An adaptive scheme with parameter identification for spacecraft attitude control

We discuss the dynamic model of a spacecraft governed by gas jet actuators or momentum wheels. Dynamic control with parameter estimation which guarantees asymptotic stability of desired trajectories is designed. We obtain an adaptive scheme which provides the convergence of the tracking errors and, in addition, for persistently exciting desired motions ensures the convergence of parameter estimates to their true values. The scheme is of composite type as it exploits both the tracking errors and prediction errors to estimate system parameters. The scheme is modified to obtain, for persistently exciting motions, instability of all steady motions with the exception of the desired trajectory. The region in the phase space is defined where exponential convergence is achieved.