Autonomous Scooping of a Rock Pile by a Wheel Loader Using Disturbance Observer

A controller for a miniature wheel loader is developed to scoop rock piles autonomously. During a scooping task operation, the load of the bucket varies momentarily according to the phase of scooping. Before the insertion of the bucket into the rock pile, the load is just the bucket weight, but after the insertion the reaction force from the rock piles is applied to the bucket. The values of the reaction forces changes significantly and they can not be identified in advance. To achieve autonomous loading, it is required for the bucket controller to work stably in both cases with the same algorithm. Therefore, a disturbance observer mechanism is installed into a miniature wheel loader “Yamazumi 3” to adapt various amounts of loads. Its effectiveness is verified by fundamental experiments.