Decentralized Control For Attitude Synchronization Under Undirected Communication Topology

This chapter developed two decentralized coordinated attitude control laws for attitude synchronization and tracking problem with undirected (it is also named bidirectional) inter-satellite communication topology. Firstly, an adaptive sliding mode control law is developed against inertia matrix uncertainties and external disturbances. The proposed control law is based on the proposed multi-satellite sliding mode vector, on which each satellite approaches its desired time-varying attitude and angular velocity while achieving attitude synchronization among satellites in the formation. The first control law requires that each satellite knows its own angular velocity and the angular velocities of other satellites it can communicate with. However, angular velocity is not always available, because of either cost limitations or implementation considerations. As a remedy to such situation, a coordinated attitude control law without angular velocity measurements is then proposed. Passivity approach is deployed to remove the requirements for angular velocity measurements. The only assumption on communication topology for the proposed control laws is that the communication links are undirected. The stability of the resulting closed-loop systems is proved by virtue of Barbalat's Lemma. Simulation results demonstrate the effectiveness of the proposed attitude synchronization and tracking approaches.