Servo Control System Of Peripheral Coarse Tracking Turntable For Satellite Optical Communication

In the space laser communication has the advantages of large information capacity,fast communication rate and long transmission distance.It can be used as the main mode of inter-satellite communication.The coarse tracking turntable technology,as one of the core technologies of satellite optical communication,has gradually become a hotspot of current research.The coarse tracking turntable achieves high-precision attitude control through servo control system,completes precise pointing and tracking of target units,and ensures the establishment and stability of communication links.Therefore,the control performance of servo system directly affects the quality of optical communication.Based on the application background of a satellite optical communication terminal project,in order to achieve stable tracking of the target communication terminal,this paper studies the servo control system of the periscopical coarse tracking turntable for satellite optical communication.By analyzing the performance requirements and system composition of the rough tracking turntable,this paper chooses a reasonable structure and formulates the overall scheme of the servo control system.The types and characteristics of driving motor,angular position feedback device and CCD image tracking unit in servo control system are demonstrated in detail.According to the technology of field-oriented control and space vector pulse width modulation,the simulation model of permanent magnet synchronous motor(PMSM)is established in MATLAB.The principle of space vector control is verified by simulation analysis.According to the structure of perimeter tracking,a coarse tracking model is established and a tracking algorithm is designed.The average error of model solution is 2.6",which meets the tracking requirements of the system.On the basis of the overall scheme and simulation analysis,the hardware design of the servo control system is carried out.The servo control board based on ARM+FPGA and the motor drive board based on DRV8312 are designed,and the specific implementation method of the working module in the FPGA is demonstrated in detail.Then,according to the principle of frequency response,the frequency response is tested and the transfer function of the system is identified,which provides the model support for the design of control algorithm.According to the theory of three-loop control,the closed-loop design is completed.The servo system is tested experimentally.Under the external disturbance of frequency 0.067 Hz and amplitude 5°,the dynamic tracking accuracy is better than 104?rad,which meets the technical requirements.In order to further improve the tracking accuracy of the optical closed-loop system,aiming at the problem of miss distance lag in the optical closed-loop system,the lag compensation is studied.The dynamic tracking accuracy of the compensation algorithm can be improved by about 16% after testing.