METHOD AND APPARATUS FOR CALIBRATING A VISION GUIDED ROBOT

A method and apparatus for calibrating a vision-guided robot of the type having a slit light unit for illuminating a workpiece with a target image, a camera for detecting the target image, a tool for working upon the workpiece and a controller for positioning the tool in response to image signals from the camera so that the camera signals correspond to stored image signals. The method includes the steps of displacing the robot from a home position to a calibration position wherein the camera is oriented toward a target, determining a camera correction value between a desired camera position and the actual camera position by comparing a perceived target image with a stored target image and incorporating the camera correction value for robot positioning during a subsequent operational movement. The method also includes a slit light calibration sequence in which the robot is displaced to a second calibration position where the slit light unit directs a light beam on a second target, the camera perceives a second target image and a light correction value between a desired slit light image and an actual slit light image is determined and incorporated for robot positioning during the subsequent operational movement. The calibration unit comprises topmost, intermediate and lower plates arranged in stairstep fashion, the topmost plate having a first pattern perceivable by the camera to enable the controller to determine spatial orientation of the plate and the intermediate and lower plates include a second pattern perceivable by the camera which enables the controller to determine the position of the slit light unit.