Adaptive filter and linear quadratic Gaussian/loop transfer recovery compensator combination control of a non-linear tip-tilt mirror

摘要

Adaptive control of a tip-tilt mirror requires precise model estimation, which is difficult for the nonlinear features of piezoelectric actuators such as creep, hysteresis and resonance. A linear quadratic Gaussian control/loop transfer recovery (LQG/LTR) based compensation of the non-linearity is used, which employs a high sampling frequency position sensor to measure the displacements of the tip-tilt mirror and feedbacks the modified command needed to make the actuator response linearly to input command. A normalized LMS adaptive filter whose gains are adjusted by weight updating algorithm to minimize the mean square error of the output is used in order to reduce the jitter introduced by kinds of broadband and narrowband disturbance. The principle of an adaptive filter and LQG/LTR compensator combination control of a nonlinear tip-tilt mirror is introduced. The method is compared with the integrator and LQG/LTR combination control by numerical simulation. Results reveal that the adaptive filter and LQG/LTR compensator combination control is more effective and has less tracking residual error.