The second advanced AEV topic Group A did was energy analysis. Since the group didn’t have chance to compare the AEV design to other groups’to make improvement, thus, the group compared different designs inside the group to try to find some pros and cons of each design. Basically the designs are made up of the same part and same amount of material, a T shape, an arm, an Arduino, battery and 2 motor with propellers. Technically the group had 2 types of designs to compare, one horizontal and one vertical. The goal was to find out how different designs have different propeller force, friction force and marks error and to choose a better design finally.
The basic procedure of this Energy Analysis topic is to measure the weight of the AEV, run the AEV on the test track with scale and with 4 lines code as shown. Then read the start, stop position of AEV from track, read marks where motors stop and AEV stops using the collected data from MATLAB program. Finally enter all needed information into a provided excel sheet, the marks error, friction force and propeller force will show up.
Firstly, the horizontal design was constructed as the picture shows (figure 1). Next, the vertical design was constructed and tested (figure 2). With the result shown, it was easy to find the vertical AEV had less marks error, more propeller force and also more friction force than the horizontal one. However, the net force is less than the horizontal one (figure 4, figure 5).
Then, the team tried to figure out why this happened, it was found out that the vertical design was not very balanced when hanging on the track (as can be seen on figure 2). This was solved by switching the wheels of the AEV to the other side of the arm and it did become more balanced than the previous one (figure 3). Finally a test was ran on the newly designed one. This time, the AEV had more propeller force, friction force and more net force than the previous unbalanced one, but the net force was still less than the horizontal one. By the way, a higher marks error was generated. (figure 6)
The result is not hard to analyze. First of all, there were definitely uncertainties and errors about the test. Each run could end up in different positions, that’s the mark errors, this could be caused by the rolling friction of the wheels on the track, and that varied for each run. The team’s results were all within the acceptable and reasonable range of error which should be fine. The most important part of this topic was to compare different designs to find out the best design to work on. According to the MCR, AEV would pause at the middle gate for 7 seconds before proceeding. Since the only force on the AEV is friction force that slows it down, thus the higher the friction force, the easier the AEV is to be controlled to stop. As a result, with almost the same material used, same weight, same code provided, and with the net force of horizontal design 5.9N, vertical balanced design 5.6N, it can be concluded that while they both functioned well running, the vertical one that has a higher friction force will work better to accomplish the AEV project goal.
The group’s later on task will focus on how to improve the vertical design.
The design of this topic is easy to understand and convictive since forces are really important factors that affect AEV designs.
Result figures
figure 1. horizontal design
figure 2. vertical design
figure 3. vertical balanced design
figure 4. horizontal design tested data
figure 5. vertical design tested data
figure 6. vertical balanced design tested data