame. The exit detection system is adapted to be in an equipped state and an unequipped state. When in the equipped state, the exit detection system is adapted to issue an exit alert in response to an occupant of the human-assist device moving in a direction toward exiting the human-assist device. When in the unequipped state, the exit detection system is adapted not to issue the exit alert in response to an occupant of the human-assist device moving in a direction toward exiting the human-assist device. The exit detection system includes a plurality of force sensors adapted to output a signal corresponding to a downward force acting on the litter frame. The controller is in communication with the plurality of force sensors, the exit detection system, and the obstacle sensor. The controller is further adapted to automatically issue an exit alert in response to the obstacle sensor detecting contact with an obstacle when the exit detection system is in the armed state.

[0013] According to another aspect of the present disclosure, the controller may be further adapted to not issue an exit alert in response to an obstacle sensor detecting contact with an obstacle when the exit detection system is in a disarmed state.

[0014] In some embodiments, the exit alert includes sending an exit alert message to a remote server.

[0015] In some embodiments, the controller is further adapted to automatically terminate the exit alert in response to the obstacle sensor no longer detecting contact with the obstacle.

[0016] In some embodiments, the controller may be further adapted to issue an obstacle alert in response to the obstacle sensor detecting contact with an obstacle when the exit detection system is in the disarmed state.

[0017] In some embodiments, the human assistance apparatus further comprises a second obstacle sensor adapted to detect when the litter frame contacts an obstacle during movement of the litter frame, and the controller is adapted to automatically issue an exit alert in response to either the obstacle sensor or the second obstacle sensor detecting contact with an obstacle when the exit detection system is in the armed state.

[0018] According to yet another embodiment of the present disclosure, there is provided a human-assist device having a litter frame, a lift system, a support deck, an obstacle sensor, an exit detection system, and a controller. The lift system is adapted to raise and lower the height of the litter frame. The support deck is supported by the litter frame and adapted to support an occupant of the human-assist device. The obstacle sensor is adapted to detect when the litter frame contacts an obstacle during movement of the litter frame. The exit detection system is adapted to be in an equipped state and an unequipped state. When in the equipped state, the exit detection system is adapted to issue an exit alert in response to an occupant of the human-assist device moving in a direction toward exiting the human-assist device. When in the unequipped state, the exit detection system is adapted not to issue the exit alert in response to an occupant of the human-assist device moving in a direction toward exiting the human-assist device. The exit detection system includes a plurality of force sensors adapted to output a signal corresponding to a downward force acting on the litter frame. The controller is in communication with the plurality of force sensors, the exit detection system, and the obstacle sensor. The controller is further adapted to automatically modify operation of the exit detection system in the first manner in response to the obstacle sensor detecting contact with an obstacle when the exit detection system is in the armed state.

[0019] According to other aspects of the present disclosure, the exit detection system may be adapted to operate at a plurality of different sensitivity levels, and the controller may be adapted to modify operation of the exit detection system in a first aspect by switching the exit detection system from a first sensitivity level to a second sensitivity level. In such embodiments, the second sensitivity level is less sensitive than the first sensitivity level so that when operating at the second sensitivity level, the occupant needs to move closer to the edge of the human assist device than would be required to move to trigger an exit alert when operating at the first sensitivity level.

[0020] In some embodiments, the exit detection system, when in an armed state, is adapted to calculate the center of gravity of the occupant, compare the calculated center of gravity of the occupant with the boundaries of the zone, and issue an exit alert if the calculated center of gravity is outside the boundaries of the zone, and the controller is further adapted to modify operation of the first aspect of the exit detection system by modifying at least one of the size, shape, or location of the zone.

[0021] In some embodiments, the controller is adapted to modify operation of the exit detection system in the first aspect by adjusting the calculated center of gravity in a manner that compensates for changes in the signal of the force sensor due to contact with the obstacle.

[0022] In some embodiments, the human assistance apparatus has at least a first obstacle sensor and a second obstacle sensor adapted to detect when different portions of the litter frame contact an obstacle during movement of the litter frame. In such embodiments, the controller may be adapted, when the exit detection system is in the armed state, to automatically change operation of the exit detection system to a second aspect different from the first aspect in response to the second obstacle sensor detecting contact with the obstacle.

[0023] Before describing the various embodiments disclosed herein in detail, it is understood that the claims are not limited to the operational details or to the structural details and arrangement of components set forth in the following description or illustrated in the drawings. The embodiments described herein may be practiced or carried out in alternative ways not expressly disclosed herein. It is also understood that the phraseology and terminology used herein is for purposes of description and should not be regarded as limiting. The use of "having" and "comprising" and variations thereof is intended to encompass the subsequently listed items and their equivalents, as well as additional items and their equivalents. Furthermore, enumerations may be used in describing various embodiments. Unless otherwise expressly stated, the use of enumerations should not be construed as limiting the claims to a particular order or number of components. Nor should the use of enumerations be construed as excluding from the scope of a claim additional steps or components that may be combined with the recited steps or components. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a perspective view of a human assist device in which one or more aspects of the present disclosure may be incorporated.

[0025] [Figure 2] FIG. 2 is a perspective view showing a litter frame of the human assistive device of FIG.

[0026] [Figure 3] FIG. 3 is a perspective view of the base of the human assist device of FIG.

[0027] [Figure 4] FIG. 4 is a block diagram of a control system that can be incorporated into the human assistive device of FIG.

[0028] [Figure 5] FIG. 5 is a side view of one embodiment of an obstacle detection sensor that can be incorporated into the human assist device of FIG.

[0029] [Figure 6] FIG. 6 is an enlarged view of the area labeled A in FIG. 5 showing the obstacle detection sensor in a first state in which it does not detect an obstacle.

[0030] [Figure 7] FIG. 7 is an enlarged view of the area labeled A in FIG. 5 showing the obstacle detection sensor in a second state in which an obstacle is detected.

[0031] [Figure 8] FIG. 8 is a partial perspective view of another obstacle detection sensor that can be incorporated into the human assistance device of FIG. 1 in addition to or instead of the obstacle detection sensors of FIGS.

[0032] [Figure 9] 9 is a bottom view showing the obstacle detection sensor of FIG. 8 with the belly pan removed from the human support device.

[0033] [Figure 10] FIG. 10 is a close-up perspective view of one of the obstacle switches of the obstacle detection sensor of FIGS.

[0034] [Figure 11] FIG. 11 is a flow chart of one embodiment of an exit detection algorithm that may be implemented by an exit detection system for a human assistive device.

[0035] [Figure 12] FIG. 12 is a flow chart of an alternative embodiment of an exit detection algorithm that may be implemented by an exit detection system of a human assist device.

[0036] [Figure 13] FIG. 13 is a flowchart of yet another alternative embodiment of an exit detection algorithm that may be implemented by an exit detection system for a human assist device.

[0037] [Figure 14A] FIG. 14A is a side view of a human support device for explaining the center of gravity of an occupant when no obstacle is detected by an obstacle sensor mounted on the human support device.

[0038] [Figure 14B] FIG. 14B is a side view of the human assist device illustrating the change in the center of gravity of the occupant after an obstacle is detected by the obstacle sensor.

[0039] [Figure 14C] FIG. 14C is a coordinate frame illustrating a first type of compensation that can be applied by the exit detection system to account for differences between the calculated centroids of FIGS. 14A and 14B.

[0040] [Figure 15A] FIG. 15A is a side view of a human support device for explaining the center of gravity of an occupant when no obstacle is detected by an obstacle sensor mounted on the human support device.

[0041] [Figure 15B] FIG. 15B is a side view of the human assist device showing a state in which the center of gravity of the occupant has changed after an obstacle is detected by the obstacle sensor.

[0042] [Figure 15C] FIG. 15C is a coordinate frame illustrating a second type of compensation that may be applied by the exit detection system to account for differences between the calculated centroids of FIGS. 15A and 15B. DETAILED DESCRIPTION OF THE INVENTION

[0043] An exemplary human assist device 20 that may incorporate one or more aspects of the present disclosure is shown in Figure 1. While the particular form of human assist device 20 illustrated in Figure 1 is a bed adapted for use in a hospital or other medical environment, it is understood that human assist device 20, in different embodiments, may be a cot, stretcher, gurney, recliner, operating table, or any other structure capable of supporting a person, whether stationary or mobile and / or medical or residential.

[0044] Generally, the human-assist apparatus 20 includes a base 22 having a plurality of wheels 24, a pair of lifts 26 supported on the base, a litter frame 28 supported on the lifts 26, and a support deck 30 supported on the litter frame 28. The human-assist apparatus 20 also includes a headboard (not shown), a footboard 34, and a plurality of side rails 36. Although the side rails 36 are all shown in a raised position in FIG. 1, the side rails 36 are each independently movable to a lowered position such that entry and exit of the human-assist apparatus 20 is not obstructed by the lowered side rails 36.

[0045] The lifts 26 are adapted to raise and lower the litter frame 28 relative to the base 22. The lifts 26 may be hydraulic actuators, electric actuators, or any other suitable device for raising and lowering the litter frame 28 relative to the base 22. In the embodiment shown in FIGS. 1-3 , the lifts 26 are independently operable to also adjust the tilt of the litter frame 28 relative to the base 22. That is, the litter frame 28 has a head end 38 and a foot end 40, the height of each of which can be independently adjusted by the nearest lift 26. The human assist device 20 is designed so that when an occupant lies on it, the occupant's head is positioned adjacent the head end 38 and the occupant's feet are positioned adjacent the foot end 40.

[0046] The litter frame 28 provides a structure for supporting the support deck 30, a headboard (not shown), a footboard 34, and side rails 36. The support deck 30 provides a support surface for a mattress or other soft cushion (not shown in FIG. 1) so that a person can lie and / or sit on the support deck 30. The upper surface of the mattress or other cushion forms the support surface for the occupant. The support deck 30 is comprised of multiple sections, some of which are pivotable about generally horizontal pivot axes. In the embodiment shown in FIG. 1, the support deck 30 has a head section 42, a seat section 44, a thigh section 46, and a foot section 48. The head section 42, sometimes referred to as the Fowler section, is pivotable about a generally horizontal pivot axis between a generally horizontal orientation (not shown in FIG. 1) and multiple elevated positions (one of which is shown in FIG. 1). The thigh section 46 and the foot section 48 may also be pivotable about generally horizontal pivot axes.

[0047] 1, the support deck 30 is longitudinally movable on the litter frame 28. That is, the support deck 30 is adapted to move on the litter frame 28 toward and away from the head end 38 and the foot end 40. In one embodiment, the human assist apparatus 20 is mechanically configured such that pivoting of the head section 42 about an associated horizontal pivot axis occurs simultaneously with longitudinal movement of the support deck 30 along the litter frame 28. More specifically, in this embodiment, the support deck 30 moves longitudinally along the litter frame 28 toward the foot end 40 when the head section 42 pivots downward toward a flat orientation, and the support deck 30 moves longitudinally along the litter frame 28 toward the head end 38 when the head section 42 pivots upward toward a raised orientation.

[0048] FIG. 2 shows the litter frame 28 in more detail, separated from the lift 26 and base 22. The litter frame 28 is shown in FIG. 2 with the support deck 30 removed. The litter frame 28 is supported by two lift header assemblies 50. A first of the lift header assemblies 50 is coupled to the top 52 ( FIG. 3 ) of a first of the lifts 26, and a second of the lift header assemblies 50 is coupled to the top 52 of a second of the lifts 26. Each lift header assembly 50 has a pair of load cells 54. Thus, the illustrated embodiment of the human assist device 20 has a total of four load cells 54, although those skilled in the art will understand that a different number of load cells may be used in accordance with the principles of the present disclosure. The load cells 54 are configured to support the litter frame 28. More specifically, the load cells 54 are configured to provide complete and exclusive mechanical support for the litter frame 28 and all of the components supported by the litter frame 28 (e.g., the support deck 30, footboard 34, headboard, side rails 36, etc.). Because of this configuration, the load cells 54 are adapted to detect the weight of any object or person supported in whole or in part by the support deck 30, as well as components of the human assist apparatus 20 supported by the litter frame 28 (including the litter frame 28 itself). The output of the load cells 54 is provided to an exit detection system, which is described in more detail below.

[0049] In some alternative embodiments, the human-assist apparatus 20 is configured with a load cell located elsewhere than on the litter frame 28. For example, in at least one alternative embodiment, the human-assist apparatus is configured with a load cell on a base frame mounted to a wheel frame having a structure of the type disclosed in commonly-owned U.S. patent application Ser. No. 16 / 917,004, filed June 30, 2020, by inventors Sukumaran et al., entitled "Human Support Apparatus with Adjustable Exit Detection Zone," the entire disclosure of which is incorporated herein by reference. When the human-assist apparatus is constructed with a base and wheel frame structure of the type disclosed herein, the load cell may be positioned on the wheel frame such that the entire weight of the base frame is supported by the load cell. Still other methods of arranging the load cell on the human-assist apparatus and / or other locations for the load cell may be utilized.

[0050] Additionally, as disclosed in the '004 application, the human assist device 20 can have a feature for expanding the width of the support deck 30 to accommodate patients of various sizes. The width may be adjusted in any increment, for example, between a first or minimum width, a second or intermediate width, and a third or extended / maximum width. The exit detection system of the present disclosure may be configured to automatically adjust in response to the width adjustment feature of the '004 application so that width adjustments do not trigger false occupant exit alerts.

[0051] As shown in Figures 1-3, the mechanical structure of human assist device 20 is similar to that of the Model 3002S3 bed manufactured and sold by Stryker Corporation of Kalamazoo, Michigan. This mechanical structure is described in more detail in the Stryker Maintenance Manual for the MedSurg Bed, Model 3002 S3, published in 2010 by Stryker Corporation of Kalamazoo, Michigan, the entire disclosures of which are incorporated herein by reference. Those skilled in the art will appreciate that human assist device 20 can be designed using other types of mechanical structures, such as, but not limited to, those described in commonly assigned U.S. Patent No. 7,690,059 to Lemire et al., entitled "Hospital Bed," and / or commonly assigned U.S. Patent No. 8,689,376 to Becker et al., entitled "Patient Handling Apparatus with Local Status Display, One-Touch Fowler Angle Adjustment, and Power-On Alarm Settings," the entire disclosures of both of which are incorporated herein by reference. The mechanical structure of the human assist device 20 may take forms different from those disclosed in the aforementioned documents.

[0052] As shown in FIG. 4 , the human-assist device 20 includes a control system 43 that oversees the electromechanical operation of the human-assist device 20. The control system 43 includes an exit detection system 56, one or more obstacle sensors 61, 161, a plurality of other sensors 66a-f, a user interface 62, an alert 64, a nurse call interface 67, and a network transceiver 73. The control system 43 may include additional components not shown in FIG. 4 , such as, but not limited to, one or more motors for driving the lift 26 and / or for moving other components of the human-assist device 20. The control system 43 may also be modified to include fewer components than those shown in FIG. 4 . For example, in some modified embodiments, the control system 43 does not include any of the sensors 66a-f and / or the control system 43 does not include an exit detection system 56 that includes one or more of the sensors 66a-f but utilizes their output. Still other variations are possible.

[0053] The exit detection system 56 is adapted to determine when an occupant, such as, but not limited to, a patient of the human assist device 20, is likely to exit the human assist device 20. More specifically, the exit detection system 56 is adapted to determine when an occupant is likely to exit the human assist device 20 prior to the occupant's actual exit and to issue an alert and / or notification to appropriate personnel so that appropriate action can be taken in a timely manner in response to the occupant's impending exit. The specific structural details of the exit detection system 56 can vary widely. Those skilled in the art will understand that components of the exit detection system 56 can be added to or omitted from one or more of the embodiments of the exit detection system 56 discussed herein.

[0054] In the embodiment shown in FIG. 4 , the exit detection system 56 includes a controller 58 and a plurality of force sensors 60. The exit detection system 56 may be in communication with one or more obstacle sensors 61, 161, a user interface 62, an alert 64, and / or one or more of the sensors 66a-f. The sensors 66a-f may take any of a variety of different forms, including one or more load cells, pressure sensors such as piezoelectric and piezoresistive sensors, Hall-effect sensors, capacitive sensors, resonant sensors, thermal sensors, limit switches, gyroscopes, accelerometers, motion sensors, ultrasonic sensors, distance sensors, potentiometers, magnetostrictive sensors, current sensors, voltage detectors, and / or any other suitable type of sensor performing its related functions. Regardless of the particular form, the sensors 66a-f report outputs to the controller 58, which, in at least some embodiments, uses the outputs to adjust the exit detection system's alert zone, adjust the exit detection system's arming zone, and / or apply compensation factors to either the occupant's calculated center of gravity or one or more ratios of the force sensor 60's output.

[0055] The force sensor 60 is adapted to detect a downward force exerted by an occupant on the support deck 30. Thus, when the occupant is positioned on the support deck 30 and is substantially stationary (i.e., not moving in a manner that involves an acceleration that exerts a force against the support deck 30), the force sensor 60 detects the weight of the occupant (and the weight of any components of the human assist device 20 that are supported directly or indirectly by the force sensor 60). In at least one embodiment, the force sensor 60 is identical to and located in the same position as the load cell 54, as shown in FIG. 2. However, it will be understood by those skilled in the art that the force sensor 60 may be implemented as other types of sensors, such as a linear variable displacement transducer and / or any one or more capacitive, inductive, and / or resistive transducers configured to produce an output that changes in response to changes in force exerted thereon.

[0056] The obstacle sensors 61, 161 are adapted to detect the presence of an obstacle (e.g., chair rail, shelf, window sill, equipment, etc.) in contact with the human-assist device. An obstacle may be anything that slows or impedes the passage or progress of the human-assist device or a portion thereof. In a hospital environment, typical obstacles that may be encountered include medical equipment, patient belongings, furniture, and fixtures. The obstacle is generally represented throughout the drawings by the reference numeral 57; it will be understood by those skilled in the art that the shape, size, and other characteristics of the obstacle may vary, as the obstacle may be essentially any object relative to the human-assist device. It will also be understood that the terms "obstacle" and "hindrance" are used interchangeably herein.

[0057] That is, an obstacle can essentially be any tangible object, fixed or movable relative to the human-assistance device, such that movement of the human-assistance device (or a portion thereof), movement of the obstacle, or a combination of movement of the human-assistance device and the obstacle causes the human-assistance device (or a portion thereof) to become an obstacle. When the human-assistance device encounters an obstacle, one or more of the obstacle sensors 61, 161 detect the obstacle. Details of the obstacle sensors 61, 161 are provided below in conjunction with FIGS. 5-10. Still other types of obstacle sensors may be used with the human-assistance device. Additionally, it is understood that in different embodiments, the number of obstacle sensors can vary, ranging from a single obstacle sensor 61 or 161 (or another type) to four or more obstacle sensors.

[0058] The obstacle sensors 61, 161 can be placed in various locations on the human assist device beyond those shown and described in connection with Figures 5-10 to provide obstacle detection in different areas. While the embodiments of Figures 5-10 utilize switches, it will be understood by those skilled in the art that the obstacle sensors 61 and / or 161 can also be implemented as other types of sensors, such as, but not limited to, any one or more of capacitive, inductive, photoelectric, infrared, ultrasonic, and resistive sensors configured to generate an output that changes in response to changes in force from an obstacle.

[0059] In some embodiments, some or all of the obstacle sensors can take the form of one or more actuator control systems. That is, in some embodiments, obstacle detection can be achieved or supplemented by a controller configuration that monitors the current draw and / or overcurrent conditions of the lift 26 or one or more other actuator systems (e.g., Fowler actuators, knee actuators, and foot actuators) of the human assist apparatus 20. By monitoring the current draw of the lift 26, the controller 58 can interpolate and detect obstacle conditions. For example, when raising the litter frame 28, if the litter frame encounters an obstacle, the current draw of each actuator will begin to increase sharply, eventually exceeding the normal current draw limits for the load. Thus, the controller 58 can identify that an obstacle has been encountered and react accordingly, as described in more detail in connection with the control system. A human assist apparatus implementing this form of obstacle detection is described in U.S. Pat. No. 10,206,834, filed December 2, 2015, by Furman et al., entitled "Obstacle Detection System and Method," the entire disclosure of which is incorporated herein by reference.

[0060] Pivot sensor 66a, in one embodiment, detects a pivot angle between head section 42 and a plane generally defined by litter frame 28. In some embodiments, pivot sensor 66a does not measure this pivot angle directly, but instead measures angle 70 indirectly by measuring the angle of another component of human assist apparatus 20 whose angular orientation has a known relationship to this angle, or by measuring the position of another component of human assist apparatus 20 whose position has a known relationship to this angle.

[0061] Each siderail sensor 66b is adapted to detect whether its associated siderail 36 is in the up or down position. In some embodiments, the siderails 36 are movable to one or more intermediate positions. In those embodiments, the siderail sensors 66b can be adapted to detect whether their associated siderails 36 are in the intermediate positions. In the embodiment of human assist device 20 shown in FIG. 1, there are four siderails 36 and therefore four siderail sensors 66b, each detecting the position of one of the four siderails 36.

[0062] In some embodiments, the siderail sensor 66b can function as an obstacle sensor. For example, in embodiments in which the siderails are electrically actuated, the siderail sensor 66b can monitor current draw and / or overcurrent associated with the actuator system for the siderail and function as the siderail sensor 66b. That is, predicted electrical signal outputs can be monitored for various positions or predicted transitions between upside rail and downside rail positions. If the current draw does not meet a predetermined baseline or other expectation, overcurrents or other patterns in the current draw can supplement or determine obstacle detection. Furthermore, even in non-electrical embodiments in which the siderail sensor can detect movement between two or more positions, an obstacle may be detected by the initiation of a transition from an up (or down) siderail state but the siderail not reaching the target state.

[0063] Alternatively, or in addition to the siderail sensor 66b, each siderail 36 may include one or more obstacle sensors 61, 161. For example, one or more obstacle switches similar to the obstacle sensors described in connection with FIGS. 5-10 may be utilized in connection with the siderail. Such a switch plate may or may not be located along the bottom surface of the siderail to provide a larger surface area for an obstacle to engage and trigger obstacle detection. In operation, if the obstacle switch is located on the bottom surface of the siderail and an obstacle occurs between the siderail 36 and the ground as the siderail moves from the up position to the down position, the obstacle switch is activated and signals the occurrence of the obstacle. An exit detection system (and / or other systems) may respond to the obstacle detection, as described in more detail below.

[0064] The tilt sensor 66c detects the tilt angle 72 of the litter frame 28 relative to the horizontal. In one embodiment, the tilt sensor 66c measures this angle directly. In another embodiment, the tilt sensor 66c includes two sensors that detect the distance each of the lifts 26 is extended and circuitry that calculates the tilt angle of the litter frame 28 relative to the horizontal from these two distances. In yet another embodiment, the tilt sensor 66c takes other forms. One or more additional tilt sensors may also be stepped on that measure the tilt angle of the litter frame 28, which changes as a result of tilting about the longitudinal axis of the human assist apparatus 20 (i.e., as a first side of the litter frame 28 changes height relative to a second side).

[0065] The tilt sensor 66c can function as an obstacle sensor in some embodiments. In such embodiments, the tilt sensor 66c can indicate that an obstacle has encountered the litter frame 28 when the reported angle from the tilt sensor 66c differs from what is predicted for the litter frame 28 (e.g., as determined by the commanded extension of the lift 26). In other words, the control system 43 can calculate the predicted tilt angle of the litter frame 28 from commands given to the lift 26, compare the predicted angle to the angle reported from the tilt sensor 66c, and conclude that an obstacle has been detected if the predicted angle differs from the reported angle by more than a threshold value.

[0066] The orientation sensor 66d detects the orientation angle of a orientation mechanism, such as a powered mattress having one or more inflatable orientation bladders (not shown), used to reorient the occupant of the human assist device 20. In at least one embodiment, the orientation sensor 66d is located inside the mattress (not shown) and directly measures the orientation angle. In other embodiments, the orientation sensor 66d measures one or more inflation pressures of one or more bladders inside the mattress and estimates the orientation angle based on the one or more measured inflation pressures.

[0067] Height sensors 66e detect either the absolute or relative height of litter frame 28. More specifically, in one embodiment, height sensors 66e detect how far each lift 26 has extended from its lowest position. In another embodiment, height sensors 66e detect how high one or more points on litter frame 28 (or any component of human assist apparatus 20 non-movably coupled to litter frame 28) are relative to a reference (e.g., floor, base 22, etc.).

[0068] Position sensor 66f detects the longitudinal position of the support deck 30 relative to the litter frame 28. That is, as described above, in some embodiments, the support deck 30 is longitudinally movable relative to the litter frame 28. In some embodiments, the human-assist apparatus 20 is configured so that the longitudinal position of the support deck 30 relative to the litter frame 28 is directly correlated to the pivot angle of the head section 42. In such embodiments, position sensor 66f and pivot angle sensor 66a may be the same. In yet other embodiments, the human-assist apparatus 20 may be configured so that the longitudinal position of the support deck 30 relative to the litter frame 28 is directly correlated to the position and / or orientation of some other component of the human-assist apparatus, in which case position sensor 66f may be configured to indirectly measure the position of the support deck 30 by measuring the position or orientation of the other component. In other embodiments, the support deck 30 may be positioned in a longitudinally and laterally fixed position relative to the litter frame 28, and position sensor 66f may be omitted.

[0069] All of the sensors 66 communicate with a controller 58 (FIG. 4). The controller 58 may comprise any electrical component or group of electrical components capable of performing the functions described herein. In many embodiments, the controller 58 is a conventional microcontroller, although not all embodiments need include a microcontroller. Generally, the controller 58 may comprise any one or more microprocessors, microcontrollers, field programmable gate arrays, systems on a chip, volatile or non-volatile memory, discrete circuits, and / or other hardware, software, or firmware capable of performing the functions described herein, as known to those skilled in the art. Such components may be physically organized in any suitable manner, such as by being mounted or otherwise arranged on one or more circuit boards, whether combined into a single unit or distributed across multiple units. The instructions followed by the controller 58 in performing the functions described herein, and the data for performing those functions, are stored in memory (unlabeled) accessible to the controller 58.

[0070] The controller 58 also communicates with a user interface 62, which in the embodiment shown in FIG. 1 is implemented as a control panel having a lid (inverted in FIG. 1) on which a number of controls are located. The controls, which may be buttons, dials, switches, or other devices, allow a user to control various aspects of the exit detection system 56. The user interface 62 may also have a display for displaying information regarding the exit detection system 56 and other aspects of the human assist apparatus 20. While FIG. 1 shows the user interface 62 mounted on the footboard 34, it is understood that the user interface 62 may be located elsewhere and / or one or more additional user interfaces may be added to the human assist apparatus 20 in different locations, such as on the siderails 36, to control various aspects of the exit detection system 56 or other systems of the human assist apparatus.

[0071] In one embodiment, the user interface 62 includes controls that allow a user to arm and disarm the exit detection system 56 and also allows the user to select different sensitivity levels used to trigger exit alerts, as discussed in more detail below. In at least some embodiments, the controls allow a user to configure the alert functionality of the exit detection system 56, including selecting among various types of alerts that can be issued by the exit detection system 56. Such types include local alerts (issued at the human assist device 20), remote alerts (issued at a remote location such as a nurse's station, hallway light, or a mobile communication device carried by a staff member), audio alerts, visual alerts, and / or any combination thereof. The user interface may also have various options for configuring the obstacle detection functionality, including both associated alert functionality and other responses to the detection of an obstacle, such as how other systems respond to the detection of an obstacle. In some embodiments, the exit detection system 56 is configurable to respond to obstacle detection in a variety of different ways. Responses can be configured for all obstacle detections or based on a region, area, or specific sensor or set of obstacle sensors.

[0072] In some embodiments, the controller 58 of the exit detection system 56 is adapted to determine the center of gravity of any load applied to the force sensor 60, compare the center of gravity to a zone, and issue an exit alert if the center of gravity moves outside of the zone. In other words, the exit detection system 56 determines the center of gravity of the combined weight of the occupant, the mattress, and / or any objects placed on the support deck 30 or litter frame 28, and the components of the human assist apparatus 20 whose weight is supported by the force sensor 60 (e.g., the litter frame 28, the support deck 30, the side rails 36, etc.), and compares it to a region (i.e., a zone) of allowable positions. If the center of gravity is not within the zone, this indicates patient exit and issues an exit alert. In one embodiment, the exit detection system 56 determines this center of gravity using the system and method disclosed in commonly-owned U.S. Patent No. 5,276,432 by Travis, entitled "Patient Exit Detection for a Hospital Bed," the entire disclosure of which is incorporated herein by reference. Other algorithms may be used in other embodiments.

[0073] In some embodiments, the exit detection system 56 is configured to distinguish between detected changes in the center of gravity of the load due to movement of the occupant relative to the support surface and changes in the detected center of gravity of the load due to movement of one or more components of the human-assist apparatus. Such movements include, but are not limited to, pivoting of one or more sections of the deck 30, tilting of the litter frame 28, longitudinal movement of the support deck 30 relative to the litter frame 28, movement of one or more side rails 36 from an up position to a down position or vice versa, a change in the height of the litter frame 28, and / or therapeutic reorientation of the occupant due to a reorientation device integrated into the mattress or otherwise disposed above the support deck 30. Alternatively, in such embodiments, the exit detection system 56 is configured to determine how much of the change in the output of the force sensor 60 is due to movement of the patient relative to the support surface 31 and how much is due to movement of the components of the human-assist apparatus. The exit detection system 56 may then compensate measurements obtained from the force sensor 60 to account for changes due to movement of the components of the human-assist apparatus 20. The manner in which this compensation may be applied is disclosed in U.S. Patent Application Publication No. 2020 / 0214599 by Kostic, entitled "Exit Detection System With Compensation," the entire disclosure of which is incorporated herein by reference.

[0074] The exit detection system 56, in at least one embodiment, is configured to distinguish between a detected change in the load's center of gravity due to an occupant moving relative to the support deck 30 and a detected change in the load's center of gravity due to an obstacle encountered by the human-assist device. If the obstacle exerts a force on the litter frame 28 or a portion thereof (or any component or portion thereof supported by the litter frame), that force or a component of that force will be detected by the load cells and will introduce an error into the calculation of the patient's center of gravity, thereby changing the load's detected center of gravity. As described in more detail below, this error can be addressed in different ways, such as, but not necessarily limited to, removing the error and / or modifying the size, shape, and / or location of the exit detection alert zone in a manner that addresses the error.

[0075] The change in center of gravity detected by the exit detection system 56 as a result of an obstacle impact can vary. Generally, the exit detection system 56 is configured to detect a change in center of gravity due to pivoting of one or more sections of the deck 30 toward the obstacle, tilting of the litter frame 28 toward the obstacle, longitudinal movement of the support deck 30 relative to the litter frame 28 such that an obstacle encounters the litter frame 28 or a component thereof, movement of one or more side rails 36 from an upper position to a lower position (or vice versa) such that an obstacle exerts an upward or downward force component on one or more of the side rails, and / or a change in height of the litter frame 28 causing the litter frame to experience an upward or downward force component from the obstacle. The exit detection system can also be configured to detect a change in center of gravity due to movement of one or more obstacles relative to the human-assist apparatus or its components (i.e., an obstacle moving in contact with the human-assist apparatus 20, rather than the human-assist apparatus moving in contact with the obstacle).

[0076] The control system 43 includes a nurse call interface 67 and a network transceiver 73. The nurse call interface 67 is adapted to communicatively couple to a conventional nurse call system so that the controller 58 can transmit information to the nurse call system, such as, but not limited to, an exit alert. In many embodiments, the nurse call interface 67 is adapted to transmit information to the nurse call system by opening and closing one or more relays that are electrically coupled to pins of a 37-pin wall outlet located in the headwall of a typical patient room. Further details regarding different embodiments of the nurse call interface 67 are provided below.

[0077] Network transceiver 73 may be a wireless transceiver adapted to communicate with one or more wireless access points of a healthcare facility's local area network. In some embodiments, transceiver 73 may be a WiFi transceiver adapted to transmit and receive wireless electrical signals using any of the various WiFi protocols (e.g., IEEE 802.11b, 802.11g, 802.11n, 802.11ac, etc.). In other embodiments, network transceiver 73 may be a transceiver adapted to communicate using any of the frequencies, protocols, and / or standards disclosed in commonly assigned U.S. patent application Ser. No. 62 / 430,500, filed Dec. 6, 2016, by inventor Michael Hayes and entitled "Network Communications for a Patient Assist Device," the entire disclosure of which is incorporated herein by reference. In yet another embodiment, the transceiver 73 may be a wired transceiver that communicates with the medical facility local network via a wired connection, such as an Ethernet cable, etc. Whether the transceiver 73 is a wired or wireless transceiver, it enables the controller 58 to communicate with one or more servers on the medical facility's computer network.

[0078] 5-7 illustrate a first type of obstacle detection sensor 61 that can be incorporated into the human-assistance device 20. In this embodiment, the obstacle sensor 61 includes a plunger-type obstacle switch 55 and a switch plate 53 configured to cooperate to detect and transmit one or more obstacle detection signals in response to encountering an obstacle. The obstacle detection sensor 61 is mounted on the litter frame 28 or footboard 34 near the foot end 40 of the human-assistance device 20. While the obstacle sensor 61 of FIGS. 5-7 includes a single obstacle switch 55, it will be understood by those skilled in the art that different numbers and types of obstacle sensors, associated components, and combinations thereof may be used in accordance with the principles of the present disclosure. For example, in alternative embodiments, the obstacle sensor 61 can be implemented with one or more lever-type switches. Additionally, capacitive, inductive, photoelectric, ultrasonic, resistive, or other types of sensors configured to generate a varying output in response to changes in force from an obstacle may be utilized as an obstacle sensor in place of the obstacle switch 55, with or without the use of a switch plate 53 or other sensor-enhancing components.

[0079] The switch 55 is mounted toward the bottom of the footboard 34 so that the switch plunger protrudes past the bottom surface of the footboard 34 and through an opening in the litter frame 28. Figure 6 shows the switch 55 and switch plate 53 in an inactive state when no obstacle is present. Figure 7 shows the activated state when an obstacle 57 physically displaces the switch plate 53, depressing the plunger of the switch 55 (not visible in Figure 7). The switch plate 53 is pivotable about a generally horizontal pivot axis between a resting acute angle below the bottom surface of the footboard 34 (Figure 6) and a range of positions (one of which is shown in Figure 7) raised toward the bottom surface of the footboard 34. The pivot axis may be provided by a hinge 59 or other flexible joint mounted toward the foot end of the bed, such as the footboard 34 or the bottom of the litter frame 28. The switch plate 53 extends diagonally downward from the underside of the litter frame 28 when no obstacle is encountered (Figure 6). That is, hinge 59 is configured to extend diagonally from the underside of footboard 34 such that switch plate 53 clears the plunger of switch 55 in a normal, resting state when no obstacles are present. The switch plate is positioned below litter frame 28 so as not to come into contact with base 22 of human-assistance apparatus 20. Specifically, switch plate 53 is positioned outside the footprint of base 22 of the human-assistance apparatus to ensure that it will not be triggered (forced upward) by contact with base 22. This is true regardless of whether the litter frame is in a longitudinally extended or retracted position, and regardless of whether litter frame 28 is in Trendelenburg, reverse Trendelenburg, or any other available configuration. In an alternative embodiment, switch plate 53 may be positioned within the footprint of base 22 with a physical structure that prevents human-assistance apparatus 20 or its components from contacting the outward-facing surface of switch plate 53 (i.e., the surface shown engaging obstacle 57 in FIG. 7 ) during normal operation.Additionally or alternatively, the movement of the human assist device may be limited by the controller to ensure that the human assist device 20 or its components cannot contact the switch plate 53 during normal operation.

[0080] When an obstacle 57 forces switch plate 53 upward, the switch plate pivots to a generally flat orientation ( FIG. 7 ) relative to litter frame 28. That is, when obstacle 57 encounters human-assist device 20 (e.g., by human-assist device movement, obstacle movement, or both), switch plate 53 is physically displaced by the obstacle, causing switch 55 to pivot toward the bottom of footboard 34 to which switch 55 is attached. After switch plate 53 applies sufficient force to physically depress the plunger of switch 55, the switch activates and transmits one or more electrical signals indicating the detection of an obstacle. The signals are transmitted to controller 58 located on human-assist device 20 for processing. Thus, if litter frame 28 is lowered and switch plate 53 contacts an obstacle, switch plate 53 compresses the switch after sufficient force is applied, causing switch 55 to transmit a signal to controller 58.

[0081] For the structure shown in FIGS. 5-7 and described herein, the obstacle switch 55 is adapted to detect the presence of any obstacle that physically displaces the switch by a threshold amount sufficient to trigger or activate the switch. Thus, the absence of an obstacle can also be detected by the lack of physical displacement above the threshold or the lack of any physical displacement at all. In this embodiment, the output of the obstacle switch 55 is provided to a controller, such as the controller of the exit detection system described in more detail below. The output of the obstacle switch 55 can also be provided to other systems instead of or in addition to the exit detection system. Some embodiments may include an operation interruption system that prevents movement of the human-assistance device or a component of the human-assistance device, such as the litter frame, in response to the obstacle detection signal. For example, the operation interruption system, when triggered by the detection of an obstacle or other object, can prevent the litter frame 28 from being further lowered or other operations from being performed in a manner that would exacerbate the encounter between the obstacle and the human-assistance device.

[0082] In this embodiment, switch 55 provides a single output signal indicating whether an obstacle is present. The switch is configured to activate in response to a force above a predetermined force threshold being applied to the plunger, causing the switch to generate a single output. Therefore, a single output signal indicating whether an obstacle is present can be provided without the need to compare multiple sensor signals. In alternative embodiments, switch 55 can provide one or more output signals, including non-binary output signals, such as values ​​indicative of various switch characteristics (e.g., an obstacle detection signal indicative of plunger travel, plunger position, actuation force, total travel force, displacement, or other characteristics). As will be appreciated by those skilled in the art, the dimensions and other mechanical characteristics of switch 55, along with its operating characteristics, can vary with its circuitry depending on the application. In this embodiment, switch 55 is a plunger-type miniature door switch with a 9 mm long stroke. This switch can be implemented in double-throw, normally closed, normally open, or other configurations.

[0083] The illustrated embodiment of Figures 5-7 only has a single obstacle sensor in the form of switch 55 and switch plate 53. This allows for obstacle detection proximate the bottom of the foot end 40 of the bed. In some embodiments, obstacle sensors can be placed or mounted elsewhere on the human assist apparatus 20 to provide additional obstacle detection signals indicative of obstacle encounters elsewhere on the human assist apparatus. Multiple obstacle sensors can be mounted relatively close together to provide increased obstacle detection accuracy, sensitivity, or to provide additional information regarding obstacles encountered in particular areas of the human assist apparatus or the characteristics of encounters between the human assist apparatus 20 and obstacles.

[0084] An example of an alternative obstacle detector 161 is shown in more detail in FIGS. 8-10. The obstacle detector 161 differs from the obstacle detector 61 primarily in the location at which it is attached to the human assistance device 20. As shown in FIG. 8, the obstacle detector 161 is located in a generally central region of the underside of the litter frame 28. The obstacle detector 161 includes four lever-type obstacle switches 65 and a belly pan 63 (FIGS. 8-10). The switches 65 and the belly pan 63 are configured to cooperatively detect and transmit one or more obstacle detection signals in response to encountering an obstacle. While the obstacle detection sensor 161 of FIGS. 8-10 includes four obstacle switches 65, those skilled in the art will understand that different numbers and types of obstacle sensors, associated components, and combinations thereof may be used in accordance with the principles of the present disclosure.

[0085] 9 shows a bottom view of the mounting plate 69 joined to the litter frame 28 with all four switches 65 installed and the belly pan 63 removed. In the illustrated embodiment, the switches 65 are installed in four openings 71 at the corners of the mounting plate 69 such that the lever of each switch 65 extends beyond the bottom face of the mounting plate 69 and through a corresponding opening 71.

[0086] Figure 10 shows a close-up of one of the corners of plate 69, showing the lever of switch 65 extending and protruding through opening 71 in plate 69. Mounting plate 69 may be one piece or multiple sections. In the embodiment shown in Figures 8-10, mounting plate 69 is a two-hinged electrical plate cover attached to the mid-bed section spanning between the two perimeter longitudinal rails of litter frame 28.

[0087] A vacuum-formed floating belly pan or cover 63 acts as an actuation barrier for obstructions and subsequent actuation of the underlying obstruction switches 65. Four switches 65 mounted near the outermost corner locations of the mounting plate 69 are covered by the belly pan 63, which also covers the hinged electrical plate 69 below the litter frame 28, perhaps best seen in FIG.

[0088] The floating cover 63 shown in FIG. 8 , when attached and restrained to the underside of the litter frame as shown, is mounted so as to float relative to the plate 69 of the litter frame 28 and move in the Z direction (up and down). As a result, the belly pan 63 acts on and activates any one or combination of the four lever switches 65 when forced upward by an encountered obstacle. For example, an obstacle may be located below the litter frame 28 within the footprint of the base such that the belly pan 63 encounters or encounters the obstacle as the litter frame 28 is lowered. Encountering an obstacle (not shown) with the pan 63 forces the pan 63 upward, compressing one or more of the four switches 65, which in turn sends a signal to a microcontroller, such as the controller 58 onboard the human assist device 20. A control system can be configured with logic for utilizing the obstacle signal, as described in more detail below. Suffice it to say that the control system can be configured to respond to obstacle detection by, for example, changing the functionality or adjusting one or more characteristics of the bed exit detection system.

[0089] Depending on the size and location of the obstacle, some, but not all, of the obstacle switches 65 may or may not be activated simultaneously. That is, an obstacle may be encountered toward one of the corners, such that only one lever switch is engaged when the belly pan 63 is pushed upward. This is due to the floating configuration of the belly pan. The controller can be configured to infer the location of the obstacle and / or other information about the obstacle based on which switches are activated. That is, the controller can be configured to associate the output of the obstacle switches 65 with the physical area of ​​the human assist device. Thus, information about where the obstacle will be encountered can be inferred based on which switches are activated and which are not. For example, if one obstacle switch is activated without the others being activated, the location of the obstacle can be inferred to be the area associated with the location of the activated switch. Or, if two or more obstacle switches are triggered, the location of the obstacle can be inferred to be the collective area associated with the locations of the triggered switches. This information can be used to alert staff about the obstacle encounter. This information can also be used to perform targeted maintenance and repairs on the human assist device.

[0090] Additionally, the controller may be configured to infer movement information related to the encounter based on the timing (e.g., timestamps) of the obstacle switches' activations. That is, the order in which the switches are activated generally indicates the movement associated with the encounter. When the timing of the obstacle switches' activations is combined with the human assist device's movement data (e.g., lift system activation), the controller may be configured to determine additional information related to the cause of the obstacle encounter, which may be recorded and / or otherwise provided to the human assist device operator or other personnel.

[0091] The exit detection system 56 is configured to cooperate with the obstacle detection sensors 61 and / or 161. That is, the exit detection system 56 is configured to utilize the output from one or more obstacle detectors 61, 161 and to alter operation in one or more ways in response to an obstacle being detected, and possibly, in response to an obstacle no longer being detected. In some embodiments, the exit detection system 56 is configured to respond to the detection of an obstacle by one of three different ways: (1) automatically disarming the exit detection system (if previously armed) in response to an obstacle being detected, (2) automatically triggering an exit alert in response to an obstacle being detected, or (3) automatically adjusting the calculations used to determine whether to issue an exit alert, the adjustment accounting for and removing changes in the load cell output that result from contact with the obstacle and that create errors in the calculated center of gravity of the patient. Each of these three different ways of responding is described in further detail with respect to algorithm 1200 of FIG. 11 , algorithm 1300 of FIG. 12 , and algorithm 1400 of FIG. 13 .

[0092] 11 , the controller 58 is configured to execute an algorithm 1200. In this particular embodiment, the exit detection system 56 is configured to automatically disarm itself in response to the obstacle sensors 61 and / or 161 detecting contact with an obstacle. The exit detection algorithm 1200 begins at a first step 1202 when the exit detection system 56 is armed, for example, by a user operating one or more controls on the user interface 62. After being armed at step 1202, the controller 58 proceeds to step 1204, where the controller 58 is configured to determine whether an obstacle is currently being encountered. This can be done by reviewing obstacle sensor data or requesting current sensor readings from one or more obstacle sensors. If an obstacle is present, then at step 1222, the bed exit detection system 56 is configured to activate an obstacle alert. The obstacle alert may be issued locally (by light, sound, and / or display of selective content on a display onboard the human assist device 20) and / or remotely, such as by sending a notification message to a remote server and / or other recipient. Additionally, in this embodiment, the bed exit system is automatically disarmed in step 1224, which ensures that an obstacle does not issue a false positive bed exit system notification due to inaccuracies introduced into the force sensor where the obstacle is either adding weight to or subtracting weight from the load cell 54.

[0093] If no obstacles are present, the system proceeds to calculate an initial center of gravity for the occupant of the human assist device 20. This calculation is performed using known mathematical techniques for calculating the center of gravity and knowledge of the relative position of the force sensor 60. Although other coordinate systems can be used, the controller 58 calculates the center of gravity using a planar coordinate system 86 (FIGS. 14C, 15C) having an x-axis 88 generally parallel to the foot end 40 of the support deck 30 and a y-axis 90 generally parallel to the side of the support deck 30. Other coordinate systems can also be used. Regardless of which coordinate system is used, the controller 58 knows the location of the force sensor 60 in the particular coordinate system used. In the example shown in FIG. 14C, the force sensor 60 is shown at a known position 87.

[0094] After determining the occupant's center of gravity in step 1206, controller 58 proceeds to step 1208, where it determines initial values ​​for one or more parameters of human assist device 20. More specifically, in the embodiment shown in FIG. 11 , controller 58 determines the following values ​​in step 1208: the current value of pivot angle 70, the current value of tilt angle 72, the current value of swivel angle 74, a current value corresponding to the current relative longitudinal position of support deck 30 of litter frame 28, the current value of height 78, and a current value indicating the current position (up, down, or middle) of each side rail 36. Those skilled in the art will appreciate that in other embodiments, algorithm 1200 can be modified to determine fewer or more of these values. Indeed, in other embodiments, controller 58 can determine any one or more of these values ​​in step 1208, or can determine additional values.

[0095] After completing step 1208, controller 58 proceeds to step 1210 (FIG. 11) to determine whether the occupant's center of gravity determined in step 1206 is outside a predefined zone. The predefined zone, in one embodiment, is defined in coordinate system 86 and, in at least one embodiment, is the trigger that controller 58 uses to determine whether to issue an exit alert. In the illustrated embodiment, the zone is generally rectangular or square in shape, although other types of zones may be used. If the occupant's center of gravity is outside the zone, controller 58 issues an alert in step 1226. If the occupant's center of gravity is not outside the zone, controller 58 proceeds to step 1212, which is generally identical to step 1204, to determine whether an obstacle is present based on obstacle sensor 61, and if so, activates an obstacle alert in step 1222 and disarms the bed exit system in step 1224.

[0096] If no obstacle is present, controller 58 proceeds to step 1216 (FIG. 11). In step 1216, controller 58 determines whether any of the initial values ​​obtained in step 1208 have changed during the interim period between steps 1208 and 1216. More specifically, in the illustrated embodiment, in step 1216, controller 58 determines whether any of the following have changed: the value of pivot angle 70, the value of each side rail 36 position (e.g., up, down, and / or middle), the value of tilt angle 72, the value of steering angle 74, the height value 78, and the position value corresponding to the current relative longitudinal position of support deck 30 of litter frame 28. In step 1216, controller 58 determines these values ​​based on measurements from pivot sensor 66a, side rail sensor 66b, tilt sensor 66c, swivel sensor 66d, height sensor 66e, and position sensor 66f, respectively.

[0097] If none of these values ​​have changed since they were initially obtained in step 1208, the controller 58 proceeds to step 1210, as described above. If, in step 1216, the controller 58 determines that one or more of the initial values ​​(from step 1208) have changed, the controller 58 proceeds to step 1218, where it determines one or more compensation factors corresponding to the changed values. That is, in step 1218, the controller 58 calculates compensation factors for all changed values. Thus, for example, in step 1218, if both the pivot angle 70 and the height 78 are different from their initial values ​​in step 1208, the controller 58 calculates a pivot angle compensation factor and a height compensation factor. Generally, in step 1218, the controller 58 calculates one or more compensation factors that provide an estimate of the extent to which the center of gravity measurement obtained in step 1218 has been affected by factors other than the movement of the occupant relative to the support deck 30.

[0098] Once the compensation factors have been calculated, the controller 58 proceeds to step 1220 and applies the compensation factor(s) to the center of gravity calculated in step 1206. The result is a center of gravity calculation that is largely free of changes in the center of gravity due to movement of one or more components of the human assist device 20 or other influences not resulting from the occupant changing their weight distribution on the support deck 30 or support surface 31. As a result, the compensated center of gravity calculation performed in step 1220 substantially corresponds to the occupant's center of gravity. The controller 58 then proceeds to step 1210 and determines whether the occupant's center of gravity (i.e., the compensated center of gravity calculated in step 1220) is inside or outside a zone that defines an exit alert condition. If outside the zone, an alert is issued in step 1226. If inside the zone, to the extent that no alert is issued and the exit detection system 56 is not shut down, control returns to step 1212 where the system checks whether an obstacle has been encountered. The manner in which controller 58 determines and applies the compensation factors in steps 1216, 1218, and 1220 is disclosed in commonly-assigned U.S. Patent Application Publication No. 2020 / 0214599 by Kostic, entitled "Exit Detection System With Compensation," the entire disclosure of which is incorporated herein by reference. Alternatively, controller 58 may be modified to not calculate and / or apply any of the compensation factors in steps 1216, 1218, and 1220, and instead skip these steps.

[0099] 11 , it is understood that algorithm 1200 includes an additional step, at least in some embodiments, of automatically re-arming exit detection system 56 when an obstacle is no longer detected. That is, after disarming exit detection system 56 in response to detecting contact with an obstacle, controller 58 repeatedly checks whether contact with the obstacle persists. If so, the exit detection system remains disarmed. If the obstacle is removed and / or one or more components of human assist device 20 are moved such that contact with the obstacle no longer persists, controller 58 is configured to automatically disarm exit detection system 56.

[0100] It is also understood that algorithm 1200 may be modified as part of step 1224 to automatically send a message via network transceiver 73 to a server coupled to the healthcare facility's local area network. This message indicates that exit detection system 56 has been disarmed. Thus, in addition to disarming exit detection system 56 in response to detecting an obstacle, controller 58 may be configured to automatically send a message to a remote server notifying it that exit detection system 56 has been automatically disarmed. Furthermore, if controller 58 is configured to automatically re-arm exit detection system 56 when an obstacle is no longer detected, controller 58 may be further configured to automatically send a message via network transceiver 73 to the server indicating that exit detection system 56 has been re-armed. The server receiving these messages may be a server running a caregiver assistance application of the type disclosed in commonly assigned International Patent Application PCT / US2020 / 039587, filed June 25, 2020, entitled "Caregiver Assistance System," the entire disclosure of which is incorporated herein by reference.

[0101] In an alternative embodiment, instead of automatically disabling (i.e., disarming) the exit detection system 56 in response to detecting an obstacle, the exit detection system 56 can be configured to automatically issue an exit detection alert in response to detecting contact with an obstacle. An example of such an embodiment is shown in FIG. 12. FIG. 12 illustrates an exit detection algorithm 1300 executed by the controller 58 of the exit detection system 56 in at least one embodiment. The exit detection algorithm 1300 begins at an initial step 1302 when the exit detection system 56 is armed. After being armed at step 1302, the controller 58 proceeds to step 1304, where the controller 58 is configured to determine whether an obstacle has been encountered. If an obstacle is present, then at step 1322, the bed exit detection system 56 is configured to activate an obstacle alert. From step 1322, the controller 58 proceeds to step 1326, where it activates the exit alert of the exit detection system 56.

[0102] In some modified embodiments, algorithm 1300 may be modified to omit step 1322 and skip directly from step 1304 to step 1326 when an obstacle is detected. In such modified embodiments, controller 58 does not issue a separate obstacle alert when an obstacle is detected and exit detection system 56 is armed, but instead issues only an exit alert. Further, in such modified embodiments, controller 58 is configured to issue an obstacle detection alert if exit detection system 56 is not armed and obstacle detection sensor 61 detects contact with an obstacle. Thus, in such embodiments, controller 58 is configured to issue an exit detection alert when exit detection system 56 is armed and an obstacle is contacted, and to issue an obstacle alert when exit detection system 56 is disarmed and an obstacle is contacted.

[0103] It is understood that the distinction between an exit alert and a fault alert can take a variety of different forms. Generally, an exit alert is always communicated to the healthcare facility's nurse call system via the nurse call interface 67 built into the human assist device 20. If the nurse call interface 67 is coupled to the nurse call system via a cable, communication of the exit alert to the nurse call system is typically accomplished by opening or closing one or more relays on the nurse call interface 67 that are in electrical communication with corresponding pins on a nurse call outlet integrated into the healthcare facility's headwall. If the nurse call interface 67 is coupled to the nurse call system via wireless communication, communication of the exit alert to the nurse call system may also be accomplished by sending a wireless signal to a wall-mounted headwall module that, in response, opens or closes one or more relays in electrical communication with the pins on the nurse call outlet.Further details regarding how the nurse call interface 67 may communicate the exit alert to a nurse call system via a cable or wirelessly are found in the following commonly assigned U.S. patent applications: U.S. patent application Ser. No. 62 / 896,075, filed September 5, 2019, by Alexander Bodurka et al., entitled "Patient Assistance Device With Nurse Call Connection Detection"; U.S. patent application Ser. No. 15 / 945,437, filed April 4, 2018, by inventors Krishna Bhimavarapu et al., entitled "Patient Assistance Device With Reconfigurable Communication"; U.S. patent application Ser. No. 14 / 819,844, filed August 6, 2015, by inventors Krishna Bhimavarapu et al., entitled "Patient Assistance Device With Wireless Headwall Communication"; U.S. Patent Application No. 16 / 215,911, filed December 11, 2018, by inventor Alexander Bodurka et al., entitled "Hospital Headwall Communication"; U.S. Patent Application No. 62 / 833,943, filed April 15, 2019, by inventor Alexander Bodurka et al., entitled "Patient Support Device with Nurse Call Voice Management"; U.S. Patent Application No. 16 / 215,911, filed December 11, 2018, by inventor Alexander Bodurka et al., entitled "Hospital Headwall Communication System"; U.S. Patent Application No. 16 / 217,203, filed December 12, 2018, by inventor Alexander Bodurka et al., entitled "Smart Hospital Headwall System"; and U.S. Patent Application No. 16 / 217,203, filed December 12, 2018, by inventor Alexander Bodurka et al. No. 16 / 193,150, filed November 16, 2018, by Bodurka et al., entitled "Patient Assistance Device with Position / Movement Sensing," the entire disclosure of which is incorporated herein by reference.

[0104] In some embodiments of the human assist device 20, the exit alert is transmitted wirelessly to one or more servers via another communication channel. In such embodiments, the controller 58 is configured to utilize the network transceiver 73 to transmit a notification to a server on the healthcare facility's local area network. The notification indicates that the exit alert has been issued. In some embodiments, the server may forward the notification to one or more portable electronic devices carried by one or more caregivers associated with the healthcare facility. Alternatively, or additionally, the exit detection alert may be forwarded to one or more servers located remotely from the healthcare facility and not part of the healthcare facility's local area network. Such forwarding may occur via an Internet gateway, router, or other conventional network appliance that communicatively couples the local area network to the Internet.

[0105] In some embodiments, the obstacle detection alert is only a local alert, including one or more of a sound or light emanating from the human assist device 20. Furthermore, such a local alert may include displaying a message on the electronic display of the human assist device. The message may indicate that an obstacle has been detected. In some embodiments, the controller 58 may be configured to send a notification message to a server in the healthcare facility's network indicating that an obstacle has been detected. This obstacle notification message may be forwarded to one or more other servers and / or one or more portable electronic devices carried by one or more caregivers. The obstacle alert is not issued via the nurse call interface 67 because a typical nurse call outlet does not have a pin (or set of pins) through which this information can be communicated. However, if the human assist device 20 is coupled to a nurse call system that can communicate this information, the controller 58 may be configured to send the obstacle alert via the nurse call interface 67.

[0106] In embodiments in which controller 58 transmits obstacle and / or exit alerts via network transceiver 73 to a server on a local area network, the server may be a server running a caregiver assistance application of the type disclosed in commonly owned International Patent Application PCT / US2020 / 039587, filed June 25, 2020, entitled "Caregiver Assistance System," the entire disclosure of which is incorporated herein by reference. In such embodiments, the caregiver assistance system may forward the exit and / or obstacle detection alerts to designated portable electronic devices (and / or stationary electronic devices) so as to notify caregivers associated with these devices of the obstacle detection and / or exit alerts.

[0107] In some embodiments of the human assist device 20, the controller 58 is configured to send an exit alert message to a remote server via the network transceiver 73 when an obstacle is detected, but to include information in the notification message indicating that the exit alert is due to an obstacle being detected and not due to an occupant exiting the human assist device 20. In this manner, a message forwarded by the server to the portable electronic device carried by the medical personnel indicates that the exit alert is caused by an encountered obstacle and not due to an occupant exiting.

[0108] 12 and algorithm 1300, if no obstacle is detected at step 1304, the system proceeds through steps 1306, 1308, 1310, 1312, 1316, 1318, and 1320, which, except as noted below, are identical to steps 1206, 1208, 1210, 1212, 1216, 1218, and 1220, respectively, of algorithm 1200 and therefore need not be described again. The only step in this set of steps of algorithm 1300 that differs from the corresponding set of steps in algorithm 1200 is step 1312. If, at step 1312, obstacle detection sensor 61 detects an obstacle, controller 58 proceeds to step 1326 of algorithm 1300, where controller 58 issues an exit detection alert. This differs slightly from step 1212 of algorithm 1200 in that when an obstacle is detected, controller 58 proceeds to steps 1222 and 1224 where it issues an obstacle alert and disables exit detection system 56.

[0109] Although not shown in FIG. 12 , it is understood that algorithm 1200, in at least some embodiments, includes an additional step of automatically deactivating the exit alert when an obstacle is no longer detected. That is, after activating the exit alert in response to detecting contact with an obstacle, controller 58 repeatedly checks whether contact with the obstacle persists. If so, controller 58 continues to issue the exit alert. If the obstacle is removed and / or one or more components of human assist apparatus 20 are moved such that contact with the obstacle no longer persists, controller 58, in at least some embodiments, is configured to automatically terminate the exit alert. This automatic termination may occur substantially immediately (e.g., within one or two seconds) after the obstacle is no longer detected or may occur after a predetermined delay period has expired. In some embodiments, the predetermined period may be configurable by the user.

[0110] In other embodiments, the exit detection system 56 is configured to respond to obstacle detection by compensating for errors introduced into the load cell measurements by the obstacle so that the bed exit system can continue to operate in an accurate manner despite the obstacle. In one example of such an exit detection system, the controller 58 is configured to execute an exit detection algorithm 1400, as shown in FIG. 13 . The exit detection algorithm 1400 begins at an initial step 1402, for example, when a user arms the exit detection system 56 by manipulating one or more controls on the user interface 62. From step 1402, the controller 58 proceeds to step 1404, where the controller 58 checks the output from one or more obstacle detectors onboard the human assist device 20 (e.g., 61, 161, and / or other(s)) to determine whether contact has been made with an obstacle. If such contact is detected by any one or more of the obstacle detection sensors, the controller 58 proceeds to step 1422, where the controller 58 issues an obstacle alert. The obstacle alerts are of the same type as the obstacle alerts issued in the other algorithms 1200 and / or 1300 described above.

[0111] From step 1422, the controller 58 proceeds to step 1430, where the controller 58 makes adjustments to the operation of the exit detection system 56 designed to account for force components detected by the force sensors 60 that result from contact with an obstacle. In other words, in step 1430, the controller 58 makes adjustments to the operation of the exit detection system 56 designed to remove or adjust for errors introduced into the calculation of the occupant's center of gravity due to the obstacle exerting a force on one or more of the force sensors 60. As discussed in more detail below, the controller 58 may be configured to perform step 1430 in a variety of different ways.

[0112] In a first aspect, shown in more detail in FIGS. 14A-14C , the controller 58 is adapted to adjust the operation of the exit detection system 56 by shifting the occupant's calculated center of gravity to eliminate the effect of obstacles on measurements from the force sensors 60. In a second aspect, shown in more detail in FIGS. 15A-15C , the controller 58 is adapted to adjust the operation of the exit detection system 56 by modifying one or more thresholds to which the controller 58 compares the processed output of the force sensors 60. For example, in embodiments of the exit detection system 56 in which the controller 58 compares the occupant's center of gravity to zones (and issues an exit alert if the center of gravity is outside the zones), the controller 58 may adjust the size, shape, and / or location of the zones in response to detecting an obstacle. In other embodiments, such as when the exit detection system 56 does not use zones and compares ratios of the outputs of the force sensors 60, the controller 58 may be configured to modify the thresholds to which such ratios are compared, as discussed in more detail below. In a third aspect, controller 58 may be configured to combine the adjustments shown in Figures 14A-14C with the adjustments shown in Figures 15A-15C to adjust the center of gravity calculation and change the size, shape, and / or location of one or more zones. Each of these different aspects of responding to obstacles is discussed in further detail below.

[0113] Turning to a first manner in which the controller 58 may coordinate the operation of the exit detection system 56 at step 1430 of the algorithm 1400 (FIG. 13), the controller 58 is adapted to continuously record the output of the force sensor 60 during operation of the human assist device 20. These recordings, typically taken multiple times per second, are stored in a memory accessible to the controller 58 and may be discarded after a period of time has passed without an obstacle being detected. When an obstacle is detected, the controller 58 automatically marks a first set of saved force outputs taken just before the obstacle was detected and a second set of outputs taken just after the obstacle was detected. While the number of records in the first set and the second set may differ, in at least one embodiment, approximately one second's worth of force recordings before the obstacle was detected are marked for the first set, and approximately one second's worth of force recordings just after the obstacle was detected are marked for the second set.

[0114] Once the two sets of measurements have been identified, the controller 58 determines the difference between the two, for example, by determining the average of the first set, determining the average of the second set, and subtracting one from the other. Other processes may also or alternatively be used to calculate the general difference between the first set of measurements and the second set of measurements. The purpose of the two sets of measurements is to capture the difference between the force sensor output immediately before an obstacle is detected and the force sensor output immediately after the obstacle is detected. This difference is presumed to be due to the obstacle.

[0115] It will be appreciated that the controller 58 calculates this difference for each load cell (force sensor 60). That is, the controller 58 identifies a first set of measurements for the right head-end load cell taken just before an obstacle was detected, and a second set of measurements for the right head-end load cell taken by the right head-end load cell just after an obstacle was detected. The controller 58 then calculates the difference between these two sets and stores it as the right head-end load cell adjustment factor. This is then repeated for the other load cells (left head-end load cell, right foot-end load cell, and left foot-end load cell). As a result, four load cell adjustment factors are generated for each of the four load cells. The controller 58 then applies each of these load cell adjustment factors to the output from each corresponding load cell measurement taken after the obstacle was detected (and continues to apply these adjustment factors until the obstacle is no longer detected, at which point it stops applying these adjustment factors). This process is described in more detail with reference to FIGS. 14A-14C.

[0116] FIG. 14A shows the human-assistance apparatus 20 when no obstacle is detected by any of the obstacle detection sensors 61 (and / or 161 and / or others). In this situation, the controller 58 calculates the unobstructed load center of gravity 110e to be located at position (X5, Y5) in the reference frame 86, as shown in FIG. 14C. If the litter frame 28 is lowered until it contacts the obstacle detection sensor 61, as shown in FIG. 14B, contact between the obstacle 57 and the litter frame 28 will cause the outputs of at least one, and possibly all four, of the force sensors 60 to change. As a result, when the controller 58 calculates the new center of gravity after the obstacle is detected (post-obstruction center of gravity 110f), it can be seen in FIG. 14C that the post-obstruction center of gravity 110f has shifted toward the head end 38 of the human-assistance apparatus 20. Specifically, in the reference frame 86, the post-obstruction center of gravity 110f is located at (X6, Y6). This shift is due to a portion of the weight of litter frame 28 (and any object supported thereon) being supported by obstacle 57. As a result of this partial support, the load cells located at the foot end of human assist apparatus 20 experience a decrease in the force they sense (and the head end load cells may also experience a decrease in force output, but the decrease is smaller due to their greater distance from obstacle 57). As a result of the decrease in force sensed by the foot end load cells, the calculated center of gravity 110f shifts toward the head end 38 of human assist apparatus 20.

[0117] As shown in FIG. 13 , vector 116 extends between center of gravity 110e and center of gravity 110f and corresponds to an obstacle compensation factor that can be used to compensate for changes in weight distribution due to litter frame 28 contacting obstacle 57. In some embodiments, controller 58 may be configured to calculate this vector and apply it to all subsequent center of gravity calculations as long as an obstacle is detected. In other embodiments, controller 58 may be configured to not explicitly calculate this vector and / or to otherwise account for this vector. For example, in one aspect described above, controller 58 is configured to store a first set of load cell measurements from each load cell before an obstacle is detected. These load cell measurements correspond to the measurements used to calculate obstacle-free center of gravity 110e. After an obstacle is detected, controller 58 may then obtain a second set of load cell measurements, compare them to the load cell measurements used to calculate obstacle-free center of gravity 110e, determine differences, and then subtract those differences from all future load cell measurements obtained while the obstacle remains in contact with human assistive device 20.

[0118] Thus, for example, if the measurements from four load cells immediately before an obstacle is encountered (or the average of multiple measurements taken immediately before the obstacle is detected) are 25 pounds, 30 pounds, 37 pounds, and 22 pounds, and the measurements (or the average of multiple measurements) from these same four load cells taken after the obstacle is detected are 20, 25, 40, and 25, respectively, controller 58 would calculate the following four differences: (1) -5.0 (20 - 25), (2) -5.0 (25 - 30), (3) 3.0 (40 - 37), and (4) 3.0 (25 - 22). As a result, controller 58, in at least one embodiment, would add 5 pounds to all subsequent measurements from the first and second load cells and subtract 3 pounds from all subsequent measurements from the third and fourth load cells. As a result, any changes in force measurements that occurred between the first and second sets of load cell measurements (i.e., during the collision with the obstacle) are removed from the subsequent calculations, and the subsequently calculated center of gravity therefore more accurately reflects the actual center of gravity of the occupant of human assist device 20. As previously described, subtracting these correction values ​​from each of the load cells (e.g., −5.0, −5.0, 3.0, and 3.0) continues until no obstacles are detected.

[0119] As noted above in the discussion of step 1430 of algorithm 1400 (FIG. 13), controller 58 may alternatively be configured to adjust the operation of the exit detection system in a manner different from that just described. Specifically, instead of adjusting the load cell measurements taken after an obstacle is detected by the load cell correction factors described above, controller 58 may be configured to make no adjustments to the load cell measurements after an obstacle is detected, but instead to make one or more changes to the size, shape, and / or location of alert zone 98. This alternative method of adjusting the operation of exit detection system 56 is better understood with reference to FIGS. 15A-C.

[0120] FIG. 15A, like FIG. 14A, depicts the human assist device 20 when no obstacle is detected. As seen in FIG. 15C, the occupant's center of gravity in this situation is an unobstructed center of gravity 110e (FIG. 15C), defined by coordinates (X5, Y5) in the reference frame 86. If the litter frame 28 were to lower from the position shown in FIG. 15A to the position shown in FIG. 15B where an obstacle 57 contacts the obstacle detection sensor 61, the center of gravity calculated by the controller 58 would change to a post-obstruction center of gravity 110f, shown in FIG. 15C. However, rather than adjusting load cell measurements obtained after an obstacle is detected, as described above with respect to FIGS. 14A-14C, the controller 58 is adapted to adjust the alert zone 98 in the embodiment shown in FIGS. 15A-15C. Thus, as seen in FIG. 15C, the controller 58 uses the alert zone 98 before an obstacle is detected and switches to using the alert zone 198 after the obstacle is detected. The controller 58 then continues to use the alert zone 198 until the obstacle is no longer detected.

[0121] As described above, the controller 58 uses the alert zone 98 (or 198) to compare the currently calculated occupant center of gravity against. If the occupant's current center of gravity moves outside the boundaries of the alert zone 98 (or 198) while the exit detection system 56 is armed, the controller 58 issues an exit alert.

[0122] Returning to FIG. 14B , when the litter frame 28 is lowered in the manner shown therein until it contacts the obstacle 57, the contact between the litter frame 28 and the obstacle 57 offloads a portion of the weight supported by the foot-end load cells onto the obstacle 57. A portion of the weight supported by the head-end load cells may also be offloaded, but this weight will be less because the obstacle strikes the litter frame 28 closer to the foot-end 40 than to the head-end 38. As a result of the offloading of a portion of the weight of the litter frame 28 (and any items supported thereon, including the occupant), the output from the head-end load cells decreases. This decrease in force measurements from the head-end load cells results in a shift of the patient's calculated center of gravity toward the head-end 38. However, this shift in the patient's calculated center of gravity is due to contact with the obstacle 57, not to the patient's actual movement toward the head-end 38. That is, the obstacle introduces an error into the calculation of the occupant's center of gravity.

[0123] 15A-15C, controller 58 compensates for such errors by altering one or more of the size, shape, and / or location of the boundaries of alert zone 98 in response to contact with obstacle 57. In some such embodiments, such as the one shown in FIG. 15C, controller 58 may be configured to shift the location of alert zone 98 toward head-end 38 / 40 without changing the size and / or shape of zone 98. In other embodiments, controller 58 may be configured to extend (change the shape of) zone 98 such that zone 98 extends a greater distance toward head-end 38 (but may continue to extend the same amount toward foot-end 40). In yet other embodiments, controller 58 may be configured to make other adjustments to the size, shape, and / or location of the boundaries of zone 98.

[0124] In some embodiments, such as the one shown in FIG. 15C , the controller 58 is configured to take into account the amount of force offloaded to the obstacle 57 and make different adjustments to the alert zone 98 based on the difference in the amount of force offloaded. In these embodiments, the controller 58 is configured to determine the value of the vector 116a. This may be done by determining the difference between the calculated center of gravity just before the obstacle is detected and the calculated center of gravity just after the obstacle is detected. The value of this vector 116a is then added to all points on the boundary of the alert zone 98 to obtain a shifted zone 198 that is shifted from the zone 98 by the same amount and in the same direction as the vector 116a. That is, the distance D between the zone 98 and the zone 198 is equal to the magnitude of the vector 116a.

[0125] In some alternative embodiments (not shown), the controller 58 may be configured to make the same changes to the size, shape, and / or position of the alert zone 98 regardless of the amount of force offloaded from the load cell 54 onto the obstacle 57. That is, whether the litter frame 28 exerts, for example, 10 pounds of force or 20 pounds of force on the obstacle 57, the controller 58 is configured to change the size, shape, and / or position of the alert zone 98 in the same manner for these different amounts of force. In some of these alternative embodiments, the controller 58 may be configured to automatically switch to using different alert zones 98 having different sensitivities in response to detecting an obstacle. For example, in some embodiments of the exit detection system 56, a user may select different sensitivity levels, which may correspond to the general size of the zone 98. In such embodiments, the controller 58 may be configured to automatically switch to using a zone 98 having, for example, minimal sensitivity in response to detecting an obstacle.

[0126] In yet another embodiment, the controller 58 may be configured to automatically switch to using a non-zone-based exit detection algorithm in response to detecting an obstacle. For example, in at least one embodiment, the controller 58 is configured to stop comparing the calculated center of gravity to the warning zones in response to detecting an obstacle and instead look for a drop in the detected total weight of the litter frame 28 greater than a predetermined threshold (which may be expressed in absolute terms (e.g., pounds) or as a percentage of the current total weight or occupant weight). In any of the foregoing embodiments, when an obstacle is no longer detected, the controller 58 may be configured to automatically revert to using the algorithm and / or zones (and / or revert to not using a compensation factor) that were used before contact with the obstacle.

[0127] In those embodiments of the human assist device 20 having multiple obstacle sensors 61, 161, the controller 58 may be configured to respond in various ways in response to which obstacle sensor 61, 161 detects contact with the obstacle 57. For example, in some embodiments, if a first obstacle sensor 61 located toward the foot end of the litter frame 28 detects contact with the obstacle 57 as the litter frame is lowered toward the obstacle 57, the controller 58 may be configured to adjust the size, shape, and / or location of the alert zone 98 in a manner that shifts the zone 98 at least partially toward the head end 38. As mentioned above, this adjustment may take into account the magnitude of the force offloaded, or may not be responsive to the amount of force offloaded to the obstacle. On the other hand, if a second obstacle sensor is located, for example, at the head end 38 of the litter frame 28 and detects an obstacle 57 when the litter frame 28 is raised toward the obstacle, the controller 58 may be configured to adjust the size, shape, and / or position of the alert zone 98 to at least partially shift the zone 98 toward the foot end 40. This adjustment may take into account the magnitude of the offloaded force or may be unresponsive to the amount of force offloaded to the obstacle. Regardless of whether the magnitude of the offloaded force is determined, the adjustment of the zone 98 may differ depending on whether the first or second obstacle sensor detects contact with the obstacle. This also applies to other sensors that may be added to the human-assistance apparatus 20 beyond the first and second obstacle sensors 61 and 61 described above, such as one or more obstacle sensors located along one or more side(s) of the human-assistance apparatus 20 (and that may prompt the exit detection system 56 to laterally modify the size, shape, and / or position of the zone 98).

[0128] 13, after making adjustments to the operation of exit detection system 56 in step 1430 in one of the manners shown in Figures 14A-14C or 15A-15C (or a combination of both), controller 58 proceeds to steps 1406, 1410, 1412, 1416, 1418, and 1420. Controller 58 proceeds to steps 1406, 1410, 1412, 1416, 1418, and 1420, which, except as noted below, are identical to steps 1406, 1410, 1412, 1416, 1418, and 1420, respectively, of algorithm 1200 and therefore need not be described again. The only step in this series of steps in algorithm 1400 that differs from the corresponding series of steps in algorithm 1200 is step 1412. If, at step 1412, the obstacle detection sensors 61 (and / or 161) detect an obstacle, the controller 58 proceeds to step 1432 of the algorithm 1400, where it activates an obstacle detection alert, and then proceeds to step 1434. At step 1434, the controller 58 adjusts the operation of the exit detection system 56 to account for the effect of the obstacle on the exit detection system. Step 1434 is identical to step 1430 described above and may be performed in various ways, as described above. After making the appropriate adjustments at step 1434, the controller 58 returns to step 1416 and continues with steps 1418, 1420, etc., in the manner described above.

[0129] 13 , it will be understood that algorithm 1400, in at least some embodiments, includes the additional step of automatically removing the adjustments made in steps 1430 and / or 1434 when the obstacle is no longer detected. That is, after making adjustments in these steps, controller 58 repeatedly checks whether contact with the obstacle persists. If so, it continues to adjust the current load cell readings and / or the size, shape, and / or position of alert zone 98. If the obstacle is removed and / or one or more components of human assist device 20 are moved such that contact with the obstacle is no longer sustained, controller 58 is configured to automatically terminate these adjustments to load cell readings and / or alert zone 98.

[0130] It is understood that in any of the embodiments of the exit detection system 56 utilizing either algorithm 1200, algorithm 1300, or algorithm 1400 (or other algorithms), the exit detection system 56 may be configured to allow a user to select which zones to utilize by the controller 58 when determining whether to issue an alert. That is, the exit detection system 56 may have multiple alert zones 98 of different sizes, shapes, and / or locations, allowing the user to select which zones to utilize, thereby allowing the user to select different sensitivity levels for the exit detection system 56. In some embodiments, the human assist device 20 has three predefined zones and is adapted to allow the user to select which of these three zones to utilize at a given time via the user interface 62. In other embodiments, a different number of zones are permitted by the exit detection system 56.

[0131] It is also understood that in any embodiment of the exit detection system 56 that allows a user to select from multiple alert zones 98, the controller 58 may be configured to define different alert zones 98 in different manners. For example, in one embodiment, the zone having the smallest area (in coordinate system 86) has its boundaries defined using the patient's first center of gravity measurement obtained by the exit detection system 56. That is, the smallest zone is centered wherever the person's center of gravity is initially located. The zone having the largest area, in at least one embodiment, is defined without consideration of the occupant's initial position, but instead has a fixed value in coordinate system 86. For example, in one embodiment, the zone having the largest area has an edge located just inboard from the outer edge of the support deck 30. Other manners of defining the boundaries of the zones may also be used.

[0132] It is further understood that in any of the embodiments of the exit detection system 56 utilizing either algorithm 1200, algorithm 1300, or algorithm 1400 (or other algorithms), the exit detection system 56 may be configured to dynamically change the size, shape, and / or location of the alert zone based on factors other than the detection of an obstacle, such as, but not limited to, the movement of one or more components of the human assist device 20. For example, in at least one embodiment, the shape and / or boundaries of the zone change based on whether the side rails are in the up or down position. When the side rails are in the up position, an occupant of the human assist device 20 is less likely to exit by climbing over the side rails. Thus, the controller 58 may, in that situation, use a zone that allows the occupant's center of gravity to approach the upper side rails closer than when the side rails are in the down position before issuing an alarm. When the side rails move to the down position, the zone is switched to have more restrictive boundaries. The more restrictive boundaries account for the fact that, with the side rails lowered, it may be easier for an occupant to exit the support deck 30 in the area of ​​the lowered side rails. One aspect of using siderail sensors to adjust the alert zone of an exit detection system is disclosed in commonly-owned U.S. Patent Application No. 2017 / 0098359 by Sidhu et al., entitled "Human Assistance Apparatus with Exit Detection System," the entire disclosure of which is incorporated herein by reference. Several other aspects of adjusting the size, shape, and / or location of the alert zone are disclosed in commonly-owned U.S. Patent Application No. 16 / 917,004 by Sukumaran, entitled "Human Assistance Apparatus with Adjustable Exit Detection Zone," filed June 30, 2020, the entire disclosure of which is incorporated herein by reference. In any of the embodiments in which the exit detection system 56 is configured to dynamically change the size, shape, and / or location of the alert zone 98 based on movement of one or more components, those changes are in addition to and in addition to any changes that may be made to the size, shape, and / or location of the alert zone 98 based on the detection of contact with an obstacle.

[0133] It will further be appreciated that algorithm 1200, algorithm 1300, and / or algorithm 1400 may be modified in many ways from those shown in Figures 11, 12, and 13, respectively. For example, any of these algorithms may be modified so that controller 58 does not utilize any compensation factors for events that do not involve contact with an obstacle. In other words, steps 1208, 1216, 1218, and 1220 (and their corresponding steps in algorithms 1300 and 1400) may be omitted in any of algorithms 1200, 1300, and / or 1400. In such an embodiment, controller 58 does not make any adjustments to the operation of exit detection system 58 when the calculated center of gravity changes due, for example, to movement of one or more components of human assist device 20 (e.g., pivoting of Fowler section 42 of support deck 30). In any of these embodiments that do not use a compensation factor for movement without contacting an obstacle, the exit detection system 56 may be configured to alternatively adjust the size, shape, and / or location of the alert zone 98, or the exit detection system 56 may be configured to utilize neither a compensation factor nor a change in the size, shape, and / or location of the zone 98. Still other modifications may be made.

[0134] 11, 12, or 13, it is understood that controller 58 is configured to repeatedly obtain new load cell (e.g., force sensor 60) measurements (e.g., without limitation, multiple times per second). These new load cell measurements are used each time controller 58 returns to step 1210, step 1310, or step 1410 and calculates the occupant's current center of gravity. This current center of gravity is then compared to alert zone 98 (or 198) in these steps, and if outside, an alert is issued (if not, no alert is issued).

[0135] As noted above, exit detection system 56 may be modified from the embodiment described herein shown in Figure 4 to have a different number of sensors 66 and / or to calculate a different number of compensation factors. Thus, in one example, exit detection system 56 is modified to not use measurements from any of sensors 66a-66f, while in other embodiments, controller 58 calculates compensation factors using any one or more of measurements from sensors 66a-66f.

[0136] As mentioned above, although FIGS. 14C and 15C illustrate only a single alert zone 98 (not counting the shifted alert zone 198), it will be understood that in some embodiments, the controller 58 changes the size, shape and / or position of multiple zones in response to detecting an obstacle.

[0137] It is also understood that the exit detection system 56 may be modified in further manners. For example, in some embodiments, the exit detection system 56 may be modified to account for changes in the occupant's calculated center of gravity due to the addition or subtraction of an object from the litter frame 28. In such embodiments, the controller 58 determines the location of the added or removed object in the coordinate frame 86 and the weight of the added or removed object, and mathematically calculates a compensation factor that accounts for such added or removed weight. Detection of added or removed objects and the location of such addition or removal may be achieved in several different manners. In one aspect, the addition or removal of an object is detected in the manner disclosed in commonly assigned U.S. patent application Ser. No. 62 / 065,242, filed Oct. 17, 2014, by Marko N. Kostic et al., entitled "Human Assistance Device with Motion Monitoring," the entire disclosure of which is incorporated herein by reference. Detection of added or removed objects may alternatively or additionally be determined by an image detection system such as that disclosed in commonly owned U.S. patent application Ser. No. 13 / 242,022, filed Sep. 23, 2011, by inventors Richard Derenne et al., entitled "Video Surveillance System," the entire disclosure of which is incorporated herein by reference. Detection and / or removal of objects may further be determined by one or more thermal image sensors such as that disclosed in commonly owned U.S. patent application Ser. No. 61 / 989,243, filed May 6, 2014, by inventors Marko N. Kostic et al., entitled "Human Assistance Device for Human Monitoring," the entire disclosure of which is incorporated herein by reference. Thus, exit detection system 56 may utilize and / or combine any of algorithms 1200, 1300, and / or 1440, or any of their modifications, with any of the system features and / or algorithms disclosed in the above-referenced U.S. patent application Ser. No. 62 / 065,242, U.S. patent application Ser. No. 13 / 242,022, and / or U.S. patent application Ser. No. 61 / 989,243.

[0138] Those skilled in the art will appreciate that the exit detection system 56 may be modified to calculate an additional correction factor that is applied when the force sensor 60 is implemented as a load cell that is only capable of detecting normal forces applied to the force sensor 60. Correction of such load cell measurements is achieved by multiplying the load cell output by known trigonometric functions, as described in more detail in commonly owned U.S. Patent No. 7,702,481, entitled "Diagnostic and Control System for Patient Assistance," at column 17, line 25 to column 21, line 30, the entire disclosure of which is incorporated herein by reference.

[0139] While the exit detection system 56 has been primarily described herein as calculating the occupant's center of gravity and issuing an alert when the center of gravity extends outside an alert zone, it is understood that the exit detection system 56 can be configured to operate in a manner that does not require calculation of the occupant's center of gravity. For example, in some embodiments, the exit detection system 56 may be configured to examine the ratio of forces exerted on the head end, foot end, right side, and left side of the litter frame 28 and issue an exit alert if the ratio exceeds a threshold. For example, if the total weight on the litter frame 28 is equal to X, the controller 58 may be programmed to issue an alert if, for example, 60 percent or more of X is distributed between the two left load cells (or between the two right load cells). In this manner, the controller 58 need not explicitly calculate the occupant's center of gravity, but instead can issue an exit alert when the weight supported on the litter frame 28 moves to either side (and / or toward the head end 38 or foot end 40) by an amount above a threshold. In such an embodiment, controller 58 may implement steps 1430 and 1434 of algorithm 1400 by modifying the threshold used to trigger an exit alert (e.g., instead of supporting 60 percent of the body weight on one side, 70 percent may be used). Still other ways of implementing steps 1430 and 1434 are possible.

[0140] Various modifications and variations can be made to the above description without departing from the spirit and broader aspects of the present invention, as defined in the appended claims, interpreted in accordance with patent law principles, including the doctrine of equivalents. This disclosure is presented for illustrative purposes and should not be construed as an exhaustive description of all embodiments of the present invention, nor should it be construed to limit the scope of the claims to the specific elements shown or described in connection with these embodiments. For example, but not limited to, any individual element(s) of the described invention may be replaced by an alternative element providing substantially the same function or providing other suitable operation. This includes, for example, alternative elements that may currently be known to those of skill in the art and alternative elements that may be developed in the future, including alternative elements that may be recognized by those of skill in the art as alternatives upon development. Furthermore, the disclosed embodiments include multiple features that are described in cooperation and that may cooperate to provide a set of advantages. The present invention is not limited to only embodiments that include all of these features or provide all of the described advantages, except to the extent expressly defined in the issued claims. For example, any reference to a claim element in the singular using the articles "a," "an," "the," or "said" shall not be construed as limiting the element to the singular.

Claims

1. A human assistance device, comprising: A litter frame and a lift system adapted to raise and lower the height of the litter frame; a support deck supported by the litter frame and adapted to support an occupant of the human assist device; an obstacle sensor adapted to detect when the litter frame contacts an obstacle during movement of the litter frame; an exit detection system adapted to have armed and disarmed states, the exit detection system being adapted to issue an exit alert in response to an occupant of the human assist device moving in a direction toward exiting the human assist device when the exit detection system is armed and not to issue the exit alert in response to an occupant of the human assist device moving in a direction toward exiting the human assist device when the exit detection system is disarmed, the exit detection system comprising a plurality of force sensors adapted to output a signal corresponding to a downward force acting on the litter frame; a controller in communication with the plurality of force sensors, the exit detection system, and the obstacle sensor, the controller being adapted to automatically switch the exit detection system from the armed state to the unarmed state in response to the obstacle sensor detecting contact with the obstacle; A human assistance device comprising:

2. 10. The human assist device of claim 1, wherein the controller is further adapted to automatically send a notification to a remote server in response to detecting contact with the obstacle, the notification indicating that the controller has switched the exit detection system to the disarmed state.

3. 2. The human assist device of claim 1, wherein the controller is further adapted to automatically return the exit detection system from the unequipped state to the equipped state in response to the obstacle sensor no longer detecting contact with the obstacle.

4. The human assist device of claim 1 , wherein the obstacle sensor is attached to a lower surface of the litter frame.

5. 2. The human assist device of claim 1, wherein the exit detection system, when in the equipped state, is adapted to calculate a center of gravity of the occupant, compare the calculated center of gravity of the occupant with a boundary of a zone, and issue the exit alert if the calculated center of gravity is outside the boundary of the zone.

6. 6. The human assist device of claim 5, wherein the controller is further adapted to change at least one of the size, shape, or position of the zone in response to movement of a component of the human assist device.

7. 2. The human assist device of claim 1, further comprising a second obstacle sensor, wherein the controller is adapted to automatically switch the exit detection system from the armed state to the unarmed state in response to either the obstacle sensor or the second obstacle sensor detecting contact with an obstacle.

8. A human assistance device, comprising: A litter frame and a lift system adapted to raise and lower the height of the litter frame; a support deck supported by the litter frame and adapted to support an occupant of the human assist device; an obstacle sensor adapted to detect when the litter frame contacts an obstacle during movement of the litter frame; an exit detection system adapted to have armed and disarmed states, the exit detection system being adapted to issue an exit alert in response to an occupant of the human assist device moving in a direction toward exiting the human assist device when the exit detection system is armed and not to issue the exit alert in response to an occupant of the human assist device moving in a direction toward exiting the human assist device when the exit detection system is disarmed, the exit detection system comprising a plurality of force sensors adapted to output a signal corresponding to a downward force acting on the litter frame; a controller in communication with the plurality of force sensors, the exit detection system, and the obstacle sensor, the controller being adapted to automatically issue the exit alert in response to the obstacle sensor detecting contact with the obstacle when the exit detection system is in the armed state; A human assistance device comprising:

9. 9. The human assist device of claim 8, wherein the controller is further adapted to not issue the exit alert in response to the obstacle sensor detecting contact with an obstacle when the exit detection system is in the disarmed state.

10. The human assistive device of claim 8 , wherein the exit alert comprises sending an exit alert message to a remote server.

11. 9. The human assist device of claim 8, wherein the controller is further adapted to automatically terminate the exit alert in response to the obstacle sensor no longer detecting contact with the obstacle.

12. 9. The human assist device of claim 8, wherein the controller is further adapted to issue an obstacle alert in response to the obstacle sensor detecting contact with the obstacle when the exit detection system is disarmed.

13. 9. The human assistance device of claim 8, further comprising a second obstacle sensor adapted to detect when the litter frame contacts an obstacle while the litter frame is moving, and wherein the controller is adapted to automatically issue the exit alert in response to either the obstacle sensor or the second obstacle sensor detecting contact with an obstacle when the exit detection system is in the armed state.

14. A human assistance device, comprising: A litter frame and a lift system adapted to raise and lower the height of the litter frame; a support deck supported by the litter frame and adapted to support an occupant of the human assist device; an obstacle sensor adapted to detect when the litter frame contacts an obstacle during movement of the litter frame; an exit detection system adapted to have armed and disarmed states, the exit detection system being adapted to issue an exit alert in response to an occupant of the human assist device moving in a direction toward exiting the human assist device when the exit detection system is armed and not to issue the exit alert in response to an occupant of the human assist device moving in a direction toward exiting the human assist device when the exit detection system is disarmed, the exit detection system comprising a plurality of force sensors adapted to output a signal corresponding to a downward force acting on the litter frame; a controller in communication with the plurality of force sensors, the exit detection system, and the obstacle sensor, the controller adapted to automatically modify operation of the exit detection system in a first aspect in response to the obstacle sensor detecting contact with the obstacle when the exit detection system is in the armed state; A human assistance device comprising:

15. 15. The human assist device of claim 14, wherein the exit detection system is adapted to operate at a plurality of different sensitivity levels, and the controller is adapted to modify operation of the exit detection system in the first aspect by switching the exit detection system from a first sensitivity level to a second sensitivity level.

16. 16. The human assist device of claim 15, wherein the second sensitivity level is less sensitive than the first sensitivity level such that when operating at the second sensitivity level, the occupant needs to move closer to an edge of the human assist device than when operating at the first sensitivity level, the occupant would need to move to trigger the exit alert.

17. The human assist device of claim 14 , wherein the obstacle sensor is attached to a lower surface of the litter frame.

18. 15. The human assist device of claim 14, wherein the exit detection system, when in the equipped state, is adapted to calculate a center of gravity of the occupant, compare the calculated center of gravity of the occupant with boundaries of zones, and issue the exit alert if the calculated center of gravity is outside boundaries of the zones, and the controller is adapted to modify operation of the exit detection system in the first aspect by modifying at least one of a size, a shape, or a position of the zones.

19. 15. The human assist device of claim 14, wherein the exit detection system, when in the equipped state, is adapted to calculate a center of gravity of the occupant, compare the calculated center of gravity of the occupant with a boundary of a zone, and issue the exit alert if the calculated center of gravity is outside the boundary of the zone, and the controller is adapted to modify operation of the exit detection system in the first aspect by adjusting the calculated center of gravity in a manner that compensates for changes in the signal of the force sensor due to contact with the obstacle.

20. 15. The human assistance device of claim 14, wherein the obstacle sensor further comprises a second obstacle sensor adapted to detect when a first portion of the litter frame contacts the obstacle during movement of the litter frame and to detect when a second portion of the litter frame, different from the first portion, contacts the obstacle during movement of the litter frame.

21. 21. The human assist device of claim 20, wherein the controller is adapted, when the exit detection system is in the armed state, to automatically change operation of the exit detection system to a second state different from the first state in response to the second obstacle sensor detecting contact with the obstacle.

22. 22. The human assist device of claim 21, wherein the exit detection system, when in the equipped state, is adapted to: (1) calculate a center of gravity of the occupant; (2) compare the calculated center of gravity of the occupant with boundaries of a zone having a first size, a first shape, and a first location; and (3) issue the exit alert if the calculated center of gravity is outside the boundaries of the zone; and wherein the controller is adapted to modify operation of the exit detection system in a first configuration by changing at least one of the first size, the first shape, or the first location of the zone to a second size, a second shape, or a second location, respectively; and wherein the controller is further adapted to modify operation of the exit detection system in a second configuration by changing at least one of the first size, the first shape, or the first location of the zone to a third size, a third shape, or a third location, respectively.

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