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Design Process 중앙대학교 전자전기공학부. Design for Electrical and Computer Engineers 2. Design Process Engineering : Problem solving through specialized scientific

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Design Process

중앙대학교 전자전기공학부

Design for Electrical and Computer Engineers

2. Design Process

Engineering : Problem solving through specialized scientific and mathematical knowledge

Engineer : People who solves a variety of problem as a routine part of their job

Engineering problem : So complex, the engineer cannot instantly see the solution. therefore,

the methodological approach becomes more important

In chapter 2, we will focus on the methodological engineering design process to tackle a complex problem

Design for Electrical and Computer Engineers

2.1 General engineering process

Customer needs

Engineer’s translation of needs including desired outcomes

Synthesis : Putting together of parts or elements so as to form a whole, typically associated with a new system

Analysis: A separating or breaking up of any whole into its part, especially with an examination of these parts to find out their nature, proportion, function, inter relationship, etc

REPEAT (Find Solutions)

Decision: Best solution being among the solution found increase number of solution generated,how many solution needed to explored?

TRADE - OFF

Design for Electrical and Computer Engineers

Let’s cast a die!!! (Example 2.1)

Engineer does not know the worth of any solution that has not been obtained, the only way the engineer can be sure to obtain the best solution is to obtain all six, however, the cost of all solution is relatively high. And the most expensive is likely to obtain 6th solution

Each face of the die has one of six possible solutions!We don’t know the value of six possible solution until castingThe cost of obtaining a solution is 1 M$.

How much money is required for the first solution?

-Probability problem >> 6 M$- Only one casting needed : 1M$

How much money is required for the 6th solution?

Decision making whether further solutions are developed is very important

Design for Electrical and Computer Engineers

2.2 Applying the general engineering process

3. SynthesisFirst attempt using LED

Oops, Engine block heateris out of order

Block heater: preventing engine oil from getting viscous on the cold winter days

1. Symptom, Problem:1. AC outlet circuit to power block heater get overloaded time

to time, the unsuspecting user plug their block heaters into dead outlets

2. Block heaters burn out and go open circuit

3. Customer has to know if things were not working properly when they plugged in their block heaters.

4. AnalysisHigh current LED is too expensive

3A (working)0.5A (Out of order)

2. Problem definitionDesign a device to be integrated with an extension cord that

will detect the difference 0.5 A (not working) and 3 A (working). The device must not consume more than 5 Watt and its manufactured cost including the cost integration must be less than 6 dollars

Design for Electrical and Computer Engineers

Which one is better? Ask to the Customer

Repeat synthesis/analysis again!

3.1 Synthesis1st solution using current transformer

4.1 Analysis- Transformer equation- Cost : 4.5$

v N d dt

3.2 Synthesis2st solution using Light bulb with momentary switch

4.2 Analysis- User has to push the switch when he or she uses- Cost : 4.0 $

Design for Electrical and Computer Engineers

2.3 Evaluation of alternative solutions

General engineering process has been described in terms of arriving at a “best” or “optimum” solution.

If a decision is difficult to make, it is probably because there is not muchdifference in the worth of the alternatives. Do not waste time agonizing over these decisions.

Simply flip the coin!!!

In most practical situations, true optimum solutions are impossible to derive. The best that can be achieved is near optimum, or the best

among several alternative.

How we decide which of several solution is the best alternative? The problem definition is the yardstick for judgment and therefore it becomes a critical step in the design process.

performance cost

Main factor judging the design

Reliabilitymaintainability

Design for Electrical and Computer Engineers

2.4 Design methodologies

Given 10,000 4-digit numbers.

Add the numbers with a hand-held calculator and submit their answers. Contestants whose answer is correct are ranked in the order of submission. Contestants submitting incorrect answer disqualified. The object is to finish with a high rank.

- Focusing on getting correct answer - Focusing on minimizing key strokes

Methodology A Methodology B

- Add all numbers and do it again until two sums are the equal

- Partitions numbers to 100 pieces- Same tactics for 100 number- Same tactics for 100 pieces

If both contestants make no errors

If both contestants make the same number of errors

A is more faster than B

B is more faster than B

Design for Electrical and Computer Engineers

- Considers only one possible solution - Considers a number of solution at a time

Methodology A Methodology B

- Completes the detailed design, implement the solution and evaluates according to design criteria

- Does not carry them to the detailed design and implementation stage instead, only completes initial or block-level design

- Repeat until satisfactory solution is obtained

- Evaluate the block-level design and discard some solution not satisfying the criteria

- Select some promising solution for further investigation

- Less expensive, Fast development time- More effort and thought is devoted to unused solution

Design methodology affects both the efficiency and effectiveness of engineer.

2.4 Design methodologies

Design for Electrical and Computer Engineers

Design methodologies

A subjective comparison of design methodologies is an onerous task for the primary reason that engineering problems have multidimensional evaluation criteria.

Design Criteria

Consumer product Industrial product

Sensitive to Cost Sensitive to Performance

A good design methodology must determine early in the process whether or not the problem can be solved

Design for Electrical and Computer Engineers

2.5 A methodology for high quality

Ideal design methodology (does not allow for correction of mistakes)

Design criteria- Consumer product: Cost- Industrial product: Quality

documentation

Practical design methodology

Design for Electrical and Computer Engineers

- Action item 1- Action item 2- Action item 3

Requirement specification

2.5 A methodology for high quality

- Action item 1- Action item 2- Action item 3

System specification

- Action item 1- Action item 2- Action item 3

Functioning module

- Action item 1- Action item 2- Action item 3

Ideal design methodology (does not allow for correction of mistakes)Practical design methodology

This chapter provides us an overview of a design methodology, In next chapter, the associated concept will be explained

Documentation