Transcript Hardware Development Methods and Tools

Hardware Development Methods
and Tools
Design Methodologies
Component Variations
Misuse
Extended TRIZ
Six Sigma
Six Sigma is a revolutionary business process
geared toward dramatically reducing
organizational inefficiencies that translate into
bottom-line profitably. The steps are:
• Define
• Measure
• Analyze
• Improve
• Control.
The basis of Six Sigma is measuring
and improving processes re: defects
• Six Sigma: 3.4 defects per million
opportunities
• Most current methodologies operate at 3 to 4
sigma, allowing ~ 25% loss of revenue because
of failure rates due to defects
• Result: unhappy, non-returning customers!
Design for Six Sigma
Design for Six Sigma (DFSS) is an approach to
designing or re-designing product and/or
services to meet or exceed customer
requirements and expectations (VOC). It
begins by conducting a “gap analysis” of your
entire product development system. This
analysis finds the gaps in your processes that
are negatively affecting new product
performance…
Methodology 1: DMADV
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Define – determine goals, VOC requirements
Measure – assess customer needs & specs.
Analyze- examine solution options
Design – develop to meet requirements
Verify – verify that you met requirements
Other Methods:
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DMADOV – prior + Optimize
IDEAS – Identify/Design/Evaluate/Affirm/Scale up
IDOV – Identify/Design/Optimize/Validate
DMEDI –
Define/Measure/Explore/Develop/Implement
• DCCDI –
Define/Customer/Concepts/Design/Implement
In General, Design for Six Sigma
• Is a structured approach to responding to the
voice of the customer
• Is augmented by standard tools such as QFD,
Failure Modes and Effects Analysis, Pareto
Charts & analyses, Feather Diagrams,
designsafe analyses, input from reliability
groups, input from QA and customer
complaint inputs, possible analyses from
MAUDE data, etc.
Some Six Sigma Tools:
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Robust design – Taguchi Method
Quality Function Deployment – QFD (done)
Design Failure Modes and Effects Analysis
Axiomatic Design – Nam Suh
Robust Design
By considering the noise factors (variation &
component deterioration) and the cost of
failure this method helps ensure customer
satisfaction. The focus is on improving the
fundamental function of the product or
process, facilitating flexible designs and
concurrent engineering. It assists in reducing
product cost, improving quality, while
simultaneously reducing development
interval.
Your Circuit Choice?
• Compensate the customers for their losses.
• Screen out circuits having large offset voltage
at the end of the production line (discard).
• Institute tighter tolerances through process
control on the manufacturing line (inspect).
• Change the nominal values of critical circuit
parameters such that the circuit's function
becomes insensitive to the cause, namely,
manufacturing variation.
Parameter Diagram, aka P-Diagram
Robust Design – Overview Step 1
Problem Formulation:
This step consists of identifying the main
function, developing the P-diagram, defining
the ideal function and S/N ratio, and planning
the experiments. The experiments involve
changing the control, noise and signal factors
systematically using orthogonal arrays.
Robust Design – Overview Step 2
Data Collection/Simulation:
The experiments may be conducted in
hardware or through simulation. It is not
necessary to have a full-scale model of the
product for the purpose of experimentation. It
is sufficient and more desirable to have an
essential model of the product that
adequately captures the design concept. Thus,
the experiments can be done more
economically.
Robust Design – Overview Step 3
Factor Effects Analysis:
The effects of the control factors are
calculated in this step and the results are
analyzed to select optimum setting of the
control factors.
Robust Design – Overview Step 4
Prediction/Confirmation:
In order to validate the optimum conditions
we predict the performance of the product
design under baseline and optimum settings
of the control factors. Then we perform
confirmation experiments under these
conditions and compare the results with the
predictions. If the results of confirmation
experiments agree with the predictions, then
we implement else repeat.
Design for Failure Modes Effect
Analysis – Form Data & Process
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Number (No.):
Item/Function:
Potential Failure Mode:
Potential Effect(s) of Failure:
Severity (S):
Potential Cause(s)/Mechanism(s) of Failure:
Occurrence (O):
Design for Failure Modes Effect
Analysis – Continued
8. Classification:
9. Current Mitigations:
10.Verification:
11.Detection (D):
12.Recommended actions:
13.Action Results:
Classification
Code To Indicate
Criteria
SC
Severity = 5 and Occurrence = 2 to 5
A potential Safety Characteristics
Severity = 4 and Occurrence = 3 to 5
A potential Key Design
KC
Severity = 3 and Occurrence = 3 to 5
Characteristics
Severity = 2 and Occurrence = 4 to 5
AO
Action Is Optional
Not SC nor KC
Axiomatic Design
• CTS – “Critical To Satisfaction” (or CR,
customer requirements)
• FR – Functional Requirements
• DP – Design Parameters
• PV – Process Variable
Matrix based, aim is to develop FR vectors that
are independent wrt DPs and result in minimal
complexity.
Redundancy
• Active redundancy: MTBF = 1/ => 3/2
• Standby redundancy: MTBF = 1/ => 2/
• Active – units are in parallel & always active
• Standby – units “swap out” when bad
Component Selection
Considerations
• Component reliability
– Vendor assessment (Hx, failure, etc.)
– Vendor audit (check facility)
– Vendor evaluation (inspect incoming)
– Vendor qualification (on-list?)
• Component history
– military & reliability groups
– government info bases
• Safety (FMEA, etc.)
Hardware & Software Techniques
ctd.
• Component Derating
– Practice of limiting the stresses
– Use 2 watt R in 1 watt situation, decrease failure
rate >30% (T, humidity, P, V, I, friction, vibration)
– Usage ratio = max stress/stress rating (.5-.9)
– Goal is reliability!
– Pacemaker example
Hardware & Software Techniques
ctd.
• Safety Margin
– =(mean safety factor) - 1
=(mean strength/mean stress) - 1
– Elevator – safety margin~2
– Medical devices – Fries - .5 and up.
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Load Protection
Environment
Product misuse
Design for variation (6 sigma)
Product misuse: Plan for
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excess application of cleaning solutions
physical abuse
spills
excess weight applied to certain parts
excess torque applied to controls or screws
improper voltages, frequencies or pressures
improper or interchangeable electrical or
pneumatic connections.
The Clean-Room Approach To ReverseEngineering:
“One person or group takes a device apart and describes
what it does in as much detail as possible at a higher
level of abstraction than the specific code. That
description is then given to another group or person who
has absolutely no knowledge of the specific device in
question. This second party then builds a new device
based on the description. The end result is a new device
that works identically to the original but was created
without any possibility of specifically copying the original.
“
-Mathew Schwartz
Extended TRIZ Design Techniques
Example: Effect of a grounding pad
Problem Statement
• Grounding pad is needed in order to conduct
current from scalpel to ground
• Grounding pad must adhere to the body,
otherwise there might be hot spots or burns
• Removal of the grounding pad causes injury,
as seen in the photo. Injuries may include
tearing of the skin, not just what is seen here.
Concept Map for Skin Problem
Ideation Process: Fill in the blanks • Brief description of the problem …
• Problem Formulation … build the diagram:
Formulate …
• » 1. Find an alternative way to obtain [the]
(conducts electricity well) that does not
require [the] (Adheres tightly to skin).
• » 2. Consider transitioning to the next
generation of the system that will provide
[the] (conducts electricity well) in a more
effective way and/or will be free of existing
problems.
Continued…
• » 3. Find an alternative way to obtain [the] (Adheres tightly to
skin) that offers the following: provides or enhances [the]
(conducts electricity well), does not cause [the] (Tears skin).
• » 4. Try to resolve the following contradiction: The useful
factor [the] (Adheres tightly to skin) should be in place in
order to provide or enhance [the] (conducts electricity well),
and should not exist in order to avoid [the] (Tears skin).
• » 5. Find a way to eliminate, reduce, or prevent [the] (Tears
skin) under the conditions of [the] (Adheres tightly to skin).
Continued •
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Select likely suggestions,
Expand upon
Select solution
…
End of chapter -