Experimental Validation of L(1) Adaptive Control: The Rohrs Counterexample in Flight

This paper presents flight-test results that examine the performance and robustness properties of an L(1) 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 confirm the ability of the L(1) 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 L(1) control as a robust adaptive control architecture with the potential of facilitating the transition of adaptive control into advanced flight control systems.