Stability overlay for adaptive control laws

This paper proposes an architecture referred to as Stability Overlay (SO) for adaptive control of a class of nonlinear time-varying plants. The SO can be implemented in parallel with a wide range of "performance-based" adaptive control laws, i.e., adaptive control laws that seek to improve closed-loop performance, but may be susceptible to instability in the presence of unaccounted model uncertainty. In this architecture, the performance-based adaptive control law designates candidate controllers based on performance considerations, while the SO supervises this selection based upon online robust stability considerations. A particular selection of a performance-based adaptive control law is not specified. Rather, this selection can be from a wide range of adaptive control schemes. This paper provides stability proofs for the SO architecture and presents a simulation that illustrates the applicability of the proposed method.