The authors would like to thank the research group for autonomous intelligent systems at the University of Bonn for fruitful discussions, useful suggestions and comments, especially Daniel Hennig and Andreas Derr. We would also like to thank the members of CMU's Robot Learning Lab for many inspiring discussions. Finally, we would like to thank the staff of the Deutsches Museum Bonn and the National Museum of American History for their enthusiasm and their willingness to expose their visitors to one of our mobile robots.
This research is sponsored in part by NSF (CAREER Award IIS-9876136) and DARPA via TACOM (contract number DAAE07-98-C-L032), and Rome Labs (contract number F30602-98-2-0137), which is gratefully acknowledged. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing official policies or endorsements, either expressed or implied, of NSF, DARPA, TACOM, Rome Labs, or the United States Government.