Lab three saw the completion of concept screening and scoring for each of the proposed AEV designs. The process of screening and scoring the designs, described in-depth below within the executive summary, yielded quantitative results that could be used to choose an effective design. The design chosen will have been the most capable of completing the task described in the Mission Concept Review.
Executive Summary
In Lab 3: Concept Screening and Scoring, the group tested multiple designs and scored each design on several criteria. The AEV’s were tested on balance, blockage, center of gravity, maintenance, durability, cost, and environmental impact, as stated in the Lab Manual within the AEV Documents (1). This lab was the first time the fully constructed AEV was used for testing. The group became familiar with design decision making, the structured method of screening and scoring design concepts, and programmed the AEV for a test operation on the track. Arduino code was written in order to complete two separate tasks. The code accelerated all motors from start to 25% in 3 seconds, ran all motors at 25% for 1 second, then ran all motors at 20% for 2 seconds. After that, all motors were reversed, ran all motors at 25% for 2 seconds, and braked all motors. This program was used to test the AEV first on the static track on the table, then on the overhead track. These test runs were helpful in getting comfortable with operating the AEV on the track and seeing how it behaved on straights, turns, and going over small bumps.
The AEV on the test track was able to operate the given functions set from the computer. Balance was not an issue, as the AEV securely stayed on the track while performing the given commands. The AEV had a well-maintained center of balance, not leaning to either side, forward or backward. The AEV was able to advance when given the command “celerate(4,0,25,3)”, however, when given the command, “Reverse” and “motorSpeed” it did not change direction, simply stopping at a point when the motors reversed rotation. There was initially some difficulties in getting the motors to rotate in the desired direction as to have the AEV travel forward or backward. It was found that commanding the motors to rotate forward made the AEV travel backward, and this issue was addressed in the arduino code, as seen in figure 3. Though the AEV was able to perform the program with balance, there was an issue with consistency, which can be attributed to the inconsistencies with the track.
Each design presents unique features that either help accomplish the objective or adhere to the Star Wars theme. The “A-Wing” and “Airplane” concepts were combined to form the final design, based off of a concept screening scoresheet. They were both the highest scoring designs out of the whole group according to the scoresheet, seen in figure 1. The “A-Wing” design did not have a good center of gravity, though the “Airplane” design did have a good center, of gravity, so that aspect of the design was added to the final design. The “Star Destroyer” Design, though it adhered to the Star Wars theme very well, could not be made to be balanced, and also would have required extensive work with the solidworks program and a 3D printer. “Design D”, could have been the most cost effective, though it lacked the detail that could have been used to fulfill the Star Wars Theme. In the Concept Scoring Matrix, seen in figure 2, emphasis was put on cost and balance of the AEV.
In conclusion, The AEV was shown to be a satisfactory model that could perform well in a full-scale test. The team also learned how to do concept screening and make decisions involved in the design process. Besides all of this, the group worked together on a test Arduino code which is documented in figure 3. The team used this code to learn about how the AEV would perform under a real scenario. The team saw that there could be potential error created by using the “brake” command which stops power from being put into the motors but does not stop the AEV from moving. This can be countered in future labs by using servo motors.
Appendix
Figure 1: Concept Screening Scoresheet
Figure 2: Concept Scoring Matrix
Figure 3: Arduino Code
References