Predictive Control For Leader-follower Satellite Formation Keeping

As a new form of spacecraft,satellite formation gradually replaces the traditional single large satellite due to its high reliability,high flexibility and low cost.Now,satellite formation is widely used in the field of earth observation,communication and navigation.For the satellite formation,keeping the formation configuration complete is the key to realize the overall function of the formation.In recent years,researchers have proposed sliding mode control,adaptive control,optimal control and other control methods to achieve formation keeping control of satellite formation.However,satellite formation faces great challenges in formation keeping control,and there are still many problems to be studied:1)How to improve the accuracy of formation keeping control;2)How to extend the operational life of satellite formation.For the above control problems including constraints,model predictive control,as an advanced control strategy,has been widely concerned because it can deal with control constraints explicitly.Therefore,this paper studies the formation keeping control methods based on predictive control by taking leader-follower satellite formation in elliptical reference orbit as the research object.The main research contents are described as follows:?1?The relative dynamics model of leader-follower satellite formation consideringJ₂perturbation under relative orbital coordinate system?LVLH?is introduced and the influence ofJ₂perturbation on formation configuration is analyzed based on the model.?2?In order to improve the control accuracy of leader-follower satellite formation keeping,an intelligent predictive control strategy is firstly proposed.Firstly,in order to ensure the safe operation of the thruster,a model predictive control strategy that can explicitly deal with the thruster control constraints is designed based on the linearized leader-follower satellite formation relative dynamics mode.Then,in order to improve the control performance of the designed predictive control strategy,a optimization module of predictive control parameters based on genetic algorithm is designed to realize the optimal tuning of predictive control parameters at each sampling time.Finally,through the simulation comparison,it can be seen that the intelligent predictive control strategy designed in this paper has higher control accuracy in the leader-following satellite formation keeping control process.?3?In order to realize the long-life operation of the leader-follower satellite formation,an economic model predictive control strategy which can explicitly consider the fuel consumption is further proposed.Firstly,an economic predictive control strategy which can consider both fuel consumption and trajectory tracking simultaneously is designed and transformed into an unconstrained optimization problem by penalty function method.Secondly,an improved adaptive genetic algorithm based on population diversity is designed.The algorithm is used to guide the change of crossover and mutation probability based on population entropy and variance.The purpose of this algorithm is to improve the quality of population solution.Finally,the improved adaptive genetic algorithm is used to solve the optimization problem of economic predictive control,and the effectiveness of the improved adaptive genetic algorithm and economic model predictive control strategy is verified by MATLAB simulation.