Contror-or-quadrotor position and attitude by the LMI-based sliding mode technique

In this paper, a robust nonlinear sliding-mode controller based on linear matrix inequality (LMI) has been proposed for controlling a quadrotor unmanned helicopter (QUH). Three subsystems have been considered in the dynamics of this quadrotor helicopter: the section that produces the lift force, the section that establishes the desired roll and pitch angles, and the section that generates the control signals in the longitudinal and transverse directions. Then, for each of these sections, a robust sliding-mode type controller has been designed, in which the sliding surface gains are obtained by the LMI method. The stability and the error convergence of this closed-loop system have been evaluated by means of Lyapunov criterion. The presented findings confirm the effective performance of the proposed approach in controlling the position and attitude of the considered QUH in the presence of external disturbances.