一种基于EIH的装配机器人标定方法

EIH Based Calibration Method for Assembly Robot

针对配置单目手眼相机(Eye in hand,EIH)的六自由度(Six degrees of freedom,6-DOF)串联装配机器人标定问题,提出了一种基于平面靶标的机器人标定方法。将平面靶标固定放置在工作台上,安装在机器人末端执行器处的EIH随机器人各关节依次转动,并拍摄靶标图像。利用ZHANG两步标定法对EIH进行标定,求出各拍摄位置处相机光心在靶面坐标系下的坐标。根据各关节单独运动时相机光心轨迹构成的圆,采用空间圆曲线拟合方法计算圆心坐标和转动关节轴线方向,并通过三焦张量约束优化各轴线方向,得到机器人各关节旋量。在此基础上,采用指数积建立机器人运动学模型。整个标定过程只需要一次安装,一组采集的标定图像。试验结果表明,该方法建立的机器人运动学模型简单有效。

A method of robot calibration is proposed on the basis of planar target in 6 degrees of freedom(6 DOF) assembly manipulator mounted monocular eye in hand(EIH). A planar target is fixed on a workbench, and photographed by EIH when each robot joint orderly rotates. The EIH is calibrated by ZHANG two steps method and its every frame optical center is gained in the target’s coordinate at the shooting position. With every trajectory circle of the optical center by each joint alone movement before, according space circle curve fitting, the center of the circle is gained, and then obtain the orientation of rotating axes, optimized by tirfocal tensor. Each joint screw is obtained. Then the robot kinematics model is established, based on the product of exponential(POE) by joints screws. The entire process requires only once installation and a collection of calibration images. Experiments show the method is feasible and convenient to set up the robot kinematics model.