Executive Summary
During lab sessions for the Advanced Energy Vehicle project, the team worked together to perform the tasks that were presented to them in the Lab Manual. Throughout the course of the project, the group had to face different challenges and overcome many obstacles. The team had to design their own AEV, using a generic design to base it off. Computer programs, such as SolidWorks, were used to model 3D parts, which helped to visualize components in three dimensions. The group had to gather information and perform tests and calculations to determine which methods and designs were the best and the most efficient.
According to the Mission Concept Review, the team was to create their AEV in order to fulfill the given scenario. The rebel alliance needs to prepare for war on remote planets to make sure the galactic empire is unaware of operations. The team will create a craft that will transport R2D2 units whilst using as little power as possible. The need for an advanced energy system, like an Advanced Energy Vehicle, is due to the base being located on a remote planet where power is luxury.
The team selected several features that they believed were the most important, like balance and maintenance, and rated their concepts based on their features. Based on the concept’s ratings, the team selected a design to move forward with, which was the Winnibago. Their design featured larger propellers, rotating wings, and a hollow body to store the Arduino and battery.
Throughout the 20 “stages” of their code and used 478 Joules of energy for each run. Nearly all of the power usage came from the stages where the craft was traveling at a constant speed (usually 60%) to the next stopping point. The craft weighed 514 grams and had a 930 J/kg energy/mass ratio. For the most part the craft performed very well during the final testing. The only issue that occurred during any run was that the AEV would stop an inch or so outside of the specified portion of the track.
Overall, the team was extremely satisfied with the design of their AEV. Their Winnebago proved to be more durable and reliable, as well as aesthetically pleasing as well. Other teams had issues with wires catching on their propellers, however the Winnibago design did not have this problem because of the internalized wiring system. The only aspect of their test that the team would have wanted to change, was the efficiency of the craft. Due to the wide wingspan, the craft was heavier than necessary and required a higher energy level to move.
If the team had more time, they would have changed a few aspects of their craft. As mentioned above, the wings would have been shrunk down and resized to minimalize the weight and leverage on their craft. They would also secure their Arduino and battery within their craft. They would also reattach their support arm in a location nearer to the back of the craft in order to better balance their AEV.
Table of Contents
Executive Summary…………………………………………………………………………………………………………………………..1
Table of Contents……………………………………………………………………………………………………………………………..2
List of Tables and Figures………………………………………………………………………………………………………………….3
Introduction……………………………………………………………………………………………………………………………………..4
Experiment Methodology…………………………………………………………………………………………………………………4
Results and Discussion……………………………………………………………………………………………………………………..5
Conclusion and Recommendations………………………………………………………………………………………………….12
Appendix…………………………………………………………………………………………………………………………………………14
Arduino Code…………………………………………………………………………………………………………………………………..14
Team Schedule…………………………………………………………………………………………………………………………………15
Models of Craft………………………………………………………………………………………………………………………………..16
Final Testing Score Sheet..………………………………………………………………………………………………………………..20
List of Figures and Tables
Figure A- Prototype 1
Figure B- Prototype 2
Figure C- New Wing
Figure D- Propulsion Efficiency vs Advance Ratio
Figure E. Protoype 1 Time vs Supplied Power
Table F- Prototype 1 Breakdown
Figure G- Final Design Time vs Supplied Power
Table H- Final Design Breakdown
Table I- Concept Screening
Table J- Concept Scoring
Introduction
In the Advanced Energy Vehicle project, the goal was to build an AEV would transport R2D2 units for the rebellion, all whilst using as little power as possible. The craft would travel around a track, stop at certain positions, pick up a trailer, and then return to the starting position. The purpose of this lab was to help the team understand the concepts of project management and teamwork, time management, and project documentation.
Throughout the course of the project, the team tested different prototypes to help them make decisions about their final project. They then combined everything that they had discovered into their final design in order to make it as efficient and run as smoothly as possible. All of the team’s observations are below in the results and discussion portion of the review.
Experimental Methodology
For the project the team was given an Arduino, two sensors, two motors and servo motors, a USB cable and a Li-Po battery, as well as access to a 3D printer to assemble their craft with. The team uploaded their code into the Arduino, and when the Arduino was started, the craft would complete the code. The sensors allowed the Arduino to sense how far the craft had traveled. The servo motors were used on the team’s design to rotate the wings of their craft. In the first prototype below, the Arduino was attached to the top of the small rectangle board, and the battery was attached below. The team’s design will call for the Arduino and battery to be placed inside of the body of the craft.
The team first created a prototype that was similar to their intended design in order to get an idea of how their craft would run. They ran the prototype on a code that they hoped would be close to their final code, and collected energy data and observations from the run. After all of their 3D parts were printed, the team assembled their craft and troubleshot both their design and code. Minor modifications were made and the team then ran the final tests of the AEV.
Results and Discussion
The first AEV prototype was the same design that was suggested at the beginning of their project. Their second prototype was very similar to the first, but the wings were straight across as seen in Figure A. It was meant to mimic the design of their first Winnibago craft that the team was working on printing and troubleshooting (Figure B). The major difference between the two designs was the fact that the first prototype did not include the rotating wings and servo.
The team was never able to actually test their second prototype, as they were not able to insert the servo motors into the vehicle. Prototype 2 was very similar to their final design with the only major change being that the wings were printed in two separate pieces, as seen below in Figure C. The team also learned that they needed to weigh down the front of their final craft so that it would not shift from the track. Their initial code used marks, but the final code that the team tested with used time.
At the beginning of their project, the team tested their propellers and calculated the propulsion efficiency and advance ratio, the comparison of which is in Figure E. From the data, it was decided by the team that they would use the larger size propeller. As seen in below the most efficient that the propellers could be was only about 16.5% efficient, which occurred at lower power settings. Since the team’s craft was of 514 grams, it would also be likely that the small propellers would not have provided nearly enough wind power.
Figure D. Propulsion Efficiency vs Advance Ratio
The first prototype was tested by the team, using a code that was close to what they hoped their final code would be. In Figure E, a breakdown of the code can be seen. The four “sections” of the code have almost identical patterns. There was a spike in power when the craft was started and stopped. The graph also made it easy to see where the team used higher power settings.
Figure E. Protoype 1 Time vs Supplied Power
Phases 1, 6, 11, and 16 were used to send the AEV to the position on the track where it needed to stop. Phases 11 and 16, however, used a higher power setting as the craft was traveling backwards and was in a different propeller configuration. Phases 2, 7, 12, and 17 were used to stop the motor and reverse its direction in preparation for phases 3, 8, 13, and 18. Those phases were used to slow and stop the vehicle.
The entire program ran for close to 45 seconds and used 247 Joules to complete a single run. Most of the used power was a result of phases 1, 6, 11, and 16. The brake command resulted in a small spike of power, and during the phases when the craft was stopped, close to no power was used.
Table F. Prototype 1 Breakdown
| Phase | Arduino Code | Time Passed (seconds) | Total Energy Used (Joules) |
| 1 | motorSpeed(4,35) goToRelativePosition(515) | 3.902 | 35.3209 |
| 2 | Brake(4) | 4.262 | 38.8640 |
| 3 | reverse(4) motorSpeed(4,35) goFor(2) | 6.002 | 53.8647 |
| 4 | Brake(4) | 6.112 | 54.1243 |
| 5 | goFor(5) | 11.04 | 54.5249 |
| 6 | reverse(4)
motorSpeed(4,35) goToRelativePosition(620) |
15.96 | 98.2526 |
| 7 | Brake(4) | 16.2 | 100.6112 |
| 8 | reverse(4)
motorSpeed(4,35) goFor(2) |
17.94 | 115.7528 |
| 9 | Brake(4) | 18.24 | 116.0064 |
| 10 | goFor(5) | 22.98 | 116.5488 |
| 11 | motorSpeed(4,45)
goToRelativePosition(-550) |
26.46 | 156.8370 |
| 12 | Brake(4) | 26.7 | 159.5498 |
| 13 | reverse(4)
motorSpeed(4,35) goFor(1) |
28.62 | 175.8386 |
| 14 | Brake(4) | 28.74 | 175.8386 |
| 15 | goFor(5) | 33.6 | 175.8386 |
| 16 | reverse(4)
motorSpeed(4,45) goToRelativePosition(-800) |
38.22 | 228.4237 |
| 17 | Brake(4) | 38.4 | 230.4557 |
| 18 | reverse(4)
motorSpeed(4,35) goFor(1.5) |
40.26 | 246.2688 |
| 19 | Brake(4) | 40.44 | 246.5245 |
| 20 | Coast to stop | 43.32 | 246.5245 |
The team edited their code in order to better suit their final design. The main change was that instead of using marks, the team used time as it made their craft stop in more consistent places. However, the team also added code to rotate their servo motors as well as code to make the craft stop a few marks before the location of the trailer and wait a few seconds.
Figure G. Final Graph of Energy vs. Time
The shape of the graph in Figure G strongly resembles the shape of the energy and time graph of the prototype. There were jumps in the graph when the vehicle started and stopped, as well a spike in the beginning when the servos were rotated to their starting position.
As seen in the table on the next page, the breakdown of the code for the final design is very similar to the breakdown for the prototype. The only major difference is the middle portion, which where the craft waited before attaching to the trailer and that 60% power was used instead of 30%. The craft took approximately 66 seconds to complete one run on the track, and used about 478 Joules of energy, close to twice the amount that the prototype used. This difference makes sense as the power level in the final design was close to twice the power level used for the prototype (due to weight differences).
Table H. Final Design Breakdown
| Stage | Arduino Code | Time Passed (seconds) | Total Energy Used (Joules) |
| 1 | rotateServo(0)
reverse(1) |
.601 | .1712 |
| 2 | goFor(8) | 7.981 | .8439 |
| 3 | motorSpeed(4,63)
goFor(5.96) |
13.8 | 97.6 |
| 4 | brake(4)
reverse(4) |
13.98 | 99.6 |
| 5 | motorSpeed(4,65)
goFor(1.2) brake(4) |
15.18 | 120.38 |
| 6 | goFor(7) | 22.2 | 120.9 |
| 7 | reverse(4)
motorSpeed(4,63) goFor(5.07) |
26.94 | 198.21 |
| 8 | brake(4)
reverse(4) |
27.48 | 207.99 |
| 9 | motorSpeed(4,65)
goFor(1) brake(4) |
28.32 | 221.85 |
| 10 | goFor(5) | 33.36 | 222.35 |
| 11 | motorSpeed(4,60)
goFor(1.2) brake(4) |
34.56 | 240.81 |
| 12 | goFor(8) | 42.54 | 248.28 |
| 13 | rotateServo(180)
motorSpeed(4,65) goFor(5) |
47.28 | 321.45 |
| 14 | brake(4)
reverse(4) |
47.82 | 331.48 |
| 15 | motorSpeed(4,65)
goFor(1.2) brake(4) |
48.84 | 347.65 |
| 16 | goFor(7) | 55.8 | 347.98 |
| 17 | reverse(4)
motorSpeed(4,65) goFor(6.25) |
61.62 | 445.4735
|
| 18 | brake(4)
reverse(4) |
62.61 | 455.3701
|
| 19 | motorSpeed(4,65)
goFor(1.5) |
63.54 | 477.8035
|
| 20 | brake(4)
Coast to stop |
66.5410
|
478.4 |
At the beginning of their project, the team rated each of their designs based on 6 criteria that they found important: balance, efficiency, Arduino access, weight, safety, and maintenance. In the concept screening, the team rated each design as positive, neutral, or negative on each aspect. Quinton’s design, which was the Winnebago design that the team selected had high scores in nearly every aspect. The design also received a good score in the concept scoring.
Table I. Concept Screening
| Criteria | Reference | Alyssa | James | Quinton | Ryan |
| Balance | – | + | 0 | + | + |
| Efficiency | 0 | 0 | + | 0 | – |
| Easy Arduino Access | + | – | – | + | + |
| Semi-light weight | + | + | – | + | + |
| Safe | 0 | 0 | 0 | + | – |
| Maintenance | – | 0 | + | + | + |
| Sum +’s | 2 | 2 | 2 | 5 | 4 |
| Sum 0’s | 2 | 3 | 1 | 1 | 0 |
| Sum -‘s | 2 | 1 | 2 | 0 | 2 |
| Net Score | 0 | 1 | 0 | 5 | 2 |
| Continue? | No | No | No | Yes | Yes |
Table J. Concept Scoring
| Quinton | Ryan | ||||
| Criteria | Weight | Rating | Weighted Score | Rating | Weighted Score |
| Balance | 20% | 4 | 0.8 | 3 | 0.6 |
| Efficiency | 35% | 2 | 0.7 | 2 | 0.7 |
| Easy Arduino Access | 10% | 3 | 0.3 | 4 | 0.4 |
| Semi-light weight | 15% | 3 | 0.45 | 4 | 0.6 |
| Safe | 10% | 4 | 0.4 | 2 | 0.2 |
| Maintenance | 10% | 3 | 0.3 | 3 | 0.3 |
| Total Score | 19 | 2.95 | 18 | 2.8 | |
| Continue? | Develop | No | |||
The 6 aspects of the team’s final design were similar to how they rated them to be. The team had no major issues with the side-to-side balance of the craft, and only minor issues with the front to back balance. The efficiency of the craft was average, as the team had suspected, strictly due to the size of the vehicle. For its size, the craft was relatively light-weight, 514 grams, likely because the team made the body of the craft hollow. The maintenance and Arduino access were also simple and easy.
Since the team decided to place all wires within their craft, it made the design look clean and uncomplicated. The team also never had any issues with the wires catching on the propellers, which is what they noticed was happening with their first prototype.
The team, however, ran into several problems throughout the course of their project. Their first, and the only major design issue, was that their initial design for their wing did not allow the team the necessary access to their servo motors. The team then created their wings to be in two pieces. The new design allowed the team to insert a screwdriver through their wing and attach the servo motors. The other major issues were with the hardware. Their wheel count sensors were also extremely inaccurate, which is part of the reason they changed their code from marks to time. The team had issues with their original servo motors and had two regular motors stop working. Two days before final testing, the team had to replace their Arduino, as it stopped executing their code once the servo motor command was called.
When the team ran their final tests, their craft ran better than they expected it to. The most points missed were 5, the least, 3, however an unofficial run missed only 1 point. The inconsistency was just enough that the craft would sometimes stop an inch or so from where it was supposed to. Besides the stopping points, the craft ran very smoothly. As mentioned earlier, the craft used 478 J which resulted in a 930 J/kg Energy/Mass ratio.
Conclusion and Recommendations
The final design of the Winnebago craft did not turn out to be as efficient as the team had hoped. It had a 930 J/kg Energy/Mass ratio, using around 478 J of energy to complete its run. The wings added a large amount of unaccounted for weight that ultimately made the craft more inefficient. The original prototype design would have been a more efficient craft. However, the Winnebago design proved to be more durable and reliable, as well as a significant aesthetic improvement. The final code of the craft also included a braking mechanism, as well as stopping before attaching to the trailer and slowly backing in. Although these were necessary additions to the code to complete the test run, they made the craft use more power, adding to its overall inefficiency. The original code tested on the prototype did not include this and therefore would have been less efficient then its first test run.
There were several issues when designing the craft but these were ultimately overcome. The largest difficulty was redesigning the wings to attach to the servo motors. The final method used, screwing the wings to the servo motor, proved to be a success. The AEV did not have any major issues while running which was a design success. No wires caught and the wings rotated smoothly. The trailer successfully attached to the AEV and minimal maintenance was needed.
Below are the changes that the team would make to their craft:
* Use new sensors to run the craft using marks instead of time to make it more consistent
* Redesign the wings to cut weight off the craft
* Check the front to back balance and move the support arm
* Secure Arduino and battery inside of craft
The team’s AEV design was superior to the other teams’ designs because of its reliability, durability, and general ease of use. Several of the other teams’ designs had catching wires, propellers or wings. The Winnebago design did not have this problem because of the internalized wiring system. It was a reliable craft that did not need any maintenance which is important. Although the design was not as efficient, it got the job done every time. This is superior to a craft that constantly breaks down.