Pneumatic Resistance Control of an Upper Limb Active Rehabilitation System

This paper proposes a pneumatic upper limb rehabilitation robot (PULRR) which is designed for bilateral upper limb active rehabilitation of the patients after stroke. The PULRR provides an active resistance rehabilitation method based on the pneumatic control system. The air kinetics of the pneumatic cylinder model and the dynamics of the pneumatic system with load are established. An antisaturation proportional-integral-differential (PID) controller is presented for the constant resistance force control through directly adjusting the position of the throttle valve spool according to the patient's active moving speed and the feedback of the air pressure in both chambers. In addition, simulation and experimental results indicate that the controller is effective in constant resistance force control. The resistance mode proposed in this paper shows great potential in active resistance rehabilitation for the patients who suffer from the dyskinesia and insufficient muscle strength of the upper limb with enhanced safety and compliance.