Optoelectronic-Based Pose Sensing for a Hand Rehabilitation Exoskeleton Continuous Structure
Bo He, Min Li, Renghao Liang, Ziting Liang, Wei Yao, Sina Sareh, Jun Xie, Guanghua Xu, Yohan Noh
Abstract
Hand exoskeleton pose monitoring is of great importance in the rehabilitation training of stroke patients to ensure precise robotic trajectory control and provide a patient recovery assessment mechanism. In this paper, a low-cost pose sensor unit based on the principle of photoelectric reflection is proposed to measure the pose of a multi-segment continuous structure in a hand rehabilitation exoskeleton. The sensor unit consists of five photosensitive elements that measure the rotation angle of an arrangement of adjacent segments, each integrated with a sensing element, to estimate the actuator’s motion. An accurate device with a user-friendly interface is then designed for calibration of the sensing elements. The experimental results indicate that the sensitivity exceeds 0.047 V/° for the sensing elements, and hysteresis and repeatability errors are less than 1.1% and 1.8%, respectively. A comparison between the proposed sensor output and the results benchmarked by a VICON motion capture system demonstrates that the sensor can measure the bending angle of the multi-segment structure with a mean error of 3.23 degrees.