Experimental Validation of L1 Adaptive Control: The Rohrs Counterexample in Flight

Abstract

This paper presents flight-test results that examine the performance and robustness properties of an L1 control augmentation loop implemented onboard a small unmanned aerial vehicle. The framework used for in-flight control evaluation is based on the Rohrs counterexample, a benchmark problem presented in the early 1980s, to show the limitations of adaptive controllers developed at that time. Hardware-in-the-loop simulations and flight-test results confirmthe ability of theL1 flight control system to maintain stability and predictable performance of the closed-loop adaptive system in the presence of general (artificially injected) unmodeled dynamics. The results demonstrate the advantages of L1 control as a robust adaptive control architecture with the potential of facilitating the transition of adaptive control into advanced flight control systems.This work was sponsored in part byNASAgrants NNX08AB97A, NNX08AC81A, and NNL08AA12I