Because of the transmission errors and the elastic deformations of reducer and lead screw-nut pair

active joints inevitably suffer from following errors that significantly degrade the dynamic contour accuracy of hybrid robots. An effective dynamic accuracy control strategy based on the grating sensors installed on the wrist and the passive limb was resented in this paper for improving the dynamic contour accuracy in these hybrid robots. After addressing the design principle of a PID + feedforward and Lyapunov stability based control law with the position feedbacks of the grating sensor and the servo motor encoder

a dynamic accuracy compensator was developed. Experimental results on a TriMule-200 hybrid robot show that the dynamic contour accuracy of the robot is significantly improved with the maximum reduced dynamic error of 82.88%

which verifies the effectiveness of the proposed dynamic accuracy control strategy.