Trajectory Tracking Control For Underactuated Thrust-Propelled Aerial Vehicles

We present a trajectory tracking control scheme for a class of underactuated thrust propelled aerial vehicles. The class of aerial vehicles is modeled as a rigid body with a constant thrust direction in the body frame. The attitude of the rigid is fully actuated while only one translational degree of freedom is actuated. Thus, the combined translational and rotational motion is underactuated. The tracking control problem is solved in a two-step approach. First, a translational control scheme that tracks the desired position trajectory is constructed assuming the translational dynamics to be fully actuated. The magnitude of the translational control input is used as the magnitude of the control thrust. Second, the unit vector representing the direction of the translational control input is used as the desired thrust direction. An asymptotically stable attitude control scheme is developed in S², such that the body fixed thrust direction tracks the desired thrust direction. The overall closed-loop system is analytically shown to be asymptotically tracking the desired position trajectory. The results are validated by numerical simulations.