Damping Control Based Speed Adjustment Strategy for a Lower Limb Rehabilitation Robot

Abstract

Active rehabilitation training based on recognition of motion intention can effectively improve the patient’s engagement in rehabilitation training, and thus improve the training effect. In this paper, a speed adjustment strategy for active training based on multi-joint damping control is proposed for bicycle training. The active force applied by patient can be calculated by the dynamic model of human-robot system, and then converted into the tangential force at the pedal of robot along the forward direction of bicycle. The tangential force is converted into the adjustment term of joint angular speed by damping control to dynamically adjust the riding speed. When the tangential force is larger than the threshold value, the pedal will deviate from the reference circular trajectory. Therefor, a speed vector pointing to the circular center is added to pull the end-effector back to the reference trajectory. Moreover, a fuzzy impedance parameter regulator is designed to adjust the training intensity, by which the impedance parameters can be regulated according to the magnitude of the patient’s active force and the deviation from the reference trajectory. Finally, in order to increase the patient’s engagement, Unity3D software is used to design the virtual scene of cycling on the road. The experimental results show that the active compliant rehabilitation training can be realized by the proposed method.