Automated system for real time tree canopy contact with canopy shakers
Abstract Most crops destined for industrial transformation employ mechanical harvesters that have been developed satisfactorily by adapting the tree to the machine features. Not all fruit trees can be adapted, and this is the case in traditional olive orchards, where canopies are very irregular and a complex harvesting system is necessary to adapt to different tree geometries and sizes. Lateral canopy shakers have arisen as an alternative system, the use of which is spreading as they allow continuous integral harvesting of several crops such as citrus fruit or, more recently, the olive. Contact between the shaker and the canopy is a key harvesting factor that must be studied. Manually positioning several shaker heads at different heights to follow the tree contour during continuous harvesting is a tedious task for an operator and may decrease potential efficiency. However, automation of shaker contact with the canopy may increase harvester efficiency. Two automatic systems composed of several electronic devices were developed and incorporated into a harvester with several shaker heads. The first system controlled canopy contact based on measuring the distance between the shaker and the tree contour. The second system measured the variation of the shaker mechanism’s hydraulic pressure in order to adjust the position of each head relative to the canopy. Both systems were compared to manual control by studying removal efficiency, harvesting efficiency, debris production and percentage of shaking time within the control intervals. Results determined the suitability of automatic harvesting systems with an increase of 5.9% in removal efficiency based on the criterion of tree resistance to shaking, with no significant differences in tree damage and an increase in field capacity ha h-1 person-1. Laser LED may be a valid technology for measuring the distance to canopy in real time and gave satisfactory results but a decrease of 7.9% in removal efficiency compared to manual sighting. The bottom, middle and top of the tree present different patterns in the harvesting process, and as resistance mode adjusts control intervals to the different patterns, it may provide a closer fit to follow than distance mode. Further improvements are required to enhance harvesting efficiency by connecting automation between the removal system and the catch frame.