Bilateral Tele-Rehabilitation System using Electrical Stimulation applying Modulated Time-Domain Passivity Control

Abstract

This paper considers a bilateral tele-rehabilitation system by using an electrical stimulation based on a scattering matrix method by applying a modulated time-domain passivity control for a human lower limb. The scattering matrix method includes a scattering transformation, a phase control filter, and a wave filter. In our previous works, a non-passive approach based on a scattering matrix method has been applied to the bilateral tele-rehabilitation system. However, variable long time delay affects the control performance in the experiment through the Internet. Because the feedforward control with the phase-lead filter is used in the patient side, the feedforward controller may provide the large control input force for the tired patient’s lower limb. The main contribution of this paper is to apply the modulated time-domain passivity control to improve the control performance of the bilateral tele-rehabilitation system. In the previous bilateral tele-rehabilitation with the modulated time-domain passivity control, the velocity and the force are communicated between the therapist and the patient. In this paper, the position and the force are communicated in the proposed bilateral tele-rehabilitation system, and the improvement of the tracking performance is expected. The proposed bilateral tele-rehabilitation system is verified in the experiment with the variable time delay. It can be confirmed that the control performance is improved by using the modulated time-domain passivity control.