The Puddles AUV project was my first experience developing the mechanical portion of an Autonomous Underwater Vehicle (AUV). I worked as part of a team to bring the Puddles AUV back to operational status after years of retirement. Mainly, I worked to reseal the hull, to provide mounting for a new battery system and to reduce the overall weight of the vehicle.
Machining
As part of this project, many of the parts opportunity to manufacture numerous parts in the machine shop. This was the first time I got the chance to work on a vertical mill and a lathe – which insight not only into the fabrication process for metal components, but into how my design can simply manufacturing. In addition to working with manual machines, I manufactured a pair of parts on CNC mills – both a Tormach and Hurco.
Measure Twice Cut Once
An important lesson I took from this project is to always verify measurements. It may seem simple, but incorrect measurements can be costly.
In the course of this project, to reduce the thrust required to keep the AUV submerged, we trimmed the hull’s length. Testing showed that 60 N of buoyancy could be removed from the hull (~13 lbs). However, when 50 N worth of volume was removed, the sub became negatively bouyant.
Turned out, the AUV’s thrust allocation system was not calibrated – the AUV turned out to be only ~30 N positively buoyant. To me, this serves as a lesson to always verify all ascpects of a measurement. Learning from this lesson, this problem was avoided on the Talos AUV utilizing a thruster dynamometer.