Vector field path following for small unmanned air vehicles

This paper presents a new method for unmanned aerial vehicle path following using vector fields to represent desired ground track headings to direct the vehicle onto the desired path. The key feature of this approach is that ground track heading error and lateral following error approach zero asymptotically even in the presence of constant wind disturbances. Methods for following straight-line and circular-orbit paths, as well as combinations of straight lines and arcs, are presented. Experimental results validate the effectiveness of this path following approach for small air vehicles flying in high-wind conditions

I. Introduction

Unmanned aerial vehicles (UAVs), large and small, have demonstrated their usefulness in military applications. Fur-thermore, there are numerous potential uses for UAVs in civil and commercial applications and the prospects for broad impact are strong. To extend the usefulness of UAVs beyond their current applications, the capability to plan paths and to follow them precisely is of great importance. Unlike piloted vehicles, which rely on the pilot to navigate over demanding terrain or to avoid obstructions, UAVs rely on automation to provide this functionality. As applications such as urban surveillance and rural search and rescue require UAVs to fly down city streets surrounded by buildings or near the surface of abruptly changing mountainous terrain, the ability to follow pre-planned paths with precision is essential. For missions involving cooperation among a team of UAVs, precise path tracking is often crucial to achieving the cooperation objective.