Study On Attitude Control Method For Flexible Multi-body Satellite

Attitude control system is a very important system in satellite. As the development of satellite and science task, the flexible appendages is increased. The typical characteristic of modern satellite is the flexible multi-body. A satellite is composed of sloar wing, antennas and tank and so on. Then these appendages’mode frequency is often close to the others. It necessary to study the flexible multi-body satellite’s dynamic and control because of flexible appendages’vabriation while the attenna pointing the tagert. Thus the control method is reasearched, which can be suspressed the vibration and attitude control.Firstly, the dynamics is built according to the data relay satellite. Then sloar wing vibration, attenaa rotating and liquid swing impact to the satellite is analyzed. The simulation result showed that the sloar wing and liquid swing is small impact to satellite attitude when uncontrolled. But it’s needed to be suppressed when high accuracy acquirement.Secondly, adopting the PID(PID Proportional, Integrated, Difference) controller theory, the dynamic equition is simplified, and two stage control method is applied. Thus the satellite antenna control and attitude control are divided into two controller. The simulation result show that, the PID controller could control attenaa rotation accuracy, but the stable speed of attitude is very slowly, and the attitude rate is vibration.Thirdly, for the question of stable speed, a sliding mode control method(SMC) is applied. The simulation result show that, the attitude stabilization speed is better than PID controller. But the attenna control is not good because of the PD(PD Proportional, Difference) controller of antenna.Fothly, for the question of attenna vibration, a new method called fuzzy sliding mode control method(FSMC) is adopted. The FSMC is applied to weak the SMC switch panel, then the attenna vibration is reduced. The simulation result show that the FSMC is more better than SMC, the attena is suppressed and the attitude is also controlled. The result of FSMC is satisfied to the design requirement.This thesis analysed the flexible multi-body controller, and three method is researched, which can be referenced for eginnering application.