Study On Robust Control Of Internet Based Tele-rehabilitation System

Tele-rehabilitation system based on teleoperation techniques and applied withcomputer technology, automatic control theory, sensor technology and testing techniques.The system can not only provide remote training and rehabilitation assessment for disabledpeople in remote areas, but also can encourage patient to participate in rehabilitation therapymore flexibly and actively.This article mainly aimed at the research on the stability, transparency, trackingperformance and time delay of tele-rehabilitation system. The designed robust controller canreduce influence of time delay and external disturbances existing in the system. That canalso ensure system has good robust stability and tracking performance even in the case ofdisturbances. Specific research contents are as follows:Firstly, this paper introduced the research background and significance of Internet-based tele-rehabilitation system and the research situations of domestic and abroad.Secondly, it introduced the conventional dynamics model and two-port network modelof teleoperation system. Furthermore, the dynamics modeling and equivalent two-portnetwork model of tele-rehabilitation system are given.Thirdly, in order to eliminate the effect of communication time delay which usuallycauses instability and bad performance of the system. Consequently, the whole system isdescribed as a state equation with time delay. Then we adopted appropriate Lyapunovfunction to analyze system’s stability and obtained the stability conditions at constrainedmotion with time delay. In addition, we established the equivalent circuit of the system andstudied a novel method of impedance matching to analyze the system’s transparency withtime delay or not. The simulation results illustrated the validity of the proposed method andthe system has good stability and transparency.Then, for the problem of time delay and external disturbances existing in theInternet-based tele-rehabilitation system, we turned the disturbances problem into the robustH_∞control problem by selecting the appropriate weighting function. The master and slavecontroller based on mixed-sensitivity H_∞control theory and μ-synthesis method isdesigned. The experimental results in the constrained motion showed that the designedcontroller achieved the project objective.Finally,1-DOF teleoperation experimental system is improved. The robust controller which was designed in this paper has realized in the LabVIEW environment. Furthermore, itdemonstrated the stability and control effect of system and carried out the tracking controlof force and position.The result of research showed that the designed H_∞controller has good robuststability and tracking performance, which laid the foundations for further study of newcontrol technology.