The most recent lab was a challenging one to get through for a number of reasons. First and foremost was that the team unfortunately forgot to bring the AEV to class during the lab period, leaving the team stuck without a model to work on. In its place, the team drew out rough sketches to go over the AEV design and discuss how every part in the AEV would be sourced over Spring Break. The team also looked at the proposed design for both the 3D-printed arm and the laser-cut body. Upon reading more carefully into the requirements for the AEV layout and design, the team agreed that the 3D-printed arm design did not provide enough of a benefit to justify the extra mass and necessary testing, and agreed to go back to the original arm design. Briefly an idea was proposed to use Servo motors to rotate the primary motors for the reversed section of the track, but the team was unable to find a practical way to implement this. The team did come to an agreement on the basic layout of the laser-cut body, however. This meant that the only necessary part not already in the kit was the laser-cut body. The team agreed to look further into this over Spring Break. After separating for a week over break, the team reconvened on Monday afterwards to work on the model. Due to the proximity of both the midterm and the Preliminary Design Report, the entire engineering class on Monday and Wednesday was given to the teams as a lab period rather than covering new material. During these periods, the team began work on Performance Test 1. This test required that the team create scenario code to run the AEV along the track and stop right before the gate, triggering the sensor. This code was then to be tested on two separate AEV designs, whose performance the team would then compare. Unfortunately, the team ran into another roadblock here, as the distance traveled by the AEV became erratic and inconsistent – sometimes travelling well past the gate and sometimes stopping just short with no change in the numbers. The team struggled with this for a while before realizing the issue was with the faulty reflectance sensor. After replacing this, the team managed to get the code working and briefly tested both designs on the track. The primary differences had to do with wing position – one used the team’s original design of vertical wings, while the other placed them at a slight angle.
The most obvious takeaway had to do with the reflectance sensor and the subsequent problems the team encountered. Team members spent a significant amount of time trying to troubleshoot the issue in the code, which could have been better spent if the reflectance sensors were checked earlier. In the future, the team will be more methodical about troubleshooting issues and will attempt to look objectively at the AEV and any possible areas that could be affecting performance. Another important takeaway had to do with the motor speed. Initially, the AEV design was stable enough that the team could run it without fear of falling off the track or bumping into anything. After running through Performance Test 1, however, the team realized that while stability did not affect the performance of the AEV, it significantly affected the AEV’s ability to stop on cue and to connect to the magnet on the R2D2 replacement. The team realized that efficiency was not the only concern with greater speed – providing too much motor power also caused issues when it came time for the AEV to perform actual tasks. By simply lowering the motor speed by ten percent the team was still able to run the AEV swiftly while also improving the success rate with regards to both the magnetic connection and stopping in front of the sensor.
Team Notes
March 27, 2017 – Lab 9
Teammates present: Iskandar Roslen, Jacob Jeffers, Abhishekh Kumar, Vince Le
Objective: Complete Lab 9A scenario code, run scenario code on both 9A designs and evaluate performance based on screening and scoring sheet
Decisions: The team has decided on running AEV Model 2 from the designs due to Model 1 having collision issues with the track. The team has also decided to cut slightly shorter wings in Model 1’s design to test again (Model 3). Jacob will take the AEV for storage.
To-do/Action items: Order custom body and wings to be laser cut. Test Model 3 against Model 2. Test Code 1 against Code 2 in Lab 9B. Complete PDR by Monday.
Reflections:
This week the team was able to rebuild the stock AEV into 2 of our own design. We were implement parts from Jacob and Vincent’s designs into two AEV’s that could be tested against each other. This lab revealed to us that while our vertical wing design could clear the track on the straights, it would bump into the track holders on the turns. This led us to rethink our design into slightly shorter wingtips and a slimmer body to prevent the roll. We will need to get these parts submitted for laser cutting.
Schedule
Code
Version 1:
//Moves AEV to gate then stops
//Moves AEV forward until position 290
reverse(4);
motorSpeed(4,35);
goToAbsolutePosition(290);
//Applies forward thrust to brake
//back(motor)
reverse(4);
celerate(4,40,40,2);
brake(4);
Version 2:
//Moves AEV to position 190 with higher thrust then cuts power to coast to gate
reverse(4);
motorSpeed(4,55);
goToAbsolutePosition(190);
brake(4);