An initial study of a combined robust and adaptive control approach to guaranteed performance flight control

In this paper an initial study is presented regarding a new combined robust and adaptive control approach to fault-tolerant flight control. The approach is based on designing a suitable tracking-error feedback (TEF) term such that the plant is stabilized over the entire uncertainty set. If such a term can be found, the adaptive control part depends only on the reference model state and the reference input. Hence, instead of dealing with a nonlinear time-varying system arising in the context of standard adaptive control, the designer needs to analyze a stable linear time-varying system. This is an important step toward the development of effective analysis tools for performance of adaptive systems. In the case when the tracking error feedback term stabilizes the plant only over a subset of the uncertainty set, the TEF term can still be used to minimize the tracking error so that a linear time-varying approximation is close to the original system. The proposed approach is illustrated on an example system through analytic development and simulations.