In the external sensors part of the lab, the team was able to understand how the reflectance sensor, when paired with the wheel with reflective tape, was able to see just how the sensor works and how it calculate how many times the wheel has rotated. The team had a little bit of difficulty at first with the sensor operating in the correct fashion, but once we zip-tied both of the sensors down, the readings were correct. If the team spun the wheel one way the readings increased, and if the wheel was spun the other way the readings decreased. The team had developed an understanding as to how the sensors should work.
Next, the team wrote a program in arduino to practice the functions it learned in the previous lab and the functions the team just learned. The functions learned were used to move the arduino to an absolute position, or position relative to the current place of the arduino. The team uploaded the new file to the arduino and attached the arduino to the new assembled AEV. The AEV was then attached to the track and the program was started and the Arduino was told to run. However, the AEV did not move. The motors ran, but the AEV itself did not move. After talking with instructional staff, it was determined that the proper amount of energy was not applied to the AEV motors. It was a little bit of a let down for the team, but it was good to see the fully constructed AEV run a program.
The second part of the lab was used to collect data on which propeller and configuration of the propeller is most efficient. The team used a wind tunnel with a motor and propeller mounted in the middle of it to gather this data. The data gathered was current, voltage, thrust scale reading and RPM at several different arduino power settings. With this data the team was able to calculate thrust calibration(grams), power input(watts), power output(watts), propulsion efficiency(%), and advance ratio. The team will be able to use the data and the calculations to determine with propeller and configuration of the propeller should be used to maximize power efficiency. The team can’t however draw any conclusions yet since not all of the propeller configurations have been tested. Below are a few of the graphs that the team has been able to assemble with the data collected.
Takeaways:
- The Arduino may need more power input than initally expected and the team is not having too great of a difficulty getting the AEV motors doing what is needed
- The sensors can be very valuable to calculate just exactly how many times the wheels have revolved
- The team will soon be able to figure out what propeller configuration will be the most efficient
