摘み取り指の弾性を活かした切断後把持戦略とその設計手法

抄録

The modern agriculture shows remarkable results in productivity for labor saving by mechanization. However, it is still difficult to replace the dexterous human ability in handling objects with mechanisms. Many tasks in agriculture depend on human dexterity especially when it comes to pluck delicate fruit without damage to preserve quality. Strawberry is one kind of fruit that needs extra handling care during plucking, due to its brittleness against force and heat. Therefore, detailed observation and evaluation need to be done in order to produce a harvesting machine. This paper proposes strategy and design of finger for strawberry harvesting. In the strategy, there are three cases which are "cutting after holding," "holding after cutting" and "same timing of cutting and holding". In the cutting after holding and the same timing of cutting and holding, it is complex and heavy for the mechanism to achieve them. In the opposite case of the holding after cutting, it is easily achieved by simple mechanism which is a holding finger with an edge. However, high velocity of closing finger is needed to certainly grasp the stem during its free fall. A problem that a general robot hand loses grasping the stem is occurred, since closing velocity is insufficient. Therefore it is applied for the insufficient velocity of the closing to follow up it on restoration of elastic deformation of the finger. It deploys a pair of elastic, flexible fingers to cut and grasp the stem before the fruit falls. An experimental device was developed for strawberry harvesting, and mounted on a harvesting robot. Its performance was analyzed and evaluated, Results showed it worked as designed and intended.