Transcript Electrical Circuits I

Silicon Prairie Initiative on Robotics in
Information Technology
Engineering
Design Tools
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Client Statement
(Need)
Problem Definition
1. Clarify objectives
2. Establish user requirements
3. Identify constraints
4. Establish functions
Conceptual Design
5. Establish design specifications
6. Generate alternatives
Design Process
Preliminary Design
7. Model or analyze design
8. Test and evaluate design
Detailed Design
9. Refine and optimize design
Final Design
(Fabrication Specs
& Documentation)
Design Communication
10. Document design
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Convergent (left brain) and
Divergent (right brain) Thinking
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Heuristics
A
heuristic is anything that provides
a plausible aid or direction in the
solution of a problem.
 Heuristics are usually unjustified and
potentially fallible.
 Engineering design is the use of
heuristics.
 Heuristics are used to cause the best
change in a poorly understood
situation within the available
resources.
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Sample Engineering Heuristics
Rules
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of Thumb and Orders
of Magnitude
Attitude-Determining
Heuristics
Risk-Controlling Heuristics
Resource Allocation
Heuristics
Miscellaneous Heuristics
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Rules of Thumb
 Ambient
temperature 20 C
 Air 80% nitrogen, 20% oxygen
 Forward biased diode voltage 0.7 V
LED 1.5V
 One
gram of uranium gives one
mega-watt day of energy
 Building construction scales as the
price of meat
 Screws have a point, bolts are flat
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Attitude-Determining
Heuristics
Quantify
or express all
variables in numbers
Always give an answer
Work at the margin of
solvable problems
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Risk-Controlling Heuristics
Make
small changes from
previous successful
solutions.
Always give yourself a
chance to retreat.
Use feedback to stabilize a
design.
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Resource Allocation
Heuristics
Allocate
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sufficient resources
to the weak link.
Allocate resources as long as
the cost of not knowing
exceeds the cost of finding
out.
At some point in the project,
freeze the design.
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Miscellaneous Heuristics
Break
complex problems into
smaller, more manageable
pieces.
Design for a specific time
frame.
Always make the minimum
decision.
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Problem Definition
 Methods
 Means
 Objective Tree
 Pairwise
Comparison Chart
 Weighted Objectives
Tree
 Function-Means Tree
 Functional Analysis
 Requirements Matrix
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 Literature Review
 Brainstorming
 User Surveys and
Questionnaires
 Structured Interviews
Building an Objectives Tree
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Building an Objectives Tree
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Functional Analysis
 What
does the design DO?
 What functions must be performed to
realize the objectives?
Put the language of the client and users
into the language of the engineer.
Put things into terminology that helps to
find ways to meet objectives.
Use terminology that can be used to
measure how well the objectives have
been met.
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What are Functions?
A
relationship between independent
variables (inputs) and response or
dependent variables. (outputs)
 Mathematics:
y  f x 
 Business
Management Theory:
Transformation function
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 labor 
 m aterials    products

  services 

technolog y  
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Black and Glass Boxes
 Like
the mathematical and management
models - relate the inputs to the
outputs
Black Box
 All
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ins and outs must be specified
What happens to each input?
Where does the output come from?
 Remove the cover to see what's going
on inside.
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Black Box of a Radio
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Radio Glass Box
(the cover has been removed)
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Function-Means Tree
A
graphical representation of the
design's basic and secondary functions
 Alternating levels of function and
means
 Begins the process of association of
what must be done and how we might
do it.
 Can be used to separate and sort
secondary functions associated with
the design.
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Heuristics
A
heuristic is anything that provides
a plausible aid or direction in the
solution of a problem.
 Heuristics are usually unjustified and
potentially fallible.
 Engineering design is the use of
heuristics.
 Heuristics are used to cause the best
change in a poorly understood
situation within the available
resources.
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Conceptual Design:
Finding a Feasible Concept.
 Break
down the overall problem into
subproblems.
Find solutions to each subproblem
Combine the subproblem solutions.
 The aim is to start with the project
definition and generate as many ways
as possible of solving the problem.
 Then select the most promising ideas
that meet the design specification.
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Conceptual Design
 Methods
 Means
 Performance
Specification Method
 Quality Function
Deployment (QFD)
 Morphological Chart
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 Brainstorming
 Synectics and
Analogies
 Benchmarking
 Reverse Engineering
(Dissection)
Convergent (left brain) and
Divergent (right brain) Thinking
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