Nonlinear Control and Trajectory Tracking of an Unmanned Aircraft System Based on a Complete State Space Representation

Conventional control strategies for holonomic Unmanned Aircraft Systems (UASs) require that, while executing a mission, the UAS attitude dynamics remains very close to zero in order to satisfy the assumption of small angles approximation. This requirement may be valid for hover flight, but not for translational flights or aggressive maneuvers. To overcome this issue, this paper presents the controllability analysis for a non-linear representation of a holonomic UAS. Under the proposed scheme, it is shown that it is possible to design control schemes for stabilizing the complete UAS state space without the necessity of separating the system in attitude and translation subsystems. A set of simulations are presented to evaluate the effectiveness of the proposed control laws. These results show that the proposed strategy enables the UAS to track a desired trajectory while keeping the attitude close to a desired value.