Multiple-model adaptive flight control scheme for accommodation of actuator failures

A new parameterization for the modeling of control effector failures in flight control applications and a stable adaptive scheme for failure detection, identification, and accommodation is proposed. The failures include lock in place, hard over, and loss of effectiveness. It is shown that the resulting representation leads naturally to a multiple-model formulation of the corresponding control problem that can be solved using a multiple-model adaptive reconfigurable control approach. We derive stable multiple-model adaptive reconfigurable control algorithms for several cases of increasing complexity, including the most complex case, wherein one of the effectors undergoes lock-in-place or hard-over failure, and all others lose effectiveness. In all cases, the stability of the overall reconfigurable control system is demonstrated using multiple Lyapunov functions, extensions of the Lyapunov method, and the separation between identification and control arising in the context of indirect adaptive control. The approach is illustrated through numerical simulations of the F/A-18 aircraft during carrier landing.