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3.4.1 Design Methodology
The total design model of
SnS
2
is shown in Figure 3.18. Market survey is the first process
in the design techniques. Various patents, journals, technical report and websites
were investigated for related information such as basic technology, industry
analysis, legal and policy issues, engineering definition, benchmarking and industry
analysis. The output from the market survey is the product requirement. The
product requirement Table 3.1 is a guideline for the development of SnS
2
. Next,
creative method and morphological chart were used as a tool to develop the conceptual
design. Subsequently, the design was visualized in three dimensional views
for evaluation purposes. Different conceptual designs were evaluated based on
weighted objective method.
Figure 3.18 The design process of SnS
2
.
3.4.2 Conceptual Design
Based on the product requirement as shown in Table 3.1, the design concepts
were generated. The development of the SnS
2
employed two methodologies for
concept generation. Brainstorming Cross, 2008 and morphological chart Pugh,
1990; Cross, 2008; Cross, 1994 were used in the conceptual stage of design.
77
Table 3.1 The description of the product requirement for SnS
2
.
No. Elements
Description
1. Performance
SnS
2
must be functional and responsive to the passenger’s head position
change for providing support. 2.
Materials
SnS
2
is made from material that is easy to find, low cost and
good for prototyping purposes.
3. Size
SnS
2
must be able to fit on the standard economy class aircraft seat.
4.
Reliable
SnS
2
must be reliable during experimental stage.
5. Weight
SnS
2
must be light weight. 6.
Strength The
functional prototype should be designed to withstand the force
from the subject’s head and air pressure. 7.
Safety
Safety is an integral part of all aspects of design. Thus
consideration should be given to the safety of all personnel
whether operating the equipment, maintaining the equipment
or installing the equipment.
8. Design
In the interests of prototyping, functionality, maintainability and
simplicity of design are key factors.
Brainstorming was the creative method used in the design of SnS
2
. Brainstorming
was used to generate as many ideas as possible and as many solutions to each
idea as possible. The brainstorming was conducted in a small group session of
about five individuals. The author also participated in the brainstorming session.
Four individuals were invited as volunteer in the brainstorming session. They were
working people. Each individual was encouraged to express their ideas freely
without critical judgment. Next, the recorded ideas were identified through the
final discussion. Lastly, the agreed ideas were changed into five design concepts.
78 The
morphological chart Pugh, 1990; Cross, 2008 is a method used to combine design
ideas in a systematic way. The combined ideas generate a solution as well as
search for possible new solutions. The morphological chart of the airbag system
for SnS
2
is shown in Figure 3.14. The sub‐functions identified are material, control
medium, shape, feedback system and actuator. For each sub‐function, there
are between two to four solutions being generated. The combinations of the
final solutions were highlighted. The final concept of the airbag system is an airbag
that is made from polyester and rectangular in shape. The polyester has been
chosen because it is easy to purchase from a shop and low cost. The airbag is
rectangular in shape because it is easy to seal with the heat sealer machine. The air
had been chosen as control medium because of the simplicity of design and control,
good in reliability and safety Wikipedia, 2010b. An air pressure sensor was
selected to detect the air pressure change inside the airbag. A proportional valve
was used to control the deflation and inflation of the airbag proportionally. An
Arduino Arduino, 2010 with an embedded ATmega microcontroller was chosen
to be the main controller for SnS
2
.
Table 3.2 The morphology chart for SnS
2
airbag prototype.
1 2
3 4
Material Polyurethane
Natural rubber
Neoprene Polyester
Control medium
Liquid Air
Shape Round
Rectangular Triangular
Cylindrical
Feedback system
Air pressure
sensor Load
cell Membrane
potentiometer
Actuator Directional
valve Proportional valve
Microcontroller ATmega
PIC ARM
Motorola
Programming language
C++ Arduino
Java Processing
Solution Sub
‐function
79
3.4.3 Final Concept and Design
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