2.1 Role & Engineering Goals

1.1 Roles & Timeline
Project Manager (Blog IC): Lucas
-  Responsible for documentation and care of mousetrap
-  Ensures completion of all tasks (on schedule)
-  Has final say for issues that cannot be settled by consensus

Drivetrain Engineer (Data Analysis IC): Ao Shen
-  Responsible for developing system to transfer energy from "engine" to wheels
-  Ensures proper testing and documentation of drivetrain materials

Wheel Engineer (IC of construction and testing): Durwa
-  Responsible for wheel choice and design
-  Sources materials for wheels
-  Works with Drivetrain Engineer to determine wheel-to-axle ratio and attachment

Chassis Engineer : Timothy
- Responsible for look and function of the chassis of the car (body of car)
- Sources for materials for the chassis
- Works with drivetrain engineer and wheel engineers to ensure function and look of the wheels and drivetrain components

Timeline:
By 20 March:
- obtain materials
- consolidate different design ideas
- complete the evaluation & decision matrices
- build the chosen mousetrap car design

By 27 March:
- test the first model of the mousetrap car twice
- make two modification to design

By 1 April:
- Final Testing
- Take video of 3 attempts and upload to blog

By 3 April:
- Complete all Blog components


1.2 Engineering Goals and Brainstorming
Design criterion to be considered:
- Weight
- Size
- Appearance
- Time to produce
- Cost to produce
- Ease of use
- Availability of materials
- Environmental Impact
- Safety

Design 1

Design 2

Design 3


1.3 Evaluation and Decision Matrices
Design criterion to be considered:
- Weight
- Size
- Time to produce
- Cost to produce
- Ease of use
- Availability of materials
- Environmental Impact
- Safety

Evaluation Matrix


Criterion
Criterion 1
Criterion 2
Criterion 3
Criterion 4
Criterion 5
Criterion 6
Criterion 7
Criterion 8
Criterion 9
Row
Total
Normalised
Priority
Value
Weight
Size
Appearance
Time to produce
Cost to produce
Ease of Use
Availability of Materials
Environmental Impact
Safety
Criterion 1

3
4
3
2
2
3
4
0
21
0.14
Weight
Criterion 2
2

4
3
3
2
3
3
0
20
0.14
Size
Criterion 3
0
0

3
0
2
0
0
0
5
0.03
Appearance
Criterion 4
2
1
4

3
4
3
1
0
18
0.12
Time to produce
Criterion 5
1
0
4
0

2
1
0
0
8
0.05
Cost to produce
Criterion 6
0
3
4
1
2

0
0
0
10
0.07
Ease of Use
Criterion 7
3
4
3
3
4
3

1
0
21
0.14
Availability of Materials
Criterion 8
2
2
4
0
0
1
2

0
11
0.08
Environmental Impact
Criterion 9
4
4
4
4
4
4
4
4
4
32
0.22
Safety
Column Total




146
1.00

Decision Matrix


Criterion
Normalised
Priority
Value
Design Option 1
Design Option 2
Design Option 3
Car Design 1
Car Design 2
Car Design 3
Votes
Score
Votes
Score
Votes
Score
Criterion 1
0.15
4
0.60
2
0.30
4
0.60
Weight
Criterion 2
0.01
5
0.07
0
0.00
4
0.06
Size
Criterion 3
0.00
3
0.00
4
0.00
5
0.00
Appearance
Criterion 4
0.12
3
0.36
2
0.24
5
0.60
Time to produce
Criterion 5
0.13
5
0.67
1
0.13
4
0.54
Cost to produce
Criterion 6
0.09
4
0.36
3
0.27
4
0.36
Ease of Use
Criterion 7
0.13
5
0.67
1
0.13
4
0.54
Availability of Materials
Criterion 8
0.15
5
0.75
0
0.00
3
0.45
Environmental Impact
Criterion 9
0.21
4
0.84
4
0.84
4
0.84
Safety
Column Total
1.00
38
4.31
17
1.91
37
3.97



1.4 Design Rationales

 Wheels
 - We used toy car tyres for both the front and back wheels. We chose to use toy car tyres because the thread pattern of the toy car tyre would give the car more traction. 

Chassis
 - The chassis of our mousetrap car is made out of the mousetrap mounted on a piece of cardboard. We chose cardboard as the main component to make up the chassis because it is lighter as compared to other materials (eg. wood, plastic). This will enable it to travel a further distance when powered by the mousetrap.

 Lever Arm and String Type
 - The lever arm is constructed by gluing several ice cream sticks together. We chose to do this so that the lever arm is sturdy and will not break when the car is moving forward, ensuring that the car moves forward steadily without any hiccups. The string that we used was nylon string. It is thin and durable, thus, it did not get in the way of the mousetrap during testing and we were able to easily coil it around the axle.

Axles
- We used copper tubes as the axles for both the front and back wheels because it could fit into the holes of the CDs we used as the back wheels and also the toy car tyre that we used as the front wheel. The diameter of the copper tube and the CDs fitted very well and there was friction between the copper tube and the CDs, such that when the string that was attached to the mousetrap pulled at the copper tube, the copper tube turned without the CDs sliding in place. This allowed the mousetrap car to move forward.

-  Positioning of Mousetrap
The mousetrap was placed at the front of the chassis. This ensures that the distance that the string is pulled by the lever is further, allowing the car to move further since the distance that the nylon string is pulled by the lever is further.

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