Adaptive actuator failure compensation for microsatelltes using uncertainty decomposition

A new adaptive actuator failure compensation scheme is developed for attitude tracking control of microsatellites with unknown inertia matrix, external disturbance and actuator failures which are uncertain in occurring time instants, values and patterns. An SDU factorization is employed to handle the uncertainty of the control gain matrix caused by the uncertainties of inertia matrix and actuator failures, which guarantees the nonsingularity of the control gain matrix estimate. The system uncertainties are estimated by the adaptive laws, and the adaptive design ensures the desired system stability and asymptotic tracking properties despite the presence of actuator failures. Simulation results of an application to a microsatellite with four reaction wheels verify the effectiveness of the proposed adaptive control scheme.