Transcript Document 7173493

Introduction to
engineering
Dr. Yan Liu
Department of Biomedical, Industrial and Human Factors Engineering
Wright State University
Engineering Versus Science
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Scientists
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Understand why our world behaves the way it does (“laws of nature”)
Study the world as it is
Thinkers
Engineers
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Apply established scientific theories and principles to develop cost-effective
solutions to practical problems
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Cost effective
 Consideration of design trade-offs (esp. resource usage)
 Minimize negative impacts (e.g. environmental and social cost)
Practical problems
 Problems that matter to people
Change the world
Doers
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ABET’s Definition of Engineering
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ABET (The Accreditation Board for Engineering and Technology )
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Recognized in the United States as the sole agency responsible for accreditation
of educational programs leading to degrees in engineering
“Engineering is the profession in which a knowledge of the
mathematical and natural sciences, gained by study, experience, and
practice, is applied with judgment to develop ways to utilize,
economically, the materials and forces of nature for the benefit of
[hu]mankind”
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Engineering Disciplines
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Major Disciplines
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Mechanical engineering
Electrical engineering
Civil engineering
Chemical engineering
Industrial engineering
Computer engineering
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A subspecialty within electrical engineering at many institutions
Specialized, Non-Traditional Fields
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Aerospace engineering
Materials engineering
Biomedical engineering
Nuclear engineering
etc.
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Electrical/Computer Engineering (ECE)
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Largest of All Engineering Disciplines
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About 353,000 or 26% (out of 1.4 million engineers) were electrical and
computer engineers (U.S. Department of Labor Statistics in 2005)
Concerned with electrical devices and systems and with the use of
electrical energy
Specialties
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Electronics
 Design of circuits and electric devices to produce, process, and detect
electrical signals
Communications
 A broad spectrum of applications from consumer entertainment to military
radar
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Electrical/Computer Engineering (ECE)
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Specialties (Cont.)
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Power
 Generation, transmission, and distribution of electric power
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Conventional generation systems (e.g. hydroelectric, steam, and nuclear)
Alternative generation systems (e.g. solar, wind, fuel cells)
Controls
 Design of systems that control automated operations and processes
Instrumentation
 Use of electronic devices to measure parameters (e.g. pressure, temperature,
flow rate, speed, etc)
 Processing, storing, and transmitting the collected data
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Mechanical Engineering
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Second Largest Engineering Discipline
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About 221,000 or 16% (out of 1.4 million engineers) were mechanical engineers
(U.S. Department of Labor Statistics in 2005)
Concerned with designing tools, engines, machines, and other
mechanical equipment
Areas
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Energy
 Production and transfer of energy and conversion of energy from one form
to another
Structures and motion in mechanical systems
 Design of transportation vehicles, manufacturing machines, office machines,
etc.
Manufacturing
 Design and build requisite equipment and tools to convert raw materials into
final products
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Industrial Engineering
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“Industrial Engineering is concerned with the design, improvement,
and installation of integrated systems of people, material, information,
equipment, and energy. It draws upon specialized knowledge and skill
in the mathematical, physical, and social sciences together with the
principles and methods of engineering analysis and design to specify,
predict, and evaluate the results to be obtained from such systems
(IIE (Institution of Industrial Engineering), 1985)
Also known as systems engineering, production engineering,
operations management
Fields
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Operations research
Human factors
Quality control
etc.
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Industrial Engineering
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Operations Research
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Uses methods like mathematical modeling, statistics, and algorithms to arrive at
optimal or good decisions in complex problems
Human Factors (or Ergonomics)
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Application of scientific information concerning humans to the design of
objects, systems and environment for human use (IEA (International
Ergonomics Association), 2007)
Physical human factors
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Cognitive human factors
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Deals with the human body's responses to physical and physiological stress
Mental processes (e.g. perception, attention, cognition, motor control, and memory
storage and retrieval) as they affect interactions among humans and other elements
of a system
Organizational human factors (macroergonomics)
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The optimization of socio-technical systems, including their organizational
structures, policies, and processes
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Industrial Engineering
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Quality Control
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Ensure products or services are designed and produced to meet or exceed
customer requirements
Similarity to Other Engineering Disciplines
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Trained in the same basic ways as other engineers
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Take foundation courses in mathematics, physics, chemistry, humanities, and social
sciences
Difference from Other Engineering Disciplines
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Emphasis on both people and technology
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Focuses on how people interact with a system
Concern for the human element leads to system designs that enhance the quality of
life for all people
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Design
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Wikipedia Definition
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Process of originating and developing a plan for a product, structure, system, or
component
Achieve Goals with Constraints
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Goals
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Constraints
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Material, cost, time, regulation, etc.
Trade-off
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The purposes of the design
 What is for? Who is it for? Why do they want it?
Which goals or constraints can be relaxed so that others can be met
Understand the Material
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A chair with a steel frame and a chair with a wooden frame are quite
different. Often the steel frames are tabular or thin L or H section
steel, whereas wooden chairs have thick solid legs.
Why? What would happen if a wooden chair were made using the
design for a metal one and vice versa?
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To design a system that involves humans, we have to
understand humans, their physiological, psychological
and social aspects and how they interact with the other
components of the system
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Bad Design (1)
What’s wrong with the design of this knife?
Although you can tell which end is the handle and which
end is the blade, it isn't clear which side of the blade cuts
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Bad Design (2)
What’s wrong with the design of this stove?
It is difficult to tell which control goes with
which burner
Good design
Arrange the controls in the same configuration as
the burners. It is quite easy to tell which burner
goes with which control
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Bad Design (3)
What’s wrong with the design of this Boombox?
People generally expect the controls for
a device to be on or close to the device.
In this example, the CD buttons should
be put next to the CD player and the tape
buttons should be put next to the tape
player.
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Good Design (1)
Fun, educational, self-explanatory
LeapFrog's "Twist and shout multiplication"
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Good Design (2)
Simple, elegant, easy to use, easy to clean
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How to Make Good Design
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Recognize that systems are built for users and thus must be designed
for the users
Recognize individual differences
Recognize that the design of things and procedures can influence
human behavior and well-being
Emphasize empirical data & evaluation
Rely on scientific method
Recognize that things, procedures, environments, and people do not
exist in isolation
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What Is NOT Good Design
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NOT just applying checklists and guidelines
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NOT using oneself as the model user
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These can help, but user-centered design (UCD) is a design philosophy and
process
Know your real users; recognize variation in humans
NOT just common sense
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e.g. “a picture is worth a thousand words” does not always hold
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QWERTY Keyboard
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Layout
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QWERTY are first six letters at the top row of alphabetical keys
The layout of the digits and letters is generally fixed except a few variations in
some nations’ keyboards
 e.g. French keyboards interchange both "Q" and "W" with "A" and "Z", and
move "M" to the right of "L"
Non-alphanumeric keys vary
 e.g. There is a difference between key assignments on British and American
keyboards
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Above 2 and 3 on the UK keyboard are the <“> and <£>, respectively, whereas
<@> and <#> are on the USA keyboard
The placement of brackets, backslashes and such like vary
Not optimal for typing
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French keyboard
US keyboard
UK keyboard
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Dvorak Keyboard
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An alternative standard keyboard layout to QWERTY, patented in
1936 by August Dvorak and William Dealey
Designed to address the problems of inefficiency and fatigue that
characterized the QWERTY keyboard layout
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Speed improvement of 10% ~ 15%
Reduction in user fatigue due to the increased ergonomic layout of the keyboard
Has failed to replace QWERTY standard
Currently, all major operating systems (e.g. Apple OS X, Microsoft
Windows, GNU/Linux) can ship the Dvorak keyboard layout in
addition to the QWERTY layout
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Dvorak Keyboard
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Ergonomics Principles of the Design
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It is easier to type letters alternating between hands
For maximum speed and efficiency, the most common letters should be the
easiest to type. This means that they should be on the home row, the center row
of alphabetical letters on a keyboard, which is where the fingers rest and under
the strongest fingers
The least common letters should be on the bottom row, which is the hardest row
to reach
The right hand should do more of the typing, because most people are righthanded
Stroking should generally move from the edges of the board to the middle. An
observation of this principle is that, for many people, when tapping fingers on a
table, it is easier going from little finger to index than vice versa
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Dvorak Keyboard Layout
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Chord Keyboard
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Only a few keys are used
Allow users to enter characters or commands formed by pressing
several keys together, like playing a chord on a piano (illustration)
Advantages
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Extremely compact and thus can be built into a device (e.g. a pocket-sized
computer) that is too small to contain a normal sized keyboard
A large number of combinations available from a small number of keys allows
text or commands to be entered with one hand, leaving the other hand free to do
something else
Disadvantages
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Lack of familiarity
Cannot be used by a "hunt and peck" method, so their use is restricted to
applications where additional training can be justified
 Hunt and peck typing (or two-fingered typing) is a common form of typing,
in which the typist must find and press each key individually
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• 12 keys, so more than 4000 combinations are
potentially possible
• User can set up key combinations as macros
for longer strings of text
Twiddler2 Developed by Handykey Corp.
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Usability
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Concerned with making systems easy to learn and use
A Usable System is
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Easy to learn
Easy to remember how to use
Effective to use
Efficient to use
Safe to use
Enjoyable to use
Why is Usability Important
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Many everyday systems and products seem to be designed with little regard to
usability, which leads to frustration, wasted time and errors
Examples of interactive products:
mobile phone, computer, personal organizer, remote control, soft drink machine,
coffee machine, ATM, ticket machine, library information system, the web,
photocopier, watch, printer, stereo, calculator, videogame etc….
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The photocopier in our college has buttons like these on its control panels
Imagine that you just put your document into the photocopier and set the photocopier
to make 10 copies, sorted and stapled. Then you push the big button with the "C" to
start making your copies.
What do you think will happen?
(a) The photocopier makes the copies correctly.
(b) The photocopier settings are cleared and no copies are made
If you selected (b) you are right! The "C" stands for clear, not copy. The copy button is
actually the button on the left with the "line in a diamond" symbol. This symbol is
widely used on photocopiers, but is of little help to someone who is unfamiliar with this.
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Usability
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Important Design Principles of Usability (Norman, 1990)
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Visibility
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All necessary controls should be visible for the user whenever he/she is supposed to
be able to use them
 The design should provide visibility to all the set of possible actions
 One control for each action that the user can take
 Only the necessary parts should be made visible, depending upon the actions
available to the user
 Much visibility is harmful since it makes the system look complicated to
use
Affordance
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The affordance of an object refers to the sort of operations and manipulations that
can be done to the object
There should be a natural mapping between the parts that are made visible and the
actions that they support
 e.g. A button, by being slightly raised above an otherwise flat surface, suggests
the idea of pushing it
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Usability
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Important Design Principles of Usability (Norman, 1990)
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Feedback
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Sending back to the user information about what action has actually been done and
what results have been accomplished
 Feedback should be provided in a form that is easy to understand and interpret
Accommodation of errors
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Minimize the chance of the error in the first place or its effects once it occurs
 Make sure that the users have the right conceptual model of the system
 Make it hard for users to commit a mistake
 Forcing functions can be introduced to prevent errors from occurring by
providing strong constraints on the system
a) Interlock that maintains a task sequence
b) Lockin that prevents premature termination of a task sequence
c) Lockout that prevents starting a faulty operation
Allow the users to reverse the results of an error or to recover the state of the system
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User-Centered Design (UCD)
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What is UCD
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UCD a design philosophy and a process in which the needs, wants, and
limitations of the end user of a product are given extensive attention at each
stage of the design process
A multi-stage problem solving process which requires designers to not only
analyze and foresee how users are likely to use a product but also test the
validity of their assumptions with regards to user behavior in real world tests
with actual users
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User-Centered Design (UCD)
Identify need for
human-centered design
Specify context of use
Evaluation design
System satisfies
specified requirements
Specify requirements
Produce design solutions
The UCD Cycle in ISO13407
(Four activities interlock and form the basis for an iterative approach to the
requirements-design-test cycle; the cycle is completed when the evaluation
of a product shows that it meets the specified requirements)
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User-Centered Design (UCD)
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Eight Steps in UCD
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Step 1: Define the context
Step 2: Describe the user
Step 3: Task analysis
Step 4: Function allocation
Step 5: Basic design
Step 6: Mockups & prototypes
Step 7: Usability testing
Step 8: Iterative test & redesign
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User-Centered Design (UCD)
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Define the Context
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Identifying the type of applications or the usage of the system
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Market
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e.g. Develop a kiosk for a zoo to provide practical information (e.g. how to get from
location A to location B) as well as content to enrich the experience
Whether this is a need for the system to justify its development
Describe the User
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The important characteristics of the users of the system
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Physical attributes (e.g. age, gender, size, reach, etc.)
Perceptual abilities (e.g. vision, hearing, touch, etc.)
Cognitive abilities (e.g. memory span, reading level, expertise level, etc.)
Personal traits (e.g. likes/dislikes, extrovert/introvert, patience, etc.)
Cultural and international diversity (e.g. languages, culture, ethics, etc.)
Special population (e.g. disabilities, elders, minors, etc.)
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User-Centered Design (UCD)
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Task Analysis
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Analyzing the way users perform the tasks when using the system
 Talk to and observe users doing what they do
 List each task
 Break tasks down into steps
Function Allocation
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Decide who or what is best suited to perform each task (or each step)
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e.g. Machine remembers login Id and reminds the user, but the user remembers the
password
Base this on knowledge of system hardware, software, users’ abilities, culture,
communications protocols, privacy, cost, etc.
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User-Centered Design (UCD)
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Basic Design
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Summary of the components and their basic design (be creative!)
 Brainstorming
Cross-check with design requirements, human factors references, hardware
specifications, budgets, laws/regulations, etc.
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Ensure that the design will support the requirements and comply with the
constraints (verification and validation in software engineering)
Mockups & Prototypes
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Rapidly mock up the system for testing with potential users
 Pen and paper or whiteboard to start
 Iterate, iterate, iterate!!
 Increasingly functional and veridical
Implement a detailed prototype of the system
 Prototyping is the process of quickly putting together a working model of
the system in order to test various aspects of its design
 Various prototyping tools are available
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Visual Basic/Visual Basic.NET, Flash, Dreamweaver, Caretta, Synopsis, etc.
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User-Centered Design (UCD)
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Usability Testing
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Get real (or representative) users to perform tasks, using the prototype
Both objective and subjective (e.g. satisfaction) measures
 Sometimes users “want” features that actually yield poor performance
Testing results are used to guide the iterative evaluation and redesign of the
system
Iterative test & redesign
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Repeat cycles of testing and reworking the system, subject to cost/time
constraints
Focus on Functionality First !
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Brainstorming
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An effective technique for generating a large number of ideas in a
group setting
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Facilitator
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Guide the session, encourage participation, write down ideas, etc.
Facilities
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At least 2 people, but no more than 10 people
A brainstorming space
Something to write down ideas (e.g. paper, white-board, etc.)
Four Rules
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Rule out criticism
Welcome freewheeling
Seek large quantities of ideas
Encourage combination and improvement of ideas
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Brainstorming
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Types of Brainstorming
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Free-form (unstructured) brainstorming
 Participants simply contribute ideas as they come to mind
 Pros
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Participants can build on each other’s ideas
Relaxed atmosphere
Cons: the less assertive or low-ranking participants may not contribute
Structured brainstorming
 Solicit one idea from each person in sequence
 Pros
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Cons
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Each person has an equal chance to participate, regardless of rank or personality
Lack of spontaneity
Rigid environment
Combination of free-form and structured brainstorming
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Design Touch Screen Zoo Information Kiosk
1. Define the Context
• Identifying the type of applications or the usage of the system
 Provide general information about the zoo (e.g. zoo hours, exhibits, shows, etc.)
 Provide information about each animal
 Provide and print zoo map
 Create and print a personalized itinerary
 Weather reporting
• Benefits to justify its development
 Enhance visitor’s experience (having fun as well as being educated)
 Can rapidly update information (general, animals, etc.)
 Reduce cost (fewer employee are needed)
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Design Touch Screen Zoo Information Kiosk
2. Describe the User
• The important characteristics of the users of the system
Physical attributes
 Age: a wide range (16 – 70)
 Size and reach: 5th percentile – 95th percentile of American population in the age of
16 to 70
Perceptual attributes
 Vision: normal
 Touch: normal
Cognitive attributes
 Reading level: Understanding of English at a high enough level to recognize and
follow on-screen commands
Culture and international diversity
 Language: English
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Design Touch Screen Zoo Information Kiosk
3. Task Analysis
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Design Touch Screen Zoo Information Kiosk
4. Function Allocation
User makes selections on the touch screen, and the machine processes the commands
5. Design
Welcome to the J&J Zoo
Please make a selection…
Main Screen
Zoo Information
Create Visit Plan
Animal Info
Today’s Weather
Zoo Map
Idle Screen
Main Screen
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Design Touch Screen Zoo Information Kiosk
5. Design (Cont.)
Zoo Information Screen
Animal Info Screen
6. Mockup & Prototype
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Design Touch Screen Zoo Information Kiosk
7. Usability Evaluation
Thirteen people who have been to zoos participated in the usability evaluation
experiment
 Each participant performed a set of tasks (predetermined by the experimenters) on the
prototyped design, and their task performance, including the number of clicks and
number of errors, was recorded
 After the tasks, each participant filled out a subjective questionnaire to rate his/her
satisfaction with different features of the design
 Evaluation data was analyzed
8. Iterative Test & Redesign
 Based on the evaluation outcome, plans to improve the design were made
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