Structure Analysis And Research On The Design Of Control System For Fast Steering Mirror

Fast steering mirror(FSM)is a precision optical instrument to control the beam propagation direction between the source and receiver in optical system.As an important component in composite axis system of the fine tracking subsystem,FSM is widely used in space optical communication,adaptive optics,astronomical telescope.In the fine tracking subsystem of the composite axis system,FSM needs rapidly rotating in a small range in order to achieve the suppression of the coarse tracking errors.All of these requirements need a higher stability and rapid response in the control system of FSM.Control method of the fast steering mirror's control system usually adopts PID control.When designing the PID control parameters by the analysis method,the most existing design methods focus on how to improve the closed-loop bandwidth of the system.But the performance indexes,method of control parameters according to the time domain performance index to design the fast steering mirror is less.In engineering application,the structure stiffness of the FSM can be influenced with the growth of working process and environmental factors and the changes in the situation.At this time,adjustments to the control parameters should be made appropriately in the control system to ensure the stability and fast response of the control system as well as the output performance of the fast steering mirror.In order to solve these problems,the design method of the control parameters are researched from three aspects of the fast steering mirror control system,those are theoretical analysis,simulation and experiment.Through the introduction of fuzzy control in the system,the output performance of the system in the control system can effectively be guaranteed after the structure stiffness' change.The main contents of this paper as the following:Researching on the products of the fast steering mirror and the control technology of the fast steering mirror,and the working principle of flexible supporting fast steering mirror driven by voice coil motor is introduced.Based on these things,the transfer function model was established,and a fast steering mirror in the practical engineering system is identified.Combined with the analysis of the structure characteristics of FSM results,an improved method of root locus is proposed to design the control parameters of the fast steering mirror' PID control system.Based on the PID control parameters,the fuzzy controller is introduced in the system tosolve the structure stiffness change in the working process of the fast steering mirror.The structure and parameters of the fuzzy controller are all designed as well as the connection with the PID controller and the simulation analysis in SIMULINK.The results show that the fuzzy control can effectively improve the output performance of the control system.A closed-loop test platform of fast steering mirror is built.Fast steering mirror' time domain performance and frequency domain performance is tested in this platform in order to verify the theoretical analysis.And the results proved the validity and practicability of the theoretical analysis.