KI-04-2000 fürs Netz.p65

The Internet provides a unique opportunity to tele-operate and monitor mobile robots. Web-controlled mobile robots can give people all over the world the ability to become telepresent at distant places. Additionally, Internet-based tele-experimentation systems for mobile robots give distributed research groups located at distant places the ability to carry out joint experiments. This way, they can share expensive robot platforms and furthermore save travel expenses. Finally, the Internet can be used for on-line demonstrations with mobile robots, for example during the presentation of research results at conferences. All these applications of Web interfaces for mobile robots require accurate visualization techniques. This includes a high level of detail as well as high update rates. Unfortunately, the Internet does only provide a restricted bandwidth. Therefore, video streams cannot be transferred at appropriate resolutions and with a frame rate required for smooth visualizations. Moreover, static monitoring cameras, which are frequently used on the Internet, have the disadvantage that they only provide a reduced field of view and that important details are occluded in certain perspectives. In this paper we present state estimation techniques for a system which provides accurate and smooth real-time 3D visualizations of the movements of an autonomous mobile robot over the Internet. The system has a client/server architecture. The server is directly connected to the robot control system and transfers changes of the state of the robot and changes of the environment to all its clients which provide the 3D visualization at high frame rates. The system uses a 3D model of the robot and its environment. To cope with changes in the environment it uses probabilistic techniques to continuously estimate the states of different types of non-static objects such as people, doors, tables, etc. based on the information acquired by the robot’s sensors. The changes of the environment are transfered to all the clients connected over the Internet which can instantly update the visualization. 2 Related Work