Adaptive nonlinear robust control of an underactuated micro UAV

In this article, we investigate a robust nonlinear control strategy to solve the trajectory tracking for a micro unmanned aerial vehicle, the quadrotor. The control technique is the computed torque control (CTC), this technique is widely used in the robot manipulators control. The CTC technique needs a strong knowledge of the model. In this regard, the complete dynamic model of the quadrotor has been established by the Euler–Lagrange formalism. After that, a robust nonlinear H∞ controller has been designed to stabilize the system with robustness. The proposed controller takes into account the underactuation characteristic of the quadrotor, so the controller is designed for the actuated degrees of freedom (DOF) with their coupling with the underactuated DOF. For the position tracking, we propose the backstepping controller. In both controllers, nonlinear H∞ and backstepping, the integral action is considered to get a null steady-state error. In order to improve performance quality, the control law has been reinforced by an adaptive action. This last has been performed by the linear parameterization property and the neural networks. The results show efficiency in the parametric uncertainties.