Robust control of an Uncertain Coaxial Rotor UAV with Input Constraint and Guaranteed Tracking Performance

In this paper, a robust trajectory tracking control scheme is developed for an uncertain coaxial rotor unmanned aerial vehicle (CRUAV) with input constraint and guaranteed tracking performance. To begin, the position subsystem model of the CRUAV is formulated as an input-constrained form by using hyperbolic tangent function and Lagrange mean value theorem, and the barrier Lyapunov function (BLF) based Back-stepping control is designed to obtain the guaranteed tracking performance. Follow that, sliding-mode control combined with a nonlinear disturbance observer (NDOB) is designed for attitude subsystem. Furthermore, the stability of the closed-loop system is demonstrated using the Lyapunov method. Finally, the effectiveness of the proposed control algorithm is verified by numerical simulations.