A Portable Measuring System for Robot Calibration

Abstract

Currently, much production time is lost in teaching and re-teaching robot programs. New techniques that avoid this, such as off-line programming, require an accurate kinematic model of the robot. To construct this model, measurements of the robot are required. At the University of Amsterdam a self-calibrating measuring system has been developed, using a camera mounted in the robot hand and a reference object. Analysis of a single image of the reference object allows us to obtain an estimate of the position and orientation of the viewing point. A much better estimate is obtained by analysing a series of images, as the essential geometrical and optical camera parameters can be derived from the redundancy in the measurements. Our experimental results show that we can compute the pose of the camera for the different images with an accuracy in the order of 0.15 mm and 1.5 arc minute. This is usually adequate for robot calibration. Introduction The positioning accuracy of robot systems can b...