Moving trajectories and controller synthesis for an assistive device for arm rehabilitation

In this study, a twisted string actuation mechanism was used to develop an assistive robotic system to assist post-stroke patients to regain mobility. The robotic manipulator used in therapy systems can apply forces to aid in specific tasks during goal-directed movements. The device was designed for the one-degree-of-freedom movement of patients´ elbow joint. To compensate the moving trajectory, the dynamics of both actuation system and robotic mechanism were identified. An angular trajectory of healthy male adults was used to drive the movement of the proposed robotic system to mimic the locomotion of real human arms. Different physical conditions, including induced torque disturbance and applicable range of actuation, were discussed. A high-gain controller with the consideration of robustness and time-delay to the torque disturbance was synthesized to ensure the control performance.