Caboose

There’s a speed bump after picking up the caboose.

We need to speed up the AEV to get pass the speedbump without falling off.

Testing on 11/3/14

So when we were testing our AEV, we were having trouble reaching the gate.

During our first attempt, the AEV flew off the track.

Throughout multiple runs, we would over shoot the gate sensor, and would hit the  “fail” test sensor.

After several testings, we realized that the AEV would stop at the gate sensor, but it would continue rolling, and it would hit the “fail” sensor. This sensor was about 6 inches away from the gate sensor.

And finally, we were able to get to the gate sensor at:

motor speed: 16%

brakes at 2 seconds

and at absolute Position of 185 marks

 

 

 

 

Sensors: test day (tuesday 9/23/14)

At first we had problems getting our AEV to travel 13.5 feet.

We reduced the number of steps to 40 steps, and that was able to move almost the whole way.

We figured out the problem was that the reflective sensors we’re tied down by zip ties. Once we tied down the sensors, they worked properly and moved the proper number of steps.

Lab 3 Appendix and Arduino Code

 

Appendix

Concept Screening Matrix

 

Criteria

Sample AEV (AEV1)

  

AEV2

  

AEV3

  

AEV4
Balance

0

+

–

+
Minimal Blockage

0

0

–

0
Aero-Dynamic

0

+

+

–
Center of Gravity

0

+

–

+
Durability

0

+

0

+
Maintenance

0

0

0

0
Cost Effective

0

0

0

0
         
Sum +’s

0

4

1

3
Sum 0’s

7

3

5

3
Sum -‘s

0

0

3

1
         
Net Score

0

4

-2

2
Continue?:

No

Yes

No

Yes
         

 

Concept Scoring Matrix

 

 

Sample AEV (AEV1)

 AEV2   AEV3   AEV4  
 

Criteria

  

Weight

  

Rating

 Weighted Score  

Rating

 Weighted Score  

Rating

 Weighted Score  

Rating

 Weighted Score
Balance 20%

3

0.6

4

0.8

2

0.4

5

1
Minimal Blockage 15%

4

0.6

4

0.6

3

 0.45

4

0.6
Aero-Dynamic 15%

3

 0.45

4

0.6

5

 0.75

1

 0.15
Center of Gravity 20%

3

0.6

4

0.8

2

0.4

5

1
Durability 10%

3

0.3

4

0.4

3

0.3

4

0.4
Maintenance 10%

4

0.4

4

0.4

4

0.4

4

0.4
Cost Effective 10%

5

0.5

5

0.5

5

0.5

5

0.5
Total Score: 3.45  

4.1

  

3.2

   4.05
Continue?:

No

   Develop  

No

   Develop
                   
                   
                   

Copy of Arduino Code
1. Accelerate all motors from start to 25% in 3 seconds.                             //celerate(4,0,25,3)
2. Run all motors at a constant speed (25% power) for 2 seconds.           //motorSpeed(4,25)
//goFor(2)
3. Run all motors at 20% power for 2 seconds.                                               //motorSpeed(4,20)
//goFor(5.5)
4. Reverse all motors.                                                                                                //reverse(4)
5. Run all motors at a constant speed (20% power) for 2 seconds.          //motorSpeed(4,20)
//goFor(2)
6. Brake all motors.                                                                                                     //brake(4)

Lab 3 Screening and Scoring

Executive Summary

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.