UAV fault-tolerant control by combined L1 adaptive backstepping and fault-dependent control allocation

This paper presents an approach to obtain fault tolerance in the nonlinear longitudinal motion control of an aircraft. The approach uses an L1 adaptive backstepping controller and fault-dependent control allocation to obtain such tolerance. In the nominal fault-free case, only the elevator will be active. The L1 adaptive backstepping controller provides some robustness to the system by handling uncertainties, which is utilized for fault accommodation if a partial fault occurs. Also, control allocation is used to redistribute control to other available healthy actuators to make the system fault tolerant against more severe faults and even to a total loss of the elevator. Simulations have been conducted on a model of a Cessna 182 and show excellent results for both the nominal and faulty scenarios.