Screening And Scoring

The purpose of this lab is to understand the concept and the method of concept screening and scoring for the decision making-to shrink the range of the AEV concepts by using specific screening criteria. In this lab, the most vital specific screening criteria are balance, minimum blockage, aero-dynamic, center-of-gravity location, maintenance, cost and durability.

The group assembled the AEV according to sample AEV designs and three brainstorm designs from group members. The group ranked these AEV designs according to screening criteria and best design was found by comparing scores in concept scoring matrix.

The Design-1 put the Arduino back under the rectangle baseplate and changed the shape of the wings. But the structure was heavier on the back and bent the base. During the first test, AEV was commanded to move 5.5 seconds forward and brake 1 second.

However, the AEV did not reach the terminal point. During the second test, the AEV was commanded to move 10.5 seconds forward and brake 2 seconds. The AEV moved the full length of the track and stopped right at the terminal point. This was a standard design and achieved 3 score in most terms.

The Design-2 solved the problems appeared on the first design. The members adopted the original shape of the wings and placed the Arduino closer to the middle on the baseplate, which made the AEV more balanced and flat.  Group members also changed the L-shape arm to T-shape arm to ensure the balance of the AEV. Based on these improvements, Design-2 achieved 4 score in balance, center-of-gravity and aero- dynamic.

In the Design-3, the group tried to improve the aero-dynamic of AEV by putting the wings at the extreme back side. The base was bent obviously because of the change of motors’ position thus changed the direction of thrusting. The change increased the engine efficiency and achieved 5 score on aero-dynamic. However, the unbalanced design made the vehicle highly unstable on the track when acceleration. Later, the design was abandoned.

The Design-4 solved the center of gravity problem plagued by previous designs. The majority of the weight was centered along the L-shape arm and distributed vertically. The design is wider with the base being vertical rather than horizontal. Since the base is vertical, air resistance increased dramatically. The design achieved full score of 5 on balance and center-of-gravity, but only 1 score on aero-dynamic. The problem can be remedied by changing the shape into streamline design.

The group chose to continue developing Design-2 and Design-4 and looked for the further improvement on these designs.