Vibration isolation and low-frequency tracking based on magnetic levitation with composite control

In spacecraft, precision equipment is severely affected by vibration excitation generated by rotor imbalance in the Control Moment Gyroscope (CMG), which is the core actuator for low-frequency attitude adjustments. Active vibration isolation (AVI) has been extensively studied by many scholars. However, traditional actuators suffer from contact friction and response delay; feedback and feedforward control alone have performance bottlenecks. As a result, the low-frequency tracking and mid-frequency isolation performance of CMG AVI are severely limited. Therefore, this paper proposes a magnetic levitation vibration isolation system (MLVIS) with composite control to optimize the tracking and AVI performance. In terms of structure, a magnetic levitation actuator is used to eliminate slow response and friction hysteresis. For the control algorithm, a composite strategy integrating integral force feedback and filtered-x recursive least squares is adopted. Through mutual compensation between the two control methods, this composite strategy mitigates the inherent time delay of feedback control and the instability of feedforward control. Experimental results show that the tracking error in the low-frequency band is 2.71% and 11.67% under single- and dual-frequency excitation, respectively, while 91.86% attenuation of the natural-frequency vibration amplitude is achieved in the mid-frequency band. These results verify the tracking and AVI performance of the MLVIS.