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Industrial Engineering and Ergonomics

© Chair and Institute of Industrial Engineering and Ergonomics, RWTH Aachen University

Univ.-Prof. Dr.-Ing. Dipl.-Wirt.-Ing. Christopher M. Schlick

Dr.-Ing. Dr. rer. medic. Dipl.-Inform. Alexander Mertens

Chair and Institute of Industrial Engineering and Ergonomics

RWTH Aachen University

Bergdriesch 27

52062 Aachen

phone: 0241 80 99 494

email: [email protected]

Unit 10

Ergonomic Design II:

Human information processing,

displays and manual controls

Fall Winter 2016/2017

10 - 2 © Chair and Institute of Industrial Engineering and Ergonomics, RWTH Aachen University

To understand the need for ergonomic design of information

displays and manual controls

To get known the principles of human information processing

To comprehend important aspects of the human visual system

To understand advantages and disadvantages of different

information display concepts

To comprehend characteristics and suitability of different manual

controls

To learn about the interrelation between information displays and

manual controls

Learning Targets


Ergonomic Design – Introduction –

displays and manual controls in planes – Concorde

Source: Wiener, Nagel 1989; Wickens 2004


Information processing –

Human-Machine Interaction

Source: Schlick et al. 2010


Information perception – sensory modalities

Visual

Eye

Color/Brightness

Auditory

Inner Ear

Tone pitch/loudness

Haptic - tactile

Skin (Vater-Pacinic –

Lamella and Meissner-

Receptors)

Pressure/contact/vibration

Vestibular

Organon vestibulare in the middle ear section

Linear and angular acceleration

Haptic - kinesthetic

Muscle spindle

Relative position and speed of parts of the body as well as forces

Gustatory

Blade

Taste

Olfactory

Mucosalspot in the upper nose region

Olfactory impressions

Perception of pain

All free nerve endings

Pain

Thermal

Skin (end-bulbs/ end-organs)

Temperature


Information perception – attributes of sensory

modalities I

Modality Organ Stimulus Range Receptors Sensation

visual Eye Electromagn.

radiation

Wavelength

400 - 750 nm

Retinal cones and

rods

Color and

brightness

auditory Inner ear Air

pressure

fluctuations

Frequencies

20 Hz - 20 kHz

Haircells in the

organ of Corti

Tone pitch and

loudness

tactile Skin Skin deformation Male: 9 mg (lips) - 350

mg (sole of foot)

Female: 5 mg (lips) - 79

mg (sole of foot)

Vater-Pacinic-

Lamella

and Meißner-

Receptors

Pressure, contact

and vibration

kinesthetic Muscle spindle,

special section

of the joints and

ligaments

Stretch of the

muscles and

ligaments, joint

position and

movement

Different according to

joint type and ligament,

e.g. biceps (angle [α],

action force [F])

Proprioceptor:

muscle spindle,

Golgi end organs,

Ruffini-corpuscles

Body part position

to one another,

body part

movement and

acceleration

vestibular Organon

vestibulare in

the middle ear

section

Acceleration of the

human body

Fluid shifts and statoliths

(gravity)

Hair cells in the

sacculus, ultriculus

and in the

semicircular canals

Linear and angular

acceleration


Information perception – attributes of sensory

modalities II

Modality Organ Stimulus Range Receptors Sensation

perception of

pain

Unspecific Impression of pain Injury and atrain Nociceptors -

mostly vacant

nerve endings from

mechanical,

chemical or thermal

sensors

Pain

olfactory Mucosalspot

in the upper nasal

cavity

Molecules in gases Depending on the

type of sub-

stance: from 1

molecule

Olfactory flagella Olfactory

impressions

gustatory Blade Molecules in fluids

Depending on the

type of substance

Gustatory papillae Taste: sweet, sour,

salty, bitter,

umami

thermal Skin Temperature Upper limit :

40°C - 47°C

(3 s exposition,

44 mm² areal)

lower limit:

-17°C

Cold: Krause end-

bulbs;

Heat: Ruffini's end

organ

Warm-cold;

for high and low

temperatures also

pain


Information perception – approach of psychophysics

Stimulus Sensation

objectively measurable subjective

sound pressure loudness

physical psychological

Psychophysics

Detection of stimuli against the background noise

Distinguishing between stimuli of the same sensory modality

Scaling of sensation and formulating of laws


0. Stimulus specificity

(selective perception on the level of sensory

organs)

Only receptor adequate stimuli trigger

sensation.

1. Absolute threshold R0

(psychometric function)

Stimulation intensity, in which a sensory

signal is recognized by the person in half of

the presentations. The probability to detect a

stimulus increases monotonically with the

intensity and typically follows an S-shaped-

curve.

Information perception – superordinate principles I

Perception is the use of the mentioned sensory systems, including the

early processing results of neural information fusion

stimulus intensitiy R

0

0,5

1

𝐹 𝑅 = 𝑃(𝑹 ≤ 𝑅)

threshold

absolute threshold R0

probability

of detection

R0

𝑓(𝑅)

R

0.5


2. Difference threshold ΔR

(just noticeable difference)

Just noticeable difference between two

stimuli of the same sensory modality, which

is detected by the person on average in half

of the presentations.

PSE = Point of Subjective Equality

0

0,25

0,5

0,75

1

stimulus intensitiy R

𝐹 𝑅 = 𝑃(𝑹 ≤ 𝑅)

PSE

probability of

answer that

test stimulus

is stronger

than standard

stimulus

Information perception – superordinate principles II

R25% R75%

75 25

2

% %R RR

R25% R75%

𝑓𝑝(𝑅)

R

PSE


Information perception – superordinate principles III

3. Difference threshold ΔR and psychophysical sensation E

Weber´s Law

Fechner´s Law

The ratio of the difference threshold to

to the standard stimulus is constant.

Weber-Fechner-Law A stimulus must grow in relation to an absolute

threshold stimulus at least logarithmically, if it has to

be precisely perceived as stronger.

k Weber factor

R intensity of instantaneous

stimulus

ΔR difference threshold

R0 absolute threshold

E psychophysical sensation

c stimulus-dependent

parameter

R

Rk

0

lnR

RcE

Source: Goldstein 2002

R

RcE

Se

nsa

tio

n E

R


Information perception – superordinate principles IV

4. Psychophysical sensation E

a) Stevens' power law as a

concretization of the

Weber-Fechner-Law

Integration

The dependence of the (physically

measured) sensation E on the stimulus

intensity R based on a direct evaluation

of the sensory sensation magnitude.

k,n stimulus-dependent parameters

R absolute intensity of stimulus

R0 absolute threshold

E psychophysical sensation

5. Time referenced law of change

Sensation changes depending on the

intensity of stimulus R and its rate of

change dR / dt.

nRRkE )( 0

1 2

dRE f k R k

dt

R

Rn

E

E


Information perception – superordinate principles V

Continuum n Stimulus Condition

Brightness (B) 0.33 5° Target in dark

Loudness (L) 0.6 Binaural perception

Taste (T) 0.8 Saccharine

Vibration (V) 0.95 60 Hz on finger

Continuum n Stimulus Condition

Cold (C) 1.0 Metal contact on arm

Heaviness (H) 1.45 Lifted weights

Muscle force (hand) (M) 1.7 Static contraction

Electric Shock (E) 3.5 Current through fingers

Stevens‘ Power Law:

Source: according to Stevens 1975

nRRkE )( 0


Information perception – multisensory perception –

fusion of multiple sensory input I

Source: Ernst & Bülthoff 2004

It describes interactions

between sensory signals that

are not fully redundant and tries

to predict the combined effect in

terms of accuracy and

resolution

Is based on maximizing the

predictive information that is

delivered from the different

sensory modalities

Often leads to higher human

reliability and performance

Multisensory combination deals with the fusion of information from the

different sensory modalities by the central nervous system:


Information perception – multisensory perception –

fusion of multiple sensory input II

Sizevisual

Sizehaptic

Σ Size

Experience the same object

property with different senses

The sensory information is

partially redundant

Combination of variances in the

sensory estimate of the property

of interest to increase resolution

Minimizing the prediction error

related to the redundant

information by averaging and

weighting the sensory signals

(weighted average)

The signal that is less noisy

receives a higher weight

Multisensory perception can be

modelled by the famous the

maximum likelihood principle

Source: Ernst & Bülthoff 2004


Visual perception: Visual field and field-of-view

Visual field Field-of-view (fov) Extended fov

Fixation With recumbent

head and eyes

With recumbent head

and moving eyes

With moving head and

eyes

Horizontal,

Flash

lights

Monocular: -60 to +95°; Binocular: -60 to +60° (opt. 15°)

Monocular: –75 to +110°; Binocular: –75 to +75° (opt. 30°)

Monocular: –125 to +160°; Binocular: –125 to +125° (opt. 55°)

Horizontal,

Colour

lights

-19 to +32° green, -20 to +36° red, -27 to 47° blue/yellow

-34 to +47° green, -35 to +51° red, -42 to +62° blue/yellow

-84 to 97° green, -85 to +101° red, -92 to +112°blue/yellow

Vertical,

Flash

lights

-75 to +55° -85 to +65° -90 to +110°

Field of view airplane

Analysis of the field

of view


Visual perception – field-of-view for monitoring and

detecting tasks according to DIN 894-2

Aptitude level Relevance

A: Recommendable This range should

be used

whereever it is

possible

B: Suitable This range can be

used if the

recommended

area can not be

used

C:Unsuitable This range should

not be chosen

1: Vertical field of view

2: Horizontal field of view

S: Visual axis, direction is determined by task requirements

SN: Regular visual axis, 15° to 30° under the horizontal

Field-of-view for detecting task

Field-of-view for monitoring task


Visual perception – visual acuity


Visual acuity depending on the site of the retinal image

(under low brightness)

rods

cones

Retina

(under high brightness)

max. physiological

resolution: 0.5´- 1´

(approx.

1 mm at 3-6 m)


Visual perception – visual acuity –

Range of accommodation

Source: Herczeg 2003

Range of accommodation and near point dependent on age

1

Df

: focal length of the lense in [m]

f

: optical power of the lense in [dpt or m-1] D 𝒇


Visual perception – color vision I

Color sensitivity as a function of the adaptation state of the retina

Source: WALD (1964)


Visual perception – application I

Small objects are best seen in black and white contrast

In low ambient light intensity (night), the eye is most sensitive to blue and green

Black and white contrast Black and red contrast

TOMTOM - nightcolors


Visual perception – application II

Lancia Ypsilon: The instruments are applied exentric,

outside the driver‘s optimal field-of-view

Sidewards head and eye movements are necessary

Distraction from the driving task


Visual perception – color vision II

The red-green-amblyopia appears in 8-9% of the male population

The blue-yellow-amblyopia appears in about 1% of the entire population

Complete color blindness only occurs in about 0.001% of the population

Thus about 10% of the male population have a color vision deficiency and 5%

of the entire population.

Color vision deficiency

Regular color perception Red-green-amblyopia

(dyschromatopsia)

Blue-yellow-amblyopia

(tritanopie)


Information displays – display types I

Analog displays

Continuous presentation of state variables

Moving scale or moving needle (pointer)

Disadvantage: Interpolation of intermediate values

Round scale with

moving scale

Round scale with

moving pointer

Sector scale Quadrant scale

Horizontal scale with moving scale Longitudinal scale with

moving pointer


Information displays – display types II

Digital displays

Transmission of discrete (i.e. categorial) state information

Binary displays, 7-segment displays

Alphanumeric displays

Hybrid displays

Representation of the magnitude of a state variable and its rate of change with two separate elements

Electronic information displays

Software-based implementation of display elements


Information displays – applications

Display type Perceptual task

Quantitativ

reading

Qualitative reading

Adjusting values

Monitoring and control

Digital display Good Unfavorable

Numbers must be

individually read and

interpreted.

Changes are poorly

noticeable.

Good

Very accurate but at fast

settings hard to read.

Relationship between control

paramater and display part

unclear.

Unfavorable

Changes are poorly noticable.

Rapid changes are barely

legible.


parameter and display unclear.

Analog display

Moving pointer

Moderate Good

Direction and magnitude

are easy identifiable due

to the pointer position.

Good

Quickly adjustable.

Good manual control by

pointer position.

Unmistakable relationship

between control parameter

and display.

Good

Pointer position is easy to

monitor and regulate.

The relationship between

control parameter and display is

easy to understand.

Moving scale

Moderate Unfavorable

Direction and magnitude

of the deviation are not

recognizable without

reading the scale values.

Moderate

At fast settings hard to read.


parameter and display possibly

misleading.

Moderate

Changes are poorly noticable.

Rapid changes are barely

legible.


parameter and display may be

misunderstood eventually.


Information displays – analog displays –

design guidelines (DIN 894-2)

Labeling and scale arrangement


Left:

Masking effect by badly

coordinated pointer shape and

inner label

Right:

Well-designed pointer shape

and labeling

Not more than three division

levels: Long, medium, short

Not more than four medium tick

marks between two long lines,

not more than four short tick

marks between two middle lines

Measured values between tick

marks should account to 1, 2 or

5 or multiples thereof


Information release – motor function – correlations

between the body forces according to DIN 33411-1

body forces

muscle and inertia forces

(acting in the body system)

action forces

(acting outwardly from the body)

form of the

exercising forces

cause of

the force

appearance of the force function of the force direction

of the

force

force

releasing

body part

active

dynamic

muscle

activity

dynamic

muscle

force

shortening muscle

force dynamic

action force

(motion force)

static

action force

(setting force)

driving force

braking force

manipulation

force

(unguided

movement)

actuating force

(guided

movement)

maintenance

force

tensile strength

reaction force

(body support)

vertical,

horizontal,

sagittal-,

frontal,

ductional

and central

force

arm,

hand,

finger,

leg,

knee, foot and

full body forces

extension muscle

force

static

muscle

activity

static (isometric) muscle force

passive

dynamic

effect of

body

masses

dynamic

inertia

force

e.g.

deceleration force

acceleration force

centrifugal force

static effect

of body

masses

static inertia force

= weight force


Determination of static applied forces according to

DIN 33411-4 by the example of the force direction –B

For a forward-directed arm force, horizontal and parallel to the body‘s

plane of symmetry, with a side angle of β = 0°, a height angle = 10° and

a relative reach of a/amax = 90% a maximal static forces of 170 N can be

generated.

Isodynes describe contours of equal maximum exerted force depending on the position of the body and the effective length of the arm.


Information generation by motor functions –

agedependency of the maximum force

Source: Lange 2005

Maximal strength

Considering the decreasing strength in old age, and the differences in both men and women

Age in years

Muscle

str

ength

in %

fro

m

the m

axim

al str

ength

Maximal strength of men = 100%


Information generation by motor functions –

mobility of the hand

Source: BGI 523 2007


Support of sensorimotor information generation –

manual controls – types of grip

Source: DIN EN 894-3:2010-01

1 Finger

2 Two fingers

3 Thumb opposed

4 Thumb at right

angle

5 Thumb

6 Three fingers

7 Evenly spaced

8 Thumb opposed

9 Fingers

10 Hand

Unidirectional force

Fast actuating

Sensing the setting

Multidirectional force

Precise setting

Continuous actuating

Holding against the

resistance

Load transmission


Support of sensorimotor information generation – manual

controls – operation & functional characteristics

Method of operation Examples Suitability

Finger Keyboard

Button

Switch

Pusher

Small control forces

High control speed

Hand Lever

Handwheel

Handle

Crank

Medium to large control

forces

Medium and large travel

ranges

Foot Footswitch

Pedal

large control forces

Source: BGI 523 2007, Götz 2007

Examples for rotary knobs



manual controls – controls I

Isotonic control (distance and angle measurement)

Provides one or two continuous control variables and returns automatically to the starting position

Manipulated parameters y proportional to distance x or angle α with respect to the initial position

Rear driving force is about the same size at each deflection distance / angle

Continuous measurement of the deflection (e.g. side stick)

Used as speed system by vehicle and plane guidance → a ~ y



manual controls – controls II

Isometric control (force measurement)

Negligible deflection, measurement of applied action forces

Manipulated control parameters proportional to applied force

E.g. 6-D manual control element to control an industrial articulated robot

Operating as speed system?

Source: Baumann 1998, Kuka


Type of movement

Axis of movement: x, y or z

Direction of movement + or -

Continuity of movement: discrete

steps or continuous

Support of sensorimotor information generation – manual

controls – movement characteristics and criteria

Source: DIN EN 894-3:2010-01

linear

Along an

axis

Control force

rotary

Around an

axis

Actuating

torque

Performance

criteria

Communication-

related criteria

Safety-related

criteria

Applied force or

torque

Visual control Inadvertent

operate

Positioning

accuracy

Tactile control Friction

Speed of

adjustment

Use with gloves

Ease of cleaning

Task related criteria



manual controls – movement compatibility


Interaction of displays and manual controls


Conformity with expectations

Compatibility with the arrangement of control unit and display in different planes

The arrangement in the center has the highest clarity on between control part movement

(black) and the reaction of the display (gray)

Less favorable is the assignment on the left side

In the illustration on the right with knob and linear scales in offset planes uncertainties

can already arise in the assignment of cause and effect


Interaction of displays and manual controls –

application



Application –

rotatory manual controls in motor vehicles

Study: Review of the application comfort depending on the applied control

forces and switch types

Investigation of seven rotary

manual controls in terms of their

suitability and their ease of use

under different setting conditions

60 test subjects in the age

between 20 and 75

Continuous variation of the

adjustable rotational resistance

moment in a region between min.

0,015 Nm and complete blockade

of the operating element


Application – Touchscreen with tactile feedback on the

driver's work station

Study: Survey on the use of touch-sensitive displays with tactile feedback

on the driver's work station

Study on the users acceptance

and distraction behavior while

using touch-sensitive display with

tactile feedback on the driver's

work station

72 test subjects in the age

between 20 and 75

Surveying different tactile

feedback concerning their

suitability for the transmission of

information to the driver


Which laws of psychophysics exist for assimilating information?

Which sensory modalities can be distinguished?

Which types of displays exist and to what extent are these suitable for different applications?

What does movement compatibility and obviousness mean?

What are the important aspects of human vision in terms of the perception of displays?

To what extent do the visual acuity and maximum force change with age?

Quick Knowledge Check


Baumann, K. & Lanz, H.: Mensch-Maschine-Schnittstellen elektronischer Geräte. Springer Berlin, 1998

BGI 523: Mensch und Arbeitsplatz 2007

DIN EN 894 Part 2 + 3: Safety of machinery ― Ergonomics requirements for the design of displays and manual controls –

Part 2: Displays. 1997 ,Part 3: manual controls . 2009

DIN 33411 Part 1 + 4: Physical strengths of man; Part 1: Concepts, interrelations, defining parameters.

1982, Teil 4: Maximum static action forces . 1987

M. O. Ernst, H. H. Bülthoff: Merging the Senses into a Robust Percept. Science 8 (4), 2004, 162-169.

Fechner, Gustav Theodor: Elemente der Psychophysik. Breitkopf und Härtel, 1860

Goldstein, E.: Sensation and Perception. Wadsworth, Pacific Grove (USA), 2002

Götz, M.: Die Gestaltung von Bedienelementen unter dem Aspekt ihrer kommunikativen Funktion, TU München, 2007

Herczeg, M.: Mensch-Computer-Kommunikation Teil 1 + 2. http://www.medieninformatik.uni-

luebeck.de/Portal/studierzimmer/lernmodule/index.html, 2003. Stand: 04.04.12

Lange W.; Windel, A.: Kleine Ergonomische Datensammlung. Köln: TÜV-Verlag GmbH 2005

Schlick, C.; Bruder, R.; Luczak, H.: Arbeitswissenschaft, Springer Berlin 2010

Stevens, S. S.: Psychophysics: Introduction to Its Perceptual, Neural, and Social Prospects. New York, NY: John Wiley and

Sons. 1975.

Literature


Wandke, H: Seminar Psychologie und Technik. http://www3.psychologie.hu-berlin.de/ingpsy/alte%20Verzeichnisse%20-

%20Arb1/Lehrveranst/seminar/psych_technik/alte_am_automaten/Ver%C3%A4nderungen%20in%20Alter%20sch%C3%B6

n.htm , 2000. Stand: 09.05.2012.

Wiener, E. L., Nagel, D. C. (1989): Human Factors in Aviation.

Wickens, C. D., Lee, J. D., Liu, Y. & Gordon Becker, S. E. (2004). An introduction to human factors engineering (2nd ed.).

Upper Saddle River, NJ: Pearson Education, Inc. p. 201.

Literature

Industrial Engineering and Ergonomics - Startseite - IAW 10... · Industrial Engineering and Ergonomics ... To comprehend characteristics and suitability of different manual ... Aptitude

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