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

•A system to automate combine harvester unloading-on-the-go (automatic offloading).•In-field validation of the automatic offloading system in nominal condition.•Automatic controller with three fill strategies and two movement control options.•Unloading-on-the-go simulation with vehicle model and grain piling model.•Stereo-camera based perception system integration for fill level monitoring.