Understanding & Applying
The Engineering Design Process
Mark D. Conner
The Engineering Academy at
Hoover High School
www.eahoover.com
A good product is the result of a good process.
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What is design?
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What is the Engineering Design Process?
Examples help
What tools are available?
Originality can be overrated.
What is Design?
Design is about creating – form and function.
It’s achieving objectives within given constraints.
The Engineering Design Process is an algorithm
for creation and invention.
What is the Engineering
Design Process?
The Engineering Design Process mirrors
standard steps in problem-solving.
Problem Definition
(Analysis)
Conceptual Design
(Synthesis)
Preliminary Design (Evaluation)
Design Decision
Detailed Design
Documentation is crucial!
(Decision )
(Action)
Define the problem in detail without implying a
particular solution.
Problem Definition
• Clarify design objectives
• Identify constraints
• Establish functions
• Establish requirements
• desired attributes and behavior
• expressed as “being” statements
(not “doing”)
• restrictions or limitations on a
behavior, a value, or some other
aspect of performance
• stated as clearly defined limits
• often the result of guidelines and
standards
• actions the design must perform
• expressed as “doing” statements
• typically involve output based on
input
• non-negotiable objectives and/or
functions
Objectives, constraints, functions and
requirements may be broad-based.
• Some items are absolute – others may be negotiable
– Functionality (inputs, outputs, operating modes)
– Performance (speed, resolution)
– Cost
– Ease of use
– Reliability, durability, security
– Physical (size, weight, temperature)
– Power (voltage levels, battery life)
– Conformance to applicable standards
– Compatibility with existing product(s)
Both functional and non-functional
requirements may be placed on a design.
• Functional requirements:
– support a given load
– respond to voice commands
– (output based on input)
• Non-functional requirements (usually form-focused):
– size, weight, color, etc.
– power consumption
– reliability
– durability
– etc.
Design involves creativity within boundaries.
Consider any viable solution concept.
Conceptual Design
• Establish design
specifications
• Generate design
alternatives
• precise descriptions of properties
• numerical values corresponding
to performance parameters and
attributes
• must live within the design space
• let the creativity flow
• don’t marry the first idea
• beware of “you/we can’t…” and
“you/we have to…”
Nail down enough design details that a decision
can be made.
Preliminary Design
• “Flesh out” leading
• “Flesh
conceptual
out” designs
leading
conceptual
designs
• Model,
analyze,
test, and
• Model,
Model
evaluateanalyze,
analyze
conceptual
test
designs
• cardboard or scale models
• computer models (CAD, FEM)
• mathematical models
• qualitative and/or quantitative
• proof-of-concept
• simulation results
• determine the optimal design
The “optimal” design solution may or may not
be obvious.
Design Decision
• Select the optimal design
based on the findings
from the previous stage
Time to go from idea to reality.
Detailed Design
• Refine and optimize
choices made in
preliminary design
• Articulate specific parts
and dimensions
• Fabricate prototype and
move toward production
There is a huge gulf
between a great idea and a
working prototype!
The Engineering Design Process is generally
iterative, not linear.
Problem Definition
(Analysis)
Conceptual Design
(Synthesis)
Preliminary Design (Evaluation)
Design Decision
Detailed Design
(Decision )
(Action)
How is the Engineering
Design Process applied?
(Part 1 – Asking Questions)
The design process begins with some initial
problem statement.
• Initial Problem Statement
– Design a robot to play this year’s game.
• Design problems are often ill-structured and openended.
• Asking questions is a great way to begin defining the
problem to be addressed.
Think in terms of questions that would help
define the problem and guide the design.
•
•
•
•
•
•
•
•
•
What scoring strategy will we use?
What type of steering is desired?
How many degrees-of-freedom does the robot need?
What maximum reach must the robot have?
How fast does the robot need to be?
How much weight must the robot lift?
What physical obstacles must the robot overcome?
Will the robot be interacting with other robots?
What sight (or other) limitations will be placed on the
driver?
• What functions must the robot perform?
Begin to categorize questions in terms of what
information the answers communicate.
Problem Definition
• Clarifying objectives
– What scoring strategy will be adopted?
– How much practice time will drivers have?
• Identifying constraints
– Can the robot touch other robots?
– Can game pieces touch the field?
– What are the dimensions of key parts of the field?
• Establishing functions
– What scoring strategy will be adopted?
– How much ground must the robot cover in a round?
• Establishing requirements
– What minimum size must the robot be to carry a given
game piece?
– How much weight must be lifted to carry a given game
piece?
Think about specific details and various means
of achieving certain functions.
Conceptual Design
• Establishing design specifications
– What is the maximum torque required to pick up a
game piece?
– What is the maximum reach needed?
– What is the smallest space in which the robot will
operate?
• Generating design alternatives
– Could the robot have 2, 3, or 4 wheels? Treads?
– Could game pieces be lifted from above or
scooped from below?
What tools are available to aid in
the Engineering Design Process?
Some simple tools can help organize the design
process.
Problem Definition
• (Questions List)
• Attributes List
• Pairwise Comparison Chart
•Objectives/Constraints Tree
Conceptual Design
• Design Specifications
• 6-3-5 Method
Preliminary Design
• Function-Means Tree
An Attributes List contains a list of objectives,
constraints, …
Problem Definition
• Objectives
– Assemble primary subassemblies on the warehouse rack
– Make no more than 2 trips into/out of the warehouse
– Move planes to flight area (without hanging them)
– Simple controls
• Constraints
– 24 rules (size & weight)
– Less that 6 inches of clearance between racks
– Approximately 6 inches of clearance bringing the plane
through the warehouse door
– Driver doesn’t have depth perception w/r/t racks
… functions, and requirements.
Problem Definition
• Functions
– Grab all 4 warehouse subassemblies (individually) with one
grabber
– Rotate fuselage 90 degrees
– Zero-radius turning
– Move FOD out of the way
• Requirements
– Be able to open the switch
– Reach the top, back airplane piece
– Support the weight of a fully assembled plane
A Pairwise Comparison Chart allows the
designer to order/rank the objectives
• “0” if column objective > row objective
• “1” if row objective > column objective
• Higher score = more important
Problem Definition
Goals
Speed
Drive
Power
Lifting
Power
DOF
Simple
Controls
Score
Speed
••••
0
0
0
0
0
Drive Power
1
••••
1
1
1
4
Lifting Power
1
0
••••
1
1
3
DOF
1
0
0
••••
1
2
Simple
Controls
1
0
0
0
••••
1
An Objectives/Constraints Tree provides a
hierarchical view of key attributes.
Clear 1x4
Move FOD
Move around
field
Zero-radius
turning
24-inch
door
Robot Design
Grab individual
parts
Rotate fuselage
Manipulate
Subassemblies
6-inch
clearance
Release/place
parts
Lift entire
airplane
Place w/o
disturbing
wings
Horizontal
clearance
Design Specifications refer to quantified values.
Conceptual Design
•
•
•
•
•
•
•
Wheel diameter = 8-10 inches
Degrees-of-freedom = 5
Minimum grabber spacing = 1 inch
Maximum grabber spacing = 4 inches
Maximum weight to be lifted = 18 oz.
Maximum vertical reach = 28 inches
Maximum horizontal reach = 12 inches
The 6-3-5 Method is one way to begin
generating design alternatives.
Preliminary Design
• 6 team members
• 3 ideas each (described in words or pictures)
• 5 other team members review each design idea
• No discussions allowed during the process
• Can be modified to N–3–(N-1)
A Function-Means Tree shows means for
achieving primary functions…and the fallout.
Preliminary Design
Move around
the field
Zero-radius
turning
Two drive
wheels
One motor
per wheel
Car-type
steering
1-2 casters
Steering
mechanism
Drive wheel(s)
Power
wheel
directly
Treads
(tank style)
Drive motor for
each tread
2-4 “wheels” for
each tread
Power
axle
Single
rotating
wheel
Rack &
pinion
Rigid bar
linkage
Power one
end of tread
Tread capable of
turning wheels
Power both
ends of
tread
Linkage to turn
two wheels
together
Sturdy tread
A Function-Means Tree shows means for
achieving primary functions…and the fallout.
Preliminary Design
IGNITE
LEAFY
MATERIALS
Electrically
Heated
Wire
Convert
electricity
to heat
Generate
electric
current
Apply heat
to leafy
materials
Focused
Sunlight
Protect
users from
post-usage
burns
Laser
Flame
Store fuel
Control
flame
Supply fuel
for flame
Ignite fuel
Butane
Miniature
heat pump
Resistive
wire
Spark
Wall-outletbased system
Control
electrical
current
Battery-based
system
Store
electricity
Gasoline
Convert chemical
energy to
electrical current
Electrical
resistance
Protect
electric
current from
flame
Generate
electric current
Function
Means
Are there any questions?