Prototype 1

 

Prototype 1 was created with not a whole lot of thought put into it.  Initially, Team G just wanted to get something on the track to begin testing with different variations and components.  What was more important at the time, was to get an understanding of how each component of the AEV worked, more than the design of the AEV itself.  Team G had faith that better design would come with time.

Prototype 2

 

The second Prototype that was created was made primarily to see what would happen if the AEV was in pulling setup, rather than a pushing one.  Ultimately, the team found that a pulling set up was much more efficient.  Since pulling the caboose would take more energy when moving on the track, Team G decided to make the AEV oriented so that once the AEV was connected to the caboose, it would pull the caboose back to the start.  This resulted in a mix of parts of Prototype 1 and Prototype 2 being used to create Prototype 3.

Prototype 3

 

Prototype 3 was used for much of the testing process.  It had great balance and stability around the wheel centered over the AEV.  For Performance Test 1 and 2, the AEV ran with very minor errors, and was quick to code.  The near perfect balance of the AEV (image below), however, came to prove as not such a good thing.  As soon as Performance Test 3 began, the code would not seem to land in the same spot.  Eventually, Max Hubert discovered that, once attached to the caboose, the AEV was becoming imbalanced, causing the wheel with the sensor to lift off of the track.  Since the code was based around distance measurements, and with the reflectance sensors not registering any distance due to its lack of contact with the track, the code was not repeatable.

Final Design

 

The final design of Team G’s AEV resulted in one where the support arm and AEV were moved toward the caboose connecting end of the AEV, with hopes to offset the balance (image below).  This resulted in more weight being placed upon the wheel the reflectance sensors, which kept it from removing itself from contact with the track.  This way, the AEV picked up every tick to ensure that the code ran correctly on a regular basis.

The final cost and breakdown of costs is listed in the chart above.  The final design ended up being approximately $170,000 over budget, but would have only been 70,000 if Safety violation had not been incurred.  Safety violations included loss of a propeller in mid-flight ($10,000), AEV dropped off track (3 x $15,000), and AEV hit the ground (3 x $15,000).  By continuing to program more efficient code and possibly reducing weight, Team G would have dropped closer to the given budget cost of $500,000.