Research And Design Of Reflection Mirror Servo Control System

Reflection mirror is a precise optical installation located between target and light receiving device and used for changing the direction of light beam.With the characteristic of small volume,light weight,fast response and high precision,it plays an important role in many areas,such as light beam stabilizing,optical communication and fine tracking in composite axis system.Bandwidth and angular resolution are important evaluation indexes of reflection mirror system.With the increasing demand for the performance of reflection mirror,it becomes very necessary to explore ways to improve its response speed and accuracy.Therefore,the following work is finished in the thesis:1.The overall structure of the whole reflection mirror control system isdesigned and the transfer function model of system is established.Then itsopen loop feature and disturbance factors in control system are analyzed.2.Control algorithm simulation experiment is done through the method ofbilinear transform.The principle of classic PID control is introduced,andActive Disturbance Rejection Control(ADRC)is used to overcome itsdisadvantages.The experiment demonstrates that the latter makes theconvergence rate of system error quicker.The steady relative error of ADRCsystem drops to 0.050%,while the error of PID control system is 0.119%.However,ADRC makes phase lag more obvious.Consequently,Zero PhaseError Tracking Control(ZPETC)is designed to reduce the phase delay andincrease the bandwidth of system,and Kalman Filter is used to avoid thedecline of noise immunity brought by the improvement of bandwidth.Theresult shows that the bandwidth of system reaches more than 1.5 times asmuch as that of PID control system.Its phase lag becomes less than 3/5 ofthat of PID system and steady relative error reduces to 0.029%.3.Fast steering mirror control system for image motion compensation isdesigned.FPGA minimum system,electrical level conversion circuitbetween FPGA and upper computer,digital to analog conversion and linearpower amplifier of manipulation variable are designed.Program design ofPID,ADRC,ZPETC and RS-232 serial communication between FPGA andupper computer are accomplished by using Verilog HDL,which is verifiedthrough the comparison between timing simulation and theoretical result.4.Reflection mirror control system for optical axis adjustment is designed andachieved.A hardware system including FPGA,motion controller,photoelectrical encoder,motor and OLED display screen is built.Programdesign of OLED display screen driver and control command sending arefinished.The result of optical axis position control shows that the overshootof system is not more than 0.3% and the steady error is less than 0.01°,which means that the system has a good performance.