农业机器人并联视觉云台研究

Decoupled Parallel Vision Table with Large Workspace of Agricultural Robot

针对智能农用机器人对机器视觉工作范围的需求,提出了一种用于农业机器人的并联视觉云台设计方案。基于双摇杆的输入输出特性,提出了一种运动支链设计方法,用于构建二自由度全球面工作空间解耦并联机构。在此基础上,衍生出两种可行的运动支链P5R和PRR,基于这两种运动支链,设计了2种二自由度全球面工作空间并联视觉云台RR&P5R和RR&PRR。通过运动学分析,分别建立了2种机构的位置关系表达式;通过尺寸优化,得到了2种机构的最优杆长比;通过对比得出,RR&P5R型并联视觉云台具有更好的输入输出性能;通过有限元分析,研究了载荷对RR&P5R型并联视觉云台运动精度的影响。结果表明,RR&P5R机构强度满足要求,但杆件的累积弹性变形导致运动副的位移偏差较大。

Aiming at the demand of intelligent agricultural robots for a wider range of machine vision,a solution of parallel vision table for agricultural robot was introduced.Based on the input and output characteristics of the double rocker mechanism,a new design method of kinematic chain was presented,which can be used to design a decoupled 2-DOF parallel mechanism with a fully spherical workspace.Two feasible kinematic chains were derived,i.e.P5R and PRR.Two decoupled 2-DOF parallel vision table with a fully spherical workspace were designed based on the above kinematic chains,i.e.RR&P5R and RR&PRR.The displacement relationship of the two mechanisms were established respectively through kinematics analysis.The optimal length ratio of the members of the two mechanisms were obtained respectively through the size optimization.After comparison,the RR&P5R parallel vision table had the better input and output performance.Through statics analysis,the restraining force at each hinge was obtained.Through finite element simulation,the influence of load on the motion accuracy of RR&P5R parallel vision table was analyzed.The result showed that the strength of RR&P5R mechanism met the requirements.However,the displacement deviation of revolute joints of RR&P5R mechanism was large,which was caused by the cumulative elastic deformation of members.