Progress Report - Mechanical Design (01/14/2012)

The aluminum hull end caps were completed with the machining of the slots and handles. I wanted to get them hard anodized and dyed blue (for aesthetic reasons), but the nearest facility, which is located in Valdosta, GA, was under heavy work load, so I decided to go ahead and install both the camera enclosure and hull end caps as they were. The hull end caps were carefully aligned so that the ends of the thermally-conductive aluminum platform which rests on the interior acrylic supports would properly fit into the end caps slots. The torpedo launchers were also installed, including a revised, more efficient mount design, and custom attachments to hold the acrylic torpedo cannons. The machinist, Jeremy, made a couple suggestions to help develop this clean design. Furthermore, I weighed each of the two ABS plastic torpedoes on a highly accurate scale in one of the chemical engineering laboratories. This, in combination with the Pro/Engineer-indicated volume of each of the 3D-printed torpedoes enabled me to determine their density. With this information, I was able to perform a couple detailed calculations in order to determine the proper depth to drill into the bottom of each of the torpedoes so that I could install a dense 3/16"-diameter stainless steel rod into the center of each of the torpedoes without changing the original center of mass location. After reaming out this hole and press fitting the rods into each of the torpedoes, the back end was filled with epoxy. This process allowed me to adjust the density of the torpedoes to the desired density of salt water, while simultaneously adding mass, inertia, and stability. Thereafter, I spray-painted the torpedoes completely white, and then laser-cut magnets to adhere to the bottom surface of each of the torpedoes, as well as to the cylindrical disk attachment on the torpedo launcher CO2 cylinder piston. These magnets will serve to prevent the torpedoes from prematurely dislodging due to disturbance forces, vibrations, etc. during the mission. The camera enclosures were also completed and attached to the frame. I came up with the idea of installing a fully-threaded rod through the center of each of the two external camera enclosures to make use of the tripod mounts on the Logitech C615 web cameras. They can simply screw into the ends of the rod, and then be tilted to orient toward the desired window face. Neoprene sealing washers were used at all locations where a screw was required on the inside of the enclosures (in order to attach the enclosures to the base, and also for the threaded rod). These will serve to maintain a reliable watertight seal. EPDM gaskets were also made at Capital Rubber, and should perform well. The hull, which rests on a bend of acrylic supports, was also installed in the center of the frame. The top acrylic supports were also screwed in to their respective complementary bottom supports in order to clamp the hull into place without introducing any severe stress concentrations. Furthermore, having already made the aluminum mounting plates for the thrusters, my teammates helped me screw the thrusters into these plates and attach the plates to the vehicle. I also ordered larger diameter, stronger, nylon gas lines, as well as compatible adapters and splitters for the CO2 distribution network. The solenoid valves were already purchased months ago, so once the CO2 tank and pressure regulator arrive (I ordered these on Friday), installation and testing of the CO2 distribution system can be performed. I will need to make a mounting plate for the solenoid valves, cut the gas lines to the proper sizes, develop and interface circuits to enable simple actuation of the solenoid valves via a microcontoller, and then write a program to allow me to actuate the solenoid valves individually, and ensure that the pressure-regulated CO2 is distributed as desired (e.g. to the torpedo launchers). The vehicle undergo a watertight test on Tuesday at the FSU Morcom Aquatics Center after an ME presentation. While I work with my teammates on the CO2 distribution system and develop mounts for both the CO2 tank and the solenoid valves, my ECE teammates will work on the computer vision (with the camera enclosures), thruster control, and hydrophones. Once the underwater SEACON connectors and pressure transducer arrive (likely next week), they will be installed on the vehicle. Holes will need to be drilled and threaded into the end caps of the hull in order to allow the female connectors to screw in (Loctite will be used as a thread sealant here). I will also need to solder (and shrink wrap) the electrical leads of the peripheral subsystems to the electrical leads of the corresponding male SEACON cables. I would like all the mechanical aspects of the vehicle complete by spring break so that the focus can be solely on programming, debugging, and developing electrical interface circuits. I also intend to eventually contribute in the development of depth and stability control algorithms, as well and velocity and turn control algorithms based on the integration of pressure sensor and inertial measurement unit. While I help the ECEs with programming, I will have Tra and Kashief work on developing the replicated PVC objects that the AUV will encounter during the actual mission so that we can test the program in a relatively mirrored environment. There is still a lot of work to do, but I will make sure we get it done.

**Also, pictures of the AUV should be up by the end of Monday

              -Eric Sloan (Mechanical Engineering Project Manager)