This is the second project of the Spring 2012 Things That Think computer science course at the University of Colorado, Boulder. The goal of this project was to create a plush that also used computing in some way. The team, comprised of Jed Diller and Ken Hoff, decided to do a dragon puppet that would sense when its mouth was open and roar with the volume varying depending on the extent to which the mouth was open. The eyes also change color, from blue to red, as the mouth is opened wider - indicating the dragon is getting mad. The lovable Toothless from How To Train Your Dragon was the dragon we modeled our puppet after. The behavior and final product can be seen below.
You may notice in the video that one of the openings of the mouth was not accompanied by a roar. This happened because the mouth was not fully closed to reset the behavior between roars.