Adaptive robust sliding mode control of quadrotor in the presence of wind disturbance

In this paper, an adaptive robust tracking control system for an unmanned quadrotor is designed .Quadrotor placed in category of rotary wing aerial vehicle, and it is an under actuated and inherently unstable system. Also the dynamic model of system is nonlinear and along with the Uncertainty, therefore it is required to design a robust control system for stabilization and tracking the desired path. This system must be capable to retain the quadrotor balance in the presence of the disturbance, undesired aerodynamical forces and Measurement error of constant parameters. The suggested controller in this paper consists of two inner and outer control loops. Inner loop controls the Euler angles and outer loop is for control the quadrotor position and translational motion, and calculating the desired angles for trajectory tracking. In this paper by utilizing the adaptive sliding mode, the controller has been designed which is no need to be given the uncertainty range and the upper bound of it will be estimated as a scalar number. In order to prevent from diverging adaptive parameters, the sigma-modification is used in adaption laws and also to achieve suitable performance in various load, the total mass is estimated adaptively. The control design is based on the Lyapunov theory and the robust stability of system in the presence of the disturbance have been shown.