Overview:
From a broad perspective, the group considered the overall goal of the AEV project: optimizing the speed of the AEV. In order to accomplish this goal, the group came to a general consensus that the propellers had to be further analyzed. With this being considered, for the first Advanced Research and Development Lab, the group decided to test various propeller configurations. The goal of testing different propeller placements was to ultimately analyze the results, and determine which configuration would result in the greatest distance, while using the same power and code.
Four different propeller configurations were tested. The first configuration tested was a “push” model, in which the propellers were fastened at the back of the AEV, and ultimately “pushed” the AEV forward. The second configuration was a “pull” model, in which the propellers were fastened at the front of the AEV, and ultimately “pulled” the AEV forward. The third configuration was a “push-pull” model, in which one propeller was placed in the front, and another was placed in the back. The propeller in the front was the “pulling” force and the propeller in the back was the “pushing” force. The fourth configuration was a “pull-push” and was merely identical to the “push-pull” setup, except for the fact that the code was reversed.
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Analysis and Results:
Each configuration (4 total) of push, pull, push-pull, and pull-push had their power and distance graphed as dependent variables over time. The same code was used throughout all runs with the AEV design remaining relatively the same with tweaks to accompany propeller configuration.
Push vs. Pull:
Figures 1 and 2 display the push configuration results with figure 1 showing the power used over a given time interval while figure 2 displays the distance traveled over the same given time interval (follows suit in ascending numerical order for each subsequent configuration discussed). The push configuration, throughout most of its run had about 6 watts being used by the motors. A peak was made in the middle of the run where the code hit a reverse command causing 10.89 watts to be used. This is similar to the pull configuration where figure 3 shows similar results. This is expected as the same code was used and thus should yield similar power consumption. Figures 2 and 4, however, display differing results where the push configuration performed better as far as distance is concerned going to a max of about 9.5 meters while the pull configuration went less than 3 meters.
Push Configuration:
Power vs Time (Figure 1): Power vs Distance (figure 2):
Pull Configuration:
**Same image as pull with code reversed**
Power vs. Time (figure 3): Power vs. Distance (figure 4):
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Push-Pull vs. Pull-Push:
In the comparison between the push-pull and the pull-push configuration the power used was similar to each other (due to code). Figures 5 and 7 display that the measured wattage was about the same in both runs. Like the push and pull configurations they displayed a sharp decline at the right where the breaking command was made. They both, however, yielded smaller wattage compared to the push and pull configurations. Figures 6 and 8 shows the distances traveled by the push-pull and pull-push configurations where the push-pull performed slightly better with a max distance of about 2 meters while the pull-push went only 1.5 meters. Nonetheless, both configurations, performed poorly in comparison to the push and pull configurations. It should be noted however, that the power used in these configurations were considerably less than that in the push and pull configurations. However, due to the team’s specialized MCR of focusing on speed, this is not as important. Moreover, the power used does not seem to be worth the considerable decrease in the distance traveled.
Push Pull Configuration:
Power vs. Time (figure 5): Power vs. Distance (figure 6):
Pull Push Configuration:
**Same image as push pull but code is reversed**
Power vs. Time (figure 7): Power vs. Distance (figure 8):
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Conclusion:
As a result of testing different configurations, the team has come to the conclusion that push configurations work more efficiently than pull configurations. However, when taking in account that the AEV will have to travel in both directions, the push-pull method to be very viable in the long run. To have at least one push propeller at all times would be very productive and allows for more variability in our code. The team also took into consideration the effects of the caboose. The team decided that running the best push method while on the way back with the caboose is the best way to construct the AEV.
After analyzing the results of this lab, one of the biggest takeaways is that the “push” configuration travels the greatest distance while using the same amount of power. With this being said, when performed, the AEV will use the “pull-push” configuration when traveling towards the gate without carrying a load. When the AEV picks up the load, it will ultimately return using the “push-pull” configuration in order to transport the load in a more timely fashion. This configuration, as described earlier, involved a propeller fastened at the very front of the AEV and a propeller fastened at the very back.