Research on Sliding Mode Control with Reduced-Order Extended Observer for Fast Steering Mirror in High-Precision Scanning Tracking Systems

Abstract: In the field of precision beam tracking, fast steering mirror (FSM) must exhibit rapid response capabilities while maintaining minimal tracking error. To meet the stringent performance requirements of FSM, the control system must simultaneously satisfy three critical specifications: overshoot below 10%, convergence time faster than 5ms, and effective tracking capability. This research is based on the practical FSM mathematical model. Considering the unknown internal and external disturbances that can prevent the acquisition of precise mathematical models, conventional control methods often fail to promptly and effectively address these disturbances, thereby compromising optimal compensation control performance. Consequently, this research develops a sliding mode control strategy integrated with an extended state observer (SMC-ESO) for comprehensive estimation of aggregate external disturbances. Furthermore, an advanced sliding mode control scheme incorporating a reduced-order extended state observer (SMC-RESO) is proposed. A comprehensive comparative analysis of these two control methodologies is conducted through multi-dimensional evaluations, including step response, sinusoidal tracking, and scanning tracking tests. Experimental results conclusively demonstrate that the proposed control strategy exhibits significantly enhanced response and tracking capabilities compared to conventional control approaches, particularly in maintaining system stability and precision under dynamic operating conditions.