Team Name: Group C Class: S3-02
1.1 ENGINEERING DESIGN
DEEP DIVE VIDEOS
View the entire “Deep Dive” episode by using the following links.
Please answer the following questions based on the videos and your understanding of the Engineering Design Process (EDP).
- What was the problem the engineers at IDEO were asked to solve?
Problems with a shopping cart was identified and these problems would affect the shoppers, thus they were asked to brainstorm ideas and solutions to solve the issues of a shopping cart and allow for a better shopping experience.
- Name two constraints that they had to deal with.
They had to deal with the time constraint. Also, they had to deal with the constraint of not being able to criticize each other’s ideas. The members were also not familiarised in the field of engineering/designing a shopping cart.
- What were two of the major concerns/issues the teams discovered from their research?
Theft of shopping carts often occur and the shopping carts were not safe for use as it might cause injuries to shoppers.
- IDEO uses several methods, processes and ideas to generate alternative solutions. What two principles or approaches appealed to you the most? Why?
The approaches are that IDEO just poured out wild ideas on the new design of the shopping cart, and then others are supposed to comment on the ideas.
Another approach is whereby IDEO went out to find out and understand more about the product they are improving on.
- How were the possible solutions prototyped and tested?
The possible solutions were presented and told of their main functions on how they would solve the issues of the current shopping cart. The possible solutions were also demonstrated on the usage of the possible shopping carts.
- Was there a redesign step in the IDEO project? What was the final outcome?
There was a redesign step in the project. The final outcome is where the cart’s wheels can turn 90 degrees so it can move sideways without having to turn. Bags can be hooked on the cart and also, the cart can hold four handheld baskets. On the cart, the user can also scan the price of the item he or she is going to purchase.
1.2 Assignment of roles
Project Manager : Chua Tuan Jin
Drivetrain Engineer : Bennett Neoh
Wheel Engineer : Darelyn Lim
Chassis Engineer : Darelyn Lim
1.3 Brainstorming
Engineering Goals
Develop a MouseTrap Car with the following specifications:
- Uses only the MouseTrap provided as the only energy source
- Has a maximum length of 30 cm, width of 10 cm, and a height of 10 cm
- Can travel a minimum distance of 5 meters carrying an egg (the egg will be provided by the teacher)
- All time-lines have to be adhered
LIST ANY KEY TERMS OR ISSUES THAT CAME UP DURING BRAINSTORMING. This does not have to be neat or even organized. It gives you a way to keep track of any idea you may have had. Include separate notes, google sketches, etc. if you have them. (Attach separate sheets if needed)
1st Idea
Speed = Small wheel : Big axle
Torque = Big wheel : Small axle
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2nd Idea
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3rd Idea
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5.7 Bibliography
Mouse trap car idea
Criteria
|
Weight
|
Size
|
Appearance
|
Time to produce
|
Cost to produce
|
Ease of use
|
Availability of materials
|
Environmental Impact
|
Safety
|
Row
Total
|
Normalised
Value
|
Weight
|
0
|
3
|
2
|
3
|
1
|
0
|
2
|
0
|
11
|
0.102 (3sf)
| |
Size
|
3
|
2
|
1
|
3
|
1
|
0
|
2
|
0
|
12
|
0.111 (3sf)
| |
Appearance
|
0
|
1
|
1
|
3
|
1
|
0
|
1
|
0
|
7
|
0.0648 (3sf)
| |
Time to produce
|
1
|
2
|
2
|
3
|
1
|
2
|
3
|
0
|
14
|
0.130 (3sf)
| |
Cost to produce
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
| |
Ease of use
|
2
|
2
|
2
|
2
|
3
|
2
|
3
|
0
|
16
|
0.148 (3sf)
| |
Availability of materials
|
3
|
3
|
3
|
1
|
3
|
1
|
3
|
0
|
17
|
0.157 (3sf)
| |
Environmental Impact
|
1
|
1
|
2
|
0
|
3
|
0
|
0
|
0
|
7
|
0.0648 (3sf)
| |
Safety
|
3
|
3
|
3
|
3
|
3
|
3
|
3
|
3
|
24
|
0.222 (3sf)
| |
Column Total
|
13
|
12
|
17
|
10
|
24
|
8
|
7
|
17
|
0
|
108
|
1.00 (3sf)
|
Criteria
|
Normal
Priority
Value
|
Design Idea #1
|
Design Idea #2
|
Design Idea #3
| |||
weight
|
0.102 (3sf)
|
4
|
0.408
|
5
|
0.510
|
3
|
0.306
|
size
|
0.111 (3sf)
|
4
|
0.444
|
3
|
0.333
|
3
|
0.333
|
appearance
|
0.0648 (3sf)
|
3
|
0.1944
|
4
|
0.2592
|
5
|
0.324
|
time to produce
|
0.130 (3sf)
|
2
|
0.260
|
3
|
0.390
|
2
|
0.260
|
cost to produce
|
0
|
4
|
0
|
5
|
0
|
3
|
0
|
ease of use
|
0.148 (3sf)
|
5
|
0.74
|
3
|
0.444
|
4
|
0.592
|
availability of materials
|
0.157 (3sf)
|
4
|
0.628
|
4
|
0.628
|
4
|
0.628
|
environmental impact
|
0.0648 (3sf)
|
4
|
0.2592
|
3
|
0.1944
|
5
|
0.324
|
safety
|
0.222 (3sf)
|
3
|
0.666
|
4
|
0.888
|
4
|
0.888
|
Total
|
3.5996
|
3.6466
|
3.655
|
1.5 Design rationale and notes
Wheels
If the wheels have more friction, it would help to the car to have more grip and this would help the car to move faster.
Also, a three-wheeled car would allow for better alignment, whereas, a four-wheeled car would increase the stability of the car.
Circumference of the wheel affects the car performance as it affects the wheel-axle ratio.The wheels should be lightweight to maximise the potential of the car.
Lever arm
The lever would help to pull the string which is attached to the axle of the nack wheels. This would help to enable the car to move.
A long lever arm would allow for more distance travelled by the car.
A long lever arm would allow for more distance travelled by the car.
Chassis Material
The choice of the chassis material would determine the strength of the frame of the car. If the material is too weak, it may not be able to withstand the force of the mousetrap, causing the whole car to be damaged.
Chassis Shape
The chassis shape would determine the aerodynamics of the car, this would help to reduce friction between the car and the air, hence helping the car to travel further.
Location of Mousetrap
The location of the mousetrap would determine the position of the lever arm too. This would affect the length the car can travel as if the mousetrap was placed under the car, the lever arm would be significantly shorter. However, if the mousetrap is placed on the car, the lever arm could be longer, enabling the car to move further when the mousetrap is released.
Axles
The axles would help to turn the wheels and this would enable the car to move.
The diameter of the axles would also affect the wheel-axle ratio as well as the surface area in contact with the wheels.
The diameter of the axles would also affect the wheel-axle ratio as well as the surface area in contact with the wheels.
String type and attachment
If the string is weak, it might break when the mousetrap is released and this would prevent the car from moving. If the string is not properly attached, the car may not get the full amount of energy from the mousetrap to move, this will cause the distance the car can travel to decrease.
The thickness of the string would determine the number of wraps around the axle as well as the surface area in contact with the axle which affects the friction.
The thickness of the string would determine the number of wraps around the axle as well as the surface area in contact with the axle which affects the friction.
1.6 Materials used
Material
|
Where is it used?
|
Reason?
|
Wooden Board
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Base of mousetrap car
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Sturdy and strong material to support the mousetrap.
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Wooden Planks
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Side of mousetrap car for attaching of wheels.
|
Strong and stable material to support the wheels and keep it in balance.
|
Nylon thread (Fishing Line)
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Attached from the axle of the car to the lever of the mousetrap.
|
It is made up of a strong material which doesn’t break easily and it can last as many test runs as we want before it wears out. The thickness of nylon thread is thin which reduces the contact surface area with the axle thus creating less friction. Also, we are able to coil more rounds (greater distance) around the axle as it allows for more space on the axle since it is thinner as compared to other strings.
|
Disc (CD Roms)
|
It will be used as the wheels of the mousetrap car.
|
It has a big diameter which allows it to turn more as the string uncoils as compared to a smaller diameter wheel. The thickness of the disc is also less as compared to other wheels, which creates less friction.
|
Balloons/Tape
|
It will be attached around the circumference of the wheels.
|
We use is so that we create more friction between the ground and the wheels, this also prevents the car from skidding, causing it to stay at the same position.
|
Thin metal rod
|
Axle
|
Friction would be reduced as the surface area in contact with the disc while the axle is turning is reduced due to the thickness of the metal rod which is thinner as compared to other axles. A smaller axle would also mean that the car would be able to travel a further distance, considering the diameter of the wheel is large (wheel-axle ratio).
|
Bottle Cap
|
On the disc
|
To hold the axle in place so that the wheel would move when the axle turns.
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1.7 Preliminary Sketch (Using Google Sketchup)
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