Systems and methods for supporting a user

Abstract

Systems and related methods for assisting a user to achieve postural changes and ambulation are disclosed. An assistance system may safely assist in a user's (e.g., elderly or physically disabled user) postural changes at any desired position without the need of a physical secondary body for assistance. In some embodiments, the assistance system may include front and back bases, each including a drive to help the system maneuver through an environment (e.g., home). The system may include a linkage formed of three or more links, including one link coupled to the front base and a second link coupled to the back base. In some embodiments, at least one of the joints between the links may be passive. The system may also include an actuator to control the pose of the system and safely lock the system at the desired pose to facilitate postural changes and ambulation.

Description

SYSTEMS AND METHODS FOR SUPPORTING A USERCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit under 35 U.S.C. § 119(e) of U.S. provisional application serial number 63 / 581,615, filed September 8, 2023, the disclosure of which is incorporated by reference in its entirety.GOVERNMENT FUNDING

[0002] This invention was made with government support under IIS2133072 awarded by the National Science Foundation. The government has certain rights in the invention.FIELD

[0003] Disclosed embodiments are related to systems for supporting a user, and in some embodiments for assisting users to achieve postural changes.BACKGROUND

[0004] The process of changing physical positions can be challenging for users such as the elderly and those with musculoskeletal disabilities. For example, users may be unable to independently raise themselves from a lowered sitting position to a standing position. Such postural changes often require the use of strong abdominal muscles and / or other musculoskeletal capabilities to support and enable the motion. In absence of such capabilities, users may rely on assistance systems which can help stabilize the user during the postural change. For example, the user can grab the arm of a healthcare provider and rely on the stability of their arm to maneuver their body. In another example, the user can grab and self- stabilize using handrails installed on walls or floors of a home or institution. Given the ubiquity of postural transitions in daily life, and the benefits of movement on mood, the use of assistance systems can significantly enhance users’ quality of life. Furthermore, persons older than 65 years old who may benefit fromminimal to intermittent weight-bearing activities of daily living represent up to 16.4% of the U.S. population (more than 5.8 million people).SUMMARY

[0005] In some embodiments, a system for assisting a user includes a front base including a front drive configured to move the front base over a supporting surface, a back base including a back drive configured to move the back base over the supporting surface, a linkage including three or more links with a front link rotatably coupled to the front base and a back link rotatably coupled to the back base, and an actuator coupled to at least one link of the linkage, wherein the actuator is configured to control a pose of the linkage relative to the front base and the back base.

[0006] In some embodiments, a method of assisting a user includes moving a front base over a supporting surface with a front drive, moving a back base over the supporting surface with a back drive, the back base operatively connected to the front base through a linkage, and controlling a pose of the linkage with an actuator, the actuator coupled to at least one link of the linkage.

[0007] It should be appreciated that the foregoing concepts, and additional concepts discussed below, may be arranged in any suitable combination, as the present disclosure is not limited in this respect. Further, other advantages and novel features of the present disclosure will become apparent from the following detailed description of various non-limiting embodiments when considered in conjunction with the accompanying figures.BRIEF DESCRIPTION OF DRAWINGS

[0008] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

[0009] FIG. 1 shows a schematic diagram of a system for assisting a user according to some embodiments;

[0010] FIGs. 2A-2C show various views of a system for assisting a user according to other embodiments;

[0011] FIG. 3 shows an exemplary path for drive bases of a scale model of a system; and

[0012] FIG. 4 shows a block diagram of a method of assisting a user according to some embodiments.DETAILED DESCRIPTION

[0013] Assistance systems employing the use of a physical body (e.g., a healthcare provider) can allow users to achieve postural changes by relying on the physical strength of the body. However, the Inventors have recognized that the presence of a secondary body within a user’s home or facility is not always guaranteed, especially given recent shortages of caregivers and projected continued shortage of caregivers. The user may therefore be reliant on the secondary body, and lose their independence, which may have mental, emotional, and physical consequences.

[0014] Conventional assistance systems can also include systems employing the use of a physical structure, such as hand-rails. The hand-rails are typically strongly affixed to a wall or floor to help support and enable postural changes for the user. For example, a hand-rail can be attached to a wall near a seat (e.g., a toilet), to provide support to the user as they maneuver on to and up from the seat. The physical structures also include walkers, which typically include weighted mass surrounding the user’s body to help support ambulation and positional changes.

[0015] The Inventors have recognized that static assistance systems, such as hand-rails, are designed and standardized in accordance with building codes. Thus, their position is typically set based on an average position of a user. In the case of hand-rails arranged by a seat, the position of the hand-rail may not be sufficiently high or low enough to accommodate the broad range of user sizes. In other words, the position of static systems such as hand-rails can be sub- optimal for the majority of users in need. Furthermore, static systems such as hand-rails are only affixed to walls and floors where they can be sufficiently stabilized to support the user.Therefore, it is quite common for seats (e.g., toilets, bathtubs) to only have a single hand-rail, requiring an uneven and unbalanced force from the user to achieve structural changes which can result in discomfort and accidents.

[0016] The Inventors have also recognized that mobile assistance systems, such as walkers, often do not provide sufficient stability for the user to achieve postural transitions. Furthermore, walkers typically have large spatial footprints, and would not be usable in tight spaces, such as bathrooms. The Inventors have also recognized that walkers can be bulky and challenging to maneuver for users with limited strength and dexterity.

[0017] In view of the above, the Inventors have recognized the benefits associated with a moveable assistance system to help users achieve postural changes and support ambulation. The assistance system may allow the user to change posture at any potential location within the environment, regardless of proximity to a wall or floor. The assistance system may also have the benefit of being tailored to a user at any suitable height or location depending on the user’ s needs in the moment. In some cases, the assistance system may be able to fully support the user in a stable manner which may help to reduce the risk of misbalance or accidents. The user may use the assistance systems independently, alleviating the need for a secondary body (e.g., healthcare provider) to be physically present at the time of need, while augmenting the relationship between the user and the secondary body. However, instances in which the device is operated by another individual and / or is remotely operated are also contemplated. Additionally, different benefits different from those noted above may also offered by the systems and methods disclosed herein are also possible.

[0018] In some embodiments, an assistance system may include two or more independently operated bases configured to move the system along a support surface disposed vertically below the bases during operation relative to a direction of gravity (e.g., a floor), a linkage connecting the bases, an actuator for controlling the orientation of the linkage relative to the bases, and handling portion for the user to grasp. Depending on the embodiment, the bases may either move passively across a surface in response to an externally applied force and / or one or more drives of the bases may be used to actively drive the bases along the support surface to adesired position and / or orientation. In some embodiments, the bases may include high traction materials (e.g., rubber) to reduce the risk of slippage, even on slippery or wet floors.

[0019] In some embodiments, the bases may be configured to allow for omnidirectional movement of the system within a confined space. The ability of the bases to move in any direction may serve to optimize the movement of the bases and avoid extensive turning or rotation of the system, allowing the system to arrive at the desired user location in a rapid manner. In some embodiments, independently operated bases may enhance the assistance system’s ability to span over obstacles (e.g., objects on the ground) when assisting the user. The bases may include a front base, positioned at the leading end of the system, and a back base, positioned at the trailing end of the system. Each base may include a drive (e.g., a front drive and a back drive), as well as a passive rotatable coupling. The passive rotatable coupling of each base may also be coupled to the linkage. For example, a rotatable coupling of the front base may be coupled to the front-most link of the linkage. The rotatable coupling may be passive, allowing the base to rotate relative to the linkage as the base is driven in a desired direction. In some embodiments, the drive may be a directional drive, such as a unidirectional tank drive or a parallel wheel drive. In some embodiments, one of more of drives may be a nonholonomic tread drive. Such drives may comprise parallel high-friction (e.g., rubber) treads, although alternative tread configurations and materials are also contemplated.

[0020] In some embodiments, the drives may be in communication with one or more controllers and / or processors to help control and command the speed, position, and / or orientation of the bases. In some embodiments, the drives may also include locking mechanisms which prevent translation of the drive and associated base across the support surface when activated. The locking mechanisms can improve the stability of the system while also facilitating the handling portion pose, as will be described in greater detail below.

[0021] In the various embodiments described herein, the linkage may include three or more links with rotatable joints arranged between the links, allowing the system to be displaced in a variety of different planes to arrive at a desired pose to assist the user in the desired postural change. For example, the rotatable joints between the links and an adjacent base and / or between adjacent links may be configured to permit rotation of the links about an axis (i.e., an axis ofrotation of a joint) that is approximately parallel to a supporting surface the bases are disposed on. In some embodiments, these axes of rotation may be approximately perpendicular to a local direction of gravity. Appropriate types of rotatable joints may include, but are not limited to, pin joints or revolute joints. Of course, other types of rotatable connections and directions of movement other than those noted above are also contemplated. In some embodiments, the linkage may be arranged in a four- link configuration, with the support surface (e.g., floor) serving as the fourth link. Thus, in some embodiments, the support surface may transform the linkage into a closed-loop chain, enhancing system stability. The linkage may be rotatably connected to and extend between the bases. In one example, the linkage may include three links, with a first link being coupled to the rotatable coupling of the front base, a second link being coupled to the rotatable coupling of the back base, and a third link coupled to both the first and second links. In some embodiments, the links may be connected to each other and / or the associated bases via a rotatable coupling such as a pivot joint though any appropriate type of coupling may be used as the disclosure is not limited in this way. For example, a base may be coupled to an associated link through a zero-length link. In either case, the displacement of the bases relative to one another and the imposed orientation of the linkage relative to the bases may serve to move the various links in space to a desired pose to position the handling portion in a desired pose within an environment.

[0022] As will be described in greater detail below, one or more joints of the linkage may be freely moving, such that movement of one base relative to another may rearrange the linkage configuration. To limit the degrees of freedom of the linkage and avoid linkage collapse, the assistance system may include an actuator coupled to at least two links within the linkage to control the pose of the linkage. Again, the two bases and underlying supporting surface may function as one of the links. Thus, an actuator may be connected to adjacent links and to a link and an associated base. Additionally, it should be understood that such connection to the links and / or bases may either be direct connections (e.g., a direct connection to portions of a link and / or base) and / or indirect connections (i.e., an actuator attached to a joint that is separately connected to the associated links and / or base). In some embodiments, the actuator may be a non- backdrivable actuator. Any appropriate type of actuator capable of controlling the relative anglebetween two adjacent links may be used including, but not limited to linear actuators, a rotational actuator, and / or any other appropriate type of actuator. Additionally, any suitably powered actuator may be used including hydraulic, pneumatic, electric, and other appropriately powered actuators. In some exemplary embodiments, an assistance system may employ the use of a linear actuator within its linkage system, which serves as an active prismatic joint. The linear actuator may not be backdrivable and may therefore be rigidly fixed when the actuator is not being driven.

[0023] In some embodiments, the actuator may also function as a lock to selectively prevent translation of the linkage after the actuator has moved the linkage into a desired configuration. For example, the assistance system may first be directed to a particular pose through actuation of the drives and the actuator. In such an embodiment, the at least one actuator may a non-backdrivable actuator which may then hold the linkage in the desired posed while the bases are held stationary. An actuator may be non-backdrivable due to an appropriate combination of friction, screw pitch, gear ratio, and / or other appropriate combination of parameters for the type of actuator being used. However, instances in which a backdrivable actuator is used are also contemplated. In such an embodiment, it may be desirable to use a separate lock which may be configured to selectively lock a relative pose between two or more links of the linkage. For example, a lock may be arranged between a link coupled to an actuator and a link connected to a drive base. The lock may be any suitable mechanism to prevent movement between links. For example, the lock may operate similarly to a bicycle disc brake. In some embodiments, the lock may be activated when the handling portion is being grasped. In this way, the linkage may be converted to a rigid body with a constant, unchanging distance between drive bases to reduce the risk of the system changing its configuration under an applied load (e.g., a user’s grasping force). Thus, the pose of the system may be locked after it is moved into a desired pose to limit the risk of movement when the user is grasping and applying pressure to the handling portion. The locking capacity of the actuator and / or a separate lock may therefore allow the assistance system to fully support the weight of the user without surrounding the user, as may be the case with a walker.

[0024] One or more handling portions of a system may be configured to be grasped by a user and may part of or extend from the linkage of a system. The handling portion may be positioned at a biomechanically optimal location to provide support to the user during postural transitions (e.g., sit-to-stand transitions or ambulation). For example, the handling portion may have one or more handles to allow the user to grasp the system comfortably and ergonomically. In some embodiments, a handling portion may be a bar or rod extending from one of the links, allowing the user to grasp the handling portion in a direction parallel to the assistance system. In some embodiments, the handling portion of the system may be presented to the user only after the system has completed its movement. Such order of operations may reduce the risk of impeding further movements while safely supporting the user’s postural transitions. In some embodiments, a handling portion may include two transverse handles, allowing the user to grasp the handling portion in a direction perpendicular to the assistance system. In some embodiments, a handling portion may include a telescoping shaft that may be configured to be extended out from and retracted towards an associated portion of the linkage which may allow the handling portion to be extended to reach the user. In some embodiments, a handling portion may be retractable to further reduce the footprint of the system between uses. A retractable handling portion may also reduce the risk of the user being impeded during postural changes. It should be appreciated that a handling portion may be in any suitable configuration or orientation to enable grasping and handling by the user. The handling portion may have one or more ergonomic features for the user’s comfort.

[0025] In some embodiments, a handling portion and / or one or more of the joints may include sensors for sensing the pressure applied to the handling portion during operation. For example, the handling portion may include at least one four-axis torque force sensor to sense the torque and / or weight applied by the user when being assisted, though other force and / or torque sensors may also be used. The data collected by the sensor may be transferred to one or more processors to identify any room for adjustment. In some embodiments, the data collected by the sensor may be communicated to a healthcare provider to help identify changes in the user’ s strength.

[0026] It should be appreciated that a handling portion may be capable of supporting either a portion, or preferably in some embodiments, the full weight of the user during operation. In some embodiments, the handling portion may be arranged in a cantilever fashion, with the handling portion extending away from the assistance system. In such configuration, the weight of the assistance system, as well as the active control of the actuator in locking the linkage pose may serve to provide safe and stable support to the user during the postural change.

[0027] The assistance system may have a generally linear footprint in some embodiments with a small width to accommodate the majority of room sizes, such as restrooms. For example, the assistance system may have a width of approximately 1 foot, although other widths are also contemplated, the elongated configuration may allow the assistance system to maneuver through tight spaces. The support system may be narrow enough to permit a user to walk alongside the support system in a narrow corridor. Furthermore, the narrow footprint of the assistance system, along with the nature of the linkage may permit the system to navigate between various objects and obstacles on the ground to readily assist the user at any position. For example, the support system may span over a coffee table to assist a user transition from a sitting position to a standing position from a couch. Of course, non-linear configurations of a support system are also contemplated.

[0028] As used herein, a pose may refer to a position and orientation of a component within a specific reference frame. For example, a pose of an assistance system may refer to both the position and orientation of the assistance system within a particular reference frame. However, it should be understood for purposes of the various embodiments disclosed herein that controlling a pose of a particular component may also include controlling a position or orientation of the component as the disclosure is not limited in this fashion. Additionally, the pose of a system including multiple components may be defined by the pose of the individual components making up the system. For example, the pose of a linkage may be defined by the individual poses of the individual interconnected links forming the linkage.

[0029] In some embodiments, the assistance systems of the present disclosure may include one or more sensors configured to determine the pose and / or any other property of the assistance system. As will be described in detail below, the sensors may be in communicationwith one or more processors, controllers, transmitters, memory storage elements, and / or any other suitable element to allow for the data collected by the sensors to be incorporated into the control scheme of the system. In some embodiments, sensors may be associated with the joints of the linkage to sense angle changes and / or displacement of the joints and / or links. The sensors may include any suitable sensor known in the art, including, but not limited to, encoders, potentiometers, displacement sensors, angular sensors, force sensors, torque sensors, and / or any other suitable sensing system. In some embodiments, photosensitive detectors (e.g., two dimensional and / or three-dimensional cameras) may be employed to sense the pose and / or other properties of the system.

[0030] In some embodiments, the assistance systems described herein may be teleoperated, allowing a secondary party (e.g., a healthcare provider) to operate the system without being physically present. Accordingly, the system may include one or more transmitters and / or receivers connected to one or more processors to transmit information between the secondary party and the assistance system. The secondary party may send a command to the assistance system to arrive at a desired pose to assist the user. The command may be communicated to the receivers and subsequently transferred to one or more processors and / or controllers to achieve the desired pose. Correspondingly, information about the surrounding environment and pose of the system may be transmitted back to the secondary party (e.g., images from a camera, force and / or torque data, pose information for the system, etc.). Accordingly, the assistance systems described herein may apply any number of controllers, processors, transmitters, receivers, sensors, storage elements, and / or any other element known in the art for teleoperation of a robotic system.

[0031] The processors, controllers, transmitters, receivers, sensors, and / or other elements of the present disclosure may communicate via any appropriate communication protocol such as Wi-Fi, cellular, Bluetooth, wired, wireless, and / or any other suitable communication protocol.

[0032] In some embodiments, the processor(s) may determine the pose of the assistance system using forward and / or inverse kinematics. Forward kinematics may use kinematic equations to determine the pose of the assistance system using known values for joint parameters (e.g., sensed angles of the joint, measured by potentiometers). Inverse kinematics may usekinematic equations to determine the joint parameters needed to achieve a corresponding assistance system pose. Alternatively, a pose of the assistance system may be determined using one or more sensors, such as one or more sensors and corresponding pose tracking algorithms which may be used to identify the assistance system within the image and determine a pose of the assistance system within the three dimensional space observed by the one or more photosensitive detectors.

[0033] In some embodiments, an assistance system may include a handling portion capable of moving omnidirectionally in three-dimensional space to assist a user. In one example, the assistance system includes a total of five actuators, including two actuators associated with two drive bases, each of which including a parallel tread, and an actuator for controlling the pose of the system. In this example, the assistance system is nonholonomic, such that passive drive bases are permitted to rotate in place without displacing the handling portion, enabling the handling portion to be moved to any suitable pose. Such a configuration transmits the downward forces applied by the user to a central link, distributing the forces and further stabilizing the system.

[0034] Operation of the assistance system is divided into two general components, determining the controls for following the waypoints of each path smoothly and determining the path the system may take to arrive at the desired handling portion pose. It should be appreciated that an associated controlled may be configured to maintain the bases apart by a minimum threshold distance during operation to help reduce the risk of instabilities. As discussed earlier, the handling portion of the assistance system may function as a cantilever, and so maintaining a minimum distance between the bases may help stabilize the system.

[0035] To determine the controls for following the waypoints of each path smoothly, the system may measure the rotation of one drive base directly by using one or more sensors (e.g., potentiometers) coupled to the drives when the other base is moving in a linear trajectory, such that the rotation may be constant.

[0036] Furthermore, as one base is moving linearly, when the other base moves to the next predetermined point, its estimated pose may be replaced by a calculated pose from the base’s real-time position. For example, the pose may be calculated as the sum of the previousposition and the change in the base drive angle. This enhanced dead reckoning of the base position may serve to correct for sharp turns made by the bases. The path may be successively shifted to redirect the base onto the original path.

[0037] The distance between the bases may be accomplished by stopping or pausing the trajectory of one or more of the bases. In some embodiments, a control scheme, such as a proportional control scheme or other appropriate control method, may be employed to create a virtual spring between the two bases. Stretching or compressing the spring may lead to the rear base speeding up or slowing down, respectively. The distance between the bases may therefore be measured directly using the frame potentiometers or other appropriate sensors. In some embodiments, the distance between the bases may not be measured through dead reckoning. Accordingly, even with significant drift, the control scheme may keep the bases within a certain distance apart, as the controls may be continuously collecting live information from sensor measurements.

[0038] In some embodiments, a helper function may be employed to calculate the final locations of the front and rear base based on a desired pose of the handling portion. The function may have inputs including orientation of the handling portion in the overhead plane, distance of the handling portion from front base in the overhead plane, and handling portion height from ground. It should be appreciated that if more than one pose yields the same handling portion pose, the pose resulting in the smallest distance from base to base may be selected.

[0039] In some embodiments, the robotic assistance system may have five independent degrees of freedom, including the in-plane position of the back base (e.g., in an x- and y- direction), the in-plane position of the front base (e.g., in an x- and y-direction), and the angle of the actuator joint. To arrive at a desired handling portion pose, the front base may first be rigidly locked to reduce the degrees of freedom from 5 to 3. The handling portion orientation may then be specified to further confine the assistance system to a plane, further reducing the degrees of freedom from 3 to 2. The control scheme may then determine a ray from the center of the front base pointing in the direction of the endpoint angle. Specifying a desired handling portion height and distance from the front base may yield two additional kinematic equations, which can be solved to find the distance between the front and back base. Finally, to find the desired locationof the back base, the back base may be directed to travel the calculated distance along the predetermined ray. It should be appreciated that such a control scheme is exemplary and that other methods of arriving at a desired handling portion pose are also contemplated.

[0040] In some embodiments, the control scheme of the assistance system may include constraints to limit the risk of singularity occurrences. For example, the linkage may take the form of a four-link linkage, in which the supporting surface (e.g., floor) may serve as one of the links. Such an arrangement of links may exhibit singularities when the linkage is at its maximum width. Thus, the control scheme may constrain the range of rotation of the joints to avoid the risk of singularities by avoiding configurations of the links approaching parallel arrangements of adjacent links.

[0041] In some embodiments, the assistance system may be controlled with a proportional-integral velocity controller with a feedforward term and an integral position control outer loop. In some embodiments, the position controller may be nonlinearly constrained to saturate at a percentage (e.g., ±10%) of the desired tread velocity, which helps to reduce steadystate position error (inherent to PI velocity control) while reducing the risk of large deviations from the intended velocity. Accordingly, in some embodiments, to prevent integrator windup, the desired tread angle may be reset each time the motor velocity is set to zero. In some embodiments, any integrators within the control system may have anti-windup protection.

[0042] It should be appreciated that although the assistance systems are described to provide stable, safe, and static support to the user, akin to a mobile hand-rail, embodiments where the systems provide dynamic support are also contemplated. For example, the assistance system may arrive at the user, the user may grab the handles of the system, and the system may actuate in a manner compatible with the biomechanical ability of the user. In this way, the assistance system may serve to support the user along a range of motions or posture changes.

[0043] In some embodiments, the assistance systems described herein may include one or more elements to help communicate the state of the system with the user. The one or more elements may communicate the locked state of the system to help achieve safe and secure operation of the system. For example, the elements may first communicate that the system is moving to its final position, and subsequently communicate that the system is locked, and thatthe user may safely use the system. The elements may include audio elements (e.g., speakers), visual elements (e.g., LED lights), tactile elements (e.g., vibrating transducers), and / or any other elements to help communicate with the user.

[0044] The assistance systems may also include one or more elements to help the user communicate with a secondary party, such as a health care provider. The elements may include audio elements (e.g., speakers and microphones), visual elements (e.g., cameras and sensors), and / or any other element to help the user communicate with the secondary party.

[0045] In some embodiments, the assistance systems described herein may be autonomously operated to reduce the need for a secondary party, such as a health care provider. In such embodiments, the user may call the system from a different region of the environment, and the system may navigate the environment to reach the user and provide assistance. The assistance systems may therefore include audio and / or visual sensors (e.g., microphones and / or cameras) to help locate the user and identify the path to the user based on an understanding of the environment.

[0046] It should be appreciated that the assistance systems described herein may be employed for any suitable user in any suitable environment. In one example, an assistance system as described herein may be employed in a home of a user with limited strength (e.g., an elderly user or a physically disabled user), a hospital for temporary or permanently low-strength users, an assisted living community, and / or any other suitable environment to facilitate user postural changes.

[0047] Turning to the figures, specific non-limiting embodiments are described in further detail. It should be understood that the various systems, components, features, and methods described relative to these embodiments may be used either individually and / or in any desired combination as the disclosure is not limited to only the specific embodiments described herein.

[0048] FIG. 1 shows a schematic diagram of an assistance system 100 according to some embodiments. The assistance system 100 may include a front base 140A near the leading end of the system 100, and a back base 140B near the trailing end of the system. Each of the front 140A and back 140B bases may include a drive 142 configured to move across the surface using wheels, tracks, or other appropriate components as well as a rotatable coupling 144. As discussedpreviously, the combination of the drive 142, which may be a unidirectional drive (e.g., tank drive) and the rotatable coupling 144 may allow the bases to maneuver in an omnidirectional fashion.

[0049] In some embodiments, the rotatable coupling 144 of the front and back bases may be coupled to a linkage formed of three or more links. As shown in FIG. 1, the rotatable coupling 144 of the back base 140B may be coupled to a link 112 through a joint 122. The link 112 may include a joint 124 located at an opposing end from the joint 122, connected to another link 116. The link 116 may include a joint 126 located at an opposing end from joint 124, connected to yet another link 114. In some embodiments, the linkage may be a four-link linkage, with the supporting surface (e.g., a floor) serving as the fourth link. Of course, embodiments with more than three physical links are also contemplated. Again, the depicted joints and links may rotate about axes of rotation that arc approximately parallel to the underlying supporting surface the bases are disposed on in some embodiments.

[0050] In some embodiments, an assistance system 100 may include an actuator 130 coupled to two adjacent links, such as links 114, 116, as shown in FIG. 1. The actuator 130 may control the pose of the linkage to deliver a handling portion 150 to the user. The handling portion 150, at the leading end of the system, may provide grasping elements for the user, to aid in postural changes and / or ambulation. As discussed previously, the actuator 130 may serve to control and lock the pose of the assistance system to provide safe and stable assistance for the user.

[0051] In some embodiments, one or more components of the assistance system 100, including the drives 142, rotatable couplings 144, joints 122, 124, 126, 128, actuator 130, and handling portion 150, may be operated by a controlling system 200. The controlling system may include controllers, processors, transmitters, and / or any other elements necessary for control and operation of a robotic system. As discussed previously, in some embodiments, the various components of the assistance system may be coupled to sensors 160. For example, one or more of the joints may be coupled to encoders to help sense the angular rotation of the joint. The various sensors 160 may be in communication with the controlling system 200 for operation (e.g., teleoperation, as discussed previously) of the system 100.

[0052] It should be appreciated that in some embodiments, the actuator may serve to control the pose of the assistance system having passive joints 124, 126. Thus, the bases 140A, MOB and the actuator may be actively controlling the pose of the system. In other embodiments, one or more of the joints 122, 124, 126, 128 may be actively controlled (e.g., rotated and / or locked).

[0053] FIGs. 2A-2C show various views of an assistance system 100 according to some embodiments. The assistance system, which may take the form of a robotic system, may include a front base 140A and a back base MOB. Each of the bases may include a drive 142, which may be an omnidirectional drive (e.g., tank drive), connected to a rotatable coupling 144 to enable omnidirectional motion of the system 100. The optional rotatable couplings are separate and apart from the rotational joints of the linkage and may be configured to permit the linkage to rotate about an axis of rotation that is at least partially perpendicular to the associated base and / or underlying supporting surface. For example, the rotatable couplings of the bases may rotate about axes that are approximately parallel to a direction of gravity when the bases are located on a level supporting surface. As described previously, the system may include a linkage connected between the two bases, including links 112, 114, and 116, as well as joints 122, 124, 126, and 128 in between. To control the degrees of freedom of the system and lock the pose of the linkage, the system may include an actuator positioned between links 114 and 116. Alternatively, the actuator may be operatively positioned between a link and an adjacent base. In some embodiments, the leading end of the system may include a handling portion 150. As described previously, the handling portion 150 may include handlebars 152 to allow the user to grasp the handling portion at various angles relative to the longitudinal axis of the system. The handlebars may be ergonomically positioned to improve the comfort and accessibility of the handling portion 150.

[0054] In some embodiments, link 116 may also include a handling portion 117 to serve as a stable hand-rail for ambulation. For example, the system may first be directed to the user in a first location where the user is seated, and arrive at a pose that can suitably support the user in a postural change. The system may continue to remain stable and stationary as the user walks along the system to arrive at a second location. The handling portion 117 may serve to stabilizethe user as they walk along the system. It should be appreciated that although the handling portion 1 17 is shown to be parallel to the link 1 16, embodiments with one or more handling portions arranged at various regions of the system to facilitate ambulation and postural changes are also contemplated.

[0055] In some embodiments, the assistance systems may be sized and arranged to support the full weight of the user and all relevant forces which may be applied to the system during postural changes. Accordingly, in some embodiments, the weight and frame dimensions of the assistance system may be informed through static force analysis of the maximum expected handlebar load and associated safety factors.

[0056] In exemplary, non-limiting embodiments, each of the links 112, 114, and 116 may have a length LI, L3, and L2, respectively, as shown in FIG. 1. Each length LI, L2, and L3, may be approximately 60 cm. Each length LI, L2, and L3 may also be greater than or equal to approximately 40 cm, 50 cm, 60 cm, 70 cm, 80 cm, and / or any other suitable length. Each link may also be less than or equal to approximately 80 cm, 70 cm, 60 cm, 50 cm, 40 cm, and / or any other suitable length. Combinations of the foregoing, including link lengths between 40 cm and 80 cm are also contemplated. It should be appreciated that embodiments in which the links are sized differently from one another are also contemplated.

[0057] In some embodiments, the length L4 of the top portion of the assistance system, as shown in FIG. 1, may be 1.2 meters. This length L4 may encompass a fully extended handling portion 150. The length L4 may be any suitable length to support a user, including, but not limited to, greater than or equal to approximately 0.8 meters, 1 meter, 1 .2 meters, 1 .5 meters, and / or less than or equal to approximately 1.5 meters, 1.2 meters, 1 meter, 0.8 meters, and / or any other suitable length. Combinations of the foregoing, including length L4 between 0.8 and 1.5 meters are also contemplated.

[0058] As discussed above, the assistance systems of the present disclosure may assist a user through a postural transition, such as between a sitting position and a standing position. Thus, the system must be capable of translating the handling portion 150 through a range of heights to accommodate postural changes of a user. In some exemplary, non-limiting embodiments, the handling portion 150 may be able to move between 0.7 meters and 1.37 metersfrom the ground, as represented by Hl in FIG. 1. In some embodiments, Hl may represent greater than or equal to approximately 0.4 meters, 0.5 meters, 0.6 meters, 0.7 meters, 1 meter, 1 .2 meters, 1.37 meters, 1.5 meters, and / or less than or equal to approximately 1.5 meters, 1.37 meters, 1.2 meters, 1 meter, 0.7 meters, 0.6 meter, 0.5 meters, 0.4 meters, and / or any other suitable height. The handling portion 150 may be able to transition between any combinations of the foregoing heights, including, but not limited to, between 0.4 meters and 1.5 meters.

[0059] In some embodiments, the assistance system may be sized to have a small footprint for storage and convenience, while still large enough to support the weight of the user. Accordingly, a projected length L5 of the system, as shown in FIG. 1, may be between 0.94 meters and 2.67 meters. The system length L5 may be greater than or equal to approximately 0.7 meters, 0.8 meters, 0.9 meters, 0.94 meters, 1 meter, 1.2 meters, 1.5 meters, 2 meters, 2.5 meters, 2.67 meters, 3 meters, and / or less than or equal to approximately 3 meters, 2.67 meters, 2.5 meters, 2 meters, 1.5 meters, 1.2 meters, 1 meter, 0.94 meters, 0.9 meters, 0.8 meters, 0.7 meters, and / or any other suitable length. The system length L5 may be between any combinations of the foregoing, including, but not limited to, between 0.7 meters and 3 meters. It should be appreciated that the system length L5 may be measured as the length of the system regardless of the position of the drive bases. For example, although link 114 shown in FIG. 1 is arranged to be positioned under the link 116 and link 112 is shown to protrude behind joint 124, length L5 encompasses the projected system length on the ground.

[0060] As discussed above, the handling portion 150 may extend away from the linkage to permit a user to grasp the handling portion. Accordingly, the handling portion 150 may extend away from the linkage at a length L6, as shown in FIG. 1. In some embodiments, the handling portion may extend a maximum distance of 61 cm, which may be sufficiently long to assist a user out of a bed or a bathtub. In embodiments, length L6 may be greater than or equal to approximately 40 cm, 50 cm, 60 cm, 61 cm, 70 cm, 80 cm, 90 cm, and / or less than or equal to approximately 90 cm, 80 cm, 70 cm, 61 cm, 60 cm, 50 cm, 40 cm, and / or any other suitable length. Combinations of the foregoing are also contemplated, including handling portions that can extend between lengths L6 of 40 cm and 90 cm.

[0061] The linkage may have a projected length L7, as shown in FIG. 1. It should be appreciated that projected length L7 may comprise the length between the bases unless there are overlapping portions of links (e.g., as shown in FIG. 1, link 116 overlapping portions of link 114). The projected length L7 of the linkage may be 66 cm in some embodiments. In other embodiments, the projected length L7 may be greater than or equal to approximately 40 cm, 50 cm, 60 cm, 66 cm, 70 cm, 80 cm, 90 cm, and / or less than or equal to approximately 90 cm, 80 cm, 70 cm, 66 cm, 60 cm, 50 cm, 40 cm, and / or any other suitable length. Combinations of the foregoing ranges, including projected length L7 between 40 cm and 90 cm are also contemplated.

[0062] In some embodiments, the front 140A and back 140B bases may have a particular footprint to both accommodate the narrow geometries where the assistance system may be employed while still supporting the user. Accordingly, the drives may span a width Wl, as shown in FIG. 2A which may be large enough to reduce the likelihood of tread slippage during rotation due to high shear forces. In some non-limiting embodiments, the drive width Wl may be 29.2 cm. The drive width Wl may also be greater than or equal to approximately 10 cm, 15 cm, 20 cm, 25 cm, 30 cm, 35 cm, 40 cm, and / or less than or equal to approximately 40 cm, 35 cm, 30 cm, 25 cm, 20 cm, 15 cm, 10 cm, and / or any other suitable width. Combinations of the foregoing ranges, including a drive width Wl between 10 cm and 40 cm are also contemplated. Similarly, the drives may span a length L8, as shown in FIG. 2A, which may be constrained by the length of the treads employed in the base, as well as geometric constraints of the homes or locations where the system may be employed. In some non-limiting embodiments, the drive length L8 may be 47 cm. the drive length L8 may also be greater than or equal to approximately 20 cm, 25 cm, 30 cm, 35 cm, 40 cm, 45 cm, 50 cm, 55 cm, 60 cm, 65 cm, and / or less than or equal to approximately 65 cm, 60 cm, 55 cm, 50 cm, 45 cm, 40 cm, 35 cm, 30 cm, 25 cm, 20 cm, and / or any other suitable length. Combinations of the foregoing ranges, including a drive length L8 between 20 cm and 65 cm are also contemplated.

[0063] It should also be appreciated that for all the aforementioned dimensions, measurements greater than or less than those described above may also be employed, as the assistance systems of the present disclosure are not limited by geometric dimensions.

[0064] As discussed above, in some embodiments, the assistance system may support the full weight of a user during a postural transition. Accordingly, the assistance system 100 may itself have heft to help improve traction with the support surface and increase resistance to tipping or other instabilities. In exemplary, non-limiting embodiments, the assistance system may weight approximately 77 kg. In some embodiments, the assistance system may weight greater than or equal to approximately 50 kg, 75 kg, 100 kg, and / or less than or equal to approximately 100 kg, 75 kg, 50 kg, and / or any other suitable weight.

[0065] In some embodiments, the assistance system may be capable of supporting a user’ s weight up to a maximum weight at the handling portion. This maximum is dependent on many factors, including the system pose and linkage configuration. For example, a system with front and back bases arranged distal from one another may support a greater supported weight at the handling portion. In some embodiments, the assistance system may securely support up to a maximum of 100 kg at the handling portion. Similarly, in some embodiments, the assistance system may support a maximum axial force of 450 N, dependent on factors such as the support floor traction (e.g., vinyl floor with a coefficient of friction of 0.6). In some embodiments, the assistance system may support a maximum lateral force of 120 N, which may be on the order of the average pull strength of an adult male (which is likely much lower in elderly persons or persons with physical disabilities).

[0066] The Inventors have recognized a lack of control schemes associated with linkage systems with actively driven bases which may undergo slippage. Accordingly, the Inventors have recognized the benefits associated with control methods generalizable to all robotic systems with two nonholonomic tread drives connected through a variable-length coupling (e.g., the linkage described herein). To ensure continuous control through a nonstationary trajectory to stabilize driftless nonholonomic systems, in some embodiments, a trajectory following scheme along with an enhanced dead reckoning system, may be employed.

[0067] In some embodiments, the assistance system may be commanded to follow a series of waypoints via dead reckoning of tread angles of the drive bases. For simplicity, the front and rear base poses may be calculated kinematically based on a desired terminal handling portion pose. In some embodiments, a navigation method may be employed, the methodincluding rotating each base to align with the subsequent waypoint and subsequently driving towards it.

[0068] The Inventors have recognized that such an approach may result in disjointed driving, as the bases may need to transition between pure translation and pure rotation at each waypoint. Accordingly, a simple algorithm to minimize jerkiness while maintaining path fidelity may be employed instead, by shifting the instantaneous center of rotation of each drive base. First, sequential waypoints that may be either duplicates or very close to one another may be removed. Next, the first three waypoints may be loaded into a segment. Next, to find the segment’ s instantaneous center of rotation, a circle may be fit to minimize the squared error. In instances where the points may be exactly or nearly linear, a circle of radius of 1000 meters may be employed used. Subsequently, the base may be rotated to be tangent to the circle, and then, the base may be driven along the circle from the first to second waypoint, as shown in FIG. 3. Once the base reaches the second waypoint, the segmentation process may be repeated using a segment comprised of the second waypoint and the two successive waypoints, until the final waypoint is reached.

[0069] FIG. 3 shows an exemplary translation path for the drive bases on a 1:4 scale model of an assistance system using the aforementioned control scheme. The corresponding initial and final system pose are overlaid onto the plot for visualization.

[0070] In some embodiments, a dummy waypoint may be added to the end of the trajectory when two lookahead points are required. While the bases may still rotate at each waypoint, the magnitude of rotation of each base may be less than conventional methods, since a portion of the rotation may be accomplished through following the circular trajectory, as shown in FIG. 3.

[0071] In some embodiments, the back base may be commanded to follow the same trajectory as the front base while remaining a nominal distance behind, such that the assistance system may slither along the support surface. While many alternative coordination strategies are also contemplated, this scheme may be particularly useful for reducing the width of a path and thereby reducing the risk of collisions with obstacles. Additionally, such a process may only require a single trajectory (e.g., the front base) as opposed to two trajectories for both mobilebases, simplifying the control scheme. Furthermore, the range of base separations may be calculated through the physical range of motion of the various joints in the system.

[0072] As discussed above, in some embodiments, the assistance system may employ sensors to measure the angles of the various joints of the system. The data collected by such sensors may significantly increase the dead reckoning accuracy of each base. In some embodiments, kinematic constraints among such sensor readings may be exploited for improved pose estimates. Further, the Inventors have recognized that risk of the treads of the bases slipping may only be present if the bases are turning, but otherwise the bases provide excellent traction when moving linearly. Thus, when a drive base follows a relatively linear trajectory or remains stationary, implying a nearly constant angle, the angle of the other base may be updated using the former base’s estimated angle and the encoders on the bases, which measure the base rotation. Similarly, the position of one base and the measured linkage pose may be used to calculate the actual position of the other base. This method may correct for any possible slippage, for example, when the latter base has undergone a sharp turn. The next few waypoints (corresponding to a path distance of approximately 0.6 m, although other distances are also contemplated) may be shifted by successively smaller intervals to redirect the base to the desired path. In some embodiments, the base position may be updated using dead reckoning through base encoder readings.

[0073] FIG. 4 shows a block diagram of one embodiment of a method for controlling an assistance system for arriving at a desired handling portion pose, according to some embodiments. As shown in block 202, the method may include rigidly locking the front drive to reduce the degrees of freedom of the system from 5 to 3, as previously discussed. Subsequently, the handling portion pose (e.g., an orientation and / or pose) may be specified relative to the front drive and the supporting surface (e.g., floor) to further reduce the degrees of freedom from 3 to 2, as shown in block 204. The system may then determine a ray from the center of the front drive in the direction of the endpoint angle of the handling portion, as shown in block 206. From there, the system may solve a first kinematic equation yielded by the height of the handling portion relative to the center of the front drive, as shown in block 207, and also a second kinematic equation yielded by the distance of the handling portion relative to the center of the front drive,as shown in block 208. Using the results of the kinematic equations, the system may then determine a distance between the front and back drives, as shown in block 210, and subsequently direct the back drive to move the determined distance along the predetermined ray, as shown in block 212. The back drive may then be rigidly locked, as shown in block 214, to provide stable and safe support to the user as they make postural changes. It should be appreciated that the method of FIG. 4 is exemplary, and that other methods of delivering the handling portion to the user are also contemplated.

[0074] The above-described embodiments of the technology described herein can be implemented in any of numerous ways. For example, the embodiments may be implemented using hardware, software, or a combination thereof. When implemented in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single computing device or distributed among multiple computing devices. Such processors may be implemented as integrated circuits, with one or more processors in an integrated circuit component, including commercially available integrated circuit components known in the art by names such as CPU chips, GPU chips, microprocessor, microcontroller, or co-processor. Alternatively, a processor may be implemented in custom circuitry, such as an ASIC, or semicustom circuitry resulting from configuring a programmable logic device. As yet a further alternative, a processor may be a portion of a larger circuit or semiconductor device, whether commercially available, semi-custom or custom. As a specific example, some commercially available microprocessors have multiple cores such that one or a subset of those cores may constitute a processor. Though, a processor may be implemented using circuitry in any suitable format.

[0075] Further, it should be appreciated that a computing device may be embodied in any of a number of forms, such as a rack-mounted computer, a desktop computer, a laptop computer, or a tablet computer. Additionally, a computing device may be embedded in a device not generally regarded as a computing device but with suitable processing capabilities, including a Personal Digital Assistant (PDA), a smart phone, tablet, or any other suitable portable or fixed electronic device.

[0076] Also, a computing device may have one or more input and output devices. These devices can be used, among other things, to present a user interface. Examples of output devices that can be used to provide a user interface include display screens for visual presentation of output and speakers or other sound generating devices for audible presentation of output. Examples of input devices that can be used for a user interface include keyboards, individual buttons, and pointing devices, such as mice, touch pads, and digitizing tablets. As another example, a computing device may receive input information through speech recognition or in other audible format.

[0077] Such computing devices may be interconnected by one or more networks in any suitable form, including as a local area network or a wide area network, such as an enterprise network or the Internet. Such networks may be based on any suitable technology and may operate according to any suitable protocol and may include wireless networks, wired networks or fiber optic networks.

[0078] Also, the various methods or processes outlined herein may be coded as software that is executable on one or more processors that employ any one of a variety of operating systems or platforms. Additionally, such software may be written using any of a number of suitable programming languages and / or programming or scripting tools, and also may be compiled as executable machine language code or intermediate code that is executed on a framework or virtual machine.

[0079] In this respect, the embodiments described herein may be embodied as a computer readable storage medium (or multiple computer readable media) (e.g., a computer memory, one or more floppy discs, compact discs (CD), optical discs, digital video disks (DVD), magnetic tapes, flash memories, RAM, ROM, EEPROM, circuit configurations in Field Programmable Gate Arrays or other semiconductor devices, or other tangible computer storage medium) encoded with one or more programs that, when executed on one or more computers or other processors, perform methods that implement the various embodiments discussed above. As is apparent from the foregoing examples, a computer readable storage medium may retain information for a sufficient time to provide computer-executable instructions in a non-transitory form. Such a computer readable storage medium or media can be transportable, such that theprogram or programs stored thereon can be loaded onto one or more different computing devices or other processors to implement various aspects of the present disclosure as discussed above. As used herein, the term "computer-readable storage medium" encompasses only a non-transitory computer-readable medium that can be considered to be a manufacture (i.e., article of manufacture) or a machine. Alternatively or additionally, the disclosure may be embodied as a computer readable medium other than a computer-readable storage medium, such as a propagating signal.

[0080] The terms “program” or “software” are used herein in a generic sense to refer to any type of computer code or set of computer-executable instructions that can be employed to program a computing device or other processor to implement various aspects of the present disclosure as discussed above. Additionally, it should be appreciated that according to one aspect of this embodiment, one or more computer programs that when executed perform methods of the present disclosure need not reside on a single computing device or processor, but may be distributed in a modular fashion amongst a number of different computers or processors to implement various aspects of the present disclosure .

[0081] Computer-executable instructions may be in many forms, such as program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Typically the functionality of the program modules may be combined or distributed as desired in various embodiments.

[0082] The embodiments described herein may be embodied as a method, of which an example has been provided. The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts arc performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments.

[0083] Further, some actions are described as taken by a “user.” It should be appreciated that a “user” need not be a single individual, and that in some embodiments, actions attributable to a “user” may be performed by a team of individuals and / or an individual in combination with computer- assisted tools or other mechanisms.

[0084] While the present teachings have been described in conjunction with various embodiments and examples, it is not intended that the present teachings be limited to such embodiments or examples. On the contrary, the present teachings encompass various alternatives, modifications, and equivalents, as will be appreciated by those of skill in the art. Accordingly, the foregoing description and drawings are by way of example only.

[0085] While several embodiments of the present invention have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and / or structures for performing the functions and / or obtaining the results and / or one or more of the advantages described herein, and each of such variations and / or modifications is deemed to be within the scope of the present invention. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and / or configurations will depend upon the specific application or applications for which the teachings of the present invention is / are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the invention may be practiced otherwise than as specifically described and claimed. The present invention is directed to each individual feature, system, article, material, kit, and / or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and / or methods, if such features, systems, articles, materials, kits, and / or methods are not mutually inconsistent, is included within the scope of the present invention.

Claims

CLAIMS1. A system for assisting a user, the system comprising: a front base including a front drive configured to move the front base over a supporting surface; a back base including a back drive configured to move the back base over the supporting surface; a linkage including three or more links with a front link rotatably coupled to the front base and a back link rotatably coupled to the back base; and an actuator coupled to at least one link of the linkage, wherein the actuator is configured to control a pose of the linkage relative to the front base and the back base.

2. The system of claim 1, further comprising a handling portion configured to be grasped by the user, the handling portion coupled to at least one link of the linkage.

3. The system of claim 1, wherein the actuator is a non-backdrivable actuator.

4. The system of claim 1 , further comprising a lock configured to selectively lock a pose of the linkage.

5. The system of claim 1, wherein the actuator is configured to selectively lock a pose of the linkage.

6. The system of claim 1, further comprising one or more sensors configured to sense the pose of the linkage.

7. The system of claim 1, further comprising at least one processor configured to command the front drive, the back drive, and / or the actuator.

8. The system of claim 2, wherein the handling portion is configured to extend at least 40 cm away from the front base.

9. The system of claim 1, wherein at least one of the front drive and the back drive are nonholonomic tread drives.

10. The system of claim 6, wherein the one or more sensors comprise at least one encoder configured to sense a rotation angle of at least one of the front drive and the back drive.

11. The system of claim 2, wherein the handling portion is configured to support a maximum lateral force of 120 N.

12. A method of assisting a user, the method comprising: moving a front base over a supporting surface with a front drive; moving a back base over the supporting surface with a back drive, the back base operatively connected to the front base through a linkage; and controlling a pose of the linkage with an actuator, the actuator coupled to at least one link of the linkage.

13. The method of claim 12, further comprising determining a path of displacement for the back drive based on the pose of the linkage relative to the front drive.

14. The method of claim 12, further comprising providing a handling portion configured to be grasped by the user, the handling portion coupled to at least one link of the linkage.

15. The method of claim 12, further comprising selectively locking a pose of the linkage with a lock.

16. The method of claim 12, further comprising selectively locking a pose of the linkage with the actuator.

17. The method of claim 12, further comprising sensing the pose of the linkage using one or more sensors.

18. The method of claim 12, further comprising commanding the front drive, the back drive, and / or the actuator with at least one processor.

19. The method of claim 14, further comprising extending the handling portion at least 40 cm away from the front base.

20. The method of claim 17, further comprising sensing a rotation angle of at least one of the front drive and the back drive with at least one encoder of the one or more sensors.

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