一种打磨机械臂的静刚度建模与实验

Static Stiffness Modeling and Experiments of Polishing Manipulator Arm

设计出一种采用(U+UPS)P+UPS并联机构的打磨3-DOF机械臂。运用子结构拆分和叠加思想,将机械臂手腕的位姿变形因素拆分为只考虑各支链拉/压变形、只考虑UP支链扭转变形、只考虑UP支链弯曲变形3个主要影响因素。通过基于矢量回路的虚功原理和结构矩阵建立3个主要影响因素的刚度模型,并根据各支链的结构特点定义了支链内各部件变形系数。通过叠加原理将各影响因素的刚度模型叠加整合为机械臂的整体刚度模型。研制出机械臂的实验样机本体,采用一套高精度机器人刚度实验系统对机械臂实验样机进行了刚度标定。实验结果表明:机械臂实验样机的位置变形实测值与理论值之间偏差均小于3μm,姿态变形实测值与理论值之间偏差均小于0.05°,机械臂实验样机的变形均在合理范围之内。

A new type of 3-DOF manipulator arm was proposed, which was based on （U ＋ UPS）P ＋ UPS parallel mechanism. Using the idea of sub structure decomposition and superposition, deforma-tion factors of manipulator arm？s wrists were divided into 3 main factors： only considering branches5 tension/compression deformations？ only considering UP branch：s torsion deformations？ only consider-ing UP branch？s bending deformations. Also , 3 main factors affecting to stiffness lished by virtual work principle and structure matrix based on vector loops. each components in the branches were defined according to the structural characteristics of each bran-ches. Then, the stiffness model of each influencing factors was integrated into the whole stiffness model of the manipulator arm by superposition principle. Finally, experimental prototype of the ma-nipulator arm was developed. Using high precision robot calibration system, the stiffness calibrationexperiments of manipulator arms were done. Experimental results indicate that the deviation between measured position deformations and theoretical position deformations are less than 3 fim, the deviation between measured attitude deformations and theoretical attitude deformations are less than 0.05 °. The deformations of the manipulator arm’s experimental prototype arewithin a reasonable range.