Adaptive Quasi-Static Motion Control of a Soft Robotic Exo-Digit in physical Human-Wearable-Soft-Robot-Interaction

Abstract

This paper presents an adaptive quasi-static model-based control algorithm for controlling the motion of a soft robotic exo-digit while physically interacting with the human hand for a continuous passive motion physical therapy. Quasi-static analytical models were developed for modeling the soft robot, the human finger, and their coupled physical interaction. A discrete-time state-space representation was derived for the position control system. A control input was designed to linearize the input-output where the input is the actuation pressure and the output is the overall bending angle of the distal end which follows the reference input. The analytical models and controller were examined through experimental testing for two case studies: 1) a step-response with a disturbance attenuation and 2) for tracking the desired angular bending of the distal end while adaptively adjusting the control gain to achieve the desired dynamic performance. The results showed the effectiveness of the adaptive quasi-static controller.