Nonlinear modeling, Measurement, and Control of a hybrid reluctance-actuated fast steering mirror

The hybrid reluctance-actuated fast steering mirror (HRA-FSM) addresses the performance limitations of conventional fast steering mirrors in terms of aperture, bandwidth, and stroke. However, the nonlinear torque characteristics that arise at large deflection angles continue to constrain further improvements in HRA-FSM performance. Existing mathematical models exhibit considerable errors, and current studies lack effective methods for nonlinearities evaluation. In this study, a novel nonlinear HRA model is developed based on a prototype system. This model establishes the mapping between nonlinear common-mode and differential-mode components to elucidate the complex angle-current coupling dynamics. Experimental validation is performed by quantifying magnetic flux density distribution differences at the stator end faces and Hall sensor measurements. This paper details the theoretical framework for nonlinear modeling, the experimental measurement principles, and introduces a feedback linearization compensation control algorithm. This approach achieves a 48.8% reduction in bandwidth fluctuation and up to 36.4% decrease in tracking error. The HRA-FSM prototype demonstrates a range-bandwidth product of 18,675 mrad Hz, surpassing the performance of existing single-axis FSMs.