Research on the Antidisturbance Method of CMG Gimbal Servo System With Parameter Uncertainty and Nonlinear Disturbances

High precision control of angular speed of the gimbal servo system in control moment gyro is a crucial aspect of spacecraft attitude control. This article focuses on addressing the challenges posed by the problems of parameter uncertainty and mismatched disturbances in the gimbal servo system of single gimbal control moment gyro (SGCMG). To address these issues, a composite control method that combines an iterative optimal control (IOC) based on parameter identification and disturbance observer (DO) is proposed. The IOC based on parameter identification aims to suppress the problem of parameter uncertainty. Forgetting factor recursive least squares is designed to estimate the time-varying parameters of the gimbal servo system in real-time. With the results of the parameter identification, IOC algorithm is formulated to dynamically adjust the optimal control law, thereby enhancing the system's robustness and addressing the challenge of parameter uncertainty. On the other hand, the DO is designed to observe and handle the mismatched disturbances. To mitigate mismatched disturbances, coordinate transformation and feedforward compensation methods are introduced. The effectiveness of the proposed method is validated through simulations and experiments conducted on the SGCMG prototype.