In Fall 2010, the project goal was to “design a mechanism so a ball (rubber ball) rolled or dropped into the device is automatically fired towards a target some distance away from the mechanism”. The target was a soda can and the ball, a standard racquet ball.
Together with Elina Lin, Chris Gebhart, Derek Remsburg, and Moonsoo Choi, we decided on a catapult, a design many other groups tried as well. Since it was to be fully automated after a ball is rolled in, we designed a trigger that takes advantage of friction to lock. The trigger mechanism itself is tensioned with a rubber band that would keep it reclined, as shown above. The trigger keeps the arm in a loading configuration, as seen below. Once the ball rolls into the arm’s cup, the dowel in the trigger would separate from the trigger and would be allowed to launch forward.
Our catapult was able to successfully take down 15 cans, about 10 cans more compared to the next best-performing group. As a result, we ended up in 2nd place out of the entire class.