Research On Autonomous Reconfigurable Control Of Satellite Cluster Under Space Disturbance

With the continuous development of space technology,the variety and complexity of space missions in orbit have increased,while the use of traditional large satellites can only due with some specific space tasks.The flexibility and adaptability of traditional large satellites have major shortcomings,making it difficult to meet the diverse needs of current in-orbit missions.In recent years,microsatellite technology has developed rapidly,and satellite clustering has become a key technology to realize spatially distributed remote sensing,multidimensional observation and coordinated in-orbit services.When performing in-orbit missions,satellite clusters can not only improve the quality of mission accomplishment,such as significantly improving the integrity and real-time observation of space targets,but also adapt to different mission scenarios through autonomous reconfiguration and coordinated cooperation,which are highly adaptable and reliable.In the process of performing different space missions,satellite cluster usually adopt wireless communication for inter-satellite state information transmission and carried out different space missions through autonomous reconfiguration,which relies heavily on the relative motion control among each member satellite.Therefore,this dissertation focuses on the problem of autonomous reconfiguration control of satellite cluster under space disturbance,and the main contents are as follows:Aiming at the space missions where some of the cluster satellites require special space configurations,a cluster construction method based on hierarchical control is proposed.In order to ensure the coordination and unity of information between satellites in cluster,the Gossip consistency protocol is adopted.And the satellites can transmit state information to each other through wireless communication links,so that the information of each satellite can be received by all satellites in a certain communication cycle.Using the idea of hierarchical control,the cluster will be divided into the leader satellite layer and the follower satellite layer according to the requirements of the specific space configuration in the space mission.For the leader satellite layer,a predefined-time predefined-bounded controller based on the finite time extended state observer(FTESO)is designed to make the leader satellites form a specific space configuration within the time required by the mission.For the follower satellite layer,the space around the corresponding leader satellite is divided according to the communication distance,and an improved artificial potential field with transition area and damping control is designed to ensure the bounded motion of the follower satellite.Moreover a repulsive potential function based on relative velocity is designed,yes all satellites do not collide during operation which can make all satellites achieve collision avoidance during operation.Finally,the autonomous construction of satellite cluster is realized through the cooperation between the leader satellite layer and the follower satellite layer.Aiming at space missions of fast scheduling among sub-cluster or cooperative motion towards the target point,a cluster autonomous reconfiguration strategy based on improved flocking control is proposed.Considering the issue of timeliness,a pilotage satellite is determined among the selected satellites,and the reference trajectory of the pilotage satellite is quickly planned by the shape curve based on the Fourier series under the premise of satisfying the constraints of motion time and thrust amplitude.Considering the satellite constraints of communication link and network delay,the minimum spanning tree with degree and radius constraints is used as the communication topology of satellite cluster.And the Prim algorithm and breadth-first algorithm are used to propose a optimization method to calculate the degree and radius constrained minimum spanning tree.According to the planned reference trajectory of the pilotage satellite and the optimized communication topology,a cluster reconstruction controller considering collision avoidance is designed by combining the traditional flocking control and artificial potential field method under the condition of communication delay.So that,the selected satellite cluster can be reconfigured to the target area autonomously,and the coordinated configuration of the cluster can be realized.For the space missions of Multi-angle observation for space targets in the presence of obstacles,a Tube-based distributed robust model predictive control strategy is proposed.First,a target point generation algorithm is designed based on the minimum potential energy method,so that the target points can be uniformly distributed on the spherical surface centered on the target spacecraft.And according to the state information of the satellites and the positions of the target points,the Hungarian algorithm is used to reasonably allocate the target point to be reconstructed,so as to reduce the action of collision avoidance and the fuel consumption.Based on the speed obstacle constraint,a distributed model predictive controller is designed for the nominal system of the satellite cluster to complete the target point tracking without colliding with other satellites and space obstacles.Considering the unmodeled disturbance and model uncertainty,an Tube-based auxiliary controller is designed on the basis of the distributed model predictive controller,so that the state errors between the actual system and the nominal system of the satellite is always in a robust invariant set.Combined with Tube-based auxiliary controller and distributed model predictive controller,the actual system of satellite cluster can achieve target tracking and collision avoidance at the same time.And the reconstruction of satellite cluster with specific spatial configuration can be completed autonomously.