作者：刘湛基, 王晗, 陈桪, 夏远祥, 杜泽峰, 李沅时, 林家平

作者单位：广东工业大学, 广东 广州 510006

关键词：机器人;坐标变换;RANSAC算法;激光跟踪仪

摘要：

激光跟踪仪对工业机器人的末端位姿进行绝对定位精度标定时，需要把测量坐标系和机器人坐标系下的坐标值转换到同一坐标系下，坐标值的比较才有意义。因为机器人运动学模型误差的存在，使得机器人坐标系下的点不能遵循着唯一确定的变换关系变换到测量坐标系，所以坐标系的变换精度不高。在建立齐次变换形式的变换模型之后，通过分析坐标系变换过程中的误差来源，提出结合最小二乘法的RANSAC快速转换算法。从测量样点中随机选择一定量的样点拟合变换模型，在获得多个变换模型之后，利用评判模型选择最优模型。结果表明：相比于常规的求解方法，机器人和激光跟踪仪的坐标转换精度提高3倍。RANSAC算法能有效地降低机器人模型误差对求解变换关系的影响，并且实验过程快速、操作简单。

Study on the method of coordinate transformation between robot and laser tracker

LIU Zhanji, WANG Han, CHEN Xun, XIA Yuanxiang, DU Zefeng, LI Yuanshi, LIN Jiaping

Guangdong University of Technology, Guangzhou 510006, China

Abstract: When the laser tracker calibrates the absolute positioning accuracy of the end position of the industrial robot, it is necessary to transform the coordinate values of the measurement coordinate system and the robot coordinate system to a same coordinate system, thus the comparison of the coordinate values makes sense. Because the existence of the robot kinematics model error makes the point in the robot coordinate system cannot follow the only definite transformation relation to the measurement coordinate system, the coordinate system transformation precision is not high. After the transformation model of homogeneous transformation is established, the RANSAC fast conversion algorithm combined with least squares method is proposed by analyzing the error sources in the transformation process of the coordinate system. A certain number of samples are randomly selected to fit the transformation model from the measurement sample. After obtaining multiple transformation models, the optimal model is selected by the evaluation model. The results show that the coordinate transformation accuracy of the robot and the laser tracker is increased by three times compared with the conventional solution method. The RANSAC algorithm can effectively reduce the influence of the robot model error on the transformation relation a, the experiment process is fast and the operation is simple.

Keywords: robot;coordinate transformation;RANSAC algorithm;laser tracker

2017, 43(11): 102-107  收稿日期: 2017-02-10;收到修改稿日期: 2017-04-19

基金项目: 广东省前沿与关键技术创新专项资金（2015B010124001）；广东省高等学校优秀青年教师培养计划（YQ2015056）；“广东特支计划”科技青年拔尖人才项目（2014TQ01X212）；东莞市产学研项目（2013509109101）

作者简介: 刘湛基(1991-),男,广东佛山市人,硕士研究生,专业方向为工业机器人的应用开发。

参考文献

[1] ALBERT N, MOHAMED S, AHMED J, et al. Comparison of two calibration methods for a small industrial robot based on an optical CMM and a laser tracker[J]. Robotica,2014,32(3):447-466.
[2] MA N, SU C, ZHANG X. Research on fast field calibration method of industrial robot[C]//Chinese Automation Congress,2015.
[3] SU C, ZHONG L, SU C, et al. Modelling and control for simultaneous laser beam alignment of a dual-PSD industrial robot calibration system[C]//International Conference on Cyber Technology in Automation Control and Intelligent Systems. IEEE,2015.
[4] 陈钢,贾庆轩,李彤,等. 基于误差模型的机器人运动学参数标定方法与实验[J]. 机器人,2012,34(6):680-688.
[5] 王智源,朱刚. 测定工业机器人位置特性的误差不确定度分析[J]. 电子测量技术,2016,39(9):8-11.
[6] BORRMANN C, WOLLNACK J. Calibration of external linear robot axes using spline interpolation[C]//Proceedings of the International Conference on Modelling Identification & Control. IEEE,2014.
[7] 刘常杰,段宇,王一,等. 机器人柔性坐标测量系统现场校准技术研究[J]. 机械工程学报,2010,46(18):1-6.
[8] SHIU Y C, AHMAD S. Calibration of wrist-mounted robotic sensors by solving homogeneous transform equations of the form AX=XB[J]. IEEE Transactions on Robotics & Automation,1989,5(1):16-29.
[9] 任永杰,邾继贵,杨学友,等. 利用激光跟踪仪对机器人进行标定的方法[J]. 机械工程学报,2007,43(9):195-200.
[10] 洪鹏,田威,梅东棋,等. 空间网格化的机器人变参数精度补偿技术[J]. 机器人,2015(3):327-335.
[11] 吴德烽,李爱国. 三维表面扫描机器人误差建模与补偿方法[J]. 机械工程学报,2012,48(13):61-67.
[12] TABB A, YOUSEF K M A. Parameterizations for reducing camera reprojection error for robot-world hand-eye calibration[C]//Ieee/rsj International Conference on Intelligent Robots and Systems,2015.
[13] CHUM O, MATAS J, KITTLER J. Locally optimized RANSAC[J]. Joint Pattern Recognition Symposium,2003(2781):236-243.
[14] FISCHLER M A, BOLLES R C. Random sample consensus:a paradigm for model fitting with applications to image analysis and automated cartography[J]. Communications of the Acm,1981,24(6):381-395.
[15] 周炜,廖文和,田威. 基于空间插值的工业机器人精度补偿方法理论与试验[J]. 机械工程学报,2013,49(3):42-48.