Adaptive control of a VTOL uncrewed aerial vehicle for high-performance aerobatic flight

Abstract

We present two adaptive control methods conceived to enable a vertical take-off and landing (VTOL) uncrewed aerial vehicle (UAV) to perform a class of aerobatic maneuvers in the presence of aerodynamic-coefficient and torque-latency variations induced by changes of the local flow fields during high-speed aerobatic flight. First, we introduce a linear time-varying (LTV) dynamical model, which is assumed to have unknown time-dependent parameters, to describe the aerodynamic effects acting on the actuation dynamics of the system. Then, we present the design of a Lyapunov-based adaptive control scheme aimed to compensate for undesired behavior of the LTV actuator dynamics, according to which we derive the control and adaptation laws from a single Lyapunov candidate function. Next, we propose a modular adaptive control scheme to address the same problem, but in which the adaptation law is specified separately from that of the controller. We use modern nonlinear theory to deduce and analyze the conditions that guarantee the global asymptotic stability of both adaptive control strategies. In order to exemplify the controller synthesis procedures, we implemented both adaptive control methods on a quadrotor UAV to perform three different types of aerobatic-flight maneuvers—namely, triple flips, Pugachev’s cobras, and mixed flips. The obtained experimental results provide compelling evidence of the effectiveness of the two proposed methods to compensate for the undesired effects induced by aerodynamic-coefficient and torque-latency variations. Furthermore, the experimental data demonstrate that both adaptive schemes significantly improve the flight performance of the quadrotor UAV during the execution of aerobatic maneuvers, compared to those achieved with a controller that disregards the LTV actuator dynamics induced by high-speed aerodynamic effects. The suitability of the time-varying approach used to model the influence of high-speed local flow fields on the dynamics of the controlled UAV was indirectly validated through data obtained during the aerobatic-flight experiments presented here.