Stability and Performance Robustness of an L_1 Adaptive Dynamic Inversion Flight Control System

摘要

Dynamic inversion is a model following nonlinear control method that is commonly used to develop flight control systems for high-performance aircraft that operate over large flight envelopes. A high-fidelity on-board model of the aircraft aerodynamics and propulsion is required for successful inversion, which imposes the need for costly and lengthy efforts for model development encompassing computational fluid dynamics, wind tunnel testing, and flight testing. Adaptive control techniques offer the potential to claim the benefits of dynamic inversion control systems while reducing the required level of model fidelity, thus saving time and money while retaining performance. This idea is not new and many designs have been proposed, but few have transitioned to production systems. This paper explores L_1 adaptive augmentation approaches that are minimally invasive to the baseline dynamic inversion flight control system with a view towards transitioning verifiable adaptive augmentation systems to operational use. Simulation results and analysis are presented for a tailless fighter aircraft showing that the L_1 augmentation achieves desired handling qualities for a wide range of plant uncertainties.