Marker Dropper – Overall Design

This entry is part 1 of 2 in the series Marker Dropper

Marker Enclosure

For our marker enclosure, we chose a crescent-shaped design. This allows us to fit two markers, one in each half of the enclosure. Moreover, the crescent shape will allow the markers to naturally roll towards the center, where there is an opening for the marker to drop through. The markers are then kept in by a front plate, which is screwed into the main enclosure.

The enclosure also includes an integrated mount for our servo. The servo has a paddle attached to its end which starts at the center, right above the drop hole. By flipping one of two directions, we can easily pick which marker we would like to drop into the bin.

Downwards-Facing Mono Camera

Although not technically part of the marker dropper itself, one of the most important components is the downwards-facing mono camera. This is mounted right next to the marker dropper and can detect the bin’s task on the pool floor. As with all of our other components, our mount for this latches around the frame, allowing its position to be easily adjusted.


We decided to use brass balls as our markers, as these are heavy enough that they will drop straight down, mostly unaffected by currents. For our emblem, we encase these brass balls with a 3D-printed spherical case that includes our school name and our team name. We chose a spherical case as it will naturally roll down towards the center of the marker dropper, so when the servo arm moves out of the way, the marker will automatically fall into the bins below.

Series NavigationMarker Dropper – Design Changes >>