Research on Antenna Servo Control Method Based on Super Twisting Terminal Sliding Mode of Disturbance Observer

Pointing accuracy is an important index to evaluate the performance of radio telescope antenna, and the servo control method of antenna is the key factor to affect the index. A new sliding mode control method based on disturbances observer is proposed to achieve global robust fixed-time stability of antenna servo system. The settling time is analyzed by using Lyapunov theory. The sliding mode variable in the proposed method adopts the variable exponential coefficient related to the state, which calculate the maximum sliding time in advance and improves the robustness of the system. The use of disturbance observer can accurately obtain and compensate the servo system interference, combined with the control input of the 2 order variable gain super twisting algorithm, which effectively alleviates the chattering phenomenon, and realizes the robustness control of the antenna. The simulation results show that the system can track the signal quickly at about 0.55 s, the tracking error is small, and the inhibition effect of chattering is obvious. The proposed control strategy can track the reference signal faster, simpler and more effectively to suppress the interference of the antenna servo system.