Research On Coordinated Control For Spacecraft Formation Under Complex Communication Conditations

With the continuous expansion of space missions,multi-spacecraft formation flying technology based on small satellite technology has become a research hotspot,and has shown great application value and development prospect in civil and military fields.As the key technology of spacecraft formation flying,coordinated control of spacecraft formation has led to extensive research.Based on the existing literatures,this dissertation deeply studies the distributed coordinated control of spacecraft formation by applying graph theory and consistency theoty,which mainly includes the following contents:Firstly,the coordinated control problem of spacecraft formation in the case of undirected communication topology is studied.Under the premise of not considering the external disturbances,a coordinated control algorithm and a finite time coordinated algorithm are proposed respectively on the basis of existing research work.Considering the input saturation factor,an improved finite time coordinated control algorithm with input saturation is proposed by introducing hyperbolic tangent function.For the proposed coordinated controller,a strict Lypunov stability proof is carried out.The simulation results show that the proposed coordinated controller can not only achieve the formation maneuver,but also guarantee the formation keeping during the transient maneuver process.Secondly,the coordinated control problem of spacecraft formation in the case of directed communication topology is studied.By using the idea of sliding mode control,a coordinated controller based on a multi-spacecraft linear sliding surface is designed in the case of that the communication topology of spacecraft formation is a directed graph with a spanning tree.Assuming that the external disturbance and its derivative are bounded,a finite time observer is designed,and then is introduced into the closed system.In order to realize the finite time coordinated control,a finite time coordinated controller based on multi-spacecraft terminal sliding surface is designed.In addition,an adaptive adaptive coordinated controller is proposed to deal with the case that only some spacecraft can obtain the desired states.The simulation results verify the effectiveness of the proposed cooperative control algorithm in the case of directed communication topology.Thirdly,the coordinated control problem of spacecraft formation in the presence of communication delays and switching topology is studied.In view of the time-varying delays of spacecraft formation,a robust coordinated controller is proposed,and then the designed controller is further extended to the case of finite swithing topologies.Considering that the tracking speed of the formation spacecraft is limited,a virtual velocity control term is constructed by introducing hyperbolic tangent function.Then,a finite time controller is proposed to ensure the finite-time stability of the closed-loop system.Further,a coordinated controller is proposed to deal with the case that bounded time delays are existed in spacecraft formation.The proposed coordinated controllers extend the communication topology from the undirected graph to the strong connected directed graph.The validity of the controllers are verified by numerical simulation.Then,the output feedback coordinated control problem without velocity measurement is studied.Considering the input saturation and the finite-time control theory,a finite-time output feedback coordinated controller is presented by constructing a passive velocity filter.In order to solve the output feedback coordinated control problem in the case of directed communication topology,an adaptive finite time velocity observer is first proposed for a single spacecraft to ensure that the velocity observation error can converge to a small value in a finite time.Then based on the proposed velocity observer,an output feedback feedback controller is proposed in the presence of the bounded communication delays.The numerical simulation shows that the proposed formation coordination controller can realize the formation maneuver without velocity measurement and ensure the formation keeping in the transient process.Finally,the six Degree-of-Freedom(6 DOF)coordinated control problem of spacecraft formation associated with coupled relative orbit and attitude dynamics is studied.A 6 DOF coupled model is established by employing the unified Eular-Lagrange formulations of relative orbit and attitude dynamics.Then an adaptive coordinated controller is designed in the in the presence of parameter uncertainties and time-varying external perturbations with unknown boundary values.The numerical simulation results show that the proposed controller can guarantee the attitude consistency and configuration invariance of the spacecraft formation while tracking time-varying reference attitude and implementing formation maneuver instruction.