I have been more and more interested in Autonomous Underwater
Vehicles and ocean exploration. I live on the coast with direct access to the
Atlantic Ocean, so it’s always been tempting to see what’s out there. In September
I attended the a 2 week summer course on ocean technology to learn more about
the problem space and investigate the industry.
To prepare for the course and showcase my talent I spent all
of August 2023 building an AUV.
I started by reading scientific papers on AUV design.
Essentially most AUVs on the market are torpedo shaped with fins for steering
and a thruster for propulsion. I didn’t find the mechanical design part of the
problem interesting, so I based my project off an open source design called
amethyst auv [https://beobachtung3d.com/]. This is an excellent design that
allowed me to progress quickly.
Since I had 1 month to build it, prior to the start of the course,
the biggest problem for me was getting all the components in time. I had to buy
all of the electronics from amazon rather than aliexpress, since it would take
too long to arrive. This made the price of the auv much higher. And it also
limited me in the design, since I could only use stuff that would arrive
quickly, rather than pick the best suited component and just wait for it.
Another problem I encountered is the actual 3d printing.
Since I wanted the chassis to be strong, I changed to PETG from PLA. This presented
a couple of problems; the filament absorbs moisture at a much faster rate. I
live in a live humid city due to the proximity to the water, which greatly
affected the printing results. The pieces came out very droopy, and I had to bake
the filament in the oven in order to dry it. I also had to dramatically reduce
the print sprint and put blue tape on the print bed to combat the adhesion
issues. All of this increased the time it took to complete the project.
In the end I wasn’t able to finish the whole thing, but I
made enough progress to show it to marine engineers and scientists to get some
feedback. I gained a lot of useful insights.
- In order to make the petg fully waterproof I will need to coat it.
- I should put brake lube on the oring that seals the waterproof compartment.
- Ballasting is super important and presents a lot of difficulties.
- Underwater positioning is a huge challenge and usually relies on underwater gps.
- I have also learned that it is possible to model currents in gazebo using the boltzman lattice method.
- Most AUVs cost thousands if not hundreds of thousands of dollars.
- You can use stereo camera vision with some algorithms to estimate how far an object is away from the robot.
I’ll probably add more information later. I have yet to fully
capture all I’ve done in the 2 weeks of the course. And the AUV project is
ongoing.
