混联机器人关节间隙误差建模及其定位精度可靠性分析

Joint clearance error modeling and positioning accuracy reliability analysis of hybrid robot

机器人末端定位精度可靠性是衡量其精度性能的重要指标,关节间隙是影响机器人定位精度的主要因素之一,建立准确的机器人定位精度误差模型是进行可靠性分析的前提。为探究空间关节间隙的随机不确定性对含有闭链机构混联机器人定位误差的影响规律,本文运用旋量理论和D-H参数法,提出一种考虑关节间隙的混联机器人定位精度误差模型;根据关节间隙模型参数的约束条件,量化间隙模型参数的不确定性,建立混联机器人定位精度的可靠性模型;采用双变量降维方法和鞍点近似方法,拟合机器人单坐标定位误差的概率密度函数,实现混联机器人定位精度高效可靠性分析。以含有平行四边形闭链机构的建筑机器人为例,验证所提模型的准确性和工程适用性,结果表明所提方法对比于传统的蒙特卡洛方法极大地提高了效率。

The reliability of robot end positioning accuracy is an important index to measure its accuracy performance.Joint clearance is one of the main factors affecting robot positioning accuracy,and establishing an accurate robot positioning accuracy error model is a prerequisite for reliability analysis.In order to investigate the influence of the random uncertainty of the spatial joint clearance on the positioning error of a hybrid robot containing a closed chain mechanism.A hybrid robot positioning accuracy error model considering joint gaps is proposed using spinor theory and the D-H parameter method.To quantify the uncertainty of the gap model parameters according to the constraints of the joint gap model parameters and to establish a reliability model for the positioning accuracy of the hybrid robot.The bivariate dimensionality reduction method and saddlepoint approximation method are used to fit the probability density function of the robot′s uni-coordinate positioning error to achieve hybrid robot positioning accuracy reliability analysis.The accuracy and engineering applicability of the proposed model are verified by taking a construction robot containing a parallelogram closed-chain mechanism as an example,and the results show that the proposed method greatly improves the efficiency compared with the traditional Monte Carlo method.