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).
1.
What
was the problem the engineers at IDEO were asked to solve?
They had to redesign the conventional shopping cart to improve on factors such as manoeuvrability of the cart, child safety, and shopping cart theft.
They had to redesign the conventional shopping cart to improve on factors such as manoeuvrability of the cart, child safety, and shopping cart theft.
2.
Name
two constraints that they had to deal with.
They had a 5-day time limit, and they needed the
cost of the redesigned cart to be around the same as the conventional one.
3.
What
were two of the major concerns/issues the teams discovered from their research?
- Child safety on shopping carts (It was found that an average of 22,000 children are hospitalised for shopping cart-related injuries every year.)
- Shopping cart theft
- Child safety on shopping carts (It was found that an average of 22,000 children are hospitalised for shopping cart-related injuries every year.)
- Shopping cart theft
4.
IDEO
uses several methods, processes and ideas to generate alternative
solutions. What two principles or
approaches appealed to you the most? Why?
The team was split into four groups and each group was tasked to build a model to tackle one concern/issue of the shopping cart. The four models would be brought together, and the best parts of each one would be tank and made into one all-rounded redesigned shopping cart. This way, there is more efficiency in the redesigning process. The final design covers all the problems at once. Allowing the team members to vote for each other ideas. The team members brainstormed for ideas and pasted them on walls, and they were later allowed to go inspect each one, and if they found it was a good idea, they would vote for it and it would subsequently be used in the design. This is effective brainstorming and narrowing down of ideas. It is also a very fair and efficient way to carry out brainstorming.
The team was split into four groups and each group was tasked to build a model to tackle one concern/issue of the shopping cart. The four models would be brought together, and the best parts of each one would be tank and made into one all-rounded redesigned shopping cart. This way, there is more efficiency in the redesigning process. The final design covers all the problems at once. Allowing the team members to vote for each other ideas. The team members brainstormed for ideas and pasted them on walls, and they were later allowed to go inspect each one, and if they found it was a good idea, they would vote for it and it would subsequently be used in the design. This is effective brainstorming and narrowing down of ideas. It is also a very fair and efficient way to carry out brainstorming.
5.
How
were the possible solutions prototyped and tested?
The best parts of the four models made to tackle one problem each were taken and combined into one cart. This cart was taken to a supermarket for the staff there to take a look at and give the team feedback on it.
The best parts of the four models made to tackle one problem each were taken and combined into one cart. This cart was taken to a supermarket for the staff there to take a look at and give the team feedback on it.
6.
Was
there a redesign step in the IDEO project? What was the final outcome?
The redesigning step was when the four models were brought together and taken a look at. The team decided to take the best aspects of each design to bring together and make into one shopping cart. The final shopping cart was then able to cover all the aspects at once.
The redesigning step was when the four models were brought together and taken a look at. The team decided to take the best aspects of each design to bring together and make into one shopping cart. The final shopping cart was then able to cover all the aspects at once.
1.2
Assignment of roles
Project
Manager - Asritha.V
Drivetrain
Engineer - William Ming
Wheel
Engineer - Bruce Ng
1.3 Brainstorming
Engineering Goals
Develop a MouseTrap Car with the following specifications:
(a) Uses only
the MouseTrap provided as the only energy source
(b) Has a
maximum length of 30 cm, with of 10 cm, and a height of 10 cm
(c) Can travel
a minimum distance of 5 meters carrying an egg (the egg will be provided by the
teacher)
(d) 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
Our first idea is a basic mousetrap car
concept. The mousetrap is placed at the front of the frame which is built of
wooden sticks. The position of the mousetrap allows more string to be used
which lead to the car travelling a longer distance. A bamboo skewer of 1cm
diameter is attached to the spring mechanism of the mousetrap. The other side
of the bamboo skewer is attached to the string. The string is coiled around the
axle of the back wheels. When the mousetrap is released, the elastic potential
energy of the spring in the mouse trap will cause the mouse trap return to its
original position, pulling the string along with it. This motion rotates the
axle of the back wheels, thus propelling the car forwards.
Weaknesses:
-
The egg may fall out
-
The frame might be too heavy which will decrease the acceleration of
the car
-
The bottle cap may be very wobbly as the mass of the bottle cap is not
distributed equally since there is an extension one side.
-
Bamboo skewer may snap when the nylon string is pulled
Improvements:
-
Make the box bigger such that the egg is enclosed inside
-
Decrease the number of wooden sticks used for the frame
-
Use CDs as wheels.
-
Bamboo skewers can be used as axels as they are lighter compared to
metal rods
|
2nd Idea
The description
of this idea is similar to our first idea. However, the egg holder is bigger
to keep the egg stable. The wheels are also changed to CDs to prevent the car
from wobbling.
Weaknesses:
-
The frame could cause the car to go slower as it’s shape is not
streamlined
-
The Styrofoam ball could be a hassle when winding up the string.
-
The car may not go far as the nylon string is short.
Improvements:
-
Reduce the number of wooden sticks used for the frame
-
Use a longer metal rod à Longer string
-
The circumference of the CDs can be lined with a thin strip of
anti-slip mat to for a better grip of the floor.
|
3rd Idea
The chassis of the car is made up of 3 wooden
sticks on each side and cardboard in the middle. These materials are used so
that weight of the car is minimized. Each wheel consists of 2CDs super glued to
each other and a strip of anti-slip mat is wrapped around the circumference to
increase traction. The axle is a bamboo skewer and a sink washer is used to
hold it in place. This combination of wheel and axle creates a large wheel to
axle ratio. Thus, the car will move a longer distance. The movement of the car
is the same as Idea 1.
Weaknesses:
-
The cardboard, on which the mousetrap and the egg holder is placed on,
will bend if the items on it are too heavy
-
The position of the egg holder will block the thin rod when it is
returning back to its original position.
Improvements:
-
Put the egg holder on the frame of the car
-
Change the cardboard to ice-cream sticks as they are flat and secure.
|
1.4
Decision Making Matrix
1.5 Design rationale and notes
Wheels
The
wheels are made of 2 CDs. We chose this material as CDs are readily available
and its diameter is also large. Larger diameters would result in a larger
circumference. A larger circumference of the CD will allow the car to cover a
further distance for each spin of the axle. Moreover, the circumference of the
wheels will be lined with a thin strip of anti-slip mat or a rubber band
super-glued to it. This allows a firmer grip on the floor, which would result
in it moving faster. The CDs are also lightweight, thus maximizing the
potential of the car.
Lever Arm
Lever Arm
The lever arm is made of a thin chopstick
with a diameter of 1cm. One end of the chopstick will be attached to the spring
mechanism of the mousetrap while the nylon string is looped to the other side
of the chopstick. The nylon string is fully coiled around the axle of the back
wheels. When the mousetrap is released, the elastic potential energy of the
spring in the mouse trap will cause the mouse trap return to its original
position, pulling the string along with it. This motion rotates the axle of the
back wheels, thus propelling the car forwards. By
attaching the chopstick directly to the lever of the spring mechanism, there
would be more elastic potential energy transferred into kinetic energy.
Chassis Material
Chassis Material
The choice of our chassis material is thin
strips of New Zealand Timber wood. The reason behind our choice is that they
are light and are strong enough to withstand the weight of the mousetrap and
the egg. The lightweight of the car would allow for a greater acceleration of
the car, which would in turn cover a greater distance.
Chassis Shape
Our chassis will take the shape of a rectangle. However, there are only 3 sticks of timber wood on each side to reduce air resistance. This enables the car to accelerate faster as the forward force is greater than the air resistance and also lesser force is needed for the car to go forward.
Chassis Shape
Our chassis will take the shape of a rectangle. However, there are only 3 sticks of timber wood on each side to reduce air resistance. This enables the car to accelerate faster as the forward force is greater than the air resistance and also lesser force is needed for the car to go forward.
Location of Mousetrap
The mousetrap is placed at the front of the frame which is built of wooden sticks. The position of the mousetrap allows more string to be used which allows the car to travel a longer distance.
Axles
The axles are bamboo skewers
as they are light and strong. Their diameter is also small which is the reason
behind our choice of bamboo skewers.
String Type and Attachment
We are using nylon string for our car. Nylon strings are able to withstand pressure without snapping and are strong. Moreover, they can be found in any shop nearby.
1.6 Materials used
Material
|
Where is it used?
|
Reason?
|
New Zealand Timber Wood
|
Used as the basic frame of the car
|
They are light and are able to withstand the weight of the
mousetrap and the egg.
|
CD
|
Used as wheels of the car
|
They are lightweight and are also strong. They also have a larger
circumference and are available in nearby stores.
|
Ice-cream sticks
|
Used as platform to put the mousetrap
|
They act as a stable and a strong platform to put mousetrap on.
|
Chopstick
|
Used as a lever arm
|
It is also light-weight and strong and doesn’t snap easily.
|
Nylon String
|
Used as a string to connect the lever arm and the car
|
It is able to withstand high pressures and is durable.
|
Anti-slip mat/Rubber band
|
Used to line the circumference of the CD.
|
It increases grip on the floor, propelling the car forward.
|
Small cardboard box
|
Egg holder
|
It traps the egg inside
securely.
|
Sponge
|
Cushioning for the egg
|
It prevents the egg from breaking as it acts as a cushion and
absorbs the impact of sudden jerks.
|
Plumbing/Sink washer
|
Used as the connection between the axle and wheel
|
It is soft and stable.
|
1.7 Preliminary Sketch (Using Google Sketchup)
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