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Still yet more projects...SER!SER was the first real attempt I made at designing and building a submarine robot from scratch. SER was an acronym for Submersible Exploratory Robot. Constructed out of fiberglass reinforced plywood, I discovered very quickly why it's best to have a spherical shape for an underwater vessel. The robot itself worked exceptionally well actually, until it got to depth. I had gotten to about 30 feet and was sitting on the bottom of the lake. Now here's the lesson learned if you ever want to build a sub: it's PSI - Pounds PER SQUARE INCH. Simple math showed that at thirty feet (approximately 15 psi) the pressure on the side of the robot added up to about a ton and a half. Basically, park you car on the side of the robot and don't let any water in! (Video cameras and water don't mix, take a tip from 'ol Ian) So at any rate it didn't crush the robot or anything, it just blew the seal around the plexiglass on the front. I guess I killed the power to it fast enough 'cause believe it or not, after cleaning out the camera and drying it out I actually got it working again and reinstalled it in SER version b and again in SER SOL II.  SER SOL IIThe next step in this R&D process was to take the lessons learned from the first and rebuild! Unfortunately, rebuilding was really the only way to go. The problem I ran into was cost: I got a quote for a 1/2" thick Lexan sphere at around $900 PER HALF (It takes two halves to make a whole sphere!). Seeing as how I was funding this pretty much myself, I went for a second option: pressurize the hull. So I constructed the hull out of 1/2" aluminum with a molded 1/2" thick lexan front gel and ran pressurized air lines down to the robot from the surface. This meant a much cheaper robot but did mean maintaining the air pressure inside the robot. A bleeder one-way check valve at the lowest point of the hull not only vented off pressure in excess of depth pressure but also vented out any water that did manage to leak into the robot. It also made a convenient depth gauge as a simple scale on the hull pressure gauge gave a depth indicator.I also found with SER that neutral buoyancy was just too hard to keep without an active ballast system. Especially because it is intended to do underwater manipulation, having active buoyancy (with a second air pressure line run from the surface) helped an awful pile. A third air line which ran up the manipulator was for odd jobs like filling air bags. In the event of a salvage operation, the plan was to tie off an air bag to the object to be hoisted, and then fill it with air from the auxiliary air line. Here it is with the manipulator attached (I haven't installed the ballast tanks yet):  And here it is after one of its test dives, the manipulator removed but the ballast tanks installed:  Click here to go to the first page!
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