Time Flies!: Fly Cam

Project: Make a navigatable (if you’ll excuse the word) camera so that visitors can scan the fly box and see the fruit flies close up.

Challenges: This was an unusual project in that it was conceptually very simple, yet took a great deal of time and effort to go from idea to reification. Typically, my projects are exactly the other way around. Specifically, the challenges were to make a machine with fairly close tolerances which would fit it into a small space.

Solutions: This project required two sets of slides bearings: left-right and front-back. Frequently, I will simply mill a grove in a piece of plastic and make a guide to fit it. This time, I wanted a little more accuracy, so I bought some manufactured slide bearings. The problem is, the bearings I had available for purchase were either cheap or expensive, with nothing in between. The pricey bearings were $80 each. Since I needed four, that adds up to $320 – just for the bearings. So I opted for the cheap bearings, which were only $7 each. Unfortunately, the tolerances in the prefabricated bearing were not as tight as those I would have made myself, and the result is a slight jitter when the camera is activated. We could have switched to the more expensive bearings, but the guests didn’t seem to be bothered by the camera’s motion during testing. Additionally, the device had to be very low profile. The front back, left-right room was ample (I had the entire cabinet under the left-hand section of the display), but the vertical space was limited to a few inches. This is another reason I stayed with the low-budget bearings: they were much lower profile than the pricey bearings, which would have added over two inches to the overall height of the mechanism.

Once the bearing problem was solved, the rest was fairly straight-forward (though nonetheless time consuming) machining, assembling, and wiring. You can see how the mechanism works in a video linked to below. Motor-driven lead screws operate the slides. The camera is mounted on the end of a boom which is attached to the camera carriage. (This allowed the entire mechanism to be placed to the right of the fly box and allowed the camera to penetrate the fly box with a slot slightly larger than the diameter of the boom. This feature was necessary since the humidity in the fly box needs to be maintained. ) The camera carriage rests on the upper slide, and the upper slide and camera carriage both rest on the lower slide. Limit switches at each end control the range of motion. Here is a picture of the FlyCam mechanism prior to its installation in the cabinet. (The camera is placed on the end of the boom that extends to the right in this picture.) Below that is a picture of the control panel. You can see the mechanism in action here and here.

Below is a picture of the FlyBox. It is viewed through a cut out in the counter. The fly box is red because red Plexi filters out the component of daylight that regulates the fruit fly’s sleep cycle and thus allows the cycle to be manipulated by alternating between red and blue LEDs within the light box itself.

Below is a view of the FlyBox in its open configuration. The little glass tubes are where the flies live. The display had to be constructed so that the tubes could be easily accessed in that the flies, which have a lifespan of few weeks, need to be switched out frequently. If the FlyCam is driven to its far right position, the little module containing the flies is easily removed.

Finally, a video showing the FlyCam in action on the monitor that is in the display. Watch as the operator leaves a close up of a living fly, explores a tube that turns out to be empty, and finally finds a dead fly at the end of its tube.

Watch the video here.