Precise Picking Height Positioning on Wild Blueberry Harvesters using Electric Linear Actuators

摘要

Mechanical harvesting remains the most cost-effective means for picking wild blueberries. Harvesting efficiency is heavily reliant on operator skill and full automation relies on precise and accurate determination of harvester berry picking height. Toaccomplish this a DC linear actuator coupled with a custom-built control system was used to monitor and regulate berry picking height during harvesting. The system provides individual and tandem control of up to five harvester picking heads with separate controls to establish baseline heights as well as for returning to a driven height set by a driving actuator. In field testing, tandem actuator control was able to adjust actuator position on multiple actuators both under and without load to within 0.60 cm of one another. Similarly, the baseline function was able to return actuators from various heights to set baselines to within 0.40 cm. Finally, the set to driven actuator height was able to match the height of the driving actuator to within 0.20 cm.These results serve to indicate that the control system functions well however, coding optimizations could be made to further increase accuracy and precision. The DC linear actuator achieved upward and downward speeds of 1.32 cm s'1 and 1.89 cm s'1 respectively while the hydraulic actuators performed much faster with upward and downwards speeds of 9.67 cm s'1 and 8.01 cm s'1 respectively.