| Fruit picking is the important link of agricultural production which exist some problems such as strong seasonality,large labor intensity and timely harvesting.At present mainly manual picking exists an increasingly prominent problem which makes effective labor shortage as the population ages and transfer of agricultural labor force make,The fruit picking robot can effectively solve this problem and improve labor productivity.End-effector as an important part of the picking robot to finish picking job which is considered to be one of the core technologies of the picking robot.The developed end-effectors of picking robot are basically designed for a particular fruit picking at home and abroad.And it makes the end-effector low efficient,poor universal,clumsy and heavy.According to the characteristics of picking fruit with hand,this paper proposed and designed three-fingered dexterous hand of the fruit picking robot combining the current dexterous hand technology.On this basis,the grasping planning of the three-fingered dexterous hand was analyzed.This research mainly includes the following aspects:1)Function Analysis and Solution Design.Analysing the function and solution of the end-effector.Summing up the typical physical parameters and mechanical parameters of the fruit.Proposing the overall plan of the end-effector.Laying the foundation for subsequent structure design of the end-effector.2)Three-fingered Dexterous Hand Structure Design for Fruit Picking.According to the overall structure and layout of the three-fingered dexterous hand.Designing the concrete structure of single finger on the basis of hand form and each knuckle proportion parameters.Designing the structure of the palm according to layout plan.Building 3D model and assembling the whole three-fingered hand using the assembly module of Catia software and analysing the movement interference by using the digital assembly module.Then putting the finger 3D model into Adams software for simulation analysis,further testing the correctness of the coupling design of the middle knuckles and distal phalanx finger.3)Three-fingered Dexterous Hand Kinematic Analysis for Fruit Picking.Establishing the kinematics model of the designed finger by D-H method.Analysing its direct and inverse kinematics,and solving the Jacobi matrix of the finger knuckles.Further analysing the kinematics of the three-fingered dexterous hand to provide theory basis of the subsequent grasping planning and control.4)Three-fingered Dexterous Hand Grasping Planning for Fruit Picking.Building the grasping model of the three-fingered dexterous hand by analysing the characteristics of picking fruit with hand.Firstly setting up the contact model of the finger,and choosing the best grasping plane.Then analysing the force closure and form closure of the three-fingered dexterous hand qualitatively to lay the theoretical foundation for the subsequent grasping planning of the three-fingered dexterous hand.Analysing the choice of the grasping planning method and the near point.Carring out comparative analysis on trajectory planning of the three-fingered grasping in the joint space and cartesian space.Finally simulating the configuration of the three-fingered dexterous hand when grasping fruits.The main innovation of this paper is that the three-fingered dexterous hand technology is applied to the design of the fruit picking robot end-effector.It makes the end-effector highly portable,the space economic and the operation more flexible,which can effectively improve the versatility,dexterity and efficiency of the end-effector. |
