In-field and inter-field path planning for agricultural transport units

Path planning in agricultural field operations involving cooperating machines (e.g. combine harvesters and transport units) has to satisfy both the objectives of the individual mobile unit and the team of the cooperating mobile units. Especially, the planning and execution efficiency for transport units can significantly affect the productivity of the whole system. In this paper a path planning method for transport units in agricultural operations involving in-field and inter-field transports was presented. The approach incorporated (1) the optimization criterions of time or traveled distance; (2) the generation of paths for both in-field and between fields movements of the transporting units; and (3) the adoption of restricted movements as imposed by the controlled traffic farming concept. A ''Metric Map'' is generated involving the creation of a geometric description of the different fields, the followed fieldwork pattern by the harvester, and the road network associated with the coupled operation. The topology of the Metric Map is then represented by a graph on where the single-source path planning problem is solved by implementing the Dijkstra's algorithm. Based on the results provided by selected scenarios, alteration between optimality criterions provides discrepancy between solutions in the range of 2-10% indicating that identification of the appropriate criterion suited to the specific operational conditions is of significant importance. Furthermore, the low computational requirements of the planer, taking into consideration the realistic demands of the harvesting operation system indicating that it is feasible to use the planner for on-line planning efforts.