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Transcript of Work Environment Physics = Ergonomicsksz.pwr.edu.pl/wp-content/uploads/katjac8795/pdf/1...5 25...
1
Grading requirements
Passing the final test (last two lectures 11.06
– first term and 18.06 – second term)
Alternative: grading by activity
Three small tests – for passing you need a half of
points
Few homeworks
Group works
Answers / questions
Information about activity grading 4.06
1
After the course you’ll get to know:
basic principles of physics with emphasis on
the work environment factors
the effects of some environmental factors
on the human body work and workload
basic ergonomic principles, tools and
methods for the assessment of workload
legal and normative basis for occupational
safety and ergonomics
2
Main goals for today
1. Definition of ergonomics
2. Basic issues of ergonomics
3. Relation between man and the
environmental factors
34
Work Environment Physics
= Ergonomics
Work Environment Physics =
Ergonomics
Ergonomic design
Work environment factors
Microclimate
Noise
Lighting
Ergonomic workload
Accessibility, usability ….
5 6
Outline
Work Environment Physics – what is this?
History
Ergonomic design
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7
Ergonomics
Nazwiskiem Ergonomji, wziętemod wyrazu greckiego ergon – pracai nomos – prawo, zasada,oznaczamy Naukę o Pracy czyli oużywaniu nadanych człowiekowiod Stwórcy siły i zdolności.
Wojciech Bogumił Jastrzębowski, 1857, Rys
ergonomji czyli nauki o pracy, opartej na
prawdach poczerpniętych z Nauki Przyrody
(The Outline of Ergonomics, i.e. Science of
Work, Based on the Truths Taken from the
Natural Science).
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History of ergonomics
Australopitec’s tools
Paleolit tools
Contemprorary tools
History of ergonomics
Ancient Greece (5th
century BC) used
ergonomic principles
in the design of their
tools, jobs, and
workplaces
Hippocrates –
description of how a
surgeon's workplace
should be designed
and how the tools he
uses should be
arranged
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History of ergonomics
Bernardino Ramazzini (1633-1714) was
aware of repetitive movement injuries to
workers.
Clerks
Cobblers and tailors
Porters
Frederick Taylor (1856-1915) Research for work
capability
Work time measurement
Scientific method of work organizing
Scientific management 1903 – Shop Management
1911 – Scientific Management
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The research of shoveling
Purpose:
Load optimization
Shovel shape optimization
Method: searching for the best relation
between load weight and workers’ capacity
3
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Frank and Lillian Gilbreth „Time and
Motion Studies".
Improving efficiency by eliminating unnecessary
steps and actions
Chronocyclography
Example: bricklaying
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Therblig – classification of work
activities
15
Motion analysis
reduction the number
of motions in
bricklaying from 18 to
4.5, allowing
bricklayers to increase
their productivity from
120 to 350 bricks per
hour
16
History of ergonomics
World War II: development of new and complex
machines and weaponry
New demands on operators' cognition
Key success factors:
hand-eye coordination of the machine's operator
decision-making
attention
situational awareness
Pilot error reduction
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Systematic investigations of toleration limits of
physical, mental and environment overload
Rational principles of device design
International organisations:
1949 – Ergonomic Society (Great Britain)
1977 – Polish Ergonomic Society - Polskie
Towarzystwo Ergonomiczne (PTErg)
History of ergonomics
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Ergonomics
Science about relation between human beings
and their work environment.
/Kenneth Frank Hywel Murrell 1949/
4
Ergonomics
Ergonomics is the science of designing the
workplace environment to fit the user
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Ergonomics
Human Machine
Work Environment
Utmost Goal: “Humanization” of Work
The Basics of Ergonomics
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Ergon – work
Nomos – law
Ergonomics = laws of work
Science of fitting workplace conditions and
job demands to the capabilities of the
working population
Ergonomic study areas
WORKERS - what they bring to the job
TOOLS - what they bring to the worker
TASKS - what the worker must do
ENVIRONMENT- the conditions
surrounding the worker and the tool
The ToolThe Task
The Work
Station and
Environment
The User
/Operator
Ergonomic focus
5
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Ergonomics
Ergonomics is the science of improving
employee performance and well-being in relation
to the
job tasks
equipment,
the environment.
Ergonomics is a continuous improvement effort
to design the workplace for what people do well,
and design against what people don’t do well.
26
Ergonomics
Ergonomics (or human factors) is the scientific
discipline concerned with the understanding
of interactions among humans and other
elements of a system, and the profession that
applies theory, principles, data and methods
to design in order to optimize human well-
being and overall system performance.
/IEA - International Ergonomics Association (2000)/
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Human – Millieu system
Human
Physical features
•Anatomy
•Body measures
•Physiology
•Stamina
Psychological
features
•memory
•perception
•attention
Millieu
Material
environment
•microclimate
• lighting
•noise
Technical devices
•Work tools
•Transport
•Supporting
equipment
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Sources or ergonomic knowledge
Human Being
Anthropometry
Anatomy
Biomechanics
Kinesiology
Physiology
Psychology
Sociology
Organisation
Work organisation
Quality management
Marketing
Technics
Mechanical engineering
Industrial design
Steering
Benefits of Ergonomics
Decreased injury risk
Decreased
mistakes/rework
Decreased turnover
Decreased lost work
days (absence)
Increased efficiency
Increased
productivity
Improved morale
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Costs
Economical
Direct
Indirect
Moral loss
Biological – ability of sustaining different
kind of load (physical, psychical and
environmental)
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35 36
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Percentage share of factors related to
working environment (Polish Central
Statistical Office, 2012)
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Ergonomics
Ergonomics is the science of designing the
workplace environment to fit the user
38
Ergonomics
Human Machine
Work Environment
Utmost Goal: “Humanization” of Work
40
Ergonomics
Ergonomics is the science of improving
employee performance and well-being in relation
to the
job tasks
equipment,
the environment.
Ergonomics is a continuous improvement effort
to design the workplace for what people do well,
and design against what people don’t do well.
41
The division of ergonomics
Mikroergonomics
perception
antropometrics
human – device systems
cognitive and decision making
processes
Human Computer Interaction (HCI)
Macroergonomics – organizations as
complex systems
II generation
I generation
III generation
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The division of ergonomics
Physical ergonomics - human anatomical,
anthropometric, physiological and bio mechanical
characteristics as they relate to physical activity
Cognitive ergonomics - mental processes, such as
perception, memory, reasoning, and motor
response, as they affect interactions among
humans and other elements of a system
Organizational ergonomics - optimization of socio
technical systems, including their organizational
structures, policies, and processes
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Physical ergonomics
Biomechanical overload
Layout design
Steering and control design
Workstation design
Work environment
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Cognitive ergonomics
mental workload
decision-making
human-computer interaction
human reliability
work stress
Work training
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Organizational ergonomics
Communication
Crew resource management
Work design
Teamwork
Community ergonomics
Cooperative work
Virtual organizations
Quality management
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The division of ergonomics
Corrective ergonomics – the improvement of
the existing state
Conceptive ergonomics – proper design
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Corrective ergonomics efects
24% efficiency increase among users of ergonomic
workstations
Research of Marvin Daindoff dla NIOSH (The National
Institute for Occupational Safety and Health)
20% efficiency increase after buying the ergonomic
furniture
Illinois University,1990
Personnel turnover decrease from 35% to 2%
Regional Bell Operating Company
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Ergonomic design
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Human – Millieu system
Human
Physical features
•Anatomy
•Body measures
•Physiology
•Stamina
Psychological
features
•memory
•perception
•attention
Millieu
Material
environment
•microclimate
• lighting
•noise
Technical devices
•Work tools
•Transport
•Supporting
equipment
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Stages of ergonomic design
1. Body measures
2. Biomechanical activity
3. User – workstation relations
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1. Body measures
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Body measures
Most important for design
Human body is the main part of every workstation
Variety of body measures
In population
Purpose: designing for everyone
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Standard distribution
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Restraining values – 5 and 95 percentile
Mode
MedianMean
Men
Women
Average
Adult
90% of population
10
Height Probability Distribution
for US men and women
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National Health Statistics Reports, Anthropometric Reference Data for Children and
Adults: United States, 2003–2006
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Centile models
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Phantoms
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Phantoms
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Simplex limitations
Minimal - reach
Maximal
Heights (headroom)
Safety measures
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Duplex limitations
User population
Adjustment
Main aim Design examplesExamples of
measurements
Users should
accommodate
Easy reach Vehicle dashboards,
Shelving
Arm length,
Shoulder height
Smallest user: 5th
percentile
Adequate
clearance to avoid
contact or trapping
Manholes,
Cinema seats
Shoulder or hip width,
Thigh length
Largest user: 95th
percentile
A good match
between the user
and product
Seats,
Cycle helmets,
Pushchairs
Knee-floor height, Head
circumference, Weight
Maximum range: 5th
to 95th percentile
A comfortable and
safe posture
Lawnmowers,
Monitor positions,
Worksurface heights
Elbow height,
Sitting eye height,
Elbow height (sitting or
standing?)
Maximum range: 5th
to 95th percentile
Easy operation Screw bottle tops,
Door handles,
Light switches
Grip strength,
Hand width,
Height
Smallest or weakest
user: 5th percentile
To ensure that an
item can't be
reached or
operated
Machine guarding mesh,
Distance of railings from
hazard
Finger width
Arm length
Smallest user: 5th
percentile
Largest user: 95th
percentile62
Three approaches
1. Design for adjustable ranges – particularly
when health and safety issues are involved
(driving a car, computer workstation)
2. Design for extremes – maximum or
minimum values
3. Design for average users – 50 percentile
figures
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Universal Design
Designing products, buildings and exterior
spaced to be usable by all people to the
greatest extend possible
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7 UD principles
1. Equitable use – avoid segregating or stigmatizing
2. Flexibility in use - i.e.right and left hand
3. Simple and intuitive use – consistent with expectation
4. Perceptible information – redundant, contrast and
compatible
5. Tollerance for errors – warnings and restricted access
to most hasardous elements
6. Low physical effort – fatigue minimizing
7. Size and space for approach and use – good approach,
reach and manipulation regardless to user body size,
posture or mobility
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2. Biomechanical and
physiological features
Give me a place to stand
on, and I will move the
Earth.
Archimedes
12
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Biomechanical and physiological
features
Physiological features
Senses activity
Fatigue
Biomechanical agility
Permissible spread of joint mobility
Prompted forces and torques
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Visual field
1. Often vision without
head and torso
movements
2. Observation and
manipulation with
bend head
3. Rare observations
4. Rare observations
with head and torso
leaned back
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Arm and forearm surface area
Normal reach
Maximal reach
Elbow level Shoulder level
Approximated data for design
A – normal reach
B – maximal reach
C – two-handed work area
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Principles of motion economy
1. Two hands should begin and complete motions at
the same time
2. Two hands should not be idle at the same time
3. Upright and forward facing posture
4. Several different natural and safe postures at
work
5. Motions of arms opposite and symmetrical
directions simultaneously
6. Momentum should be used whenever possible
7. Smooth curved motions are better than straight-
line and sharp changes
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1. Two hands should begin and
complete motions at the same time
Counterbalance to each other
Equal workload
Minimizing total time required
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2. Two hands should not be idle at
the same time
Except: rest
Preferred hand for
more complex
control actions
Allocating the time
between two hands
minimizing the
cycle time
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3. Upright and forward facing posture
Twisting and bending is
always harmful and need
counterbalance
Worse hand – eye
coordination if people not
directly face the work
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4. Several different natural and safe
postures at work
Postural freedom
Avoiding stress and
overload by static and
unnatural postures
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5. Motions of arms opposite and
symmetrical directions simultaneously
Keeping body balance
Motions require less effort
Movement compatibility
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6. Momentum should be used
whenever possible
Reducing forces and muscular effort
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7. Smooth curved motions are better
than straight-line and sharp changes
Sharp changes in direction require added
physical force to overcome momentum and
sustain high rates in acceleration
F=ma change in directions takes time,
force and effort
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3. Relation analysis
User - device
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3. Relation analysis
Analysis of all activities
Equipment choice
Working posture choice
Bondable points
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Equipment choice
Task
Layout criteria by McCormick
Importance
Frequency of use
Sequence of use
Similar functionality
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Computer aided layout optimalization
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Working posture choice
Task
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Consulting the workers
measures
Example: working height for standing
posture
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Factors influencing working height
Worker’s measures
Task features
Precision
Used force
Object size
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Working height for standing posture
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Bondable points Six Pillars of Ergonomic Design
1. User Orientation: Design andapplication of tools, procedures, andsystems must be user-oriented, ratherthan just “task” oriented
2. Diversity: Recognition of diversity inhuman capabilities and limitations,rather than “stereotyping”workers/users
3. Effect on Humans: Tools, procedures,and systems influence human behaviourand well-being
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Six Pillars of Ergonomic Design
4. Objective Data: Empirical information and
evaluation is key in design process, rather
than just use of “common sense”
5. Scientific Method: test and retest
hypothesis with real data, rather than
“anecdotal” evidence or “good estimates”
6. Systems: object, procedures, environments,
and people are interconnected, affect one
another, and do not exist in “isolation”
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Grandjean layout principles
1. For standing people, the appropriate table
height depends on kind of work
2. For seated people, the appropriate table
height depends on chair height
3. Tools, materials and controls should be
located close to the point of use
4. There should be a definite and fixed place
for all tools and materials
90
16
1. For standing people, the appropriate
table height depends on kind of work
For high precision work, tables should be up to 10
cm higher than elbow height
For heavy work as much as 20 cm below elbow
height
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2. For seated people, the appropriate
table height depends on chair height
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3. Tools, materials and controls should
be located close to the point of use
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4. There should be a definite and
fixed place for all tools and materials
Gravity feed bins
and containers
Materials arranged
in the sequence of
use
5S
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Design of tools
Basic reference point –
human hand
Dymorphism on size and
forces
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1. Fit the tool for the body size of
user
Hand tools are frequently designed for the
"average male" hand
Grip diameter = 20% of hand length equals
Modifying handle grip
Use a replacement handle, if available.
If the handle is too small, add a sleeve or
cushion (or duct tape)
If a handle is too large, sand it down to a
smaller diameter if it is made out of wood.96
17
2. Avoid nonneutral hand movements
Push or pull in the
direction of the
forearm
Keep the wrist
straight
97
3. Avoid static overload
Avoid pressure points ans pinch points
Avoid vibrations transmission
98
4. Do not operate tools frequently
and forcefully by hand
Avoid repetitive work
Automatization
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5. Provide good coupling between
hand and handle
100