Path planning for in-field navigation-aiding of service units

Agricultural field operations, such as seeding, harvesting, spraying, and fertilizing, are typically carried out by multi-machinery systems comprising one or more self-propelled or tractor-pulled units, and one or more service - mainly transport - units. The operation of a service unit must be carefully planned because its execution efficiency can significantly affect the productivity of the whole system.In this paper, an algorithmic approach for the generation of optimal in-field paths to be followed by service units, was developed and demonstrated. Both stationary and on-the-go unloading operations are supported. The approach was based on an abstraction of a field as a two-dimensional grid, with each grid cell representing obstacle, free, initial, or goal region. By defining also the action spaces of the grid states (service unit moves one cell up, down, left, or right), the arcs and nodes of a discrete transition graph are created and by using a graph search algorithm the optimal path is generated. A number of simulated experiments were performed in order to demonstrate the paths that result from invoking the above-mentioned planning method.The algorithmic path generation can provide the basis for a navigation tool dedicated to service units, which can increase the overall field efficiency of the operations executed by cooperating machines and reduce the adverse effects of the heavy machine traffic on the soil. The low computational requirements of the proposed method make it feasible as an implementation of the optimal planning for large scale operations executed by cooperative machines.