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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
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.
The concept of ErgonomicsThe concept of Ergonomics
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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
The concept of ErgonomicsThe concept of Ergonomics
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 .
ManMan--MachineMachine SystemsSystems
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.
ManMan--MachineMachine SystemsSystems
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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
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)
MainMain areasareas ofof ergonomicsergonomics
Man - Machine SystemHuman 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)
MainMain areasareas ofof ergonomicsergonomicsDepending on the actual task, any level ofcompatibility could become important or even critical!
Man - Machine SystemHuman 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)
MainMain areasareas ofof ergonomicsergonomicsFor example physical working place design mainlyrelates to
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Man - Machine SystemHuman subsystem
Body dimensionsArm, leg, trunk, head, etc.
Control sizes, distancesHandle, pedal, pushbutton, etc.
Physiological characteristicsReaction to high/low
temperature, luminance, noise, 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 requirementsClimate, luminance, noise, etc.
User Interface (UI)
MainMain areasareas ofof ergonomicsergonomicsThe design of the physical environment mainlyrelates to
Man - Machine SystemHuman 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)
MainMain areasareas ofof ergonomicsergonomicsThe ergonomic product design may relate to any level
Man - Machine SystemHuman 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)
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
MainMain areasareas ofof ergonomicsergonomics
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.
MainMain areasareas ofof ergonomicsergonomics
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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.
MainMain areasareas ofof ergonomicsergonomics
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.
MainMain areasareas ofof ergonomicsergonomics
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
Example: VDT ergonomics
Lob
Lbg
Example: VDT ergonomicsSmaller contrast
Lob
Lbg
Even smaller contrast
Example: VDT ergonomics
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ModulationModulation TransferTransfer FunctionFunction AreaArea (MTFA)(MTFA)
A monitor által biztosított és a szem által érzékelt kontraszt atéri frekvencia függvényében
Example: VDT ergonomics
spatial frequency, cpd
display resolution limit
human sensationthreshold
ComparingComparing thethe spatialspatial resolutionresolution ofof thethe VDT VDT andandthethe humanhuman visionvision systemsystem byby thethe jndsjnds
Example: VDT ergonomics
spatial frequency, cpd
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
10
12 12
34
5678
910
11
How much is the time?(This watch runs normally)
Example: role of cognitive schemata
Result: 10:12in both cases
Do this calculation„by heart”:
1144924 ++Now do this
calculationalso „by heart”:
XIIVILXXIV /)( ++Result: VII
Result: 7
Example: role of cognitive schemata
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