Path Planning for Spot Spraying with UAVs Combining TSP and Area Coverages

TL;DR

This paper presents a combined heuristic approach for UAV path planning in agricultural spot spraying, optimizing for minimal path length while avoiding obstacles and covering multiple patches efficiently.

Contribution

It introduces a novel combination of TSP heuristics and area coverage path planning tailored for UAV agricultural applications, evaluated on real-world scenarios.

Findings

A specific TSP-refinement heuristic is particularly effective.

Coverage path lengths significantly impact total path length.

Including headland paths improves coverage efficiency.

Abstract

This paper addresses the following task: given a set of patches or areas of varying sizes that are meant to be serviced within a bounding contour calculate a minimal length path plan for an unmanned aerial vehicle (UAV) such that the path additionally avoids given obstacles areas and does never leave the bounding contour. The application in mind is agricultural spot spraying, where the bounding contour represents the field contour and multiple patches represent multiple weed areas meant to be sprayed. Obstacle areas are ponds or tree islands. The proposed method combines a heuristic solution to a traveling salesman problem (TSP) with optimised area coverage path planning. Two TSP-initialisation and 4 TSP-refinement heuristics as well as two area coverage path planning methods are evaluated on three real-world experiments with three obstacle areas and 15, 19 and 197 patches, respectively. The unsuitability of a Boustrophedon-path for area coverage gap avoidance is discussed and inclusion of a headland path for area coverage is motivated. Two main findings are (i) the particular suitability of one TSP-refinement heuristic, and (ii) the unexpected high contribution of patches areas coverage pathlengths on total pathlength, highlighting the importance of optimised area coverage path planning for spot spraying.