基于各向异性误差相似度的六自由度机器人定位误差补偿  

Positioning error compensation of 6-DOF robots based on anisotropic error similarity

作　　者：高贯斌[1,2] 牛锦鹏 刘飞 那靖[1,2] GAO Guanbin;NIU Jinpeng;LIU Fei;NA Jing(Faculty of Mechanical and Electrical Engineering,Kunming University of Science and Technology,Kunming 650500,China;Yunnan International Joint Laboratory of Intelligent Control and Application of Advanced Equipment,Kunming University of Science and Technology,Kunming 650500,China)

机构地区：[1]昆明理工大学机电工程学院,云南昆明650500 [2]昆明理工大学云南省先进装备智能控制及应用国际联合实验室,云南昆明650500

出　　处：《光学精密工程》2022年第16期1955-1967,共13页Optics and Precision Engineering

基　　金：国家自然科学基金项目(No.51865020);云南省科技计划基础研究专项重点项目(No.202201AS070033)。

摘　　要：多关节机器人的绝对定位精度远低于重复精度,目前通常采用运动学标定或空间误差补偿来提高机器人定位精度。空间误差补偿通常采用反距离加权来预测定位点的误差并进行补偿,但反距离加权的权值评价单一且各参考点权值过于平均限制了补偿精度的提高,为此,本文基于空间误差相似度提出一种包含距离和方向的定位误差预测和补偿方法。首先,推导出机器人定位误差模型,将机器人工作空间划分为由若干立方体组成的网格,研究在空间网格中定位点与参考点的相对方向与误差相似度的关系,并构建以距离和夹角余弦为误差传递因子的误差传递函数。其次,考虑定位点各坐标轴方向误差和参考点误差的相似性存在较大差异,基于误差传递函数提出一种各向异性的相似度建模和误差补偿方法,利用网格中各参考点的误差分别计算定位点各方向的误差。最后,通过实验对所提方法进行验证,并与传统的反距离加权插值补偿方法进行对比,实验结果表明:经过误差补偿后,机器人定位误差在各坐标轴方向的最大值和平均值都有显著降低,误差最大值和均值由补偿前的1.03 mm和0.30 mm分别降至0.11 mm和0.04 mm,与反距离加权方法相比补偿后机器人定位精度更高、各方向更均匀。The positioning accuracy of multi-joint robots is much lower than the repetition accuracy.Currently,kinematic calibration and spatial error compensation are the primary techniques adopted to improve robot positioning accuracy.In spatial error compensation,inverse distance weighting is typically used to predict the error of a positioning point.However,as a single weight,the inverse distance cannot accurately represent the influence of each grid point because the weight is too average,resulting in a poor compensation result.To improve the positioning accuracy of robots,a positioning prediction and compensation method,including distance and orientation,is proposed based on error similarity.First,a positioning error model is derived from the kinematic model using differential kinematic theory,and then,the relationship between joint angles and the positioning error is analyzed.The robot workspace is divided into a grid of several cubes,and the effect of the direction of the positioning point relative to the reference point on error similarity is investigated.The error transfer function is then derived using the cosine of the included angle and the distance as the error transfer factor.Second,a method for anisotropic similarity modeling and error compensation is proposed based on an error transfer function that uses the error of reference points to calculate the error of the positioning point.The proposed method is verified through experiments and compared with the traditional inverse distance weighting method.After compensation,the maximum and average positioning errors of the robot decrease significantly along all directions,as demonstrated by the experimental results.The maximum and average errors along x-,y-,and z-directions decrease from 1.03 mm and 0.30 mm to 0.11 mm and 0.04 mm,respectively.Furthermore,the proposed method provides greater compensation accuracy than the traditional inverse distance weighting method.

关 键 词：机器人 绝对定位精度 误差补偿 标定 

分 类 号：TP242.2[自动化与计算机技术—检测技术与自动化装置]