Upper-Limb Tele-Rehabilitation System with Force Sensorless Dynamic Gravity Compensation

Abstract

Tele-rehabilitation provides remote physiotherapy services for patients who have limited access to hospitals. This paper proposes a sensorless tele-rehabilitation system for the upper-limb using two robots in master–slave configuration. The system provides a transparent haptic feeling between the therapist and the patient by simultaneous tracking of both position and torque. The torque is measured using the reaction torque observer. Furthermore, an online recursive numerical parameter estimation method is proposed to identify the gravity disturbance in bilateral teleoperation. The system automatically estimates the parameters using the reaction torque observer output’s data while the therapist is delivering remote physiotherapy services. The estimated gravity torque is compensated in the system as an improvement of the transparency of the teleoperated system. Therefore the therapist would feel only the abnormalities of the patient’s arm. Estimated parameters automatically update the system and enhance the performance. The proposed method was practically verified with a master slave tele-rehabilitation system. Results suggest the applicability of the proposed method.