One of the goals I’ve had for most of my AUV project was to make it as modular as possible, which would allow future upgrades and change of mission in the future — Want to take video? Swap out the sonar with a video module. Need better control in the water column for inspecting things? Add lateral thruster modules. Want to take water quality samples? Swap out the sonar module for a water quality sensor module… And the list goes on.
To achieve this, years ago I came up with an idea for a universal bulkhead design, which would allow each module to plug into any other, provided that the electrical interfaces matched through the bulkheads. The design would also allow mix-and-matching of flooded and non-flooded compartments, depending on the payload and mission configuration.
The design is fairly simple, each bulkhead essentially consists of two identical rings with a flat plate bulkhead sandwiched in between them. The bulkheads are screwed together and O-rings keep everything sealed up nice and tight. The compartment tubes are held into place by a series of radial screws (not properly shown in the photo above) which don’t clamp down on the tube (causing stress points in the material) but rather act as pins to prevent the tube from sliding out.
One of the challenged was getting the design to play nicely with standard cast acrylic tubing, with its loose tolerances. This necessitates usage of large diameter o-rings to make up for the variance in tube diameters. One option could have been to machine the acrylic tube’s inside diameter to appropriate tolerance, but I decided that the difficulty of doing so with the tools available to me outweighed the convenience of using stock cast acrylic profiles.