Fast and precise scanning and tracking control of space beam based on adaptive LMS algorithm

Fast and precise beam scanning control is strictly required in aerospace, especially the space precise optics. To meet the requirements of fast and precise beam control for space science and technology as well as national defense applications, the adaptive least-mean square (LMS) algorithm was given to control the beam pointing and tracking of piezoelectric steering mirrors. Firstly, the adaptive LMS control method and the model identification of fast steering mirror were described. Then, the piezoelectric fast steering mirror model was identified and compared with the known reference model. The tracking control performance of the adaptive LMS algorithm under different frequencies and iterative steps was simulated. Finally, the unknown piezoelectric steering mirror was identified by experiments, and the adaptive LMS algorithm was designed for the input-output scanning and tracking control. The experimental results show that the tracking errors of the adaptive LMS algorithm arc 2.5% (3 sigma), 1.9% (3 sigma) and 2.4% (3 sigma) for 2Hz, 10Hz and their compound sinusoidal scanning signals, respectively, which arc better than the PI control errors. The adaptive LMS algorithm can effectively track multi-frequency reference signals and provide a reliable technical means for fast and precise space beam pointing and tracking.