Optimized Design And Realization Of Satellite Laser Communication Coarse Pointing Control System

As a new approach of space communication, satellite laser communication haslots of advantages, such as high carrier frequency, large information capacity,point-to point emission and reception which means communicated information isnot easily be stolen and interfered. So it has great market prospect and importantstrategic significance. Acquisition, pointing and tracking (APT) is the key toachieve satellite laser communications, and coarse pointing system is an importantsubsystem to implement APT function. This topic is based on a lasercommunication coarse pointing systems scheme of one satellite. An optimizeddesign is proposed, in addition, the hardware and software is designed andimplemented. The main tasks are to achieve the control and drive functions.First, the basic composition, tasks and the required control indicators of coarsepointing system are outlined. As servo control system, coarse pointing system hasthe general parts of a control system. The main task of the system is to realizecontrol, drive, data communication with other units, etc. In order to drive theoptical antenna to achieve fast and accurate pointing and tracking, the requirementfor bandwidth and accuracy of coarse pointing system is very high.Second, in order to design the system controller, drive circuit and program, thecontrol theory of brushless DC motor which is used as the system’s actuators hasbeen discussed and analyzed. According to the characteristics of the brushless DCmotor used in this system, the appropriate control methods are determined,including stator winding conduction control mode, PWM type, etc., and amathematical model is established for controller design and simulation.Third, as the parameters of the PID controller which is used in the originalscheme is not easy to tune and the problem of poor adaptability, the fuzzy adaptivePID controller is applied to system. The model of brushless DC motor, terminalload and controller is built in Simulink. Both of the controllers are simulated andcompared.Then, the integrated structure of the system is designed. Compared to theoriginal module structure, it has the advantages of compact structure, simplecommunication system, higher reliability and efficiency. High-performanceTMS320F2812is used as the main chip for data processing and control algorithms.Drive circuit is designed according to the control method and the specificparameters of the motor. Communication circuit is designed in accordance with thecommunication interface requirements. In order to improve the reliability ofsoftware, the program structure is designed as interrupt trigger based, including the software module of sampling, control, drive, communication etc.Finally, the PC program for system test is designed using LabVIEW. Datacommunication with the system is through the serial port. It can send controlinstruction to the system to carry on pointing test and tracking test, to verify theperformance indicators of the system being designed.