A novel nonlinear hybrid controller design for an uncertain quadrotor with disturbances

In this paper, two adaptive robust nonlinear controllers are proposed. A hybrid controller is developed and applied to a quadrotor to attenuate the chattering effects, and to achieve finite time convergence and robustness aims. Firstly, integral backstepping control is combined with adaptive terminal sliding mode to control the attitude of the quadrotor. The derivative of control signal is obtained from a terminal second-layer sliding surface, and contains the integral of the switching control law. Secondly, an adaptive robust PID controller is designed for the position control of the quadrotor and is improved for free chattering and robust performance against external disturbances. Finally, the adaptive control law is modified for practical applications. The stability and robustness of the proposed controller have been proved using the classic Lyapunov criterion. Then the hybrid controller has been successfully applied on the quadrotor with considering disturbances, noises and uncertainties.