The first graph is showing the Power vs Distance traveled in a plot. This graph makes sense because the code ran made the AEV use power, but it was not able to move the AEV. Therefore when it reaches higher powers it stays straight in the middle, as it never reaches a power where it is able to move. Meanwhile, the second graph shows Power vs Time. This just shows the amount of power used as it follows the code, the most being between 5.33 and 6.67 seconds.
Code used along with an explanation, using the Energy vs. Time plot:
celerate(4,0,25,3); //Accelerate both motors from 0% to 25% in 3 seconds (Beginning of graph to about 3 seconds)
motorSpeed(4,25); //Hold both motors at 25% speed for 1 second. (3 seconds onward until 4 seconds.)
goFor(1);motorSpeed(4,20); //Hold both motors at 20% speed for 2 seconds. (4 seconds until about 6 seconds)
goFor(2);reverse(4); // Reverse both motors, 25% speed for 2 seconds. (This is where the spike is, as it reverses motors and it uses a lot of energy)
motorSpeed(4,25); (Holding this from around 6 seconds until 8 seconds.)
goFor(2);brake(4); //Brake both motors. (From 8 seconds until the AEV isn’t using any energy)
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Advanced R & D
Power Braking:
Below is the resulting data from our tests Power Breaking vs. Coasting which plotted Power v. Distance:
What does this test show?
These tests tell us that the power breaking is more effective at stopping the AEV, but uses more power. The pro’s to using the power brake is that it provides a more accurate stopping procedure vs. coasting. However, the problem with power braking is how much power it uses. When the AEV runs the whole course we want to make sure we conserve as much energy as possible so that the AEV can perform its function without any hitches.
Moving forward we are sure to use power braking and will consider even adding a SERVO brake to our unit.
Power Brake Code:
celerate(4,0,45,2);
motorSpeed(4,47); //6 feet between start and incline
motorSpeed(4,45);
reverse(4);
motorSpeed(4,50);
goFor(2);brake(4);
Coasting Code:
celerate(4,0,45,2);
motorSpeed(4,47); //6 feet between start and incline
motorSpeed(4,45);
goFor(3);
(Raw Data at the bottom of the page)
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Track Variance:
Listed Below are our results from our Track Variance testing:
What do these tests show?
Our track variance test was conducted using the same code for each run. The only thing that varied was what track the test was performed on. We ran two tests on each track. What the statistics show is that there is a little variance between the tracks. In terms of distance, the standard deviation was a three-quarter of a foot, which is quite a lot. However, we caution very strongly against this number as what this number is showing how far the AEV traveled from start to finish running the same code on each track. In an idealized situation, the AEV would perform the same on each run, but we can’t expect this to be true with how many other factors we need to consider. First, the breaking system we used was the power braking, which has variability in it as the R & D section above shows. This test would better be performed with a unit containing a SERVO brake. We also only ran two tests per track due to time constraints. More tests would have most likely yielded a smaller standard deviation.
The code used for Track Variance Tests:
motorSpeed(4,45);
goToRelativePosition(305);reverse(4);
motorSpeed(4,50);
goFor(2);brake(4);
Raw Data:
The files are downloadable as a .zip file to keep them contained easily.
Power Braking vs Coasting:
Track Variance:
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Performance Test 1:
The goal of performance test 1 was to direct our AEV through the first gate of the test track. To accomplish this our AEV had to travel a certain distance and stop at the first gate, wait for 5 seconds, and pass through the gate. We tested this with two different designs listed below. We tested two different designs with the same code and moved forward with the design which used the least amount of energy.
We had three days to design the code and complete the performance test. We abandoned design two quickly, as the design was heavier and would have required more energy to move and stop. We designed the rest of the code with design 1. As such, we were able to complete performance test 1 on the third day of testing.
The graph below shows the energy used by the discarded design.
Performance Test 2:
The goal of Performance Test 2 was to test the AEV design to create more consistency and was able to minimize energy usage. The AEV was to get to the gate, stop and wait, then continue to pick up the caboose, which was the main area where it was decided that energy could be saved. There were two codes used (Shown below) with one being the original code, while the other is the energy efficient code. The energy efficiency was achieved by switching out sections of using energy to slow down the AEV with instead allowing it to coast down the ramp to the caboose.
This resulted in a more efficient AEV that was able to coast down the ramp to get to the caboose, and once it reached near the bottom, a slight brake was applied to allow it to fully slide into the caboose without allowing the AEV to move the caboose. This design allowed Performance Test 2 to be completed very quickly and was an easy switch to allow less energy.
Less Energy Code:
motorSpeed(4,32);
goToRelativePosition(244);
reverse(4);
motorSpeed(4,40);
goFor(1);
motorSpeed(4,0);
goFor(7);
reverse(4);
motorSpeed(4,30);
goFor(4);
motorSpeed(4,0);
goFor(4);
reverse(4);
motorSpeed(4,10); //Less energy to allow it to slide into the caboose
goFor(2);
brake(4);
More Energy Code:
motorSpeed(4,32);
goToRelativePosition(244);
reverse(4);
motorSpeed(4,40);
goFor(1);
motorSpeed(4,0);
goFor(7);
reverse(4);
motorSpeed(4,30);
goFor(4);
reverse(4);
motorSpeed(4,10);
goFor(4); //This section is where more energy is used
brake(4);
Final Performance Test:
The final test was to run the AEV through the full track, stopping at the gate, waiting, picking up the caboose, then returning to the gate, waiting, then going to the “loading” point with the AEV and caboose. The Code used can be seen here. The final results with Power Vs. Distance can be seen below.
Along with the AEV needing to get back to the starting point with the caboose, it also allowed for safety procedures to be handled and to show how much energy was being used. This AEV uses a lot of energy but can be slightly faster when compared to other AEV designs. An example of safety would be the AEV going back to the beginning of the track, it is important the AEV does not bounce off the end, but instead slows down to a complete stop. This performance test showed the AEV’s design did consume more energy than other designs, but it may be possible to lower energy in some sections where it may not need as much as it was using originally.
