Spacecraft Attitude Synchronization Control Under Constrained Communication

Spacecraft attitude synchronization control plays an important role in mission such as space interferometry and long-distance laser communication,so it has attracted much attention in recent years.However,due to the distance between satellites and the limited capacity of communication equipment,inter satellite communication often has such problems as insufficient bandwidth and delay.And the uncertainty of the model,the external disturbance also makes the multi satellite system difficult to achieve sufficient synchronization control accuracy.On the basis of summarizing the existing research results,the cooperative attitude control of spacecraft under communication constraints and internal or external disturbances is studied.The main contents of this paper are as follows:Satellite attitude synchronization problem under communication bandwidth constraint is studied.Firstly,established multi satellite attitude synchronization control model based on the undirected communication topology,and an eventtriggered algorithm is introduced in the communication link.In this algorithm,the threshold is set according to the current system state to determine whether the change of the state is large enough to refresh the output to avoid useless communication and to reduce communication pressure.The stability of the controller is proved by Lyapunov stability theory,and it is proved by mathematical simulation that event-triggered can reduce the communication frequency and save more communication resources than traditional communication methods.Based on the above event-triggered control method,the influence of system parameter uncertainty and external disturbance torque is further considered.The adaptive control method avoids the direct use of the moment of inertia parameter,so the control error is not introduced.For the disturbance torque,the slid ing mode adaptive method is used to compensate,which is simple and effective and does not need to know the disturbance upper bound.Simulation analysis shows that the control law can significantly improve the satellite attitude synchronization control accuracy.Considering the existence of time-varying delay in the communication,the control law which is still stable under the delay communication is designed by using the backstepping method,and it is pointed out that the control law only need strong connected communication network without request to undirected communication topology.Furthermore,considering that event-triggered is also a kind of communication delay,it is proved that the control law is also applicable under event-triggered strategy.The mathematical simulation results also show the validity of the control law under the communication delay.