Research On Attitude Coordination Control For Spacecraft Formation Flying

With the development of space exploration and aerospace technologies,spacecraft formation flying of multiple spacecraft has become an important working mode.As a key technology of spacecraft formation flying system,the attitude coordination control has attracted much attention due to its unique technical advantages and wide application background.Considering the actual demands of fast attitude coordination and high robustness for spacecraft formation flying system in the presence of inadequate feedback information,parameter uncertainties,external disturbances,actuator saturation and actuator fault,this dissertation focuses on attitude coordination control algorithms design.The main contents are as follows:In the absence of angular velocity measurements,a distributed leader-following velocity-free coordinated attitude tracking control algorithm for multiple spacecraft formation system is proposed when a subset of the followers can receive the information of the dynamic leader.A distributed finite-time state observer is developed to estimate the state of the leader.Furthermore,by introducing a filter on the basis of passivity theory,the angular velocity information of the followers is not required.Based on the distributed finite-time state observer,the finite-time angular acceleration observer and the auxiliary compensation system,a distributed leader-following velocity-free attitude coordination control algorithm for multiple spacecraft is designed to regulate the following spacecraft to track a common time-varying reference trajectory simultaneously.The attitude coordination tracking control problem for multiple formation spacecraft with unknown time-varying external disturbances,inertia uncertainties and actuator saturation is studied.Two adaptive decentralized coordinated attitude tracking control laws are proposed to rely on the assumption that the state of leader is available to every follower.The first control law is robust adaptive against external disturbances and time-varying inertia under the directed topology.A dynamic adjustment function is designed to limit the amplitude of control torque.Furthermore,an adaptive attitude coordination tracking control problem for multiple spacecraft with actuator saturation is investigated.In the presence of unknown time-varying inertia,persistent external disturbances and actuator saturation,a robust adaptive coordinated attitude controller is proposed to synchronize the followers with the dynamic leader.The distributed attitude coordination tracking control problem for multiple spacecraft in the presence of the unknown time-varying inertia uncertainties and external disturbances is investigated with the assumption that the information of the leader may be only available to a subset of the followers.Aiming at solving the problem,two distributed attitude coordination tracking control algorithms are proposed.First of all,a new class of distributed finite-time leader's state observer for each follower is proposed.Meanwhile,a new dynamic self-adjustment matrix is designed to reduce the overshoot of the system.On the basis of the distributed finite-time observer,self-adjustment matrix and the adaptive law,a distributed coordinated attitude coordination tracking control law is designed.With the demand for fast tracking,a fast nonsingular terminal sliding mode based distributed finite-time attitude coordination tracking controller is proposed.Both controllers can guarantee that the follower spacecraft can track a common time-varying trajectory of the leader.The fault-tolerant attitude coordination and tracking control problem for spacecraft formation with unknown time-varying external disturbances and inertia uncertainties is studied.First of all,based on adaptive control,consensus algorithm and redundant faulttolerant control,a decentralized adaptive fault-tolerant attitude synchronization tracking controller is presented to achieve the asymptotic synchronization of the states of all spacecraft.Then,with the demand of fast convergence and the assumption that only a subset of the followers can obtain the information of the leader,on basis of distributed finite-time observer,adaptive control,consensus approach,graph theory and finite-time theory,we develop a distributed adaptive finite-time fault-tolerant coordinated attitude tracking controller to stabilize the formation system in a finite time.Finally,considering the actuator saturation problem,a distributed adaptive finite-time fault-tolerant control law is further designed.The proposed finite-time fault-tolerant controller is more practical owing to reducing the conservation of the actuator.