Inside the Watertight Compartment – Design

After designing the watertight compartment we started working on laying-out its internals. This section of the submersible is the brain of the robot – it houses the computers, sensors, and power electronics that give RoboGoby life.

This section has two parts: the electronics plate and the rails. The electronics plate houses all of our electronics (custom PCBs, ESCs (electronic speed controllers), ODROID-XU3) to make accessing everything easier. The rails act as a guide for the electronics plate as well as help hold in our power supply and Ethernet over Power (EoP) unit.

We are planning on using small neodymium magnets to connect the electronics plate to the rails and to hold the rails together. This makes it easy for us to put the interior of the compartment together without having to unbolt anything or epoxy anything to the aluminum frame. All of the shallow, small holes in the pictures below are for small magnets.

Electronics Plate

Our electronics plate is extremely simple – it's a piece of Delrin plastic with holes for mounting all of our electronics. The plate is 12 inches long with the ESCs mounted down one side of the plate and custom PCBs on the other. The ODROID takes up an entire end of the plate. The Delrin plate also has holes for mounting the magnets mentioned in the introduction. 

Electronics Plate

Magnet Mounts:

Because the electronics plate is going to be very thin (~1/16"), we were not going to be able to mount the magnets directly into the sheet of Delrin. Our solution was to 3D print some small mounts for the magnets. The front of the mount has a pocket for the magnet and the back has a protrusion to fit into the electronics sheet.

Magnet Mount Front

Magnet Mount Side

Rails

There are two rails (one on each side) that are each made up of a large and small part.

Large:

The large pieces are the part of the rails we will not be removing. We'll hot glue these into place at the back of the compartment. The large pieces will act as rails for our electronics plate while also holding our power supply in place. You can see the upside down 'L' in the picture below – this shape perfectly fits the form of our power supply and help holds it in place.

Large Rail

Small:

This is the removable part of our rails. It's added after putting in our power supply and is used to secure the power supple between the two rails. Again you can see the upside down "L". This "L"  is designed to hold the power supply snug against the Large Railing's "L". The small rails attach via magnets to the large stationary rails.

Small Rail

EoP Mount:

The last component that's part of our rail system is the EoP mount. This mount is another removable parts that magnetizes to part of one of the Small rails. It's used to hold the EoP in place within the compartment.

Entire Interior:

This picture shows the electronics plate, rails, and power electronics in their organized states. The large gray box on the bottom is the power supply, which sits next to the EoP in its mount. Above those, on the railings, is the elctronics plate.

Assembled Mid-section