Rainer Stiefelhagen Hazim Kemal Ekenel Christian Fügen Petra Gieselmann Hartwig Holzapfel Florian Kraft Kai Nickel Michael Voit Alex Waibel Enabling Multimodal Human-Robot Interaction for the Karlsruhe Humanoid Robot. 840-851 2007 23 IEEE Transactions on Robotics 5 http://dx.doi.org/10.1109/TRO.2007.907484 db/journals/trob/trob23.html#StiefelhagenEFGHKNVW07