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Project Scope

During the fall 2006 semester of our senior design class our team was tasked with creating a mechanical design that could record specific data that could be used to develop a 3 dimensional map of the caverns.  This data would be used by scientists from the Woodville Karst Plains Project to have a better understanding of how the cave systems in the panhandle of Florida are linked and how water pollution affects neighboring regions.  This project was developed to provide the diving teams from the Global Underwater Explorers with a tool which can be used to record data when they reach cave systems that are too small for humans to enter.  Until this project was presented to us the only way that the GUE divers could retrieve data from the caverns was by making several multi hour long dives into the caverns and retrieve the required data from the stationary sensors that where placed in remote locations in the caverns.  Therefore they can only acquire data where they are able to reach.  Other means of determining cavern routes and runoffs included dispersing different color dyes into the caverns to estimate where they go.  All this information helped clarify our design outline for the spring semester.

For the spring 2007 semester of the senior design class group 6 was to evaluate the feasibility of different systems and schemes which could be used to map the Karst water system. The team had to define several design constraints before beginning. Some design constraints that needed to be addressed included tethered vs. untethered, self-propelled vs. drifting, one expensive design vs. several small designs, what data would be most useful for mapping, and which sensors would be best suited to collecting that data. Other considerations included the size of tunnel that the robot would have to be able to pass through, how far it would need to travel, robot survivability, communications, and robot retrieval.

This semester group 6 needed to build a working prototype of the untethered submersible robot. This prototype must be able to accomplish some of its main goals such as: staying as neutrally buoyant as possible, traversing the underwater cave systems without getting stuck or leaking water, and resurfacing for retrieval. These are the three main goals that group 6’s prototype must accomplish in order for it to be considered a successful prototype.

            What group 6 did this semester was order the components and fabricate the housing for the submersible robot. The group also did rigorous testing on the prototype to see if the design could stay close to neutrally buoyant. Also, group 6 did tests on whether or not the prototype is too heavy or too light with its total component package. This was a very important part of the testing because it could make or break the goal of achieving close to perfect buoyancy. Another area of emphasis was on the resurfacing method that would be used for the prototype. One of the earlier designs had internal C02 cartridges mounted to the inside of the housing, but that later changed as the group realized that getting that idea to work will be harder than originally thought. The miniature C02 cartridges though threaded would need to be punctured at the tip in order to release the gas. Since the group had no way of being able to do this short of fabricating our own device to release the gas, group 6 had come up with the idea of using a external 9-12oz C02 tank with a manual valve on it for simplistic purposes.  This proved to be a viable solution to the problem.

            At the beginning of the semester the team set a group of tasks that needed to accomplish before the semester was done.  Mainly, to have completed the sensor package, fabrication of the housing, assembly of the prototype, getting the prototype to be as neutrally buoyant as possible, and hopefully completing a test run in a small cavern system to see if it can traverse the caverns without leaking and resurfacing all on its own.

            What the group expected as of the start of this semester was the completion of the housing within the first six weeks and having it tested to see if it will remain water tight.  That goal was achieved just a week shy of scheduling due to the fact that the ordered parts arrived late.  The fabrication of the housing was the teams’ top priority.  Group 6 ordered clear PVC pipes as the main part of the housing and closing it off on both ends with threaded PVC caps. The inside of the housing contains several layers to hold separate components such as the sensor package and the solenoids. Group 6 had to do all of the fabrication and threading of this housing on their own, it was built completely from scratch. Since the team chose the external C02 tank they then had to fabricate brass fittings for it and run a line to the bottom of the housing so that it can connect with the solenoids on the inside.