Hybrid Gradient Vector Fields Based on Maneuver Space for Path-following Guidance

Guidance path-planning and following are two important functionalities of unmanned aerial vehicles (UAVs), but only a few approaches deal with both. In this study, an innovative hybrid gradient vector fields algorithm based on maneuver space (HGVFs-MS) for path-following guidance is proposed to control fixed-wing UAVs to follow a generated guidance path and oriented target curves in three-dimensional space, which can be any combination of straight lines, arcs, and helixes as motion primitives. The strategies designed in earlier studies have flaws that prevent the UAV from following arcs that make its turning angle too large. The switching strategy proposed in this study solves this problem by introducing the concept of the virtual waypoints. Finally, the performance of the HGVFs-MS algorithm is verified by three representative simulation scenarios. The simulation considers the constraints of the aircraft, and its results indicate that the algorithm performs well in following both lateral and longitudinal control, particularly for curved paths.