Projective virtual reality in space applications: a telerobotic ground station for a space mission

Commanding complex robotic systems over long distances in an intuitive manner requires new techniques of man-machine- interaction. A first disadvantage of conventional approaches is that the user has to be a robotic expert because he directly has to command the robots. He often is part of the real-time control loop while moving the robot and thus has to cope with long delays. Experience with space robot missions showed that it is very difficult to control a robot just by camera images. At the IRF, a new approach to overcome such problems was developed. By means of Projective Virtual Reality, we introduce a new, intuitive way of man-machine communication based on a combination of action planning and Virtual Reality methods. Using data-helmet and data-glove the user can immerse into the virtual world and interact with the virtual objects as he would do in reality. The Virtual Reality System derives the user's intention from his actions and then projects the tasks in to the physical world by means of robots. The robots carry out the action physically that is equivalent to the user's action in the virtual world. The developed Projective Virtual Reality System is of especially great use for space applications. During the joint project GETEX (German ETS-VII Experiment), the IRF realized the telerobotic ground station for the free flying robot ERA on board the Japanese satellite ETS-VII. During the mission in April 1999 the Virtual Reality based command interface turned out to be an ideally suited platform for the intuitive commanding and supervision of the robot in space. During the mission, it first had to be verified that the system is fully operational, but then out Japanese colleagues allowed to take the full control over the real robot by the Projective Virtual Reality System. The final paper will describe key issues of this approach and the results and experiences gained during the GETEX mission.