Chapter 6 Concept Evaluation

6.1 Introduction

6.2 Information representation in concept evaluation

6.3 Evaluation Based on Feasibility judgment

• It is not feasible.

• It is conditional

• It is worth considering

Example: the bikeE suspension

6.4 Evaluation Based on Go/Nogo Screening

1. Are the critical parameters that control the function identified?

2. Are the safe operating latitude and sensitivity of the parameters known?

3. Have the failure modes been identified?4. Can the technology be manufactured with

known processes?5. Does hardware exist that demonstrates

positive answers to the preceding four question?

6. Is the technology controllable throughout the product’s life cycle?

6.5 Evaluation Based on A Basic Decision matrix

Example:

Using the decision matrix:

6.6 Robust Decision Making

• Improve the method used to evaluate the alternatives (step 4 of decision matrix):

Satisfaction= belief that an alternative meets the criteria

Belief = knowledge + confidence

Redefine:Belief=confidence placed on an alternative’s ability

to meet a target set by a criterion, requirement, or specification, base on current knowledge.

Knowledge: A Measure of the information held by a decision-maker about a feature of an alternative defined by a criterion.

One way to measure knowledge is to consider the words that are generally used to describe knowledge and compare them with the probability of having correct information.

Another way of knowledge measurement: five points measurement

Two factors help keep the decision-maker self-assessment:

Confidence: The first scale:

The second scale: five point scale:

• Belief=p(k)*p(c)+(1-p(k))*(1-p(c)) (8.1)

Eg. Elastomer eliminate the shocks from bumps:

6.7 Evaluation Based on an advanced Decision matrix

• Step 1: choose the criteria for comparison.

• Step 2: Develop Relative importance weightings

• Step 3: Select Relative Importance Weightings

• Step 4: Evaluate Alternatives .

• Step 5 Compute Satisfaction

Satisfaction =Σ(belief*importance weighting)

Example:

A B

D C

Spindle Lens

SledRF AMP

DSP CPUData hand shaking

RF, TE, signal

PowerDriver

PowerDriver

Track

FocusPUH

DecoderData

Host

SSP

Sled motorencoder

Tangential direction

Light beam

Split photo-detector

Criteria Importance Alternative

Linear guide Voice coil

1 Can support the optical system

50 0.77 0.3

2 Move fast 20 0.5 0.9

3 Can correct the light abbreviation

20 0.8 0.8

4 Can Do small adjustment

10 0.8 0.6

Satisfaction 62 55

CD Driving system

• Fred’s quotes:

6.8 Product Safety and Liability

6.8.1 Product Safety1. Design safety into product.

2. Add protection device.

3. Warning.

6.8.2 Product Liability

• Product liability due to:1. The product was defectively designed a. keep good records to show all that

was considered during the design process.

b. use commonly accepted standards when available

c. Use state-of –the-art evaluation techniques for providing the quality of the design before it goes into production

d. Follow rational design process.

2. The design did not include proper safety devices.

3. The design did not foresee possible alternative uses of the produce

MIL-STD 882B