Output torque tracking control of direct-drive rotary torque motor with dynamic friction compensation

Abstract

Accurate output torque tracking control problem of Direct-Drive Rotary (DDR) torque motor is concerned in this paper. An adaptive robust torque control algorithm with LuGre model based dynamic friction compensation is proposed to improve the torque tracking accuracy. Adaptive robust control (ARC) backstepping design technique and Lyapunov stability theorem are employed to design the controller to deal with both structured and unstructured uncertainties in a practical control system. In the ARC algorithm, discontinuous projection based parameter adaptive law is utilized to estimate unknown system parameters, and robust control law ensures the robustness of closed-loop control system. In order to further improve the torque tracking control performance, LuGre model based dynamic friction compensation is designed to estimate and compensate friction torque in the practical torque motor system. The mathematically design procedure of the proposed algorithm is developed. Finally, the proposed algorithm is implemented on a practical DDR torque motor control system. Experimental results with three compared control algorithms validate that the proposed algorithm can effectively improve the torque tracking performance and LuGre model based dynamic friction compensation is also necessary for high-accuracy torque tracking control.