Research On Fault Tolerant Control Of Space Optical Communication Terminal

Space optical communication which uses laser as a carrier signal is a communication method. It is a basic technology of inter-satellite communication network, satellite-ground communication network and nearearth communication network. Fault-tolerant control is a new way to improve the reliability and safety of system. This paper takes space optical communication terminal as the object, researching fault-tolerant control method for the space environment disturbance, photoelectric encoder failure and actuator failure problems.The effect and criticality from complex space environment to system are analysised in this paper with the statistic data of spacecraft failure both at home and abroad. Aiming at the problems of single event effects, microgravity environment and temperature variation, fault-tolerant control strategies including triplication redundancy, watching dog and time sequence of communication are designed in hardware and software. The environment experiments on ground are carried out to ensure the safety and reliability of optical terminal.Code hopping which occurred in sighting control system photoelectric encoder affects the accuracy of system. The reason and expression of code hopping are analysised in this paper for this problem. A kind of online fliter which has function of fault detection, diagnosis and correction is designed by using data difference, curve fitting and powers summing. Real data test shows that this method can decrease the effect from code hopping to accuracy of system.For the problem of terminal actuator failures, parameter uncertain and noise in system, the design method of robust fault-tolerant controller is given by using H_∞optimization theory and linear matrix inequality approach. The result of numerical simulation shows the state feedback control law could make the uncertain closed loop system stable and have capability to suppress interference even in the actuator failure case.