Research On Servo System Of Single Reflect-Mirror Tracking And Pointing Turntable Based On Strapdown Stability

Optoelectronic tracking and pointing turntable is widely used in optoelectronic detection,laser communication and other systems on moving platforms(airborne,vehicular and shipborne).In order to reduce the influence of platform attitude disturbance and vibration on the line of sight stability of optoelectronic tracking and pointing turntable,it is necessary to design a reliable stability loop to isolate the influence of attitude disturbance and vibration.With the development of optoelectronic tracking and pointing turntable towards miniaturization and low cost,the direct stabilization scheme is obviously insufficient.Strapdown stabilization scheme provides a new solution for line of sight stabilization control of optoelectronic tracking and pointing turntable with limited volume.This topic is based on an airborne laser communication terminal project,in order to establish a stable communication link,the servo control system of the single reflect-mirror tracking and pointing turntable prototype under strapdown stable conditions is studied.Firstly,the research status of the tracking and pointing turntable at domestic and abroad is summarized,and the line of sight stability control technology of the tracking and pointing turntable is analyzed.Through the analysis of the performance and application background of the tracking and pointing turntable,a reasonable structure is selected.Comparing the advantages and disadvantages of direct stabilization and strapdown stabilization,the strapdown stabilization control technology is selected as the line of sight stabilization scheme of single reflect-mirror tracking and pointing turntable,and the selection of driving and measuring elements in servo system is demonstrated in detail.This paper designs a servo control system with STM32+FPGA as the main control and DRV8312 as the drive.The correlation analysis method is used to scan the frequency of the single reflect-mirror tracking and pointing turntable,and the amplitude frequency characteristic curve of the tracking and pointing turntable is identified to obtain the mathematical model of the frame,which provides support for Strapdown stability control algorithm and servo control strategy design.According to strapdown stability control technology,the kinematics model of single reflect-mirror tracking and pointing turntable is established,and the angular velocity compensation algorithm is used to decouple the single reflect-mirror tracking and pointing turntable.In order to solve the problem that the dynamic characteristics of gyro speed measurement link and grating speed measurement link do not match due to strapdown stability control,the matched filter algorithm is adopted to improve the decoupling accuracy of tracking and pointing turntable by 28.1d B at 3Hz.The tracking differentiator is designed to suppress the increasing noise of differential velocity measurement.Finally,based on the research of Strapdown stability control algorithm,the grating speed loop,gyro stability loop and grating position loop controllers are designed by the compensation method of lead lag;the disturbance observer is used to compensate the disturbance torque of the system.Lastly,under the disturbance of 5° and 2Hz,the stability accuracy of azimuth frame is 30.2?rad,which is better than the stability accuracy of 50?rad;under the disturbance of 1° and 2Hz,the tracking accuracy of 5°and 0.2Hz is 112.5?rad,which is better than the system design index of 150?rad,which meets the requirements of establishing airborne laser communication link.