1. Approach Design Definition with Synthesis and Analysis of Alternative Solutions Leading to a Decision

2. General Engineering Process Problem or Expression of Need Design Constraints Evaluation and Synthesis of Alternative Solutions Analysis (perhaps including experimentation) Decision (justification of selected solution) Solution Adapted from Salt & Rothery, Design for Electrical and Computer Engineers Elements of Approach

3. How Design Approach Relates to Design Description Elements of Approach Design Description Design Tradeoffs Background & Theory Functional Overview

4. Block Heater Example General Problem Constraints Sometimes automobile block heater 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 users of potential problems (then could reset breaker or run car during day)

5. Block Heater Example Engineering 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

6. Block Heater Example Approach 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

7. Block Heater Example First Approach, First Attempt Analysis reveals that LEDs must carry 4 amperes of forward current – not practical due to LED cost 1 ohm

8. Block Heater Example First Approach, Second Attempt More analysis using flux equation reveals realistic solution

9. Block Heater Example Second Approach, First Attempt Alternate working solution found. Even though it cost less, it is rejected because the switch would have to be depressed (not hands-free operation)

10. Evaluation of Alternatives Design Constraints are 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.

11. Design 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

12. Summary of Approach Components 1.Functional Overview 2.Theory & Background 3.Synthesis of Design Options 4.Analysis of Options 5.Justification of Design Decision 6.Detailed Design Description