PT2.2 - 3 designs and decision making matrix

Designs

1.
This car will have 3 axles, the back wheels, the front wheels and the "multiplier". The multiplier is an axle connected to a large cylinder to increase the distance traveled by the car.
















2.
This car uses an extended axle to increase the distance traveled. Balloons are cut up and attached to the cds to create wheels with more traction.



3.
This car uses 1 large central wheel as it reduces as it hopefully increases the chance of it going straight. However, this might create the problem of the car wobbling.















Decision Matrix
Some of the decision matrix we are weight, size, time to produce, stability, traction and cost. Out of these,  we chose stability, traction, cost and weight as we felt that these 4 were the key factors towards the car's score.

Stability is important as the score of the car is calculated by displacement, not distance. This means that if the car wobbles and turns, the distance traveled won't be counted, and if the car goes backwards, it reduces the score. We therefore need to ensure that the car goes as straight as possible.

Traction is also important as without traction, the wheels will just spin on the spot, instead of propelling the car forward. Traction can be increased through the use of rubber.

Cost is an important factor as reducing the cost will allow us to redo the entire car if it does not perform like we wanted to

A car with a higher weight will require more energy to travel the same distance compared to a lighter car, and because the only energy source is the mousetrap, there is a limited amount of potential energy stored in the mousetrap. We therefore need to make the most use out of the limited energy source by reducing the weight of the car.




Criteria
Weight
Traction
Cost to produce
Stability
Row total
Normalised Priority Value
Weight
-
3
1
1
5
0.278
Traction
0
-
3
3
6
0.375
Cost to produce
2
0
-
1
3
0.167
Stability
2
0
2
-
4

Column Total: 18
0.222




Criteria
Normal
Priority
Value
Design Idea #1
Design Idea #2
Design Idea #3
Weight
0.278
2
0.556
4
1.112
5
1.39
Traction
0.375
3
1.125
4
1.5
1
0.375
Cost to produce
0.167
2
0.334
4
0.668
2
0.334
Stability
0.222
4
0.888
4
0.888
1
0.222

Total

2.903

4.168

2.321


We have decided to build design 2





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