A multiple model-based reconfigurable flight control system design

Abstract

We consider a problem of designing a reconfigurable control strategy that achieves acceptable flight performance in the presence of wing battle damage for a tailless advanced fighter aircraft (TAFA). This is a complex practical problem since wing damage results in abrupt variation in the aircraft dynamics. Hence fast and accurate control reconfiguration is vital for assuring aircraft survivability. Our suggested reconfigurable controller is based on the concept of multiple models, switching, and tuning. The overall control system consists of multiple parallel identification models, describing different percentages of wing damage, and corresponding controllers. Based on a suitably chosen switching mechanism, the system quickly finds the model that is closest to the current damage mode, and switches to the corresponding controller achieving excellent overall performance. In addition, the boundedness of the signals in the system is guaranteed if the switching interval is chosen to be sufficiently small. It is shown that the key element is the design of sufficiently robust individual controllers for each of the damage conditions. This has been accomplished using a combination of inverse dynamics and output error feedback control laws. The properties of the overall system are illustrated through simulations using linearized TAFA models provided by Boeing. Simulation results have demonstrated the potential of the multiple model-based approach to solve complex practical reconfigurable control design problems.