Operation Bunny

This project was undertaken by four Stanford University undergraduate students - Catherine Tran, José Gutierrez, Emily Sataua and Jasmine Lee - during the winter of 2013 in Stanford's Mechanical Systems Design course. Our Professor was Chris Gerdes and our head Teaching Assistant was Holly Russell. All four members were equally involved in the ideation, fabrication, testing, and analysis phases of this project.

Project Objective

The goal of this project was to create a battery-operated mechanism with the look and gait of a rabbit. This mechanism was to hop up a wooden ramp and topple a hinged piece of wood at the top of the ramp within 30 seconds. Along with a rabbit-like look and gait, the mechanism was to have one more rabbit-like feature such as being able to stand on its hind legs or wiggling its ears.

Our Solution

We chose to run a 3V, six-speed motor at its fourth speed, which left the motor running with an approximate gear ratio of 115 (details attached in a document at the bottom of this page). This motor rotated a small shaft, which made up one of the four bars we used in a four-bar linkage to represent the rabbit's gait. The linkage - made completely of masonite - caused the legs to expand and contract as a live rabbit's legs would. We also added two #11 Xacto blades to each foot to give the mechanism more traction on the ramp. Our final major mechanical breakthrough for this project was to give the rabbit ramp guides. We realized that our mechanism was prone to both tipping backwards and turning either right or left as it walked up the ramp. So, we created protrusions that prevented the mechanism from doing so. In the end, our rabbit ran like this:

After a few aesthetic adjustments and with the addition of the battery pack, our final product looked like the image below.

Since our rabbit had blades for traction on the ramp, we chose to make our rabbit a vampire complete with sharp teeth and blood-shot eyes. Instead of having our mechanism stand on its hind legs or wiggle its ears, we chose to have our rabbit chase a bleeding carrot. The carrot moved up and down in time with the rabbit's legs as if it was being dangled on a string for the rabbit to chase.