Robust attitude synchronisation controllers design for spacecraft formation

The attitude synchronisation control problem for spacecraft formation with switching communication topologies and information transmission delays is addressed. Common Lyapunov functions are employed to tackle such a problem. To compensate the adverse effect on an individual spacecraft arising from model uncertainties and external disturbances, parameter estimation variables and nonlinear integral terms are incorporated into the Lyapunov functions. The main result of this research is that one of the presented controllers can render a spacecraft formation consistent to a given trajectory globally with dynamic information exchange graph and non-uniform time-varying delays while coping with the parameter uncertainties and unexpected disturbances. In addition, several corollaries of the main results are provided. By virtue of a corollary of Barbalat´s lemma, attractiveness of the proposed controllers for the corresponding closed-loop systems is proven. Numerical simulations are also included to demonstrate the theoretical results.