Coordinated standoff tracking using path shaping for multiple UAVs

A coordinated standoff target tracking strategy using path shaping for multiple unmanned aerial vehicles (UAVs) is presented. In performing a tracking mission of a ground target of interest, UAVs are to approach a target and to keep a standoff distance from it with a prescribed inter-vehicle angular separation around the target in order to track it while acquiring accurate target information. Since fixed-wing UAVs without hovering capability fly efficiently at a nominal airspeed, it is desirable that they can keep angular separation between vehicles while holding a constant velocity in a mission duration point of view. The work presented here introduces a new path shaping technique using two constant curvature segments satisfying the turn radius constraint and having more flexibility and fewer discontinuous points on a curvature command compared with the Dubins path at the expense of the path length. Moreover, a simultaneous arrival concept is introduced as a coordinated tracking strategy for multiple UAVs, which initialises UAVs on a standoff orbit.