Decoupling modeling design and high-precision position control of fast steering mirror

For a two -axis fast steering mirror (FSM) based on the flexible chain structure support and voice coil motor drive, the two axes are strongly coupled. This strong coupling may decrease the system positioning accuracy. In this study, the electric kinematics model associated with the voice coil motor and the motion and frequency equations associated with the flexible chain structure were analysed. A comprehensive system model was established considering shaft coupling, a digital controller with compensation coupling was designed, and the method of active compensation was used for decoupling. The experimental results showed that compared with the traditional non-decoupling control algorithm, the decoupling control method decreased the coupling degree from 7% to 0.8% and reduced the positioning accuracy error from 1.5% to 0.3%.