Modeling and Control of an Unmanned Aerial Vehicle with Tilt Rotors Equipped with a Camera

In this work, we present a control law for an unmanned aerial vehicle (UAV) carrying a camera through a two degrees of freedom (2-DOF) gimbal mechanism. The vehicle is an H -shaped quadrotor with an additional mechanism that allows the independent projection, along the longitudinal direction, of the thrust generated by each rotor. This particular characteristic shows useful during the execution of some specific tasks, especially the ones that require high velocity. A control law is designed to deal with the underactuation and nonlinearities behavior of the vehicle, that are expressed mathematically by the Euler-Lagrange formulation. The control structure is arranged in four subsystems, designed to control the dynamics of the UAV position, attitude, rotors inclination, and camera pointing. For the position control, the inverse dynamic is used to linearize the translation subsystem, and then a robust H∞ controller is applied. For the remaining subsystems, the Super-Twisting Sliding Mode Control is applied. We present, through simulation, the performance of the designed control structure, proving that the controlled UAV is stabilized and able to track given trajectories even in the presence of unmodeled dynamics, parametric uncertainties and external disturbances (such as wind gusts).