A Distributed Control Strategy for Satellite Formation Flying

Satellite technologies have progressed significantly in the last years from the early experiments made by scientists in the last century. Nowadays, a challenging problem that attracts scientists, engineers and space agencies is the design of space missions composed of clusters of satellites. Therefore, achieving certain configurations for the members and granting synchronization of their attitude are of key importance. The topic of formation control is well known and discussed in robotic systems and aerial vehicles research and in this thesis is applied to clusters of spacecrafts. In the same field of coordination of multi-agent systems lies the attitude synchronization problem for satellites. Most of the control laws developed to achieve a desired formation consist of a centralized or hierarchical architecture, where one or more vehicles, called the leader, follow a predefined trajectory and other members of the formation, called the followers, track them. In this thesis, instead, a distributed control law for formation control and attitude synchronization of satellites is presented. In this way, the control does not lean on a single satellite of the group, thus being more robust. The exchange of information between the spacecrafts is represented and studied as a graph; many studies on distributed network extensively use this mathematical tool and a better analysis of the problem can be performed. Furthermore, the developed control law is applied to scenarios where the communication between interacting spacecrafts is not considered to be continuous but takes place only at certain instants of time. Finally, tests are presented to show the effectiveness of the control and how it reacts to different settings. A Simulink implementation is also developed to show interactive ways to control the formation and to test the behavior of the proposed control strategy to changes of reference formation.