Digital control strategy for scanning of moving mirror in fourier transform spectrometer

The control system of moving mirror scanning is an important part of the Fourier transform spectrometer, and its dynamic and static performance determines the interference effect and the spectral resolution of the spectrometer. To meet the requirement of the uniform velocity of moving mirror scanning, a completely digital control scheme is proposed with FPGA as the key hardware, and this scheme is applied to the moving mirror movement in the spectrometer. According to the need of the current detection and the velocity detection, a dual closed loop control composed of current loop and velocity loop is realized, with current loop and velocity loop using PI control and fuzzy PID control respectively. The experiment results show that the current curve is smooth in the uniform scan phase of moving mirror, and that the peak current is 0.5 A in acceleration and deceleration period. Additionally, when the angular velocity of moving mirror is 30°/s in the uniform section, the maximum relative error is less than 4%. From research results, it can be drawn that the digital control strategy can significantly improve the velocity stability of moving mirror, and meet the performance requirements of the control system.