31th Colloquium of Automation, 5th-6th November 2009, Leer
Manual harvesting of white asparagus is a physically hard and exhausting work. Asparagus is grown in earth dams and the workers have to bend down to inspect the dam surface, dig out each stalk about the half and cut it with a special knife. Furthermore the asparagus stalks have different ripening times so harvesting needs to be done every day on the same dam. To make this work faster and more reliable an automatic harvesting system has been developed during the AutoSpar project. This electrically driven system moves along an asparagus dam and detects the asparagus stalks that are breaking through the surface of the earth. A camera system locates all asparagus tips in the current working area. These positions are passed to a control unit that calculates the optimal harvesting sequence. Afterwards the harvesting tool is automatically moved to the appropriate position using a cross table arrangement. A special harvesting tool is pushed into the soil next to the stalk and a blade cuts the stalk 25 cm below the surface. This tool has been optimized for easy ground penetration and maximal robustness against the damaging influence of the soil. In subsequent the stalk is picked up by a handling system and gently placed in a box.