Adaptive robust stabilization of rigid spacecraft in presence of disturbances

In this paper the problem of robust stabilization of rigid spacecraft subject to a gravity-gradient disturbance has been considered. Different control laws have been derived either in the cases of knowledge of the inertia matrix of the system or when only estimations of its parameters are available. It is assumed that the entire state of the system can be used to implement the control. An overparametrization of the initial parameterization is introduced in order to give a bound on the disturbance independent on the inertia matrix of the spacecraft. Simulations show the different performances of the controls derived and demonstrate the improvements due to the adaptive control.