Development and experimental validation of a system for agricultural grain unloading-on-the-go

This paper describes the development, simulation, and experimental validation of a novel grain unloading-on-the-go automation system (automatic offloading) for agricultural combine harvesters. Unloading-on-the-go is desirable during harvest, but it requires highly-skilled and exhausting labor because the combine operator must fulfill multiple tasks simultaneously. The automatic offloading system can unburden the combine operator by automatically monitoring the grain cart fill status, determining the appropriate auger location, and controlling the relative vehicle position and auger on/off. An automation architecture is proposed and experimentally demonstrated to automate the unloading-on-the-go process. To simulate the automatic offloading operation, a grain fill model and vehicle dynamics models were developed and validated with in-field testing. To allow for different operator-selected unloading scenarios, the automatic offloading controller has three fill strategies and two movement control options, “open-loop” and “closed-loop”. Simulation results demonstrated that both movement control options can achieve the fill target. The automatic offloading controller was implemented on a dSPACE MicroAutoBox II and integrated into a combine harvester. A PC-based user interface was developed for the combine operator to monitor unloading status and provide commands during the test. In addition, a stereo-camera-based perception system was connected to the automatic offloading controller via an Ethernet cable for grain fill profile measurement during unloading. In-field testing demonstrated that the automatic offloading system can effectively automate the unloading-on-the-go of a combine harvester to fill a grain cart to the desired level under nominal harvesting conditions. The achievable fill level for a 1000-bushel grain cart without spillage ranges from −0.7 m to −0.2 m for the near-edge grain height relative to the cart edge.