Clearance of flight control laws via parameter-dependent Lyapunov functions

Lyapunov-based analysis is a widely used tool to assess robust stability of dynamic systems affected by parametric uncertainties. When the uncertain parameters are constant, it is well known that parameter-dependent Lyapunov functions allow one to reduce conservatism of sufficient conditions for robust stability. In this paper, we consider several different techniques for robustness analysis of systems with LFR uncertainty structure, based on parameter-dependent Lyapunov functions. Such techniques are applied to LFR systems derived from real-world flight control schemes, with the aim of finding the largest region in the uncertain parameter space and/or in the flight envelope, for which robust stability is guaranteed. The trade off between conservatism and computational burden is analyzed for each considered technique.