气动球果采摘柔性手爪设计与实验

Design and Experiment on Pneumatic Flexible Gripper forPicking Globose Fruit

针对球形果实采摘问题,采用气动多向弯曲柔性驱动器设计了2种规格带有回转腕部功能的多自由度3指采摘柔性手爪。该采摘柔性手爪采用中心对称结构,其柔性手指与驱动器复合一体,在气压下可产生贴合球果表面的弧状变形,3指协同配合运动抓取球果,并通过腕部旋扭分离方式完成采摘。研究了“刚柔耦合”驱动器的材料和制造工艺,建立了柔性驱动器形变模型,获得了其气压下的形变特性,并进行了相关实验验证。试制了采摘柔性手爪物理样机,研究分析了柔性手爪的工作空间、抓取模式和采摘时的力学性能,并在实验室搭建的采摘平台上进行了多种球果模拟采摘实验。结果表明,该采摘柔性手爪具有3种抓取模式,物形适应性好,抓取柔顺可靠、动作灵活,采摘主动安全、损伤小,适于多种球果的采摘。该柔性手爪采摘球果的尺寸范围为30~130 mm,三指交错强力握取球果的最大质量为1.28 kg。

In order to complete the globose fruit picking well,a multi DOF flexible three-finger gripper of which wrist can rotate was designed by using flexible pneumatic multi-directional bending actuator.The flexible finger,which was compounded with the actuator to form a whole,bended to an arc to fit the surface of the globose fruit when supplied the air pressure.Three fingers cooperated with each other to grasp the globose fruit tightly and the wrist was twisted to separate it from the tree.The fabrication process of the“rigid-flexible coupling”actuator was investigated and acquired,and subsequently a physical prototype of flexible gripper was manufactured.The deformation model of the flexible pneumatic actuator was built and the deformation characteristics of the flexible actuator when supplied air pressure were obtained.Then the experiments were carried out to verify the theoretical model.Also,the physical prototype of the flexible gripper was trial-manufactured.The working space,grasp pattern and mechanical properties of grasping were studied and a variety of globose fruit picking experiments were carried out on the picking platform built in the laboratory.The results showed that the flexible gripper can well complete three kinds of grasping patterns,and it was flexible and reliable and had good compliance to suit the globose fruit.In addition,the flexible fingers were safe to the delicate surface of the fruit which reduced the damage of the fruit greatly.The size of globose fruit that the flexible gripper can complete was ranged from 30 mm to 130 mm,and the maximum mass was 1.28 kg when flexible gripper staggered grasp with three flexible fingers.The research laid a foundation for the further application of flexible gripper.