Swamp Monkey Enrichment Device
My freshman year of college, I took an introduction to engineering class. I was placed on a team of five freshman and tasked by the Houston Zoo with designing and building a device to provide enrichment to their population of Allen's swamp monkeys.
Our solution was a rotating feeder: food would be placed in the upper corner of the device and the monkeys would have to rotate it various ways to get the food out. Our first design was three PVC pipes stacked on top of each other (Figure 1) and secured with metal rods running through holes in all three pipes.
Figure 1: Initial Rotating Feeder Design
The decision to use PVC sheets instead of pipes as well as more serious consideration into how zookeepers would insert food into the device led to our second design (Figure 2). This design featured a removable cap attached with industrial strength Velcro. The food would be placed in the upper right corner and the monkeys would have to rotate the device left and right to get the food to fall through the holes and eventually to fall out of the device. The sides had handles for the monkeys to grab and inside the handles would be some noisemaker to provide extra enrichment. This design led to our first prototype (Figure 3) that we constructed as physical model to discuss with the zoo. We built this prototype using cardboard, felt, duct tape, and Velcro.
Figure 2: Second Design
Figure 3: First Prototype
The zoo voiced concerns with the removable lid so our next solution was an acrylic cover that could be secured with lock nuts. Making the cover removable also made the device easier to clean. The zoo also gave us samples of the types food that they would be placing in a completed device. The bigger than expected sizes led to our switching from multiple smaller holes on each level to one big hole on each level. The handles also changed. These results can be seen in the CAD drawing (Figure 4) and our second (Figure 5) and third (Figure 6) prototypes.
Figure 4: Final CAD Drawing
Figure 5: Second prototype
Figure 6: Third Prototype
Testing the device in the monkeys’ habitat demonstrated the need for a leash to be installed to prevent the monkeys from simply dunking the device in the water to get the food to float out. We constructed a leash of steel rope surrounded by long segments of PVC pipe to prevent accidental strangulation. The leash was attached to the device by use of an eye bolt. (Figure 7).
Figure 7: Final Prototype with Leash
We ended up delivering two working prototypes to the Houston Zoo. The prototypes were mirror images of each other: one had the hole on the bottom left and the other on the bottom right. These prototypes are still in use.
Teammates on the project were Alexandra Eifert, Julio Ledesma, Emily Lisa, and Nathaniel Williams