The pictures below are of us in the process of constructing the submersible.
Unfortunately, the "basic" model was not as easy to finish as expected. We ran in to a couple of difficulties. One of our motors wasn't functioning and as a result could not power one of the propellers needed to make the submersible fully run. After using a multimeter on the board, we realized that it was not the motor that wasn't functioning correctly, it was the switch that was causing all of the difficulties. To solve this issue, we had to unsodder the old switch from the board and sodder the new one back on. This step also gave us some difficulty because melting the sodder off the board to release the old switch was not easy to do. To fix this, we were able to find a sodder vacuum which essentially sucks the melted sodder off the board once the heat of the soddering iron melts it to a certain extent. This worked successfully so that the new switch could be successfully secured on the board. With the new switch in place, all motors were working successfully and powered each of the three propellers.
We chose not to permanently secure the PVC pipes with glue or adhere the motors in place on the PVC pipes because we felt that they might not be where we would want them for our future modifications. For example, the third motor is not actually needed in our final model because the ballast tank will be used to control the depth.
On the day of the event, our group attended the fair from 9 AM to 2 PM. It was a good learning experience because there were SeaPerch professional there to advise us and give us pointers. We tested out our submersible in the water for the first time. From the first test run, we could see that our submersible would need to be ballasted (weighted) to function correctly. The Sea Perch volunteers there were able to tell us that we could slit the cylindrical foam floats to make it easier for us to try out different float sizes on our submersible. This was helpful because then we did not have to take apart our submersible each time we tried to figure out the best ballast weight system for our submersible. Another issue we noticed was our design. We chose to veer off the original design proposed by the SeaPerch kit to better accommodate the ballast tank system design used in our future modification. The resulting design was much wider and a somewhat inverted compared to the original design. We noticed that the weight of our new design was not proportioned in the same way and as a result the weight of one side was heavier than the other making it extremely hard to ballast the submersible in the standard SeaPerch way. From this information, we realized that we were going to have to set aside more time to ballasting the submersible as it was not easy t get right and because it was vital to the effectiveness of the design. We also realized that thought it was important for us to realize how hard it was to ballast the submersible correctly, we did not want to waste time ballasting the basic version of our submersible now because it would require different ballasting once our modifications were put in place.
The Sea Perch booth at the Franklin Institute was also interesting to see. There was a mock set up of the actual competition Sea Perch hosts so that students can test their submersibles against each other by maneuvering their robots through an obstacle of hoops at various heights. This was engaging to see because we were able to see what Sea Perch was originally about and how we were going to change it to make improvements.
There is a picture of our group, below, in front of the fire truck that filled up the Sea Perch pool that kids could use to try out the underwater submersibles.
Later on this week, we ordered parts for the ballast system and will be waiting for those parts to arrive. Shortly after, we went to the machine shop to see if we could find any of the other parts we needed lying around. We found a large PVC pipe that could be used as a tank if we get an endcap to secure an end. As for the arduino and depth sensor, once we talked to the advisor in charge of the arduino based engineering projects, he advised us to look in to Open Log which can be found using the following link: http://www.sparkfun.com/products/9530. Open Log would be used to help us log the data. However, it has not been ordered yet because we are trying to figure out if it can be done without Open Log to save money.
Excellent!
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