Summary
During the fifth week of lab, a concept scoring matrix was used to analyze the different AEV models. The purpose of this lab was to become more familiar with techniques for design decision, to become more familiar with a structured method to score and screen design concepts, to program and test a sample AEV on the track, and to perform concept screening and scoring methods with the various AEV design concepts using the sample AEV as a reference.
After studying the sample concept scoring matrix as found in the lab manual, the team built an AEV based off of a design concept established in Lab 04. The AEV was built so that it had a rectangular part vertically placed in the middle with the arm with connecting wheels attached to this piece. One end of the AEV has a part with two cut outs, and the other end has two extensions where the propellers are attached. The battery was placed on the bottom of the AEV and the Arduino was placed on the right side of the vertical piece in the center (See appendix). A simple program was written where the AEV ran on the straight track and then the team developed successful criteria that would help to evaluate each design. Finally, the team performed concept screening for each of the designs created in Lab 04.
Results and Analysis
The results from lab five were qualitative judgements that needed some concrete method of measuring them in order to compare the different AEV designs. A Concept Screening Matrix and Concept Scoring Matrix were used in order to quantify the experimentation.
Table 1: Concept Screening Matrix
Table 2: Concept Scoring Matrix
The Concept Screening and Concept Scoring Matrices, shown above, helped evaluate the group’s judgements of each individual design. The reference is the standard design the group was instructed to build and more importantly, the design used in previous labs. This design was served in the screening reports as a baseline to compare the other designs to. A discussion of each design compared to the reference follows.
Design 1 was designed by Connor Higgins. This design was not able to be constructed because it required parts that needed to be 3D printed and therefore, was compared theoretically to the reference design. The balance of this design was one criteria where this design struggled, mainly because of the arms that would hold the propellers. The weight of the propellers on the end of the arm would most likely torque the body of the AEV, reducing the balance. The weight and cost of this design were good because of the lightweight materials used. Aerodynamically, the design was very sleek and had a low profile, making it ideal. The durability and flexibility, the ability to modify the design if needed, of the design was another couple of areas where the AEV was okay but not spectacular.
Alador Sisay created Design 2. As this part also required 3D printed materials, it did not run on the track. The balance of this design was not spectacular but was not poor either. This is because of the shape of the 3D printed section. This 3D printed section was large in shape which increased the weight and cost of the design while also reducing the aerodynamics of the vehicle. The design however was very durable, but lacked in flexibility.
The third creation, Design 3, see Appendix A, was made by Kristin Crowell she scrapped her last design. This design was able to be tested on the track and performed very well. When placed on the track rail, the vehicle sat evenly without any lean to one side or the other. In regards to the code, It seemed that 25% power was enough in order to get the AEV to run, however, the acceleration of the motor speed up to that point was not enough to move the AEV due to the static frictional force of the wheels on the track. With regards to the criteria, the weight and cost and aerodynamics were all tremendous because of the AEV’s small amount of lightweight materials used. Because of the design’s material usage and openness, is extremely durable and flexible.
The last design was Design 4, by Amanda Killian. This design involved a 3D printed shell that was not present, so the design was not tested on the track. Theoretically, the design showed a good promise for its balance on the track due to its symmetry. The weight and cost were slightly above average because of the materials used. Because the design was modeled after a Star Wars spaceship, the shape makes it very aerodynamic. This shaping and solid shell make the design very durable, but also reduces its flexibility.
As the Concept Screening and Scoring Matrices helped motivate, the group decided to pursue Design 3, by Kristin Crowell, for future lab experimentations because of its superior performance both on the track and theoretically when compared to the other designs.