Autobalancing Control for MSCMG Based on Sliding-Mode Observer and Adaptive Compensation

This study proposes an autobalancing control method for the magnetically suspended control moment gyro (MSCMG) to achieve clean vibration force and torque properties. The rotor imbalance of the MSCMG generates centrifugal force and moment, which degrade the performance of the MSCMG. Since the voltage-type power amplifiers are used onboard and the dc voltage on the spacecraft is limited, the characteristics of the current loop must be taken into consideration. Moreover, the active magnetic bearing deviates from its equilibrium point when the rotor attempts to rotate around its principle axis of inertia, which leads to errors for the traditional linearized electromagnetic force model. To reject the influence of magnetic force parameter perturbation, a sliding-mode observer is designed to obtain the rotor imbalance owing to its robustness about the model error. Then, an adaptive compensation algorithm is designed to produce the target coil current to compensate the displacement stiffness force, leading to a clean vibration electromagnetic force output. It can automatically compensate the variations of the power amplifier and the induced electromotive force, and perfect imbalance vibration suppression is achieved for both vibration force and vibration torque. The simulation and experiment results demonstrate the effectiveness and superiority of the proposed method.