Position Tracking Control of Tailsitter VTOL UAV With Bounded Thrust-Vectoring Propulsion System

This paper presents an adaptive position tracking controller for a special kind of tailsitter vertical take-off and landing (VTOL) unmanned aerial vehicle (UAV). The distinctive part of this VTOL aircraft is its thrust-vectoring propulsion system, which allows the aircraft to achieve long-range flight at high-efficiency. However, there are two main problems encountered in the control design for this aircraft in vertical mode. One problem is that the mass and inertia tensor are unknown parameters because of the fuel consumption. The other problem is that the thrust vector is bounded both in amplitude and orientation, leading to the boundedness of control input. In this paper, we use a complementary filter to estimate the mass and an adaptive law to compensate the error caused by inertia uncertainty. A Lyapunov-based control law with nested saturation function is proposed to solve the problem of input boundedness. Finally, the global asymptotic stability is proven for the simplified model and the effectiveness is illustrated through simulation.