Human Factors in Product Design 2000.4.15. Myung Hwan Yun Department of Industrial Engineering Pohang University of Science and Technology.

Human Factors in Product Design

2000.4.15.

Myung Hwan Yun

Department of Industrial Engineering

Pohang University of Science and Technology

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Which product do we purchase?

Satisfaction

• Performance• Cost• Image & Impression

Introduction

Purchasing Point of Product • Product Usability Evaluation Method

• Human Interface Element Measurement Technique

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Emerging Paradigm of Product Development - Ergonomics in a New Product Design-

Concurrent engineering/Cross-functional team (Andreasen et. al., 1987)

Strong emphasis is on

– efficiency and performance

– ease of design

– materials/parts cost

– manufacturing requirement Ignored

– customer needs

– potential demand

– effectiveness of design

– product usability (Roozenburg and Ekels, 1995)

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Identification of Customer Needs

Needs 와 Product 는 독립 Functional specification 이 Product 에 의존 Identification of the need

– The most important part of product development– related to the conceptual design, design selection, competitive

benchmarking

Importance of customer needs 를 파악한다해도– systematic implementation to the design process 은 어려움

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Identification of Needs - Series of Ergonomic Analysis-

Expert Ergonomists Evaluates the Product Matrix analysis

– Human characteristics– Product functions,– Human-product interface

Ideas

– New product ideas– New product functions– Design improvements

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New Paradigm for Product Development

Old Paradigm New Paradigm

Concept Engineering-Oriented

Consumer-Oriented

Product Scope Product itself ProductProduct-User InterfaceProduct-Task Interface

Product-User-Environment Interface

Emphasis PerformanceManufacturing

cost

Potential DemandImplicit NeedValue-added

Target Pricecompetitiveness

Additional DemandReplacement Demand

Potential DemandLeadership Engineering

DevelopmentMarketing and Planning

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Concept of Product Evaluation

Customer evaluation

Measurement of product characteristics

Objects for evaluation and measurement

Product Evaluation

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Systematic Design Process

Transforming

– consumer needs and

potential demands

– to design/function

Various models included

– Hierarchical Analysis

– QFD

– AHP, MADM

Identification ofFunctional Requirement

Identification ofOperational Constraint

Hierachical Structure ofProduct Functions

Hierachical Structure ofErgonomic Variables

Relationship Matrix ofErgonomic Function and

Product Function

Weaknessesof Human Function

Possible Improvementof the Product

Shortcomingsof the Product

High Touch Ideas

Evaluated Ideas

Design Solutions

Data Survey

Mock-up/T&E

Working Prototype

MADM Analysis ofNew Idea

AHP Evaluation ofHigh Touch Criteria

Existing ProductSpecification

ConsumerMonitoring

ErgonomicData

Regulation

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Usability Evaluation Technique

Usability Dimension of Consumer Electronic Product (Han et al, 1998)

– Image & Impression Dimension– Performance Dimension– Developing A/V Measurement

Checklist

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Human Characteristics Variable

Subclass Ergonomic VariableVisual Sensing Viewing Angle/Visual Field

Visual Feedback/Visual Fatigue EffectGlare Effect/Eye Movement

Visibility/Legibility/ReadabilityColor Perception/Texture PerceptionDark/Light Adaptation/Visual Acuity

Auditory Sensing Pitch/LoudnessAuditory Feedback/Speech Intelligibility

Sound Localization/Auditory Fatigue EffectTactile Sensing Pressure Perception/Roughness Perception

Vibrotactile Perception/Tactile FeedbackTwo Point Threshold/Tactile Fatigue Effect

Kinesthetic Kinesthetic Feedback /Kinesthetic SensitivityAttention Focused Attention/Selective Attention

Divided Attention/Sustained AttentionDetection Visual Search

Channel Processing Judgement/Identification/InterpretationEstimation/Decision Making

Conceptual CompatibilityMemory Working Memory/Long-Term Memory

Chunking/Rehearsal/Association

About 150 Items on the list Hierarchically Classified Used as a checklist to evaluate the product

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Performance Measurements(II)

Quality of the resultant task output Subjective performance satisfaction

MultiplicityMultiplicity

Time DelayTime Delay

ComplexityComplexity

VisualVisual

PhysiologicalPhysiological

Bio-ElectricBio-Electric

System response delay time Acknowledgment delay time Relative system delay

Relative task length

User input Task length

Mode switch System errors

Rating

Eyelid activity Pupillary dialation

Eye movement GSR(Galvanic Skin Resistance)

Heart rate Respiration volume and rate

EKG(Electrocardiogram) EMG(Electromyogram) EEG(Electroencephalogram) ECP(Evoked Cortical Potentials)

Body temperature Blood presure

TaskTask

SubjectiveSubjectiveSubjectiveSubjective

InterfaceInterfaceInterfaceInterface

PhysiologicalPhysiologicalPhysiologicalPhysiological

44 44 itemsitems

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Image and Impression Measurements

Semantic Differentials

DL ScalePaired Comparison ScaleEquisection Scale

Ratio Production/EstimationMagnitude Production/Estimation

Simple Rating Scale

Likert’s Summated Rating scaleRepertory Grids

Favorable/unfavorable user commentsGood/bad features recalled by usersFrustrations/satisfactionsPleasantness/unpleasantness

Absolute scale

Ratio Scale

Partition Scale

Confusion Scale

Verbal Reports

User Comments& Opinions

ECP(Evoked Cortical Potentials)Bio-electricEEG(Electroencephalogram)EMG(Electromyogram)ECG or EKG(Electrocardiogram)

Visual Pupillary DialationEyelid ActivityEye Movement

Physiological GSR(Galvanic Skin Resistance)Respiration Volume and RateHeart RateBody TemperatureBlood Pressure

PsychophysicalPsychophysicalPsychophysicalPsychophysical

DescriptiveDescriptiveDescriptiveDescriptive

PhysiologicalPhysiologicalPhysiologicalPhysiological

26 26 itemsitems

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Performance Measurements(I)

AccuracyAccuracy

EfficiencyEfficiency

SpeedSpeed Task completion time Time spent in errors

Time spent using help or documentation Time to learn specific functions Time to search the specific commands User delay time

User idleness Relative user delay

Ratio of task completion and error-free time Ratio of successes to failures

Number of available commands not invoked Percentage of functions learned Number of commands used to perform task

Frequency of errors Frequency of failed tasks Frequency of losing control of the system Number of out-of-tolerance condition

Number of repetitions of failed commands Number of times interface misleads the user

Frequency of requests for help information

Number of tasks completed per unit time

TaskTaskTaskTask

SubjectiveSubjective

InterfaceInterface

PhysiologicalPhysiological

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High Touch is a Systematic Approach- Trend Analysis -

Category Automobile ComputerPerformance

Criteria(Past) Power, Speed

?

Speed(CPU)Memory

?(Present) Safety

ComfortSoftwareUsability

UserPopulation

(Past) Driver?

Programmer, Operator?

(Present) Whole Population Whole PopulationHigh Touch (Past)

?

(Driver seat)Fixed Seat

?

(Workstation)Fixed Workstation

?(Present)

?

Adjustable Seat

?

Interchangeable Workstation,?

Trend?

Power Seat?

Multi-MediaMultitasking

Future Computerized Memory SeatIntelligent Seat

?Customized Workstation,

Information Center)

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High Touch 는 시스템적 접근 - Functional Transitivity -

Transitivity TV Audio VCR

Equalizer

TV

Audio

VCR

Picure in Picture

Video Equalizer

Audio-in-Audio Program-in-Program

Preset-equalizerpre-set video quality

pre-set video quality

ProgramReservation

ViewingReservation

ListeningReservation

Video Equalizer

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Relationship Matrix Analysis :Activity vs. Human Characteristics

Activity

Human

Characteristics

승차

준비

승차 자세

시야

조절

안전

벨트

착용

시동 출발

준비

주행 정차 ......

생략

Visual

Auditory

Tactile

Sensing

Kinesthetic

Attention

Detection

Channel

Processing

Information

Processing

Memory

......(생략)

(number of dots : number of Ideas)

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아이디어 실습

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아이디어 창출

쉽고 !

간단하게 !

많은 수로 ( 한 주에 1500-2000 개 )

판단은 나중에

다른 사람의 생각에 기초하여

주제에 초점을 맞추어

한번에 한 사람씩

시각적으로 표현 (Visual (idea, posted, arranged))

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Product Function – Washing Machine

Major Component Design ItemDisplay Display Method/Display Type

Display - Size/Color/Brightness/MaterialControls Switch Type/Shape/Size/No. of

Controls/Labels/Control Sequence/ProgramWash Tub Size/Power Supply/Interior Shape/Exterior

Shape/Attachements/HandlePulsater Pulsator

Size/Shape/Speed/Program/Movement/Material

Water Supply Connection Type/Capacity/ConnectionLocation/

Case Size/Material/Shape/Height/DoorAttachment/Handle Grip

Door Door Type/Screen/Color/Material/Hinge/Grip/Window

Pre-Wash Pre-Wash Station/Rinse Inlet

Hierarchically Classified Functional Breakdown of the product

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Matrix Analysis

Productparameters

Dis

pla

y

Co

tro

l

Wa

shtu

b

Pu

lsa

ter

Wa

ters

up

ply

Ca

se

Do

or

Pre

-wa

sh

Sa

fety

de

vice

importance

visual sensing 1

Auditory Sensing 4

Tactile Sensing 2

Kinethetic 3

Attention 3

Detection 3

Channel Processing 4

Memory 5

sum scores 251 639 279 18 89 420 153 45 375 2269

priority (%) 11 28 12 1 4 19 7 2 16 100

Ergonomic attributes

36

927

9027030

180 2060

654

6

60

999

27

54 6

15

36

135 45

18

135 135

108

54 54 54 54

180 90

140

54

A QFD matrix Human

Characteristics vs. Product Function

152 X 126 cells Based on the

question “Can there be a new

product function satisfying human characteristics X in the product variable Y ?”

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Measures Of Design Quality

Number of component parts and product options Percentage of standard parts Use of existing manufacturing resources Cost of first production run First six months cost of engineering changes First year cost of field service repair Total product cost Total product sales Sustainable development

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Quality Function Deployment (QFD)

Translates the “voice of the customer” into technical design requirements Displays requirements in matrix diagrams First matrix called “house of quality” Series of connected houses

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House Of Quality

6. Technical assessment and target values

1. Customerrequirements

4. Relationship matrix

3. Productcharacteristics

Importance

2. Competitiveassessment

5. Tradeoffmatrix

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Series Of QFD Houses

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Benefits Of QFD

Promotes better understanding of customer demands Promotes better understanding of design interactions Involves manufacturing in the design process Breaks down barriers between functions and departments Focuses the design effort Fosters teamwork Improves documentation of the design and development process Provides a database for future designs Increases customer satisfaction Reduces the number of engineering changes Brings new designs to the market faster Reduces the cost of design and manufacture

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Design For Robustness

Product can fail due to poor design quality Products subjected to many conditions Robust design studies

– controllable factors - under designer’s control

– uncontrollable factors - from user or environment Designs products for consistent performance

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Consistency Is Important

Consistent errors are easier to correct than random errors Parts within tolerances may yield assemblies which aren’t Consumers prefer product characteristics near their ideal values

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Potential Functions Considered

Major Component Design VariableControls Switch Shape Redesign (Size Coding)

Brailed Control ButtonHidden/Open Control SelectionWater Supply SelectionSloping of the Control SectionChoice/Taste Selection

Displays Touch Screen OperationWarning Signal ImprovementTask Guidance SystemAutomatic Lighting AdjustmentVoice Instruction

Wash Tub Interior LightingSelf-CleaningHeat Blower Pre-Drying

Pulsator Combination PulsatorRaised Pulsator

Water Supply Controllable Water OutletAuto Detergent InputOptimum Course SelectionWater Supply BufferWaterfall Supply

Case Ergonomic GripPower Cord ReelClothes Sorting StationPre-Wash/Utility Basket AttachmentDetachable Hangers

Door Transparent DoorAuto-Door

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The Working Prototype

9 functions selected– combination pulsator– pulsator elevation– ergonomic handle grip– power door, – self-cleaning tub– sloped display panel– personal wash program, – tub lighting, – washing progress display

Evaluated to be very successful

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The Production Model

adopted combination pulsator, ergonomic handle grip design, sloped display, new rinsing tool and wash habit programming

In the first six month, the total sales was $ 20 million

increased the market share of the company from 34% to 42%

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High Touch - Hit Product-

Hand-Wash Washing M/CM/S : 8% increase in 3

months(1995)

Elevator Microwave OvenTop M/S in Korea

(1995)

KOBONet Profit $ 100 million

(1990)

UF-Type Water PurifierBest Seller Product

in Korea (1996)

AI RemoconGood Response in Market

(1989)

Double Compressor Refrigerator

Good Response in Market(1996)

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High Touch - Recent Efforts-

Double Deck VCR

Hands-FreeCamcorder

UF-TypeWater Purifier

Pyramid VCR

Double CompressorRefrigerator

MovableAir Conditioner

Hand-WashWashing M/C

ElevatorMicrowave Oven

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CONCLUSION Ergonomic method successfully applied in home appliances

product Ergonomics can be efficient and helpful

– in the new product development Major manufacturers in Korea adopted similar approach New Product Design

– human capabilities

– physical limits

– personal habits

– cultural characteristics

– individual preferences Competitive Advantage

– Personalized products

– Consumer taste

– Tailored functions

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Lessons Learned - Ergonomists in Product Development -

Involve Early in the Development Process Use Process Planning

– Approval from the Management

– Documentation Establish a Formal Process

– Budget

– Schedule

– Reporting Don’t be afraid to Fight It is very easy to Do Nothing