1 ergo n anatomy

ERGONOMICS-WHAT IS IT?
The word derived from two Greek words:
“Nomoi” meaning natural laws “Ergon” meaning work
Hence,
ergonomics is the study of human capabilities in
relationship to work demands.
 Ergonomics, also called human factors engineering,
studies the physical and behavioral interaction between
people and their environments. This environment
could be the workplace, the home, or even the car.

ME 690 - HUMAN FACTORS ENGINEERING (3 – 0 – 0) 3
INTRODUCTION
Introduction to Human Factors and ergonomics, ergonomics and its areas of application in the work
system, a brief history of ergonomics, scientific management and work study, human relations and
occupational psychology, Fitting task to the man, attempts to humanize work, modern ergonomics.
HUMAN BODY AS A MECHANICAL SYSTEM
Posture stability, Body Mechanics, anatomy of the spine and pelvis related to posture, lumbo-pelvic
mechanism, low back pain and muscular fatigue, psychosocial factors and physical stressors, tolerance formechanism, low back pain and muscular fatigue, psychosocial factors and physical stressors, tolerance for
collisions and shocks, spinal compression, measurement of musculoskeletal pain in the workplace, system
integration and role of occupational factors.
ANTHROPOMETRY AND WORKSTATION DESIGN
Anthropometry and its uses in ergonomics, sources of human variability, factors influencing the
change in body size of populations, anthropometric surveys, design to fit a target population, cost-benefit
analysis and trade-offs, digital human models, workstation design and reach, design adjustable products,
space planning for offices, industrial workplace layout.
Anatomy of human posture, Fundamental aspects of standing and sitting, effective workstation
design, visual, postural and temporal requirements, holding times for static postures, footrests and foot
rails, ergonomics of seated work, dynamic postures, visual display terminals, guidance for office
workstation design, work surface design, static work-risk assessment, rapid entire body assessment of
working posture using composite risk zone ratings

REPETITIVE RISK ASSESSMENT AND DESIGN OF MANUAL
HANDLING
Risk factors associated with pain and injury, models of the development of
work related musculoskeletal disorders (WMSDs), hand tools and handle design,
limits for hand/wrist exertions in repetitive work, key board design, cell phones
and E-games, cursor control devices, strain index, prevention of WMSDs.
Biomechanics of human walking (Gait), postural control in dynamic tasks,
anatomy and biomechanics of manual handling, back injuries, foot-floor interface,
slips, trips and falls, design of manual handling and carrying tasks, NIOSH
lifting equation.
DISPLAY, CONTROLS AND VIRTUAL ENVIRONMENTS
Visual design, measurement of light, avoidance of glare, key principles
for display design, head mounted displays, auditory displays, Designing Displays
and Controls, Key Principles for Display Design, Guiding Visual Search in
Complex Displays, Auditory Displays, Design of Controls, Voice Control, System
Integration
Cognitive Fatigue and Human Performance, Factors Affecting Mental Workload,
Behavioral Design: Nudging and Friction, Attention Restoration Theory.

S.No Week Topic Mode of
Delivery
1. 1 - 2 Introduction to Human Factors and ergonomics - Ergonomics and its areas of application in
the work system - A brief history of ergonomics - Fitting task to the man - Modern
ergonomics.
Chalk & talk,
ppt
2. 3 - 4 Posture stability- Body Mechanics - anatomy of the spine and pelvis related to posture -
Lumbo-pelvic mechanism - Low back pain and Muscular fatigue.
3. 5 - 6 Tolerance for collisions and shocks - Spinal compression - Measurement of musculoskeletal
pain in the workplace - System integration, Role of occupational factors.
4. 7-8 Anthropometry and its uses in ergonomics - Sources of human variability - Anthropometric
surveys- Design to fit a target population.
5. 9-10 Fundamental aspects of standing and sitting, effective workstation design, Dynamic
postures - Guidance for office workstation design - Work surface design - Static work-riskpostures - Guidance for office workstation design - Work surface design - Static work-risk
assessment - Rapid entire body assessment of working posture using composite risk zone
ratings
6. 11-12 Risk factors associated with pain and injury, models of the development of work related
musculoskeletal disorders (WMSDs)
7. 13-14 Biomechanics of human walking (Gait) - Postural control in dynamic tasks - Anatomy and
Biomechanics of manual handling Back injuries - Design of manual handling and carrying
tasks - NIOSH lifting equation.
8. 15-16 Visual design - Measurement of light - Avoidance of glare - Key principles for display design
- Cognitive Fatigue and Human Performance - Factors Affecting Mental Workload -
Behavioral Design - Attention Restoration Theory.
9. 17-18 Final Examination

Course Assessment Methods
S.No Mode of Assessment Week/Date Duration % Weightage
1. Written Test - 1 6th Week 1 hour 20%
2. Written Test – 2 11th Week 1 hour 20%
3. Group Task / Assignment / Mini
project - -
20%
CPA Written Test
(Portions including Written Tests
1 & 2)
14th Week 1 hour 20%
4. Final Assessment 18th Week 3 hours 40%
Essential Readings: Textbooks, reference books, etc.
i. R.S. Bridger, Introduction to Ergonomics, 2nd Edition, Taylor &Francis, 2003i. R.S. Bridger, Introduction to Ergonomics, 2nd Edition, Taylor &Francis, 2003
ii. Sanders, M.S. and McCormick E.J. Human Factors in Engineering and Design (7th Ed.). McGraw-
Hill, Inc, 1997.
iii. Kroemer, K.H.E., Kroemer, H.B., and Kroemer-Elbert, K.E. Ergonomics: How to Design for Ease and
Efficiency (2nd Ed.). Upper Saddle River, New Jersey: Prentice Hall, 2001.
iv. Wickens, C.D., Lee, J.D., Liu, Y., Gordon Becker, S.E. An Introduction to Human Factors in
Engineering (2nd Ed.). Upper Saddle River, New Jersey: Pearson Prentice-Hall, 2004.
v. Dul, J. and Weerdmeester,B. Ergonomics for beginners, a quick reference guide, Taylor & Francis,
1993.
vi. Green, W.S. and Jordan,P .W, Human Factors in Product Design, Taylor & Francis, 1999.
vii. Pamela McCauley Bush, Ergonomics: Foundational Principles, Applications, and Technologies, CRC
Press, 2012.
viii. G.Salvendy (edit), Handbook of Human Factors and ergonomics, John Wiley & Sons, Inc., 1998

ERGONOMICS
OSHA defines ergonomics as the science of “designing
the job to fit the worker, instead of forcing the worker
to fit the job.”
Ergonomics refers to the interactionErgonomics refers to the interaction
between
The Work
The
Worker
The
Workspace

Physical/mental
capability,
preexisting
conditions, etc
•Heavy, Frequent,
or Awkward
Lifting
•Pushing, Pulling
or Carrying Loads
•Working in
Awkward Postures
•Hand Intensive
Work
•Repetitive motions
•Forceful exertions
•Vibration
Noise,
temperature,
humidity etc

ERGONOMICSERGONOMICS
• It is a developing body of knowledge
whose goal is to provide and maintain a
healthy “user friendly” environment.
• Properly applied, ergonomic principles
support each person's desire to find a zone
• Properly applied, ergonomic principles
support each person's desire to find a zone
of individual comfort.
• Adapting tasks, work stations, tools, and
equipment to fit the worker can help reduce
physical stress on a worker’s body and eliminate
many potentially serious, disabling work related
musculoskeletal disorders (MSDs).
Definition:

ERGONOMICS
 Ideally, ergonomics:
– Makes the job safer by preventing injury and illness
– Makes the job easier by adjusting the job to the worker
– Makes the job more pleasant by reducing physical and– Makes the job more pleasant by reducing physical and
mental stress
– Saves money
Proactive- recognizing, anticipating and reducing risk factors at planning
stage of work process.
Reactive – identifying risk factors and problems asso with work place and
controlling them
NIT
TRI
CHY

INTRODUCTION TO ERGONOMICS
The study of interaction between people and machine
and the factors that affect the interaction .The
purpose is to improve the human machine interaction

WHY IS ERGONOMICS IMPORTANT?
Industries increasingly require higher production
rates and advances in technology to remain
competitive and stay in business. As a result, jobs
today can involve
 Frequent lifting, carrying, and pushing or pulling
loads without help from other workers or devicesloads without help from other workers or devices
 Increasing specialization that requires the worker to
perform only one function or movement for a long
period of time or day after day
 Working more than 8 hours a day
 Working at a quicker pace of work, such as faster
assembly line speeds and having tighter grips when
using tools

THE HISTORY OF
ERGONOMICS
1950 1960 1970 1980 1990 2000
Thebirth of Ergonomics (Ergonomics of„scales and handles”)
Department of Ergonomics and Psychology
www.erg.bme.hu

1. ERGONOMICS OF "SCALES AND
HANDLES"
•World War II: at least 400
aircraft losses due to bad
cockpit design (mostly due to
upgrades during the war)
•Engineering Psychology•Engineering Psychology
labs are established
•Research is focused on
designing the best interface
based on anthropometric
data and a few sensory
thresholds
•Next big boost: space race

THE HISTORY OF
ERGONOMICS
1950 1960 1970 1980 1990 2000
Thebirthof Ergonomics(Ergonomicsof scales and handles)
www.erg.bme.hu
System Ergonomics, Productionsystems

2. SYSTEM ERGONOMICS (INDUSTRIAL
ERGONOMICS)
•Corporations “discover”
ergonomics
•Optimization of tools, work
processes and the
environment itself lead to
increased efficiency, safety
and comfortand comfort
•Everything designed for the
„average user”
•Research is focused on
whole systems not only
“handles” – man- machine
system optimization
•Ergonomics “breaks free” of
exclusive military foundingDepartment of Ergonomics and Psychology
www.erg.bme.hu

THE HISTORY OF
ERGONOMICS
ProductErgonomics
1950 1960 1970 1980 1990 2000
System Ergonomics, Productionsystems
www.erg.bme.hu

3. PRODUCT ERGONOMICS
•The ergonomic approach
spreads to other areas:
education, sports,
transportation
•The product itself is in the
center of attention
•Products are not only
designed for a hypothetical
average user –
diversification starts to
happen – user groups (rich,
poor, disabled, gender,
ethnicity)Department of Ergonomics and Psychology
www.erg.bme.hu

THE HISTORY OF
ERGONOMICS
Cognitive Ergonomics
Product Ergonomics System
1950 1960 1970 1980 1990 2000
Ergonomics, Production systems
www.erg.bme.hu

4. COGNITIVE ERGONOMICS
 Catastrophes that were
caused by human error:
Three Mile Island,
Chernobyl,
 Personal Computers become
common – software
ergonomics
The focus of research is
similar to that of “scales and
handles”, but this time the
most important aspects of
interface design are cognitive
factors (e.g. memory and
attention span) not
sensorimotoric properties –
(nerves or their actions)Department of Ergonomics and Psychology
www.erg.bme.hu

THE HISTORY OF ERGONOMICS EXTENDED
UX
Cognitive Ergonomics Product Ergonomics
System Ergonomics, Production systems
1950 1960 1970 1980 1990 2000 2010+
System Ergonomics, Production systems
The birth of Ergonomics (Ergonomics of scales and
handles)
www.erg.bme.hu

5. USER EXPERIENCE
Emotional response comes first in every situation (read at:
Zajonc). If that first emotion if good, more likely the
customer will buy our product.
www.erg.bme.hu

HISTORY OF ERGONOMICS
In the work environment, the selection and creation of
tools, machines, and work processes continued.
Over centuries, the effectiveness of hammers, axes and
plows improved.
With the Industrial Revolution, machines such as theWith the Industrial Revolution, machines such as the
spinning jenny (a machine that produced yarn to make
cloth) and rolling mills (a method of flattening iron ore
into flat sheets) were developed to improve work
processes. This is the same motivation behind much of
ergonomics today.

 Wojciech Jastrzebowski created the word
ergonomics in 1857 in a philosophical narrative,
"based upon the truths drawn from the Science of
Nature".
 In the early 1900's, the production of industry was still
largely dependent on human power/motion and
ergonomic concepts were developing to improve worker
productivity.
 Scientific Management, a method that improved
worker efficiency by improving the job process, became
popular.

 Frederick W. Taylor was a pioneer of this approach and
evaluated jobs to determine the "One Best Way" they could be
performed. At Bethlehem Steel, Taylor dramatically increased
worker production and wages in a shoveling task by matching the
shovel with the type of material that was being moved (ashes, coal
or ore).
Frank and Lillian Gilbreth made jobs more efficient and less Frank and Lillian Gilbreth made jobs more efficient and less
fatiguing through time motion analysis and standardizing tools,
materials and the job process. By this approach, the number of
motions in bricklaying was reduced from 18 to 4.5 allowing
bricklayers to increase their pace of laying bricks from 120 to 350
bricks per hour.

 World War II prompted greater interest in human-
machine interaction as the efficiency of sophisticated
military equipments like airplanes could be
compromised by bad or confusing design. Design
concepts of fitting the machine to the size of the soldier
and logical/understandable control buttons evolved.
 After World War II, the focus of concern expanded to
include worker safety as well as productivity. Research
began in a variety of areas like Muscle force required
to perform manual tasks, Compressive low back disk
force when lifting, Cardiovascular response when
performing heavy labor ,Perceived maximum load that
can be carried, pushed or pulled.

ATTEMPTS TO HUMANIZE WORK
 In the 1960s in Sweden the VOLVO motor car company
which was suffering from high absenteeism tried to find
new way of assembling cars in an attempt to have more
stable and productive work force there the conventional
line production was replaced by the unit production .line production was replaced by the unit production .
 The British Quality of working life program in 1980
attempted to combine new approaches job design with
technological change under the premise.

MODERN ERGONOMICS
There are four domains of ergonomics namely;
1. Hardware Ergonomics
2. Environmental Ergonomics2. Environmental Ergonomics
3. Cognitive Ergonomics
4. Macro ergonomics

HARDWARE ERGONOMICS DEALS WITH;
 Control design and location parameters and functional
aspects for communication and easy operation
 Visual displays, codes, scales and markings
 Anatomical and anthropometric (static &dynamic)
match establishment
Working posture, body supportive devices match along Working posture, body supportive devices match along
with context fit and workstation
 Range of body movement characteristics and thus
limitations of man (Materials handling, repetitive
movement, work related musculoskeletal disorders).

Environmental Ergonomics: Human environment interface
concerning human capabilities and limitations with respect to
the demands imposed by various environmental modalities
and relevant (safety and health).
Cognitive Ergonomics: Human perception and information
processing (memory)to reduce error, and system mismatch to
increase usability, functional reliability and safety
(stereotype behavior).(stereotype behavior).
 Users' behavioral demands in designing consumer products.
 User-centered interface- computer simulation.
 Effect of psychological stressors on human performance; etc.
 Mental workload, decision making, skilled performance

MACRO ERGONOMICS
It deals with specific aspects of
 Workstation design
 Work process design
 Work organization Work organization
 Shift work sitting

FUTURE DIRECTIONS OF ERGONOMICS
 Technology push is the main factor influencing the
directions and growth of ergonomics. Rapid development
of usable system a priority in many organizations.
 In developing countries there is still a need for basic
ergonomic design of factories and offices.

 The future of ergonomics will be strongly dependent on the
ability of Ergonomists to integrate outside our profession
with a range of stakeholders.
 These include universities and external funding agencies
that will support the education and research programs
required to sustain vitality in the profession.

 The future for ergonomists will require
development of wide-based skills that include
strong technical and research competencies.
 This requires a holistic approach to ergonomics
to achieve practical outcomes to the benefit of
the stakeholders (Communication, Personnelthe stakeholders (Communication, Personnel
resource management, Task design, Design of
shift hours, Team and Cooperative work,
Quality management, participatory design.

ERGONOMICS AIMS AT
 Fitting work to the man.
 Motivating men at work by adapting the
work system to include
 Human tasks
 Working equipment
 Working space and
 Working conditions
 to suit the capabilities and requirements of
human operator

ERGONOMIC CONSIDERATIONS
 In Design of Equipments
 Speed
 Accuracy
 Comfort and
 Safety of the operator Safety of the operator
 Major cause for Human Error is Variability
of
 Human characteristics
 Work
 Working Conditions and
 Environment

VARIABILITY – HUMAN CHARACTERISTICS
 Health, strength, Age, Sex
 Education, Training, Experience, Intelligence,
Interest, Anthropometric data
 Motivation, Reaction Time, Personal
Background,
 Attitude towards work and Personality
Characteristics

VARIABILITY – WORK
 Physical loads
 Perceptual loads
 Mental loads
 Displays and Warning Systems
 Controls
 Compatibility of Inputs and Outputs

VARIABILITY – WORKING CONDITIONS
 Workplace Layout
 Postures
 Motions and Movements
 Fatigue
 Monotony and Relaxation Allowances Monotony and Relaxation Allowances
 Comfort
 Safety and Health
 Working Hours and Shift Working Conditions

VARIABILITY – ENVIRONMENT
 Illumination, Ventilation (covered in OHS)
 Noise
 Heat and Humidity
 Cold
 Vibration

The system can be improved by
1. Designing the user interface to make it more
compactable with the task and the user this makes
it easier to use and more resistant to errors.
2. Change the work environment to make it safe
3. Change the task to make it more compactable with
the user characteristics.
4. Change the way the work is organized to
accommodate the people’s needs.

EXAMPLES
 The work environment can be improved by
eliminating vibration and noise and providing
better seating, better ventilation or lighting.
 Work organization can be improved by enabling
the workers to work at their own places, so as tothe workers to work at their own places, so as to
reduce the psychological stress.
 in an information processing task we must
design the interface so as to reduce the load on
the users memory.

IMPLEMENTATION OF ERGONOMICS IN A SYSTEM
By eliminating aspects of system functioning that
are undesirable uncontrolled or unaccounted
such as
 Inefficiency: when worker output produces sub
optimal output.optimal output.
 Fatigue: in badly designed people tired
unnecessarily.
 Accidents injuries and errors: due to bad
design ,physical stress and mental stress.
 User difficulties
 Low morale and apathy

FOCUS OF ERGONOMICS
The focus of ergonomics is
on the interaction between
the person and the machinethe person and the machine

FOCUS OF ERGONOMICS
 Human factors focuses on human beings and their
interaction with products, equipments, facilities,
procedures and environments used in work and
everyday living.
 The emphasis is on human beings and how the design
of things influences people.of things influences people.
 Human factors, then, seek to change the things people
use and the environments in which they use these
things to better match the capabilities, limitations
and needs of people.

DESCRIPTION OF HUMAN MACHINE SYSTEM
For ergonomics human is the
part of the system and mustpart of the system and must
be fully integrated into the
design stage so human
requirements are system
requirements

HUMAN MACHINE SYSTEM
 Equipment that is usable and safe .
 Task that are compatible with the peoples
expectations limitations and training.expectations limitations and training.
 An environment that is comfortable and appropriate
for the task.
 A work organization that recognizes the people's
social and economic needs.

COMPATIBILITY- MATCHING DEMANDS TO CAPABILITIES
Ergonomic entropy:
this is a disorder in the system functioning that
occurs owing to a lack of compatibility in some or
all of the interaction involving the human
operator .operator .
The incompatibility can occur due to
 Human requirements for optimum system
functioning were never considered at the design
stages .
 In appropriate task design.
 Lack of prototyping .

APPLICATION OF ERGONOMICS
Applications are mostly in
 i) Occupational stress, health hazards.
 ii) Management
 iii) Design iii) Design

APPLICATION AREAS SPECIFIC TO
OCCUPATIONAL HEALTH AND SAFETY:
 Occupational risk management
 Work schedule & sustained performance
 Psychosocial approach occupational health
 Manual material handling
 Work related musculoskeletal disorders
 Warning and risk perception
 Safe design

APPLICATION IN MANAGEMENT
 Work process management, efficiency
 Productivity and human resource utilization
 Work study and time study
 Management of work/rest cycle
 Personnel deployment and Shift work Personnel deployment and Shift work
 Human cost of work and cost benefit effects for the
modifications done
 Manual material handling
 Work ambient environment monitoring
 Human work and efficiency

HUMAN COMPONENTS
 Effort
 Sense
 Central processes
Effort; the three primary effort are the hand, feet, and
voice, more generally the musculoskeletal system and
the body weights can be regarded as effort.the body weights can be regarded as effort.
Sense: the sense are the means by which we are aware
of our surroundings humans are said to have five
senses.
Central process: to carry out activities we need energy
which is provided by the physiological process
providing energy to working muscles. The brain can be
regarded as the information processing unit.

MACHINE COMPONENTS
The machine component include
1. Controlled process
2. Display
3. Controls3. Controls
4. The immediate environment
5. Work space
6. The physical environment
7. Work organization

 Controlled process: the basic operation of the machine
e.g. Nuclear fission, digging vegetable garden,
automatically sorting information.
 Display: this is the action of the machine or its local
environment. In hazardous systems the human operator
has no direct access to the process and interact with the
process through the displays.
 Controls: human interact with the machine through Controls: human interact with the machine through
controls .controls are also important source of feed back
during the execution of control process.
 The immediate environment: this is the place in which
the work is carried out and consists of physical work space.
 Work space: the 3D space in which the work is carried
out. In complex systems the work space is fixed.

 The physical environment: many aspects of physical
environment can affect the worker, ergonomists are
most interested in noise vibration lighting and climate
contamination and pollution of the environment.
 Work organization: work organization as its most Work organization: work organization as its most
basic level refers to immediate organization of human
machine interaction, it refers to the organizational
structure in which the work activity is embedded.

PRINCIPLES OF ERGONOMICS
1. Work in Neutral Postures
 Your posture provides a good starting point for evaluating the tasks
that you do. The best positions in which to work are those that keep
the body "in neutral.”
Maintain the "S-curve" of the
spine
Your spinal column is shapedYour spinal column is shaped
more or less like an "S."
It is important to maintain the
natural S-curve of the back, whether
sitting or standing. The most
important part of this "S" is in the
lower back, which means that it is
good to keep a slight "sway back,"
When standing, putting one foot up
on a footrest helps to keep the spinal
column in proper alignment.

Working for long periods with your
back in a “C-curve” can place
strain on your back.
Good lumbar support is often
helpful to maintain the proper
curve in the small of your back.
Keeps elbows at sides
The neutral posture for your arms is to
keep you elbows at your sides and your
shoulders relaxed. This is pretty
obvious once you think about it, but we
don’t always do it.
Keep Wrists in Neutral
There are several good ways to think
about wrist posture. One way is to keep
the hand in the same plane as the
forearm, as this person is doing here by
using a wrist rest along with the
computer mouse.

A slightly more accurate
approach is to keep your hands
more or less like they would be
when you hold the steering wheel
of your car at the 10 and 2 o’clock
position — slightly in and slightly
forward.
Here’s an example of how this
principle applies to tool design.
Working continuously with the pliers
as shown in the left-hand picture canas shown in the left-hand picture can
create a lot of stress on the wrist. By
using pliers with an angled grip,
however, the wrist stays in its
neutral posture

2.Reduce Excessive Force
 Excessive force on your joints can create a potential for fatigue and
injury. In practical terms, the action item is for you to identify specific
instances of excessive force and think of ways to make improvements.
For example, pulling a heavy cart
might create excessive force for
your back. To make
improvements it might help to
make sure the floor is in good
repair, that the wheels on the
cart are sufficiently large, andcart are sufficiently large, and
that there are good grips on the
cart. Or a power tugger might be
needed.
Or another example of reducing
force is to use a hoist for lifting
heavy objects, like this vacuum hoist
in the drawing.

Another kind of example is having
handholds on boxes or carrying
totes. Having the handhold
reduces the exertion your hands
need to carry the same amount of
weight.
3. Keep Everything in Easy Reach
The next principle deals with keeping things within easy reach. In many
ways, this principle is redundant with posture, but it helps to evaluate a
task from this specific perspective.
Reach Envelope
One concept is to think about the
"reach envelope." This is the semi-
circle that your arms make as you
reach out. Things that you use
frequently should ideally be
within the reach envelope of your
full arm. Things that you use
extremely frequently should be
within the reach envelope of your
forearms.
task from this specific perspective.

Much of the time, problems with reach are simply matters of
rearranging your work area and moving things closer to you.
This is not exactly a hard concept to grasp; what is difficult is
having the presence of mind to notice and change the location
of things that you reach for a lot.
Often it is a matter of habit — you are unaware that you
continually reach for something that could be easily moved
closer.
Or sometimes, the work surface is just too big,
causing you to reach across to get something. One
option is just to get a smaller surface. Another
option is to make a cutout — this way youroption is to make a cutout — this way your
reaches are cut, but you still have plenty of space
for things.
Or another common problem is reaching into
boxes. A good way to fix this is to tilt the box.
Once again, there are thousands of other
examples of ways to reduce long reaches. The
point is for you to think about when you make
long reaches, then figure out how to reduce that
reach.

4.Work at Proper Heights
 Working at the right height is also a way to make things easier.
Do most work at elbow height.
A good rule of thumb is that most work
should be done at about elbow height,
whether sitting or standing.
A real common example is working with a
computer keyboard. But, there are many
other types of tasks where the rule applies.
Exceptions to the Rule
There are exceptions to this rule, however. Heavier
work is often best done lower than elbow height.
Precision work or visually intense work is often
best done at heights above the elbow.
Sometimes you can adjust heights by extending the
legs to a work tables or cutting them down. Or you
can either put a work platform on top of the table
(to raise the work up) or stand on a platform (to
raise YOU up).
Or to be a little more complicated, there are ways
to make stands and work tables instantaneously
adjustable with hand cranks or pushbutton
controls.

5.Reduce Excessive Motions
 The next principle to think about is the number of motions you make
throughout a day, whether with your fingers, your wrists, your arms, or
your back.
One of the simplest ways to reduce manual
repetitions is to use power tools whenever
possible.
Another approach is to change layouts of
equipment to eliminate motions. In the exampleequipment to eliminate motions. In the example
here, the box is moved closer and tilted, so that you
can slide the products in, rather than having to
pick them up each time.
Or sometimes there are uneven surfaces or lips that
are in the way. By changing these, you can eliminate
motions.
As always, there are more examples, but you should
be getting the idea.

6.Minimize Fatigue and Static Load
 Holding the same position for a period of time is known as static load. It
creates fatigue and discomfort and can interfere with work.
A good example of static load that everyone has
experienced is writer’s cramp. You do not need
to hold onto a pencil very hard, just for long
periods. Your muscles tire after a time and
begin to hurt.
In the workplace, having to hold parts and tools
continually is an example of static load.continually is an example of static load.
In this case, using a fixture eliminates the need to
hold onto the part.
Having to hold your arms overhead for a few minutes
is another classic example of static load, this time
affecting the shoulder muscles. Sometimes you can
change the orientation of the work area to prevent
this, or sometimes you can add extenders to the tools.

7.Minimize Pressure Points
 Another thing to watch out for is excessive pressure points, sometimes
called "contact stress.“
A good example of this is squeezing hard onto
a tool, like a pair of pliers. Adding a cushioned
grip and contouring the handles to fit your
hand makes this problem better
Leaning your forearms against the hard edge of a
work table creates a pressure point. Rounding outwork table creates a pressure point. Rounding out
the edge and padding it usually helps.
We’ve all had to sit on chairs that had cushioning
and so understand almost everything we need to
know about pressure points. A particularly
vulnerable spot is behind your knees, which
happens if your chair is too high or when you dangle
your legs. Another pressure point that can happen
when you sit is between your thigh and the bottom
of a table.

8.Provide Clearance
 Having enough clearance is a concept that is easy to relate to.
Work areas need to be set up so that you
have sufficient room for your head, your
knees, and your feet. You obviously don’t
want to have to bump into things all the
time, or have to work in contorted postures,
or reach because there is no space for your
knees or feet.
Being able to see is another version of this
principle. Equipment should be built and tasks
should be set up so that nothing blocks your view

9.Move, Exercise, and Stretch
 To be healthy the human body needs to be exercised and stretched.
You should not conclude after reading all
the preceding information about reducing
repetition, force, and awkward postures,
that you’re best off just lying around
pushing buttons. Muscles need to be loaded
and your heart rate needs periodic
elevation.
If you sit for long periods, you need to shiftIf you sit for long periods, you need to shift
postures:
Adjust the seat up and down throughout the day.
Move, stretch, and change positions often.
Depending upon the type of work you do,
different exercises on the job can be helpful.
If you have a physically demanding job, you may
find it helpful to stretch and warm up before any
strenuous activity.
If you have a sedentary job, you may want to
take a quick "energy break" every so often to do a
few stretches

10.Maintain a Comfortable Environment
 This principle is more or less a catch-all that can mean different things
depending upon the nature of the types of operations that you do.
Lighting and Glare
One common problem is lighting.
In the computerized office, lighting has become
a big issue, because the highly polished
computer screen reflects every stray bit of light
around.
But many other types of tasks can be affected by poorBut many other types of tasks can be affected by poor
lighting, too. Concerns include glare, working in your
own shadow, and just plain insufficient light.
One good way to solve lighting problems is by using
task lighting; that is, having a small light right at
your work that you can orient and adjust to fit your
needs.
Vibration
Vibration is another common problem that can
benefit from evaluation. As an example, vibrating
tools can be dampened.

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