X3D-UML: 3D UML Mechatronic Diagrams are designed to provide a 3D UML view with both hardware and software. To demonstrate this we extended the concept of 3D UML integrated with ARToolkit. As a summer project, Jin Qian coded an integration between osgPython and Lego NXT robots to enable visual debugging. This video demonstrates that this approach allows us to naturally see the internal states of the robot. For example we can see when the sensor state is triggered and what the robot is "thinking" when still. www.x3d-uml.org Update: This will be presented at the 21st Australian Software Engineering Conference, 6-9 April 2010, Auckland, New Zealand. aswec2010.massey.ac.nz