Fault tolerant control for actuator failures with application to a twin otter aircraft

In this paper, an adaptive fault tolerant control (FTC) scheme is proposed for the control surfaces of a twin otter aircraft. With some actuator groups as backups, the scheme includes two modes: the direct adaptive compensation mode and the supervisory switching mode. In the former mode, the failure of an actuator group can be adaptively compensated by the remaining healthy actuators, while the latter is employed to switch the controllers from a totally failed group to a healthy one if the failure is detected by one of the thresholds that are designed to supervise some state variables related to system stability. As a result, some drawbacks of existing adaptive failure compensation techniques such as the possible actuator saturation and the failure of entire actuator group can be overcome. The effectiveness of the proposed scheme is validated by using the aircraft simulation.