Research Of Flexible Spacecraft Attitude Maneuver Algorithm

The paper mainly focus on the rapid maneuver control problem of flexible satellite. Using SGCMG as the actutor of flexible satellite, vector avoidance and control algorithm in large angle attitude maneuver are studied. The SR inverse and null motion steering logic are used to control SGCMG.. Based on artificial potential field method, achievable path in attitude maneuver can be abtained by avoiding the path unexpected. As the flexible satellite system is complecated, variable structure control is used to enhance the robustness of the system. Besides, to offset the flexible apendages interfere with the controller better, Neural network compensator is used to approximate the system uncertainties. Simulations of flexible sattelite attitude controller with vector avoidance are taken to verify the algorithm.First, dynamic equations of flexible satellite are derived and simplified, and mode observer is constructed based on mode equation.Secondly, selection method of parameters in SGCMG SR inverse logic is improve to arrive better control precision outside singularity. Considering that greater control moment is demanded along the roll axis and pitch axis, hybid actutor comprised of double parallel configuration control moment gyros and flywheel is adopted, and null motion steering law is devised to avoid SGCMG from singularity.Then the avoidance of obstacle vector in attitude maneuver path is studied. Regional minimum problem of artificial potential field is analyzed first,then improvement is proposed based on artificial potential field method and differential term is introduced to performance of vector avoidance algorithm.At last, variable structure controller is introduced into the flexible satellite control problem. The variable structure controller owns strong robustness and can move rapidly in the sliding surface, and considering that there is phase difference in the coupling between apendages'vibration and satellite body, integral sliding surface is designed to remove the influence of vibration. And to compensate the uncertanties more accurately, Neural network compensator is used to approximate the system uncertainties and the compensation term is introduced into variable structure controller. Finally, simulation comparison is made between attitude maneuver with and without vector avoidance, and the results show the effectiveness of the algorithm.