基于欠驱动原理的脐橙采摘末端执行器的设计与试验

Design and Experiment of End-effectors for Picking Navel Oranges Based on the Underactuated Principle

果蔬采摘机器人的末端执行器是采摘机器人的重要组成部分,直接影响采摘的成功率与采摘效率。通过分析脐橙特性,基于欠驱动原理设计了一种夹剪一体的脐橙采摘末端执行器。其整体机构由一个两层3指机械爪手构成,两层手指中的一层为剪切机构载体,另一层则为对果实抓取固定的夹持手指;剪切机构由摇杆滑块机构组成。构建剪切机构与机械手的力学模型,根据需求对相关零部件进行了设计与选型;判断了防止机械手剪切机构发生干涉的运动误差范围,并对关键受力部位进行了有限元分析。结果表明,因关键受力点变形导致的运动误差在安全误差范围内,验证了结构的合理性。通过Adams软件对其进行运动学仿真,进一步证明了该末端执行器的可行性。最后,通过末端执行器实物样机进行脐橙采摘剪切试验,机构整体采摘成功率为95%,采摘周期为4.3 s。

The end-effector of fruit and vegetable picking robots is an important part of the picking robot,which directly affects the success rate and efficiency of picking.By analyzing the characteristics of navel orang-es and based on the underactuated principle,a clamping end-effector for picking navel oranges is designed.The overall mechanism is composed of a two-layer and three-finger mechanical claw.One of the two layers of fingers is the carrier of the shearing mechanism,the other layer is the clamping finger for grasping the fruit,and the shearing mechanism is composed of a rocker slider mechanism.By building the mechanical model of the shear mechanism and the manipulator,the relevant parts are designed and selected according to the requirements.The motion error range of the shear mechanism is determined to prevent the interference of the manipulator.The fi-nite element analysis on the key force parts is carried out,and the motion error caused by the deformation of the key force points is analyzed within the safety error range.The kinematic simulation of the end-effector is carried out by Adams software,and the results prove the feasibility of the end-effector.Finally,the picking and shearing test of navel oranges by the end-effector prototype shows that the overall picking success rate of the mechanism is 95%,and the picking cycle is 4.3 s.