Design of a Sliding Mode Controller in the Presence of Wind Disturbance for a Novel Recovery System of Vertical Take-off and Landing UAV Equipped with Manipulator

In this study, a novel recovery system was designed for a vertical take-off and landing (VTOL) UAV. In the desired position, the manipulator moves the cables and gripper toward a fixed rod, then the gripper grasp the rod and the arm disconnects from the gripper. Therefore, the VTOL is hung through 2 light cables. Due to coupled dynamics, the effects of the manipulator are considered as disturbance. Then by using the theory of linear and angular momentum and the changes in the center of mass and inertia of the manipulator, an estimation of the force and torque due to the movement of the arm is presented. This system must be efficient against wind disturbance, undesired aerodynamic effects and parameters error. Therefore the sliding mode controller is designed to track the desired trajectory of VTOL. Results of simulation show that the estimation of torques that is applied to the VTOL due to arm movement is done correctly. The designed controller also has a good performance in tracking the desired trajectory and reducing the effects of disturbance caused by arm movement.