Powered orthotic system for cooperative overground rehabilitation
Inventors
Zoss, Adam • Swift, Tim • Berg, Alec • Strausser, Katherine • St. John, Erick Brendan
Assignees
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Publication Number
US-10369021-B2
Publication Date
2019-08-06
Expiration Date
Abstract
A powered orthotic system, such as an exoskeleton, is employed for overground rehabilitation purposes by adapting and adjusting to real-time needs in a rehabilitation situation whereby the system can be initially controlled to perform gait functions for a wearer based on a predetermined level of assistance but the predetermined level of assistance can be varied, based on one or more rehabilitation parameters or specific needs of the wearer undergoing therapy, through the application and adjustment of appropriate variables associated with operation of the system.
Core Innovation
The invention provides a powered orthotic system, including an exoskeleton, for overground rehabilitation of a wearer to perform gait functions. The powered orthotic system is initially established to perform gait functions based on a predetermined level of assistance, and during rehabilitation the predetermined level of assistance is adaptively varied based on a rehabilitation parameter of the wearer.
The adaptive variation is implemented by establishing a desired assistance profile and creating a tunnel region around a desired assistance trajectory. Along the desired assistance trajectory, one or more segments are defined, and to each segment a function proportional to a distance from the desired assistance trajectory is assigned, so that assistance is varied in relation to the distance from the desired assistance trajectory.
In another approach, the adaptive variation is implemented using a real-time trajectory. A previous position along a trajectory is determined, a current position along the trajectory is determined, and a rate of progress along the trajectory is determined, and from these values a future trajectory is estimated and the rehabilitation assistance is varied accordingly.
Additional aspects include maintaining overground progression using a virtual back wall and balancing motion using coordinated torques between legs. A virtual back wall is established by computing a trailing back wall that follows behind a trajectory of a path of the wearer and advancing along the path even when the wearer reduces or ceases progress, with assistive force modification when the back wall position matches the wearer position, and torque coordination is provided by identifying an imbalance between hip joints that results in adverse motion of the torso and adjusting torsions in the hip joints to balance forces.
Claims Coverage
The partial content includes three independent claims. Each independent claim recites an overground rehabilitation method or system that initially sets a predetermined level of assistance and then adaptively varies that assistance based on a rehabilitation parameter, with different main mechanisms for varying assistance.
Predetermined assistance varied using a tunnel region around a desired assistance trajectory
A method of performing overground rehabilitation that initially establishes the powered orthotic system to perform gait functions based on a predetermined level of assistance defined by a desired assistance profile, wherein varying the predetermined level of assistance includes creating a tunnel region around the desired assistance profile by defining a desired assistance trajectory, defining one or more segments along the desired assistance trajectory, and assigning to each segment a function proportional to a distance from the desired assistance trajectory.
Predetermined assistance varied using real-time trajectory estimation from previous and current positions
A method of performing overground rehabilitation wherein varying the predetermined level of assistance includes providing a real-time trajectory by determining a previous position along a trajectory, determining a current position along the trajectory, determining a rate of progress along the trajectory, and estimating, from the previous position, current position, and rate of progress, a future trajectory.
Virtual back wall forcing continued motion along a path
A method of performing overground rehabilitation wherein varying the predetermined level of assistance includes establishing a virtual back wall by computing a trailing back wall that follows behind a trajectory of a path of the wearer, allowing the trailing back wall to advance along the path even if the wearer reduces or ceases progress along the path, identifying a condition when a position of the back wall is identical to a position of the wearer, and modifying an assistive force applied to the wearer to force continued motion along the path.
Torque coordination between hip joints based on imbalance condition
A method of performing overground rehabilitation wherein varying the predetermined level of assistance includes coordinating torques between legs of the wearer by identifying a condition of imbalance between hip joints of the powered orthotic system that results in adverse motion of a torso of the powered orthotic system and adjusting torsions in the hip joints to balance forces.
Exoskeleton controller using segmented desired assistance trajectory or future trajectory estimation
An overground rehabilitative powered orthotic system including an exoskeleton with a torso portion, at least one leg support including a thigh link and shank link connectable at a hip joint and knee joint, a first actuator controlling the hip joint, a second actuator controlling the knee joint, a plurality of sensors, and a controller configured to control the first and second actuators with adaptive, variable levels of assistance by initially establishing the exoskeleton to perform gait functions based on a predetermined level of assistance and adaptively varying the predetermined level of assistance based on a rehabilitation parameter, wherein the controller is configured to define a desired assistance trajectory, define one or more segments along the desired assistance trajectory, and assign to each segment a function proportional to a distance from the desired assistance trajectory, or determine a previous position along a trajectory, determine a current position along a trajectory, determine a rate of progress along the trajectory, and estimate a future trajectory.
Across the independent claims, the main inventive coverage is adaptive, variable assistance for overground rehabilitation that is initially set from a predetermined level of assistance and then varied using either a tunnel region with distance-proportional segment functions, a real-time estimate of a future trajectory from previous and current positions and rate of progress, or mechanisms including a virtual back wall with assistive force modification and coordinated hip-joint torque adjustments based on an imbalance condition.
Stated Advantages
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