SRI International, Menlo Park, CA 94025, USA.
École de Technologie Supérieure (ÉTS), University of Quebec, Montreal, QC H3C 1K3, Canada.
Sensors (Basel). 2018 Oct 10;18(10):3380. doi: 10.3390/s18103380.
This work shows the feasibility of calibrating an industrial robot arm through an automated procedure using a new, low-cost, wireless measuring device mounted on the robot's flange. The device consists of three digital indicators that are fixed orthogonally to each other on an aluminum support. Each indicator has a measuring accuracy of 3 µm. The measuring instrument uses a kinematic coupling platform which allows for the definition of an accurate and repeatable tool center point (TCP). The idea behind the calibration method is for the robot to bring automatically this TCP to three precisely-known positions (the centers of three precision balls fixed with respect to the robot's base) and with different orientations of the robot's end-effector. The self-calibration method was tested on a small six-axis industrial robot, the ABB IRB 120 (Vasteras, Sweden). The robot was modeled by including all its geometrical parameters and the compliance of its joints. The parameters of the model were identified using linear regression with the least-square method. Finally, the performance of the calibration was validated with a laser tracker. This validation showed that the mean and the maximum absolute position errors were reduced from 2.628 mm and 6.282 mm to 0.208 mm and 0.482 mm, respectively.
这项工作展示了通过使用新的低成本无线测量设备在机器人法兰上进行自动化校准过程来校准工业机器人臂的可行性。该设备由三个数字指示器组成，它们彼此正交固定在铝制支架上。每个指示器的测量精度为 3 微米。测量仪器采用运动学耦合平台，可定义准确且可重复的工具中心点 (TCP)。校准方法的基本思想是让机器人自动将这个 TCP 带到三个精确已知的位置（固定在机器人底座上的三个精密球的中心），并且机器人末端执行器的方向不同。这种自校准方法在小型六轴工业机器人 ABB IRB 120（瑞典韦斯特罗斯）上进行了测试。通过包括其所有几何参数和关节的柔顺性，对机器人进行了建模。使用最小二乘法的线性回归来确定模型的参数。最后，使用激光跟踪仪验证了校准的性能。验证结果表明，平均和最大绝对位置误差分别从 2.628 毫米和 6.282 毫米降低到 0.208 毫米和 0.482 毫米。
