Nonsingular Terminal Sliding Mode Control of Voice Coil Actuator Fast Steering Mirror Based on Tracking Differentiator

To achieve precise tracking control of the voice coil actuator fast steering mirror (VCA-FSM) with large measurement noise, a nonsingular terminal sliding mode control (NTSMC) method based on tracking differentiator (TD) is proposed. Firstly, the high precision mathematical model of VCA-FSM is obtained by using the Hankel matrix system identification method based on pulse response. Then, the linear extended state observer (LESO) is used to filter the angle signal with noise and extract the differential signal of the angle signal based on TD. Next, the sliding surface and control law of NTSMC are designed, and the sign function is improved in the control design to ensure the continuity of the control quantity. Finally, the high precision servo control experiment of VCA-FSM is carried out based on the Matlab/dSPACE semi-physical simulation platform. The experimental results show that tracking the desired angle position signal with a amplitude of 0.05rad and a frequency of 10Hz, the maximum tracking error is 0.0035rad and the standard deviation is 0.0015rad, and compared with the traditional linear sliding mode control method, it is reduced by 20% and 13%, which verifies the effectiveness of the designed control method. The control method designed in this paper meets the requirements of VCA-FSM control system for fast dynamic response and high steady-state accuracy.