System-Prototype Validation

 

Final Test Result: 

The main goal of this data collection is to use the AEV prototype to simulate a car travelling different routes around campus which focuses on energy consumption or usage. In the final test, we did a non-stop run and a 6-stop-run on the straight track to simulate traveling in real life with and without traffic.  

By comparing the data that extracted from Arduino and analyzed in Matlab, we find out that the no-stop-test used remarkably less energies than the 6-stop-test. This figure shows that the 6-stop-test used around 182 J energy whereas no-stop-test used about 78 J energy. This result successfully indicates that traveling without traffic in our campus can potentially save more than 50% energy produced from the vehicles. However, since we only did the two tests once, we didn’t take the average value into calculation, so there are some potential errors. We will test each case for five times and take the average value later to more accurate data for further calculation. 

  Figure 1: Comparison of no-stop-run and 6-stop-run 

Some of our user needs are not included in our test plan and this causes the problem. In our correlation matrix, it shows that many of the users want to have less construction and wider roads, but this is not applicable in the test. We successfully showed that our project will fulfill one of the needs which is to save energy by reducing traffic, but we don’t have a methodology to satisfy the others. Moreover, we designed a load test with our prototype carrying a caboose. This is to figure out how much energy a truck would consume while it’s traveling. But we didn’t test it in the final. Overall, our prototype works pretty well but we still need to come up with some other ideas to include other user needs as more as possible.  

Validation: 

The prototype performed spectacularly, meeting and surpassing all design requirements as seen in Figure 4.  The requirements targeted all of our user needs, but three user needs in particular were prioritized above the others: fast travel time, safety through stability, and reliable servo brakes.  

Travel time, with the engines at less than 40% of maximum power, was on average more than five seconds under the ideal time of 15 seconds as seen in Figure 1. An increase in motor power can easily be increased to meet the user’s travel time needs of any realistic situation. The engine power could even be decreased, possibly to 20-25%, to consume even less energy. Doing so would offer both decreased costs and emissions to the user in the long run. 

Balance and sway during travel was a mere five degrees as compared to the ideal maximum of 15 degrees. Minimal sway on the vertical axis is vital to prototype safety and stability as it prevents the chance of the prototype crashing and/or falling of the track. The stability can be used to offer a sense of safety and security to users. This value could be further reduced by adding weight to the prototype’s center of mass, but this would unnecessarily increase cost and power to operate. Thus, we are satisfied with the low value of five degrees. 

Servo brakes, in both slow and fast tests, stopped the prototype within one inch, with the ideal value being no more than six inches. Well-functioning and reliable servo brakes are essential to users as it offers a sense of safety and security to the user; a vehicle without a braking system would be complete nonsense to any user. Braking distance could be further decreased by using an additional servo motor or stickier brake material, but this would add unnecessary cost and weight since the current brake distance greatly exceeds the requirement. 

The user needs of energy efficiency and consumption were not prioritized but are optimized incredibly well as a result of the removal of stops from test runs. This can be seen in the miniscule energy use of the prototype in the no-stop run as seen in Figure 1. Cost, also not a priority, is expected to be relatively low given the minimal amount of materials implemented within the prototype, well under the ideal amount of $150 in additional parts. Lastly, the user need of a load being deliverable can also be met using an increase of motor power, which is readily available given all tests passed with less than 40% of motor power.   

All prototype requirements were met, with expectations being greatly exceeded in multiple cases. All user needs, prioritized or not, were satisfied. While some users may believe additional measures such as additional brakes or weight should be added to the prototype to improve its capabilities, the team is highly satisfied with the performance of the prototype and feels that any additions will add unnecessary weight and cost.  

Appendix: 

AEV Runs  Distance  No stop usage (joules)  6 stop usage (joules)  Percent increase 
  28 ft  78.07  182.83  234.19% 
Real world Car Comparisons with no traffic  Driving Straight  CO2 (kg per gal)  Distance (Mi)  Gal (25 mpg) 
    8.89  1.90  0.08 
  CO2 for 1 trip/car  100,000 cars  CO2 per semester (75 days)  CO2 per person 
  0.68  67541.20  5065590.00  50.66 
  Cost for 1 trip ($2.50/ gal)  Cost 100,000 cars  Cost per semester  Cost per person 
  $0.19  $19,000.00  $1,425,000.00  $14.25 
Real World Car comparisons with traffic stops  With traffic stops (% increase)  CO2 (Kg per gal)  Distance (Mi)  Gallons (at 25 mpg) 
  234.19%  8.89  1.90  0.08 
  CO2 for 1 trip / car (Kg)  100,000 cars (Kg)  CO2 per semester (75 days) (Kg)  CO2 per person/semester (Kg) 
  1.58  158174.74  11863105.22  118.63 
  Cost for 1 trip (2.50/gal)($)  Cost 100,000 cars ($)  Cost per semester ($)  Cost per person/semester ($) 
  $0.44  $44,496.10  $3,337,207.50  $33.37 
Potential Savings  CO2 for 1 trip / car (Kg)  100,000 cars (Kg)  CO2 per semester (75 days) (Kg)  CO2 per person/semester (Kg) 
  0.91  90633.54  6797515.22  67.98 
  Savings for 1 trip (2.50/gal)($)  Savings 100,000 cars ($)  Savings per semester ($)  Savings per person/semester ($) 
  $0.25  $25,496.10  $1,912,207.50  $19.12 

Figure 2: Prototype energy/costs translated to automotive fuel/costs. 

 

Figure 3: Cost of commuting around campus per semester (~15 weeks) 

 

Figure 4: CO2 emissions from campus commuters per semester (~15 weeks) 

 

Figure 5: Vehicle Requirements /Final Testing Score Card