Unload control of double fast steering mirrors of the control system

Double fast steering mirror (FSM) are made of a fast steering mirror driven by piezoelectric actuator and a fast steering mirror by voice coin motor, which provides not only high control bandwidth and high resolution but also a wide range of angle for the tracking control system. A classical control system of double fast steering mirror is that each CCD sensor provides line of sight error to control relevant FSM respectively, resulting in complexity and weakening optical energy. The proposed system works by depending on single CCD sensor, which implies that it is crucial to decouple the control double fast steering mirror .An unload technique is designed to solve this problem .The FSM driven by piezoelectric actuator is driven using line of sight from CCD, while the other FSM is followed it. Error attenuation transfer function is modeled and used to analyze stabilization and performance of the control system, which is optimal only if the control bandwidth of FSM driven by piezoelectric actuator is ten times more than that of the FSM driven by the voice coin motor. The experimental results are in great accordance with theoretical analysis.