Coverage planning for capacitated field operations, part II: Optimisation

• GPS-recorded fertilising operations are compared to algorithmic generated plans.
• Algorithm plans reduce the non-productive distance with 15.7%–43.5%.
• Algorithm plans reduce the total travelled distance with 5.8%–11.8%.
• Algorithm use spate-space search (A*) and a travelling salesman problem solver.

Capacitated field operations refer to the operations that involve material flow where there are capacity constraints to the load that the machine is able to carry. A capacitated operation cannot therefore be completed in one operation and the machine has to interrupt the operation, leave the field and travel to an out-of-field facility for refilling (or unloading) and to return back to the field to resume the operation. This paper develops an algorithmic approach for the optimisation of capacitated field operations using the case of liquid fertilising. The approach is based on the state-space search technique where a solution is a sequence of pre-defined driving actions which are applied to the initial state that transform it to a goal state under the criterion of the minimisation of the non-productive travelled distance. In order to minimise the branching factor of the state-space search, the sequence of the working tracks is optimised in a post-process stage where the non-productive travelled distance in headland turnings is further minimised by implementing the travelling salesman problem methodology. In order to assess the improvements in the operations efficiency derived from the presented method, three fertilising operations were recorded and the optimised plans were compared to the conventional plans followed during the operations. Savings in the non-productive travelled distance was 15.7 %–43.5 %, while savings in the total travelled distance was 5.8 %–11.8 %.