Conclusions
Our design came out extraordinarily well. We accomplished all of our goals (kinematic, mechanical, and aesthetic), it looks great, and we are very proud of the mechanical components we added to make everything work! We were stressed for time towards the end, so we should have done much more work earlier, especially when every other team was using the Maker Space right when we wanted to. A few design hurdles were noticed at T-minus 3 days, but with dedicated work Michelle and Matt were able to overcame these last minute hurdles (and Steven was able to provide feedback remotely to help us accomplish our task); needless to say it was a full team effort all the way to the end and we are ecstatic to have been able to produce what we presented at the end of the semester. The three of us put in a tremendous amount of work and learned a lot of valuable lessons through the design and build process of our mechanism.
Commentary
Our original design had a snapping motion from a Geneva mechanism and several springs. However, this upward snapping motion had to be pretty powerful as the portion that needs the most torque is the last portion of the snap. This led to the coin being "thrown up" back out of the mouth. We could have designed around this problem, either by fine-tuning the tongue's action to throw the coin backwards on the upward journey, by having an upper jaw that would direct the coin back into the throat, or having a more clip-in like interface for the coin to be slid into instead of just on top of the tongue. However, due to time limitations we ultimately decided to remove the snapping motion and replaced the Geneva mechanism design with full gears. This change allowed us to create a smooth biting motion, which while not what we had initially planned, still achieved the same functional effect of a creature swallowing a coin that we wanted.
Special Thanks:
We would like to extend a special thanks to Steve Ferraro and the entire staff in the Maker Space for their help throughout (but especially during the last week of) the semester. We would also like to thank Dr. Ashish Deshpande for providing us with the tools, support, and knowledge base to successfully synthesize and build our robot and to his graduate students for their insight and expertise on Arduinos, programming, motor control, and general robotics design.