Adaptive Exoskeleton Torque Control for Impaired Joint Rehabilitation
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Solution Overview
Problem
Conventional physical rehabilitation methods using exoskeletal robots impose prescribed dynamics of healthy joints on impaired joints, leading to out-of-sync movements and inadequate assistance due to mismatched speeds between the robot and the patient.
Innovation Solution
A method and apparatus that provide deficit-adjusted adaptive assistance by determining the current movement phase of an impaired joint using sensor data, calculating adaptive timing and magnitude of robot-applied torque based on the difference between normal and impaired robot state parameter traces, and applying these adjustments to the exoskeletal robot joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional exoskeletal robots impose prescribed dynamics of healthy joints on impaired joints, then the robot can provide standardized rehabilitation assistance, but the robot and patient become out-of-sync due to speed mismatch
Solution Approach 1:
The system dynamically adjusts the robot's movement parameters in real-time to match the patient's actual joint movement speed and trajectory. The controller continuously modifies the prescribed dynamics based on sensor feedback, transforming the static healthy joint model into a dynamic adaptation that follows the impaired joint's actual movement patterns, thereby maintaining synchronization.
Solution Approach 2:
The system changes key movement parameters such as speed, amplitude, and timing of the robot's assistance based on the detected deficit between healthy and impaired joint traces. By adjusting these parameters to match the patient's reduced speed and altered movement pattern, the robot maintains reliable synchronization while still providing therapeutic rehabilitation assistance.
2Productivity
If the robot moves at normal speed to match healthy joint dynamics, then standardized rehabilitation can be provided, but the impaired joint movement is inhibited rather than assisted
Solution Approach 1:
The system changes the speed and timing parameters of the robot's movement to match the impaired joint's reduced velocity. Instead of forcing normal-speed movement, the robot adapts its parameters to the patient's actual movement capabilities, making assistance easier while maintaining rehabilitation effectiveness through deficit-adjusted parameters.
Solution Approach 2:
The system allows the patient's natural movement patterns to guide the robot's assistance. By using sensor data from the patient's own joint movement to determine the robot's response parameters, the system enables the patient's movement to serve itself, reducing inhibition and improving ease of operation.
3Reliability
If the robot adapts to the patient's reduced speed, then synchronized assistance can be provided, but the rehabilitation effectiveness may be reduced compared to normal-speed training
Solution Approach 1:
The system changes the robot's movement parameters to match the patient's speed while incorporating deficit-adjusted assistance that targets specific impairment areas. By modifying parameters such as torque magnitude and timing based on the difference between healthy and impaired traces, the system maintains synchronization while preserving rehabilitation effectiveness through targeted parameter adjustments.
Solution Approach 2:
The system dynamically adjusts the balance between matching patient speed and providing therapeutic challenge. The controller continuously modifies assistance parameters during movement to maintain synchronization while introducing appropriate resistance or support to ensure rehabilitation effectiveness, creating a dynamic equilibrium between reliability and productivity.
Data Source
AI summary
A method includes determining, on a processor, a current movement phase for a compound joint function based on sensor data. The method further includes determining, on the processor, a respective robot state parameter trace for each movement phase in a normal and impaired subject. The method further includes determining, on the processor, a deficit parameter for each movement phase. The method further includes determining, on the processor, an adaptive magnitude for the robot applied torque based on the deficit parameter of the current movement phase. The method further includes applying, to the robot joint, the adaptive magnitude for the robot applied torque for the current movement phase, based on an adaptive timing for the current movement phase. An apparatus is also described for providing deficit-adjusted adaptive assistance during movement phases of the impaired joint.