Research On Pointing And Tracking Control Of Satellite Laser Communication Terminal

Satellite laser communication is an important satellite communication solution be-cause of its advantages such as board bandwidth , high speed and good performance onanti-jamming.Thetechnology of acquisition, pointing and tracking(APT) is a key technol-ogy for the satellite laser communication system and is used to establish communicationslinks.In this paper studies the principle and the work flow of APT system;studies the de-sign of coarse pointing control unit and the scan methods of the APT system.At the sametime,the application of variable structure control(VSC) in coarse pointing system is sim-ulated.According to the process of establishing and keeping the communication link ,thestructure and subsystem of the APT system is introduced. The scan principle and the scanmethod is analyzed in detail.The concept of equivalent coverage is proposed to evaluatethe coverage of uncertainty area by beacon beam, and simulation results show that equiv-alent coverage is more efficient than complete coverage.The coarsepointing control unitis responsible for calculating the trajectory of coarsepointing device and sending the data to motor drive control unit,and the reliability of com-munication between the units is important. Considering the reliability requirements ofaerospace products, the designed of hardware and software of coarse pointing control unitthat is based on previous system are modified.The coarse pointing control unit is com-posed of instruction and data transmission interface module, trajectory planning module,motion control interface module and system debugging circuit module. The control pa-rameters are sent to coarse pointing control unit by main control unit, which can enhancethe adaptability of the APT system to the space environment.Moreover, the principle of VSC and its application in tracking problem are intro-duced. The application of VSC in coarse pointing system is simulated and the result isgiven. Considering the influence of satellite platform vibration to the tracking error ofAPT system, the reason of vibration is introduced and vibration power spectral densityis analyzed. The anti-jamming of the variable structure control system is simulated andthe result is given. The reliability design of system which is included with hardware andsoftware is analyzed in detail.