Performance Test 1
For the first Performance Test, the AEV is to stop at the gate (trip only the first marker – green tape) for seven seconds and then pass through. Aside from completing the run, the design goal of Performance Test 1 was to decide the final AEV design from the two semi-finals (wings vs. no wings). Due to the time lost from troubleshooting the integration of the servo arm as a manual break, testing the two designs was not completed until the first day of Performance Test 2 preparation.
Figure 1: Power vs. Time for Control vs. Second Design
Figure 2: Power vs. Distance for Control vs. Second Design
Table 1: The Energy of Each Design
From Figure 1 and Table 1, since the code was kept constant for both designs, the energy used by each is basically the same. The second design (no wings) used less energy due its lighter weight. However, Figure 2 shows that the control (with wings) can travel farther on its way back with the load. Coupled with the results of the Propeller Configuration Tests during the Advanced R&D, the group once again concludes that angled wings provided more thrust. The wings, though created a more back heavy design, gave the AEV more stable stops. From further observations, as opposed to the control, the second design had safety issues; it tend to rock from side-to-side as it accelerates down the rail.
Thus, the team ultimately decided to keep the wings on the AEV as safety takes precedents over a small margin of energy difference.
Performance Test 2
For the second Performance Test, the AEV must continue from the gate and connect to the caboose (load) without recoiling out of the loading dock. The AEV must wait for five seconds before leaving. In regards to the design goals, two codes were tested for the most energy efficient one.
Figure 3: Power vs Time for Control vs. Second Code
Figure 4: Power vs. Distance for Control vs. Second Code
Table 2: The Energy of Each Code
The difference of the two codes correlated to the percent power used and using coasting in addition to the servo. From Table 2, it is clear that the consumed energy for the second code (higher percent power and coasts) is less than the control. While executing the second code, the AEV did not have much stability side to side.
Once again, the team ultimately decided to use the control code as a safety is most important in regards to the team’s Approach to MCR.
Final Performance Test(s)
The Final Performance Test(s) requires completion of the MCR. The AEV is to pass the gate after seven seconds, continue to the load, connect to the load, wait for five seconds, return to the gate without the load disconnecting, pass the gate again after seven seconds, and return to the starting dock without recoiling out of it. The team was given three chance to successfully complete the test.
Figure 5: Power vs. Time for All Final Performance Test Runs
Figure 6: Power vs. Distance for All Final Performance Test Runs
Table 3: The Time and Energy of Each Final Performance Test Runs
Comparing the three runs from Figure 1 and 2, and explicitly in Table 3 there is a discrepancy in energy usage. This is a result of the unique codes written to counter the limitations of each run. The friction between the rail and the AEV wheels and the battery played a huge role on the consistency of each run. Though the backbone of the codes are identical, the last goTo Absolute(); and goFor(); for the final brake(4); differed in order to ensure the AEV trips only the green tape on the return trip to the gate and reaches the starting dock.
During the first run, the AEV successfully completed the test with the least amount of energy and fastest time. During the second run, the AEV was unable to reach the starting dock on the return trip, and used the most energy. For the final run, the final goFor(); was adjusted to ensure the AEV reaches the dock. This last run was successful and used the second most energy. From the three runs, the average top two cost $565,595.
With the completion of the Final Performance Test(s), Team J now has one of the most safe and energy efficient AEV design.
