Set-Based Design
Our operating assumption is that we
want to be better designers and we are
looking for ways to improve our
techniques.
Review
Creativity/Brainstorming
Creativity is a divergent thinking skill in
which we postpone judgment and try to
see a situation from as many different
perspectives as possible.
Brainstorming is a term used for the
creative generation of many ideas.
What Do We Do With Brainstorming?
• How quickly did you select an idea for your
device?
• How many ideas did you generate before you
got there?
• With brainstorming the idea is to go back and
look at all of the ideas that you generated and
generate many feasible ideas. (not to decide
on an idea and then make a brainstorming list)
Now what?
• Typically, use a concept selection technique to
select one or two ideas for continuation.
• Selecting the “best” solution at this stage is
challenging.
• Maintaining several concepts for longer times
in the design cycle may be better
• We will compare “set-based design” to “pointbased design”
Courtesy Durward Sobek,
Montana State University
Rather than pick the best!
Was the design of the radiator for
the Harley V-Rod more Point-Based
or more Set-Based?
Explain
Sobek and Ward define principles that provide
the framework for set-based design
Map the Design Space
– Define the feasible regions
– Explore trade-offs by designing multiple alternatives
– Communicate the sets of possibilities
Integrate by Intersection
– Look for intersections
– Impose minimum constraint
– Seek conceptual robustness
Establish feasibility before commitment
1.
2.
3.
Narrow sets gradually, balancing the need to learn and the need to decide
Stay within set once committed
Control by managing uncertainty at process gates
Pursue radical and known solutions in parallel
“Toyota’s Principles of Set-Based Concurrent Engineering”
Sobek, Ward, and Liker, Sloan Management Review, Winter 1999
Define the feasible regions
• Decompose the overall design into functional elements
• Develop feasible regions for performance and constraints
• Engineering checklists
– Manufacturing may have: acceptable design radii, material
thickness ranges, ...
– Design may have material property ranges (strength,
conductivity, …)
– Design may have Regulatory constraints (safety, environmental
impact, ...)
• Question:
– What would be on the engineering checklists for
the V-Rod Radiator?
– How did your company maintain design standards
Explore trade-offs by designing
multiple alternatives
• Develop alternative solutions
• Develop a solid understanding of alternatives using the
method that makes most sense:
– prototyping
– Analysis
Question: For the Harley prototype radiators, did
they”converge on a best guess” (p.74 Sobek) then test
and iterate, or did they test several prototypes in parallel?
Communicate the sets of possibilities
• Describes communication between functional groups (and with Chief
Engineer)
• Attempt to develop a full understanding of each others capabilities and
needs
• Don’t communicate your best idea (or your best idea at one operation
state)... Provide description of several options over a wide operation
range
Look for intersections
• Find regions where feasible designs from the
different functions overlap
• Negotiated between functional groups with the CE
• Attempt to optimize total system, not individual
parts
Question: How would you as the engineer
define the feasible design space for the
radiator? (e.g. Cooling Rate = f(?))
Impose minimum constraint
• “Make each decision in its time”
• Know the difference between constraints and
goals.
Seek Conceptual Robustness
• We will discuss Robustness in some detail
later in the course.
• Conceptual Robustness relates to “system
level” performance.
• In general a “robust” design is less sensitive to
changes (changes can come from redesign of
other components, manufacturing, consumer
use, environmental conditions, …)
Narrow sets gradually, balancing the
need to learn and the need to decide
 Develop understanding before making a decision
 Recognizes that design is a decision based process:
 determine preferences
 generate alternatives
 generate expectations
Stay within set once committed
• Always have a fallback design.
• Maintaining a range of designs from
aggressive to conservative helps stay with in
the set.
Question: Did Harley have fallback designs?
Control by managing uncertainty at
process gates
• This is best understood once you are in the
process
Pursue radical and known solutions in parallel
•
•
Pursue unproven high pay-off solutions along with low risk backup
solutions
This gives market flexibility. Toyota’s Prius was a high risk design
that hit the market at a good time while the Camry continued their
more conservative design alternative in the same size category.