Patent ID: 11911914
Assignee: COGNEX CORPORATION
Field: Handling (Mechanical engineering)
Classification: CPC B  G | IPC B

Claim 10:
11. A method for hand-eye calibration of a robot manipulator with respect to a vision system camera defining an optical axis, comprising the steps of:
providing relative motion between a calibration target and a field of view (FOV) of the vision system camera, and performing a pre-calibration process that generates a rough transformation between an X-Y-Z coordinate space of the robot manipulator and a coordinate space of the vision system;
moving to a plurality of positions from results of the pre-calibration process and acquiring images at each of the positions with the vision system;
wherein a field-of-view displacement effect, along at least one of an x-axis and a y-axis of the coordinate space of the acquired image, is induced in which a location of at least one of the robot manipulator and the calibration object is offset from the optical axis at a differential rate based upon the relative motion, as the robot manipulator and the calibration object are in rotation with respect to each other;
locating features of the calibration object in the images; and
computing a hand-eye calibration transformation from the coordinate space of the robot to the coordinate space of the vision system camera during the pre-calibration process to guide the robot manipulator,
wherein some of the features of the calibration object move outside the FOV in at least one acquired image based upon the differential rate, and
wherein a three-point calibration is thereby performed with at least some of the features of the calibration object of at least one acquired image outside the FOV.