Title: Approach
1Approach
- Design Definition with Synthesis and Analysis of
Alternative Solutions Leading to a Decision
2General Engineering Process
Problem or Expression of Need
Design Constraints
Evaluation and Synthesis of Alternative Solutions
Elements of Approach
Analysis (perhaps including experimentation)
Decision (justification of selected solution)
Solution
Adapted from Salt Rothery, Design for
Electrical and Computer Engineers
3How Design Approach Relates to Design Description
Elements of Approach
Functional Overview
Design Description
Background Theory
Design Tradeoffs
4Block Heater ExampleGeneral Problem Constraints
- Sometimes automobile block heaters power sources
are dead (unpowered) - Sometimes heaters burn out (open)
- Heaters use120-Volt Power at 300 to 400 Watts
- Want indicator in extension cord to warn uses of
potential problems (then could set breaker or run
car during day)
5Block Heater ExampleEngineering Problem
- Design detection device integrated into extension
cord - Detect difference between 0.5 and 3.0 amperes
- Present binary conclusion to user
- Consume less than 5W
- Integrated manufacturing cost less than 6
6Block Heater ExampleApproach
- Functional Overview
- Diagram of System
- Broad description of needed functionality
- Background and/or Theory
- Types of binary indicators
- Implications of including in extension cord
- Possible Designs Evaluation of Alternatives
- Series indicator design
- Transformer coupled design
- Switch activated design
- Detail Design Description
7Block Heater ExampleFirst Approach, First Attempt
1 ohm
Analysis reveals that LEDs must carry 4 amperes
of forward current not practical due to LED cost
8Block Heater ExampleFirst Approach, Second
Attempt
More analysis using flux equation reveals
realistic solution
9Block Heater ExampleSecond Approach, First
Attempt
Alternate working solution found. Even though it
cost less is rejected because switch would have
to be depressed (not hands-free operation)
10Evaluation of Alternatives
- Design Constraints the yardstick against which
alternatives are evaluated - Cost and performance usually the main factors
- Solution will be near optimal (never perfect)
- Other issues are reliability, maintainability,
sustainability, manufacturability, time to
market, etc.
11Design Methodologies Used in Approach
- Choice of methodology will depend on project
specifics - Objective is to identify the best solution with
minimum engineering cost - Usually involves triangulation to develop
confidence in design - Analysis
- Simulation
- Experimentation
12Summary of Approach Components
- Functional Overview
- Theory Background
- Synthesis of Design Options
- Analysis of Options
- Justification of Design Decision
- Detailed Design Description