The Leader-Following Attitude Consensus For Spacecraft Formation

Modern spacecraft often perform space missions by formation flying.Replacing traditional single large satellite with formation cooperation can not only reduce costs but also maintain the flexibility of satellites in orbit.It is necessary to achieve attitude consensus during the spacecraft formation flight.This paper mainly investigates the problem about the attitude consensus for spacecraft formation.The unit quaternion is used to describe the spacecraft attitude information,and then the mathematical model of spacecraft formation is established.Finally,the distributed control law is designed to achieve attitude consensus.The attitude consensus for a rigid multiple spacecraft system will be considered.In this system,the attitude parameters of the leader are known and the communication topology between the followers is a connected undirected graph.Then a distributed control law based on virtual angular velocity estimators is designed to achieve attitude consensus for the rigid multiple spacecraft system.This algorithm by constructing the virtual angular velocity estimators simplifies the construction of the Lyapunov function.By the result of simulation experiments,this algorithm improves the performance of the controller.Considering spacecraft often have flexible attachments in reality,the attitude consensus for a flexible multiple spacecraft system whose communication topology is a connected undirected graph will be investigated.The difference between the flexible spacecraft and the rigid spacecraft is the vibration effect caused by the flexible attachment.Therefore,the flexible modal parameters should be considered when constructing the mathematical model for the flexible spacecraft formation system.Since the flexible mode is difficult to measure directly,the modal observer is designed to estimate flexible mode,then a distributed controller based on the modal observers is proposed to achieve attitude consensus.In reality,there is a case where the communication topology between the multi-agent systems is a directed graph.Therefore,the attitude consensus for a leader-following rigid spacecraft formation system whose communication topology is a directed graph is alsostudied in this paper.Considering a rigid spacecraft formation system whose communication topology is a directed graph containing a directed spanning tree.Constructing target attitude observers to observe the attitude information for the leader,and then a distributed control law based on these target attitude observers is proposed to achieve attitude consensus for this system.