Friction compensation for an m-Level telescope based on high-precision LuGre parameters identification

Abstract

Friction torque severely weakens the tracking accuracy and low-speed stability of an m-level TCS (telescope control system). To solve this problem, a friction compensation method is proposed, based on high-precision LuGre friction model parameters identification. Together with dynamometer calibration, we first design a DOB (disturbance observer) to acquire high-accuracy TCS friction value in real time. Then, the PSO-GA (a hybrid algorithm combined particle swarm optimization algorithm and genetic algorithm) optimization algorithm proposed effectively and efficiently realizes the LuGre model parameters identification. In addition, we design a TCS controller including DOB and LuGre model parameters identification based on double-loop PID controller for practical application. Engineering verification tests indicate that the accuracy of DOB calibrated can reach 96.94%of the real measured friction.When azimuth axis operates in the speed cross-zero work mode, the average positive peak to tracking error reduces from 0.8926″ to 0.2252″ and the absolute average negative peak to tracking error reduces from 0.8881″ to 0.3984″. Moreover, the azimuth axis tracking MSE reduces from 0.1155″ to 0.0737″, which decreases by 36.2%. Experimental results validate the high precision, facile portability and high real-time ability of our approach.