Chapter 6
Product Development
R. Fries
Hardware & Software Techniques
• Block diagram the system (Visio)
• Consider Redundancy – active or standby
– Active: failure of one parallel component - the
second still works
– Standby: failure of component – replacement
– MTBF =mean time between failures = 1/λ
– Active MTBF=3/(2λ)
– Standby MTBF=2/λ
Hardware/Software Cont.
• Consider component reliability
– Vendor assessment (Hx, failure, etc.)
– Vendor audit (check facility)
– Vendor evaluation (inspect incoming)
– Vendor qualification (on-list?)
• Consider component history – military &
reliability groups, government info bases
• Consider safety (FMEA, etc.)
Hardware/Software Cont.
• Consider component derating
– 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 Cont.
• Safety margin must be considered
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Safety margin=safety factor-1
=(mean strength/mean stress)-1
Elevator – safety margin~2
Medical devices – Fries - .5 and up.
Load protection must be considered
Environment must be considered (see 112)
Product misuse – consider
Design for variation (6 sigma?)
Software Engineering Management
• Planning for safety (FDA!)
• Planning for risk assessment
• Planning for method
– Waterfall
– Incremental delivery
– Spiral
– Cleanroom
– Code and fix, …
Software Engineering Management
• Choose design method
– Top-down
– Data driven
– OOP
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Language (Assembler/C++/Qbasic?etc.)
Testing
Requirements
Hazard Analysis!!! (FDA)
Software Engineering Management
• Requirements traceability (FDA)
• Software architecture design
– Well defined modules (logical)
– Other vendor – standalone
– Single purpose modules
– Cohesion & coupling
– Naming
– Integration
Structured/Unstructured Design
Techniques
• Computer/database assisted:
– Ideation International IWB
– TRIZ
– Techoptimizer
– Others…
• Example done in class, another in text
Structured/Unstructured Design
Techniques
• Axiomatic Design
– Nam Suh, MIT
– Requirements, design parameters, process
variables, customer needs = vectors
– Try to solve, disassociate functional
requirements and design parameters
– Highly mathematical
– Acclaro Software
Structured/Unstructured Design
Techniques
• Structured, step by step, 8 steps
• Pahl and Beitz
• Semistructured – Wilcox, Engineering
Design for Electrical Engineers, Ulrich and
Eppinger Product Design and
Development
Structured/Unstructured Design
Techniques
• Reverse engineering
• Redesign
• Etc.