Satellite Formation Station-keeping And Reconfiguration Via SDRE Approach

Satellite formation flying(SFF) is an important technology for future space mission.Formation-keeping is the technique that accurately maintains the formation geometryaccurately under orbital perturbations. Formation reconfiguration is performed tocontrol a satellite from a current formation to a newly desired formation. The excellentcontrol performance of time and fuel saving is the key technical index in satelliteformation. In this thesis, regarding the master-slave mode of formation flying satellitesas the research object, the State Dependent Riccati Equation approach is applied in thecontrol system design of satellite formation-keeping and formation reconfiguration.Firstly, a relative motion dynamic model of SFF is proposed. Based on theassumption of two-body motion, the dynamic model of relative motion between thestars is established. In order to design the SDRE controller, a specific pseudo-linearform with state-dependent coefficients is derived from the nonlinear dynamics model bynegative binomial series.Secondly, a SDRE formation-keeping controller is designed from the SDCpseudo-linear model. The SDRE approach is based on the nonlinear model, so it’s moreaccurate. In addition, the weight matrices of Q(x) and R(x) are the function of the states,so it is more flexible to select. In this thesis, we compare the SDRE controller with theLQR controller, and substitute the two controllers into the nonlinear dynamic model.The simulation results show that the SDRE controller is better than the LQR controllerin the transition process time and fuel consumption.Finally, look on the formation reconfiguration as large distance formation-keepingissue, a SDRE formation reconfiguration controller is designed, and compare it withLQR formation reconfiguration controller. The SDRE controller has better performancethan LQR controller. In addition, regard the formation reconfiguration issue as atracking issue, and based on the LQR controller, a output tracking controller is designedusing a reference model. It has the same effect as SDRE controller, but the SDREcontroller is based on nonlinear model, and has more practical significance.