Research On Relative State Determination And Control For Satellite Formation

Satellite formation offers more powerful and robust architectures than single, traditional large satellite and is an enabling technology for a number space missions. A lot of space missions are depend on the relative state, including the relative position, velocity and relative attitude and attitude angular velocity, determination and control precise. This dissertation takes system demonstration and validation of small satellites formation flying as the background; the theory and algorithms of relative state determination and control are investigated. The main contributions are as follows:First, the relative state autonomous determination approaches are studied detailedly. The traditional Hill equation has many disadvantages, so here we derived a set of relative orbital equation of motion, which takes the J2 pertubation in consideration. To the relative orbit determination, using the intersatellite relative distance and azimuth angle, and an UKF approach is introduced to estimate the relative position and velocity; To the relative attitude determination, each satellite uses its own on-board attitude sensors to determine its attitude, and exchange the information through the communication link between formation satellites, and then the relative attitude is determined through simple mathematical operation. Simulation results indicate that both approaches are effective and suitable for precise autonomous relative state determination.Secondly, a model predictive control methord are designed for the satellite formation initialization control. The main reasons for the interest of control engineers in MPC are therefore its ability to handle inequality constraints systematically and effectively during the design and implementation of the controller and the on-line optimization can be typically reduced to either a linear programming. At last, this approach is demonstrated through the simulation.Finally, considering the majority of formation missions have strict requirements for the relative attitude control accuracy between coordinated satellites in formation. In this thesis, take an example of the mission of two satellites, assuming that the relative position and attitude are known, a variable structure based fully decentralized relative attitude coordination control laws is derived. The stability is proven through Lyapunov function. The simulation results indicate that the proposed control laws can efficiently minimize the relative attitude error in the presence of disturbances and the model uncertainties.