During the lab for week 3 team G became familiar with the AEV’s positioning sensors. The team did this by first installing the sensors onto the AEV wheel arm. The sensors work by reading two reflective strips that are located on the wheel. Once the sensors were attached the team proceeded to calibrate the sensors. Depending on which sensor reads the reflective strip first, the arduino board interprets the AEV as moving forwards or backwards. For team G when the AEV was tested moving in the forward direction the arduino interpreted the AEV as moving in a backwards direction. To fix the issue the team switched the ports on the arduino that the sensors were plugged into. For the final calibration test the team wrote a piece of code that would command the AEV to go forward a given number of sensors readings and then come to a stop once the number of forward readings had been reached. The AEV executed the given commands and the team moved to the second part of the lab.
For the second part of the lab the team analyzed propulsion and advance ratio efficiency. This part of the lab used two different types of propellers and a wind tunnel. The purpose of this part of the lab was for the team to understand propeller efficiency and to chose a propeller design for that would best suite the needs of their AEV to complete the mission.
Both parts of the lab this week were important for the AEV build project. Becoming familiar with the sensors will allow the team to write lines of code that command the AEV to go to certain positions on the track. It also allows the team to preprogram the AEV’s every stopping point along the track. This is important first to stop at the access gate and secondly to stop to pick up the r2-d2s and to stop at drop off point. The second part of the lab was important for efficiency reasons. At the beginning of the project the team was given multiple propeller styles. From this part of the lab the team learned which propellers would be more efficient for their AEV build.
Result and Analysis
The propulsion efficiency in relation to the Advanced Ratio for Propeller 2510 and Propeller 3030 are represented below in Figure 1 and Figure 2.
Figure 1: Propulsion Efficiency versus Advance Ratio for the 2510 propeller
Based on the Figure 1, the Advanced Ration increased as the propulsion efficiency decreased. It can be concluded that 2510 propeller configuration is not an optimal configuration as a high Advance Ratio is only achieved when the system is inefficient. There will be too much use of battery power that could make it impossible to complete the mission for AEV.
Figure 2: Propulsion Efficiency versus Advance Ratio for the 3030 propeller
Based on the Figure 2, the 3030 propeller configuration is more efficient as the configuration propulsion efficiency and the Advanced Ratio were complementary to each other. The graph showed that as the Advanced Ration increased, the propulsion efficiency increased as well. The team will utilize this configuration with careful step in maintaining the Advanced Ration at around 0.5 for maximum efficiency.
The thrust scale reading in relation to the Arduino Power setting 3.
Figure 3: Thrust versus Power for Each Propeller Used
Based on Figure 3, propeller with 3030 configuration experienced more thrust at every power setting of the Arduino compared to the propeller with 2510 configuration. This result strengthen the team’s choice on the 3030 propeller configuration as it also provides greater thrust in addition to its efficiency.