Hysteresis compensation and composite control for Piezoelectric actuator

Fast Steering Mirror (FSM) is the core part in terminal fine aiming system of inter-satellite laser communication. As the driving device for FSM, Piezoelectric actuator's (PEA) hysteresis characteristics seriously affect FSM's position accuracy, and therefore have adverse influence on stability of inter-satellite communication link. In order to solve this problem, a modified Prandtl-Ishlinskii (MPI) model was proposed to describe PEA. On this basis, a feed-forward linearization approach for PEA was presented to achieve feed-forward inverse compensation for hysteresis. Meanwhile, a composite control method was developed by combining the MPI model and the incremental PID control algorithm, then the composite control algorithm was implemented in DSP later. At last, the performance of proposed algorithm was verified on test platform. The experimental results indicate that when system was input with damped sinusoidal and constant amplitude sinusoidal curves of 10 Hz and 100 Hz respectively, model error was within 0.59%. Under damped sinusoidal input curve of same frequency under 100 Hz, the greatest error of traditional PID algorithm was 59.31μrad, and that of proposed composite algorithm was 14.22 μrad. Experimental data shows that MPI model can accurately depict hysteresis characteristics of PEA and corresponding composite control method has obviously better dynamic tracking performance than traditional PID method, which can satisfy requirements of practical application to FSM.