Vibration Isolation and Control of Variable Stiffness Fast Steering Mirror Based on Extended State Observer and Sliding Mode Control

Fast steering mirror (FSM) play a crucial role in the precise control of light beams in electro-optical tracking systems. When FSMs are mounted on vehicular motion platforms, conventional passive isolation systems often fail to meet the stringent isolation requirements of FSM. To address this issue, this paper proposes a method that combines the advantages of passive isolation and active control to enhance the isolation and control performance of FSM. The proposed approach employs a variable stiffness negative stiffness mechanism (NSM) to reduce the stiffness of the FSM, thereby improving isolation performance. An extended state observer (ESO) is used to observe and compensate for total disturbances, and a sliding mode controller (SMC) is designed to enhance the rapidity of the FSM's response and improve disturbance rejection characteristics. Simulation results indicate that the proposed method effectively suppresses disturbances under road step disturbances. The addition of NSM enhances the vibration isolation and control performance of FSM, while the inclusion of ESO further improves the disturbance rejection capability of FSM.