Adaptive control for tilt-wing VTOL UAV

Control of complex Vertical Take-Off and Landing (VTOL) aircraft traversing from hovering to wing born flight mode and back poses notoriously difficult modeling, simulation, control, and flight-testing challenges. This paper provides an overview of a robust adaptive control for autonomous flight of the GL- 10 tilt-wing, tilt-tail, long endurance, VTOL aircraft control system. The GL-10 prototype aircraft efficiently combines two challenging mission objectives: long endurance and VTOL capability. The primary challenge for this project is not proving the basic aircraft configuration feasibility, as tilt-wings do indeed fly, but developing the flight control and flight test feasibility given schedule, resource constraints, and additional complexity from concurrent development for portions of the conceptual design, fabrication, and control development. The flight control system challenges are characterized by large flight envelope, highly nonlinear dynamics through transition regime and loiter requirement at just below the stall angle-of-attack while dealing with a sparse aerodynamics database resulting in large uncertainties. An L1 robust adaptive control was chosen to deal with these challenges. The paper present control law development and flight test results for the GL-10 VTOL tilt-wing, tilt-tail distributed propulsion UAV.