提出一种改进的柔性视觉测量系统标定方法。建立了包含手眼关系误差与机器人运动学参数误差的系统误差模型。在机器人末端安装结构光传感器构建了机器人柔性视觉测量系统, 并在机器人工作空间中固定一个标准球作为标定参考物。标定时, 机器人被控制在不同位姿下测量球心坐标。首先, 应用机器人的理论模型初步标定手眼关系; 然后, 基于球心约束, 通过迭代算法同时得到准确的手眼关系和实际的机器人运动学参数。基于ABB IRB2400工业机器人进行了系统标定实验, 并利用激光跟踪仪进行精度验证。 结果表明: 标定前后机器人柔性视觉测量系统的距离测量标准差由0.566 mm降低到0.173 mm, 充分验证了改进方法的有效性和实用性。该方法提高了手眼关系的精度; 不需要采用任何昂贵的外部设备, 适合工业现场使用。

An improved calibration method for robotic visual flexible measurement systems was proposed and a mathematical model for hand-eye errors and kinematic parameter errors of a robot was established. The robotic flexible visual measurement system was set up with a line-structured laser sensor mounted on the robot end and a standard sphere was fixed in the robot workspace as the calibration target.In the calibration, the robot was controlled to measure the coordinates of the standard sphere center at different poses. The initial hand-eye transformation was firstly identified by theoretical kinematic parameters of the robot, then, based on constraint of sphere center,the exact hand-eye transformation and real kinematic parameters were identified with an iterative algorithm at the same time. A calibration experiment for the robotic flexible visual measurement system was performed based on an ABB IRB2400 robot and the accuracy verification experiment was conducted by a laser tracker. The results show that the distance standard deviations of the robotic visual flexible measurement system before and after calibrations have been reduced from 0.566 mm to 0.173 mm, which verifies the validity and practicability of the method proposed. The method improves the accuracy of the hand-eye relationship and does not need external measuring devices, so is suitable for industrial applications.