Modular trajectory / path following controller using nonlinear error dynamics

With the emergence of unmanned aerial vehicles in recent time, the research on trajectory and path following control methodologies became increasingly popular due to various applications for these test platforms. In this context, this paper presents a trajectory / path following controller, which is derived based on nonlinear dynamic inversion of nonlinear error dynamics between a specified trajectory / path and the aircraft. The controller is designed as a modular part of an integrated auto flight system comprising the handling of system automation as well as waypoint lists, trajectory generation, standard autopilot functionality, and inner loop control. The modular structure introduced in this paper is emphasized by explanations of the generic interfaces and remarks towards testability. An illustrative example shows the efficacy of this trajectory / path following control concept.