Research On High-Precision Formation Flying Control

Satellite formation flying has been paid much attention because of its advantages including low cost,high reliability and high flexibility,and researchers has made great achievements on it in both theory and practice.An important direction of formation flying at present is high-precision formation technique,which is the precondition of constructing virtual space telescope.The realization of this technique relies on not only the development of navigation systems and propulsion systems,but also appropriate control approaches.There are mainly two kinds of control scenarios: formation establishing and formation maintenance.Therefore,the work in the dissertation including these two parts.Since the high-precision metrology system used introduces an additional LOS constraint which does not exist in usual formation flying missions,model predictive control is used in formation establishing,which is inspired by the researches on spacecraft rendezvous.This approach can optimize the establishing duration and fuel consumption whilst the related constraints are satisfied.Moreover,this approach has relatively low computation workload,thus meeting the requirement of real-time calculation.Considering various disturbances existing in real environment may induce undesired constraint violation,the chance-constrained ideology is further used to design a robust model predictive control approach.The robust approach ensures that the constraints can be satisfied in a probabilistic sense.The prime objective of formation maintenance is undoubtedly the high maintenance precision,and it is also of great importance to reduce fuel consumption to prolong the life of the mission.Sliding mode control possesses strong robustness,which can achieve high maintenance precision,but cannot take fuel consumption into consideration.On the other hand,linear quadratic optimal control can optimize the fuel consumption,but its maintenance precision is relatively low since only the nominal model is concerned in this approach.Therefore,sliding mode control is combined with linear quadratic optimal control to form a new control approach named after optimal sliding mode control,which possesses the advantages of both.Then optimal sliding mode control is applied in formation maintenance.The hovering configuration in used in the simulation studies.This configuration matches the scene of virtual space telescope aiming at high-resolution earth observation,which is one of the most important application scenes of high-precision formation technique.The simulation results validate the effectiveness of the approaches proposed in this dissertation.