A new approach to adaptive actuator failure compensation in uncertain systems

In this paper, we aim to develop controllers for uncertain systems in the presence of possible actuator failures. A new scheme is proposed to design output feedback controllers for a class of uncertain systems having redundant actuators, with which the relative degrees of transfer functions are different. To deal with these actuators using backstepping technique, we introduce a pre-filter before each actuator so that its output is the actual control input to the actuator. The orders of the pre-filters are chosen properly to ensure all their inputs can be designed at the same step based on the backstepping approach. To compensate for the effects of possible faulty actuators, more uncertain parameters than system parameters are required to be identified. With our proposed scheme, the global boundedness of the closed-loop system can still be ensured and the system output can be regulated to zero when some of the actuators are stuck at some fixed values.