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.
Keywords telescopes — instrumentation: detectors — methods: analytical
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