Over the past weeks, team Q has been conducting tests on the reflectance sensors and propellers to determine the most efficient use of each part of the AEV. Two different tests were run on the reflectance sensor. They were changing the number of marks per rotation of the wheel and distance of the wheel from the sensor, both were run to determine if the accuracy of the AEV could be increased.
The number of marks was increased from 8 to 16 for the first set of tests and 8 to 14 in the second set of tests. This was done by placing electrical tape on the wheel to change the number of instances the wheel sensor could sense a change from light to dark. However, when the marks were changed, the AEV never stopped and the tests were inconclusive. When the number of marks was returned to the normal 8, the AEV stopped at the prescribed mark 14 feet away from the starting position. Thus, the team concluded that the most effective number of marks for the wheel is 8 marks.
All sets of tests were conclusive for the changing of the distance of the wheel from the sensor. The goal of the tests was to have the AEV stop its motors as close to the distance 14 feet away from zero, which is about 345 marks away from zero. The tests were run from the twenty foot mark towards zero. When the reflectance sensor was at its normal distance from the wheel, the average marks away from zero that the AEV stopped with this configuration was 342.6 marks. To increase the distance from the sensor, a notecard was folded in half multiple times to create a distance equivalent to eight layers of the notecard, as seen in the picture below. The average distance away from zero for the set of tests with this configuration was 318.1 marks. The final set of tests were conducted with two pieces of folded notecard, making a distance of 16 layers of notecard. The average marks from zero with this configuration was 316.7 marks. From these results, the team concluded the most effective distance for the wheel to be from the sensors is its normal distance when the wheel is secured firmly to the arm.
As for the propeller tests, three different propellers were tested a total of five times each. The propeller types were a small propeller with a flat tip, a large propeller with a flat tip, and a large propeller with a rounded tip. Each test, the AEV was coded to run 247 marks at 30% power.
The small, flat tip propeller had inconclusive tests, as it was able to move the AEV, but at a certain point stopped. Therefore, the propeller would not be useful in actual transportation.
The large flat tip propeller began moving slowly, but took much longer to travel the same distance as the rounded tip propellers at the same power. It took about 50 seconds for the flat tip propellers to travel the prescribed distance, and only 12 seconds for the rounded tip propellers to travel the same distance. This led the group to choose the the rounded tip propellers as the most efficient propellers for the AEV as the moved the AEV the fastest over 247 marks at the same power as both types of flat tip propellers. The speed is important as not only would a higher speed save time, it would save money compared to the other propellers because less power is necessary to travel the same distance in a shorter period of time versus a longer period of time.
Key Priorities
Moving forward, especially in the near future after Advanced Research and Development 1&2, the team is still focused on design aspects to make the AEV run as efficiently as possible. Using data provided by the research fo teams K and L, the team will be able to implement different changes to the AEV design, such as motor configuration and the use of a servo motor. It is a priority of the team to not only pass the upcoming performance tests, but to move as efficiently as possible. Therefore, a servo motor would allow the AEV to stop more efficiently and provide the passengers with a smoother ride. Now that initial testing is done, the team must begin to consider the budget more and ensure the the AEV is both efficient and cost effective.