concept_of_ergonomics.pdf

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THE CONCEPT OF THE CONCEPT OF ERGONOMICSERGONOMICS

BME 2006BME 2006

THE BASIC CONCEPTS, THE BASIC CONCEPTS, VIEW AND APPROACH OF VIEW AND APPROACH OF

ERGONOMICSERGONOMICS

Outline of presentationOutline of presentation

•• The concept of ErgonomicsThe concept of Ergonomics•• A brief historical overviewA brief historical overview•• ManMan--Machine Systems (MMS)Machine Systems (MMS)•• UsabilityUsability•• MainMain areasareas ofof EErgonomicsrgonomics

The concept of ErgonomicsThe concept of Ergonomics


• ergos (work) + nomos (laws) = ergonomics• Ergonomics = human factors• Ergonomics = a science and practice that

deals with the interaction of Man, Machine and their Environment

• A short definition: ergonomics is human centered technological development

Sanders and McCormick (1993): „Human factors" (ergonomics)• discovers and applies information about human

behavior, abilities, limitations and other characteristics

• to the design of tools, machines, systems, tasks, jobs, and environments

• for safe, comfortable, and efficient human use.


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Main tasks and possibilities of ergonomics at theworking places:

• protecting the health and safety of workers• increasing work efficiency• increasing work satisfaction and feeling of comfort• providing possibilities for personal development

(developing skills, personality, social relationships, etc.)

The The conceptconcept ofof ErgonomicsErgonomicsErgonomics• has a broad interpretation: human centered technological

development,• is the science and practice of developing Man-Machine

Systems,• is not limited to working activity, • is not limited to the ergonomics of scales, handles and

pedals either,• is interdisciplinary science and practice.Therefore the complex subject of ergonomics can only be

understood and practiced successfully on the basis ofapproaches from different directions.

The The conceptconcept ofof ErgonomicsErgonomics

The three main optimizationalgoals of ergonomics:

• Safety• Comfort• Efficiency


A brief historical overviewA brief historical overview

Ergonomics outside the world of work:Product ergonomics

Production systems, environmental ergonomics, system ergonomics.

The birth of ergonomics. Classical ergonomics (‘ergonomics of scales and handles').

1950 1960 1970 1980 1990 2000

Cognitive/software ergonomics.

A brief historical overviewA brief historical overview

ManMan--Machine SystemsMachine Systems

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Ergomomics deals with the optimization of different ”Man-Machine Systems” (MMS). Examples:

• ”worker – working tool"• „socio-technical system„ (factory, ship, aircraft etc.)• ”sportsman – sport device"• „driver – vehicle" • "operator – controlled system"• „user – product”• „soldier – weapon”• „housewife – household appliances”• „human – computer system” etc.

ManMan--Machine SystemsMachine SystemsMan - Machine System

Human subsystem

Body dimensionsArm, leg, trunk, head, etc.

Control sizes, distancesHandle, pedal, pushbutton, etc.

Physiological characteristicsMuscle power (arm, leg, etc.),

Perceptual characteristicsVision, hearing, touch, etc.

Cognitive characteristicsMemory, thinking, etc.

Cognitive requirementsMemory, thinking, etc.

Motivational and emotionalcharacteristics

Motivational andemotional requirements ?

Technical subsystem

Perceptual requirementsVision, hearing, touch, etc.

Physiological requirementsPower/force needs (arm, leg, etc.),

User Interface (UI)

ManMan--MachineMachine SystemsSystems

A MMS always has • a human subsystem, • a technical subsystem, • and a user interface (UI)”.

These subsystems can further be devided into smallarand even smaller elements as necessary dependingon the particular aim of the analysis.

If the human subsystem and the technical subsystemare not compatible, the particular activity may not besafe, comfortable and efficient and therefore the usermay experience increased stress.

The stress will be the topic of a whole lecture later on.

ManMan--MachineMachine SystemsSystemsThus the human subsystem, for example, can be

broken down into• antropometric, • physiological, • perceptual, • cognitive, • emotional,• etc. sub-subsystems, that can further be devided into

even smaller elements if necessary .


The technical subsystems, on the other side, can have a very big variety and therefore we cannot give here even a general level description.

The technical subsystems of the following MMSs, e.g. have very different main characteristics and workingbehavior

• a pilot and the aircraft, • a control operator and the NPP,• a designer and the CAD system,• a bank official and his information system,• a bank system administrator and the system itself, • client and the ATM,• a tennis player and his racket, etc.

ManMan--MachineMachine SystemsSystems• The user interface (UI) is the machine as the

human perceives it - GARDINER és CHRISTIE (1987)

• The user gets into touch with the perceptible surfaceof the machine and creates a general judgementabout the whole system based only on thisperceptible surface.

• Therefore the same technical equipment/device/tooletc. may appear differently for different users.

• As a consequence of learning during usage theperceived quality of the same UI may change evenwithin the same person.


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UUsabilitysability

It is not enough, if a product It is not enough, if a product is is aaesthetic, original, or esthetic, original, or novelnovel iin its appearance….n its appearance….

it has also to be usable!it has also to be usable!

UsabilityUsability

GeneralGeneral frameframe: : efficiencyefficiency ofof workingworking activityactivity

CostsBenefitsEfficiency =

Human performance

Human expenditures

UsabilityUsability

Efficiency =Benefits

Costs

If efficiency is considered in the context of using a certain tool, the key term becomes usability

That the use of the tool makes possible

That the use of the tool requires

(Usability)

UsabilityUsability

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• Usability is the central concept of ergonomics. • Usability is umbrella term for all those factors,

which influence the efficiency of any humanactivity done by technical tools, by shaping thatvery tools.

• For the usability of software products see: ISO/IEC 9126 international standard.

• The usability factors are measurablecharacteristics of usability.

UsabilityUsabilityThe most important usability factors :• Speed of activity,• Number of error committed during the activity, • The user’s possibility to correct these errors by the help

of this tool,• The users expenditures during learning the system,• The endurance of the skills built during learning ,• The user’s possibility to costumize this tool to the

circumstances,• The user’s possibility to rearrange the activity by the

help of this tool,• The user’s general satisfaction with this tool.

UsabilityUsability

The designer’s primary task is to find thebest compromise between

• usability, • functionality• and financial costs.

A summary of „Usability techniques” will be thetopic of a whole lecture later on.

UsabilityUsabilityMan - Machine System

Human subsystem









Technical subsystem



User Interface (UI)

MainMain areasareas ofof ergonomicsergonomics

Man - Machine SystemHuman subsystem









Technical subsystem



User Interface (UI)

MainMain areasareas ofof ergonomicsergonomicsDepending on the actual task, any level ofcompatibility could become important or even critical!










Technical subsystem



User Interface (UI)

MainMain areasareas ofof ergonomicsergonomicsFor example physical working place design mainlyrelates to

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Physiological characteristicsReaction to high/low

temperature, luminance, noise, etc.






Technical subsystem


Physiological requirementsClimate, luminance, noise, etc.

User Interface (UI)

MainMain areasareas ofof ergonomicsergonomicsThe design of the physical environment mainlyrelates to










Technical subsystem



User Interface (UI)

MainMain areasareas ofof ergonomicsergonomicsThe ergonomic product design may relate to any level










Technical subsystem



User Interface (UI)

MainMain areasareas ofof ergonomicsergonomicsSimilarly human factors of safety may also relate toany level and even beyond (to organizational issues)

•• InIn thethe followingfollowing thethe usualusual mainmain areasareas ofofergonomicsergonomics areare listedlisted

•• SomeSome ofof themthem willwill be be givengiven a a shortshort exampleexamplestillstill withinwithin thisthis lecturelecture

•• SomeSome ofof themthem willwill be be givengiven a a wholewhole lecturelecturelaterlater onon

•• InIn thethe casescases ofof thethe rest rest wewe havehave toto confineconfineourselvesourselves simplysimply toto listinglisting themthem herehere


The usualusual mainmain areasareas ofof ergonomicsergonomics::

• Information input

• Human output and control

• Workplace design

• Environmental conditions

• Product ergonomics

• Cognitive/software/web ergonomics

MainMain areasareas ofof ergonomicsergonomicsInformation input

• Information input and processing• Text, Graphics, Symbols, and Codes• Visual Displays (example: VDT ergonomics)• Auditory, Tactual, and Olfactory Displays• Speech Communications• Cultural Stereotypes (example: role of

cognitive schemata)• etc.


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Human output and control• Physical Work and Manual Materials Handling• Motor Skills• Human Control of Systems• Controls and Data Entrs Devices• Hand Tools and Devices• etc.

MainMain areasareas ofof ergonomicsergonomicsWorkplace design

• Applied Anthropometry• Arrangement of Components in Physiscal

Space• Interpersonal Aspects of Workplace design• etc.


Environmental conditions• Illumination• Climate• Noise• Motion• etc.

MainMain areasareas ofof ergonomicsergonomicsProduct ergonomics

• Needs analysis Consumers’ behavior study• User profile identification• Prototype building • Safety testing (example: test conditions)• etc.


Cognitive/software/web ergonomics• Analytic software usability methods (Cognitive

Walkthrough, Heuristic Methods, GOMS-basedMethods, etc.)

• Empirical software usability methods (theINTERFACE method, etc.)

• Automated website evaluation methods • Applying Data Mining (DM) techniques as

website traffic analytic tools: webmining

MainMain areasareas ofof ergonomicsergonomicsPicture quality of CRT devices

Based on the Modulation Transfer Function Area (MTFA)

Based on the „just noticeable differences” (jnd)

The principle color VDT

Example: VDT ergonomics

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A Contrast sensitivity and spatial frequency

Example: VDT ergonomics Example: VDT ergonomicsA Contrast sensitivity and spatial frequency

spatial frequency, cpd

Con

tras

tsen

sivi

ty

Con

tras

tnec

esar

yfo

rpe

rcep

tion

structured field

unstructuredfield

Picture Picture qualityquality ofof CRT CRT devicesdevices

Light vertical lines (stripes) will be presented ondark background by a given VDT and theobject/background contrast is studied as a function of „line density”.

Contrast:

C =Lob - Lbg

Lbg

Lob = luminanceof object

Lbg= luminanceof background

Example: VDT ergonomicsHigh contrast

Lob

Lbg


Lob

Lbg

Example: VDT ergonomicsSmaller contrast

Lob

Lbg

Even smaller contrast


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ModulationModulation TransferTransfer FunctionFunction AreaArea (MTFA)(MTFA)

A monitor által biztosított és a szem által érzékelt kontraszt atéri frekvencia függvényében



display resolution limit

human sensationthreshold

ComparingComparing thethe spatialspatial resolutionresolution ofof thethe VDT VDT andandthethe humanhuman visionvision systemsystem byby thethe jndsjnds



VDTHigh picture qualityLow picture quality

A kontraszt és a téri frekvencia szemléltetése

Highcontrast

Lowcontrast

Low temporalfrequency

Small temporalfrequency

Medium temporalfrequency

Example: VDT ergonomicsReceptor sensitiveto low wavelengths

Receptor sensitive tomedium wavelengths

Receptor sensitiveto high wavelengths

ONOFF

ONOFF

( BLUE GREEN RED

BLUE

+YELLOW

-GREEN

+RED

-

A színérzékelés egyszerűsített modelljeExample: VDT ergonomics

The The principleprinciple ofof thethe holehole maskmask colorcolor VDT: VDT: creatingcreating colorcolor pixelspixels byby thetheredred (R), (R), greengreen (G) (G) andand blueblue (B) (B) electronelectron gunsguns

electron gunsIn the tube

electron beam

phospour layerhole mask

triplett

Example: VDT ergonomicsHow much is the time?

(This watch runs backwards!)

12 1110

98

7654

32

1

Example: role of cognitive schemata

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12 12

34

5678

910

11

How much is the time?(This watch runs normally)


Result: 10:12in both cases

Do this calculation„by heart”:

1144924 ++Now do this

calculationalso „by heart”:

XIIVILXXIV /)( ++Result: VII

Result: 7


SafetySafety testing testing ofof productsproducts andand processesprocessesExample: test conditions

SafetySafety testing testing ofof productsproducts andand processesprocessesExample: test conditions

SafetySafety testing testing ofof productsproducts andand processesprocessesExample: test conditions Example: test conditions

concept_of_ergonomics.pdf

Documents

system ergonomics

possibilities of ergonomics

environmental ergonomics

cognitivesoftware ergonomics

birth of ergonomics

human factors ergonomics

complex subject of ergonomics

human behavior