Research On Key Technologies Of Fine Tracking System In Space Laser Communication

With the continuous development of space technology,the role of space laser communications in global communications has become increasingly evident.The smaller size of the laser communication system and the better communication performance become the trend of future development.For the free space laser communication system,in order to achieve long-distance laser communication,reducing the free space power attenuation is an important technical approach,which requires the beam spread angle of the communication beam is emitted near the diffraction limit angle.While the narrow laser emission beam causes many technical challenges in beam alignment,therefore,the fast,accurate acquisition,aiming and tracking(PAT)technology of beam communications of long-distance and high-precision becomes particularly important.In the PAT technology,fine tracking technology plays a crucial role.Based on the composition and principle of the fine tracking system,this paper starts from the three major components of the detection unit,the executing agency,and the control compensation unit.Through analyzing the principles,modeling and simulation,and experimental testing,this paper has systematically studied the key technologies of the fine tracking system in space laser communications.Summarized and analyzed the existing spot detection technology,focusing on the characteristics of CCD,QD and other devices,studied methods and technical measures to improve the spot detection accuracy,and analyzed the methods of outputting off-target distance of the detection system at high speed.Researched the devices that may be selected by the fine tracking servo actuator,established the actuator model,and designed a variable structure compensation controller for the characteristics of different vibration for the different near-space laser communication platform,and use matlab software to complete the overall tracking system modeling and simulation analysis.Finally,a fine tracking information processing unit was designed which integrates functions such as image acquisition,filtering,spot center calculation,control compensation,and outputting off-target distance in real-time in FPGA.Set up an experimental platform to simulate the vibration environment of the real platforms,applied relevant technologies in the research to the fine tracking system.Through the experimental method,the performance of the fine tracking system was tested.The results show that this system can complete the performance of the fine tracking system and lay a foundation for the practical application of the space optical communication system.