基于双目立体视觉的工业机器人在线温度补偿

工业机器人在工业现场进行连续高速作业过程中,电机发热和关节摩擦生热将导致机械臂本体温度升高,引起机器人末端定位漂移,严重影响机器人的重复定位精度和作业精度。针对制造现场的工业机器人,提出了一种基于双目立体视觉的温度误差在线补偿方法,并基于微分运动学和双目视觉原理构建了温度误差补偿模型。在机器人末端安装基准球,同时在基座附近固定视觉测量传感器,机器人完成作业循环之后,以不同的姿态带动基准球至传感器视场内进行补偿测量。此外,通过分析各关节参数随时间变化的规律,筛选出符合温度漂移规律的显著性参数进行补偿,有效降低了补偿测量次数和耗时。实验结果显示,补偿后机器人的重复定位精度可维持在±0.1mm的水平,能够显著改善制造现场工业机器人的作业精度,且整个补偿测量过程耗时10s左右。

In-line thermal compensation of industrial robots based on binocular stereo vision

When an industrial robot is operational continuously at a high speed, the heating of the motor and joint friction heat will result in a higher temperature in the manipulator; furthermore, the position of the end flange will drift and significantly influence the robot's repeatability and accuracy. To deal with these problems, in this paper, an in-line thermal compensation method based on binocular stereo vision was presented for an industrial robot working in the manufacturing field. A thermal compensation model was established based on the principles of differential kinematics and vision measurement method. In this method, a standard sphere was installed at the end of the robot arm and a vision sensor was installed around the base of the robot. After working in a regular circulation, the robot carried the standard sphere to the working field of the vision sensor to be measured from different postures. Besides, significant parameters were chosen to compensate for the thermal error from all joint parameters after analyzing their time-varying patterns. With fewer parameters that correspond to the thermo-drifting pattern, the measuring times and time consumption could be effectively reduced. The experimental result demonstrates that the proposed in-line thermal error compensation method can maintain the repeatability of the robot within ±0.1 mm and the compensation time is approximately 10 s, which can noticeably improve the operating precision of the industrial robot at the manufacturing site.