Robot System And Method For Calibration

摘要

A method and a system for calibrating a first coordinate system Rf of a robot unit with a second coordinate system Cf of an object identification unit, wherein the robot unit includes a robot arm with an end effector and the object identification unit includes a camera unit. The calibration is performed using a calibration marker on the end effector. The method determines the intrinsic and the extrinsic parameters of the camera unit in two steps, a first step where the intrinsic parameters and a rotational part of the extrinsic parameters are determined, and a second step where a translational part of the extrinsic parameters are determined.

主权项

1. A method for calibrating a first coordinate system Rf of a robot unit with a second coordinate system Cf of an object identification unit, wherein the robot unit comprises a robot arm with an end effector and the object identification unit comprises a camera unit, the end effector further comprises a calibration marker, the method comprises
moving the end effector to a plurality of first target points wherein the first target points are chosen to include movement of the end effector in all three axes of the first coordinate system Rf of the robot unit and wherein the end effector maintains a same orientation, while generating position measurements in the first coordinate system Rf and position measurements in an image plane coordinate system IPf for the calibration marker with the object identification unit for each first target points; calculating intrinsic parameters Cint of the camera unit and a rotational part of the second coordinate system Cf of the object identification unit based on the measurements in Rf and IPf; moving the end effector to a plurality of first orientations and for each of these orientations moving the end effector in a translation pattern while maintaining the same first orientation of the end effector and while generating position measurements in Rf and IPf identifying the translation pattern; calculating a depth value Z from the camera unit to the calibration marker for each second target point based on said position measurements identifying the movement along the translation pattern; transforming position measurements in pixels in IPf to position values in the second coordinate system Cf based on the depth value Z and Cint; calculating a translational part of the second coordinate system Cf of the object identification unit based on the translation and reorientation between the first orientations; and using the rotational and the translational parts to store a relation between Rf and Cf to enable collaboration between the robot unit and the object identification unit.