The Study On The Analysis And Suppression Of Satellite Vibration In The Optical Communication Between Satellite And Ground

As a new communication between satellite and ground, optical communication isbecoming replace RF communication with its unique advantages. In the developmentsof optical communication, the alignment of communication terminal is still a seriousproblem. As an important part of optical communication, the acquisition, pointing andtracking (APT) system is an effective way to get fine alignment and its performancehas a great impact on the design of optical parameters, the complexity of thetransceiver terminal, the error rate in communication and the burst errors. Due to theusing of diffraction limit to transmit the beam, the power of the received signal issensitive to the alignment errors of transmitter. The big alignment errors of transmitterwill lead to the intolerable signal attenuation on the ground and reduce the systemperformance significantly. Therefore, it’s an urgent need to improve the accuracy ofAPT system and reduce the alignment errors.This paper firstly analyzes the main factors influencing the alignment errors in theAPT system. The vibration of satellite is the biggest one. Therefore, analyze thecauses of satellite vibration and summarize the features of satellite vibration: highamplitude in the low frequency, low amplitude in the high frequency and widespectrum on the basis of the data of satellite vibration. According to the characteristicsof satellite vibration, the vibration suppression scheme is proposed, using thecombination of the passive vibration isolation and control algorithm and focus on theimprovement of control algorithm. Then, use the method of mechanism modeling toanalyze the model of key components of control system, and use the result of themechanism modeling and the method of system identification to get the actual modelof controlled object. According to the model, design the closed-loop feedback controlalgorithm. In order to get better vibration suppression, add the feedforward control tothe control system and analyze a simple feedforward controller and its disadvantages.For those disadvantages, use the adaptive filtering algorithm to design thefeedforward controller. Design two kinds of adaptive feedforward controller with theLeast Mean Square algorithm and the Recursive Least Square algorithm and combinewith the feedback control to form the composite control. Design three simulations totest and verify the impact of the delay of reference signal and parameter changes ofthe object on the feedback control and two composite controls. And verify the performance of the three algorithms. Finally, constructs a hardware platform based onPC/104and use the Model Integrated Software Design Method to test and verify thedisturbance suppression performance of the three control algorithms.