Optical target location using machine vision in space robotics tasks

For practical use of robotics in space machine vision is required to automatically locate objects in order to guide an autonomous control system or to assist a human teleoperator. The vision task is facilitated by placing optical targets or markings in advance on the objects to be located. We have experimented with techniques to locate such optical targets from monocular images. These include camera calibration determination of the camera to tool endpoint transformation feature extraction and pose estimation. This paper describes our experiences with these techniques as they were implemented in an integrated robot-vision system to perform tasks characteristic of space construction and servicing. The accuracies of the target location techniques were also verified separately using an optical bench and positioning devices. The usefulness of the optical target location system was demonstrated in the autonomous control of two Cincinnati Milacron T3-726 robot arms. 1 .