Group G – Hannah, Jeremiah, James, and Sydney Progress Report Week #9
Instructor –Dr. Li 3/4/19
Week #9
Situation
The first item that was investigated in the Advanced R&D Performance Testing was the Servo Motor. The servo motor is capable of rotating to a desired angle and maintaining its position. The reason as to why the servo motor was utilized was to effectively stop the AEV in a more efficient matter. After attaching the servo motor on the arm of the AEV, the lever arm hit the front wheel of the AEV to create friction against the front wheel causing the AEV to stop.
The second item that was investigated in the Advanced R&D Performance Testing was the Battery Testing. This topic was chosen to wanted to see the relationship between battery voltage and number of test runs as well as to determine if there was a relationship between battery voltage and distance traveled. The Lithium polymer battery is the sole power source of the AEV, so understanding the potential it has in affecting the AEV performance is an interesting point. After each test run on a straight track, the distance and voltage was recorded and repeated until satisfaction was found.
The final item that was investigated in the Advanced R&D Performance Testing was the Propeller Configuration. After doing the Wind Tunnel Lab, the orientation of the propellers was found to have a serious effect on their efficiency. To find the optimal propeller configuration, propellers were tested in four different combinations. 3030 and 2510 propellers were tested as well as the distance between them and the end of the AEV. The data was downloaded from the Arduino and uploaded to the AEV Analysis Tool in MATLAB to create a graph of Power vs. Time and Power vs. Distance, with all the different combinations included on each. The best propeller configuration was found utilizing that data.
Results & Analysis
In the first lab, the servo motor was affixed to the L-shape arm on top of the AEV right behind the front wheel. The servo arm would rotate, make contact with the wheel, and stop the AEV. The team decided to keep the servo on the AEV, with a few modifications. The first modification was finding the right amount of rotation for the servo arm so that it makes sufficient contact with the wheel. The second modification was adding tape to the servo arm so that there is more friction between the arm and the wheel. With these modifications, the AEV was able to come to very quick stops, almost on-par with reversed-motor braking. The servo also draws far less battery energy than the motor braking. Based on this information obtained, that servo will be kept as it is, possibly with a new material on the arm that has a higher coefficient of friction than the current duct tape material.
In the second lab, the battery’s voltage was recorded after each run. The voltage was later compared to the number of test runs and the distance traveled.
Fig 1. Voltage vs. Number of Test Runs
Figure 1 shows that, for each test run, the battery decreased in voltage by approximately .02V.
Fig 2. Voltage vs. Distance
Figure 2 shows how much power is consumed compared to the distance traveled. The voltage decreases by about .02V for every 22ft traveled. That’s about .001V per foot.
In the third lab, four propeller configurations were tested. The first configuration was orange propellers with the motors moved as back in their brackets as possible and the second configuration was gray propellers with the motors moved back as much as possible. The third configuration was orange propellers with the motors moved up as far as possible and the fourth configuration was the gray propellers moved up as much as possible. The team selected the first configuration with the orange, moved back motors (Fig. 4).
Fig 3. Power vs. Time
Fig 4. Motor not Slide Forward
Fig. 5 Motor Slide Forward
Figure 3 shows that the power used with the orange propellers, no matter what the position, was greater than the power used with the gray propellers. This is likely because of the larger mass and surface area of the orange propellers.
Fig 6. Power vs. Distance
Figure 6 shows that the distance traveled was far greater for the orange propellers than that of the gray propellers. The motors moved back also had an increased distance compared to when the motors were moved up. The group will be moving forward with the orange, moved back motor as it was far more efficient when comparing energy consumed and distance traveled.
Takeaways
The main takeaways from the labs were primarily design-based. The servo motor will be kept on the AEV because of its efficient properties and the AEV will continue to be used with orange propellers with the motors moved back because of the increased distance traveled. After the labs, the group found that, with team member fully contributing, the project goes very fast and very easily. Communication is also key because it allows the team members to coordinate their work effort to finish objectives faster. When all team members are on the same page, the work goes by very smoothly. Time management is also very important because team members can determine what they have time to get done in lab and what they have to do outside of lab.
Forwards Looking Plan
One of the main goals being pursued is the performance tests and ensuring the design is as sound and efficient as possible. First a choice must be made of the most efficient AEV from two designs. Evaluate based on MCR, analyze all differences between the designs. The focus will be on design flaws and energy efficiency. Also finding the best code for braking and starting the AEV will be a top priority. Performance test two also falls under Lab 9A, this means the team may start testing two separate code solutions. The codes will be analyzed for how efficiently they meet the project objectives.
The critical design review draft is also on the forward looking agenda for lab 9A. It establishes the base standard to ensure the AEV will appease the requirements in the given time-frame. The final results are a top priority of the design review. The team will collaborate and come to a conclusion.
Weekly Goals
- Meeting to complete the objective of the week, focusing on performance testing 1
- CDR Draft, purpose of lab, discuss findings
- Website update 3, elaborate on current AEV findings
Weekly Schedule.
