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Introduction to “Human Factors (Ergonomics) ”

Ergün Eraslan, Prof.Dr. Yıldırım Beyazıt University

What is Ergonomics?

“Ergonomics” • Ergon = work • Nomos = laws • “the laws of work” Alternative Names • Humans Factors Engineering (the US military term for HF) • Human Engineering • Occupational Psychology • Engineering Psychology (concerned with perceptual and cognitive factors) • Applied Experimental Psychology

Human Factors Defined ďƒ˜

Human Factors discover and apply information about human behavior, abilities, limitations, and other characteristics to the design of tools, machines, systems, tasks, jobs, and environments for productive, safe, comfortable and effective human use.(Sanders and McCormick, 1993)

Human Factors Defined (2) ďƒ˜

Human Factors (Ergonomics) a body of knowledge about human abilities, human limitations, and other human characteristics that are relevant to design. (Chapanis, 1991)

ďƒ˜

Human Factors Engineering (ergonomics implementation) the application of human factors information to the design of tools, machines, systems, tasks, jobs, and environments for safe, comfortable, and effective human use . (Chapanis, 1991)

ďƒ˜

Human Factors a branch of engineering wherein the social sciences of psychology and sociology are applied to various problems related to the interaction of human beings and products, equipment, facilities, procedures, and environments.

Human Factors Defined (3) The latest formal definition of Ergonomics: ďƒ˜

Ergonomics the scientific discipline concerned with the understanding of the interactions among human 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. (International Ergonomics Association Executive Council, August 2000)

Human Factors Engineering  

concerned with the design of human-machine systems seeks to achieve high levels of system  



effectiveness safety

explicitly considers human     

requirements characteristics capabilities limitations wants and preferences

HFE is a Multidisciplinary Field 

Psychology  





Cognition Sensation and Perception

Medicine, physiology, life sciences 

Engineering      

Anthropometry Biomechanics Systems design Mechanical Electrical Etc…



Computer Science 



How the human body works Programming

Occupational Safety

Related Disciplines

Topics in ergonomics

What is Ergonomics?

Ergonomics • Ergonomics is the study and optimization of the interaction between people and their physical environment by considering their physical, physiological, and psychological characteristics.

Occupational Ergonomics • Concerns the application of ergonomics principles specifically to the workplace and related tasks.

What is Ergonomics?

What Ergonomics is NOT 1. NOT just applying “universal� checklists and guidelines blindly 2. NOT using oneself as the model for design since there is diversity and variation 3. NOT just using common sense since must be based on real data and information

What is Ergonomics?

Six Pillars of Ergonomic Design “Wisdom” 1. User Orientation: Design and application of tools, procedures, and systems must be user-oriented, rather than just “task” oriented 2. Diversity: Recognition of diversity in human capabilities and limitations, rather than “stereotyping” workers/users 3. Effect on Humans: Tools, procedures, and systems are not “inert”, but do influence human behaviour and well-being

What is Ergonomics?

Six Pillars of Ergonomic Design “Wisdom” 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”

What is Ergonomics?

Life-Cycle of Products, Procedures, and Systems 1. Initial Idea: driven by customers, technology change, competitors, problems, needs 2. Requirements: user, manufacturer, standards, government, cost, profit, marketing/sales.

3. Concepts: design alternatives, comparison, choose best one 4. Design: detail parts, integrating with rest of system, prototype testing, optimization

What is Ergonomics?

Life-Cycle of Products, Procedures, and Systems 5. Manufacturing: material, processes, assembly 6. Distribution/Sale: shipping, display, delivery, installation, warranty 7. Use: security, safety, access, maintenance, repair 8. Disposal: toxicity, recycling, reusability, upgrade

Goals of Ergonomics     

Increase the efficiency and productivity of humanmachine systems.

Increase the safety of man-machine systems both for the operators of these systems and the general population.

Increase the quality of system performance.

Improve the reliability and maintainability of systems.

Improve the quality of life for workers by optimizing both their physical and mental workloads.

Human-Machine Systems Operator

Sensing

Machine Display

Information Processing Control Psychomotor Performance

What is Occupational Biomechanics?

Biomechanics “Biomechanics uses the laws of physics and engineering concepts to describe motion undergone by the various body segments and the forces acting on these body parts during normal daily activities” (Frankel and Nordin, 1980) Occupational Biomechanics “Occupational biomechanics is the study of the physical interruption of workers with their tools, machines, and materials so as to enhance the worker’s performance while minimizing the risk of musculoskeletal disorders.” (Chaffin et al., 1999)

Biomechanical Modeling Methods

Anthropometric Methods

Mechanical Work Capacity Evaluation Methods

Kinesiology Methods

Bioinstrumentation Methods

Classifying and Evaluating Work

OCCUPATIONAL ERGONOMICS & BIOMECHANICS Material Handling Limits

Worker Selection Criteria & Training Hand Tool Design Guidelines

Workplace & Machine Guidelines

Seating Design Guidelines

Improved Performance & Reduced Risk of Mechanical Trauma [Chaffin et al, 1999]

The Need for Ergonomics Evidence from Epidemiology  Disabling work injuries in US (1990) = 1.8 million  Permanent Impairment in US (1990) = 600,000  Sprains/Strains account for 43% of work injuries  Musculoskeletal conditions in US (1988) = $126 Billion  Reduction of worker’s compensations costs by 36-91% by companies using Ergonomics in workplace  Areas of Injury 



61%(back), 8%(knee), 7%(ankle), 6%(shoulder), 3.3%(wrist), 3% (neck)

Causes of Injury 

Overexertion (31%), impact (24%), and falling (17%), other (28%)

Philosophy of Ergonomics (Layman’s definition)

“Fit The Task To The Person”

Definitions (1)     

system: set of related, dynamic entities behavior: input, state, output over time goal: desired system behavior(s) function: activity performed to achieve goal system performance     

accuracy speed cost energy consumption etc.

Definitions (2) ďƒ˜ human-machine system: system

with one

or more human components ďƒ˜ human-machine interface (interface) : controls, displays, and other features that transmit information and energy between humans and machines

Systems  We will always be considering systems

which include a human 

manual systems (hand tools)  wooden spoon



mechanical systems (power tools)  electric hand mixer



automated systems (supervisory control needed)  counter-top bread maker

Definitions (3)  task: function performed by

human  human-machine system performance     

system performance plus safety health comfort satisfaction

Examples of Human-Machine Systems  wrench/mechanic  machine tool/machinist  Automobile/driver  Airplane/pilot  Computer/user

The Human Role in HumanMachine Systems 

sensing and monitoring  



reasoning   







planning problem solving decision making

controlling 



observing/estimating system state and behavior comparing against desired state and behavior

manipulating controls changing system state

communicating powering

Human Factors  human and workplace attributes and

requirements, which influence HMS performance   

physical factors sensory factors cognitive factors

Physical Factors         

geometry weight, mass kinematics strength atmospheric requirements thermal requirements motion limits radiation limits etc.

Sensory Factors  reliable sensory detection

(algılama)  reliable sensory discrimination (ayırma)  etc.

Cognitive Factors  perceptual capabilities & limitation  memory capabilities & limitations  decision biases  etc.

Human Performance  speed  accuracy (freedom  time to learn  satisfaction  safety & health

from error)

Human Error 

types of error with respect to intention   



slip: correct intention, incorrect execution (fail) mistake: incorrect intention, execution as intended lapse: failed to carry out intention (forgot something)

types of error with respect to outcome     

Omission (atlama) commission (görev) Sequence timing Deviation (sapma)

Human Factors and System Performance

 since 

a human is an essential HMS subsystem and HMS subsystems interact

 poor human performance degrades

system performance

Goals of ergonomics 1.

Reduce injuries and illnesses

2.

Increase productivity Increase quality of work Increase worker safety Increase worker satisfaction and morale Decrease fatigue Decrease turnover Decrease absenteeism Decrease ‌‌?

3.

4.

5.

6.

7.

8.

9.

HFE Activities  HFE research  HF design  HF evaluation

Ergonomics Activities  Worker / Workplace Accommodation  Physiological Stress Prevention  Environmental Stress Prevention  Equipment design  Error Minimization

Factors Influencing Ergonomics     

Occupational Safety & Health Legislation (mevzuat) Equal Employment Opportunity Product Liability Litigation (ürün sor. hukuku) Quality of Life Expectations Responsible & Concerned Management (ilgili)

Current Emphasis in Ergonomics

 Workplace Design

 Cumulative Trauma (CTD) Prevention  Manual Materials Handling (MMH)  Noise Control  Legislation

& Regulations

Two Types of Ergonomics ďƒ˜ External - Concerned with product

design. ďƒ˜ Internal - Concerned with job and workplace design.

How do you apply Ergonomics?   



Primarily, by changes in the design of workplace or work area.

Education & Training Proactively: Ensure that any new equipment, tool, or products brought into the workplace are designed with adjustability in mind.

Same thought for product design changes, workstation modification, and methods.

Examples of Ergonomic Designs

      

Angled soldering iron (havya) (lehim aleti) Bent-handle pliers (kerpeten) Paint brush with pistol-grip handle (tabanca kabzası) Meat-cutting knife with pistol-grip handle (et kesme bıçağı) Adjustable chair (ayarlanabilir oturak) Adjustable computer workstation (Ayarlanabilir bilgisayar terminali) Writing instruments (yazma aygıtları)

Examples of Ergonomic Designs

 Assembly line that flips automobile

onto its side (bantta yan dönüş)  Automobile control panel  Adjustable-height conveyor belt (bantlı konveyör)  Adjustable computer keyboard  Many, many others!

Secret of Ergonomics

“Adjustability”

Primary Techniques of Ergonomics

Methods Analysis / Design  Workplace Design  Equipment Design  Tool Design  Operator Assignments Note: Basic understanding of industrial engineering, biomechanics, psychology, and physiology, underlying these techniques. 

Benefits of Ergonomics  Improved safety and health  Increased productivity  Increased operator acceptance  Improved attitude toward change  Lower worker’s compensation

premiums (tazminat)

What’s Stopping Ergonomics?  Negative attitudes

(tutumlar)  “Ownership” conflicts (mülkiyet prob)  Omission from engineers’ training  “Quick-fix” focus (kestirme çözüm)

Biggest Problem of All --- !

Designing for the

“Average Person�

--- Whoever they may be !!!

Ownership Conflicts  Safety Vs.. Human Resources  Human Resources Vs.. Medical  Medical Vs.. Safety  Engineering Vs.. All of the Above

Training of Engineers  Engineers are not taught ergonomics at

universities  Fixation is on “things,” not on people  Often times, engineers are assigned ergonomics responsibilities, simply because they have a technical background

Ergonomics Costs to Much!

Fixing Existing Problems Typical Return on Savings Associated with Ergonomic Improvements is $4 for every $1 Invested

Eliminating Potential Problems Addressing Ergonomic concerns in the design & acquisition stage can return as much as $10 of savings for every $1 invested

A History of Human Factors 

Early History 

Industrial revolution (late 1800s & early 1900s)



Gilbreth & Gilbreth



World war II • Fitting the person to the job selection, training • Fitting the equipment to the person



1945-1960: The Birth of a Profession 

1945: Engineering Psychology Lab.



1949: Ergonomics Research Society



1957: Ergonomics (Journal)

A History of Human Factors 



1960-1980: A Period of Rapid Growth 

Military-Industrial complex (before 1960)



Space program



Expand beyond military and space

1980-1990: Computers, Disasters, and Litigation 

Computer technology



Technological disaster Litigation: expert witnesses



• design • warnings and instructions

A History of Human Factors 

1990 and Beyond 

Computer technology



Aviation safety



Design of medical devices



Design for the elderly



Quality of life and work

History of “Human Factors” in Design Early Civilization • development of simple tools and utensils for hunting, gathering, farming, building, and fighting • materials included stone, bone, and wood (and much later … metals) • driven by survival and recognition of need for crafting utensils that would be comfortable & easy to use

History of “Human Factors” in Design 1400s • Leonardo da Vinci studies function of muscle and bone 1500s • Galileo uses concept of constant period of oscillation (salınım) to measure heart rates with a pendulum (sarkaç) 1600s • William Harvey postulates the existence of capillaries (kılcal damar) in connecting veins (damar) and arteries (atardamar) for proper circulation 1700s • Stephen Hales measures arterial pressure & correlates it with hemorrhage (kanama)& ventricular forces; shows how aorta’s elastic properties convert pulsatile flow from heart into smooth flow

History of “Human Factors” in Design 1700s: Ramazzini (physician) observes the Workplace “Manifold is the harvest of diseases reaped by craftsmen … As the … cause I assign certain violent and irregular motions and unnatural postures ….by which … the natural structure of the living machine is so impaired that serious diseases gradually develop.” [Quoted in Chaffin et al., 1999]

History of “Human Factors” in Design Late 1800s / Early 1900s: The Industrial Revolution • Frank and Lillian Gilbreth • study of human motion and workplace management • skilled performance, fatigue, workstations & equipment for physically disabled • e.g. surgical teams study - improved efficiency by suggesting new protocol: surgeons should call for instrument which is placed in extended hand by nurse • forerunners of “human factors” research

History of “Human Factors” in Design The Best Way to Lift Bricks • Frank and Lillian Gilbreth: “…to lift 90 pounds of brick at a time is most advantageous physiologically as well as economically …”

Bricks/Lift

1

18

24

Weight/Lift (lbs)

5

90

120

Work/Hour (kCal)

520

285

450

Bricks/Hour

250

600

300

Optimal Procedure [Data Source: Moore and Andrews, 1997]

History of “Human Factors” in Design 1900-1945: Workplace was “Task Oriented” • people adapted to the job and equipment required • tests developed for better worker selection and training • BUT, still an “efficiency gap” that called for a paradigm shift by fitting job/tools to the person

History of “Human Factors” in Design 1945-1960: “Human Factors” Profession is Born • first engineering psychology labs established in US & Britain • first ‘Ergonomics Research Society’ formed in Britain • first book on human factors in engineering design • first scientific journal in 1957 – ‘Ergonomics’ • International Ergonomics Society launched in 1959

History of “Human Factors” in Design 1960-1980: Rapid Growth • up to 1960, human factors research limited to military • interest and need fed by “Race for Space” • expansion beyond military and space research to industry and workplace (e.g. computers, automobiles, and other consumer products)

History of “Human Factors” in Design 1980-Today: Computers, Disasters, & Lawsuits 





Computers - desire for “people-oriented” technology grew through ergonomically designed computers, user-friendly software, and office design Disasters – Three Mile Island, Chernobyl, and various high-profile chemical plant explosions were linked to lack of attention to “human factor” considerations Lawsuits – courts came to recognize the need for experts in explaining human behaviour, responses, defective design, and effectiveness of workplace warnings and instructions

Summary       

Ergonomics isn’t new Fit task or work area to people Ergonomics is accomplished by design changes Ergonomics is stopped by several factors Contributions come from many fields Quantifiable benefits associated with it Ergonomic projects pay for themselves rapidly

Introduction to Work Physiology

Physiology Vs.. Work Physiology Physiology

“The study of the functions of the systems within the body, and how they (systems) work.”

Work Physiology “The study, description, evaluation, and explanation of the physiological changes in the human body resulting from either a single or repeated series of exposure to work stresses.”

Physiology Vs.. Anatomy Physiology “The study of the functions of the systems within the body, and how they (systems) work.”

Anatomy “A detailed study of the specific parts of the body to include name, location, size, shape, individual contribution, at something greater than the cellular level. It is almost always accompanied with a laboratory, requiring cadaver (kadavra) dissection, as part of the experience.”

Where Physiology Fits In!

General Topic Areas         

Musculoskeletal System Neuromuscular System Muscle Metabolism Cardiovascular System Oxygen Transport Respiratory System Response to Temperature Employee Placement and Selection Repetitive Motion Disorders

Definitions Stress(yüklenme)- Any external force or event that acts on the body Environmental Work Psychological Social 

Strain (gerilme)- To stretch or force beyond the normal, customary or legitimate limits

Definitions Homeostasis- A tendency toward uniformity or stability in the normal body states of the organism Homeostasis is the property of either an open system or a closed system,[1] especially a living organism, which regulates its internal environment so as to maintain a stable, constant condition. Multiple dynamic equilibrium adjustments, regulation mechanisms, make homeostasis possible.

Inherent Tendency

Exercise Phys. Vs..

Work Physiology Primary differences are in the target populations and in some assumptions about where and how they are working.

Exercise Physiology

Exercise Physiology  Goal: Maximize the physiological

efficiency of the target population  Target Population: Fit, healthy, young, motivated  Environment: Usually optimum or controlled

Work Physiology

Work Physiology 

Goal: 



 

To insure worker can perform task efficiently and safely within the environment To accurately measure and evaluate the amount of energy needed to perform the job

Target Population: All kinds of people (literally!)

Environment: Usually not optimal or controlled (noise, heat, vibration, stress, etc.)

Uses of Work Physiology 

  



Can job be safely accomplished---for the stated duration using prescribed tools and procedures?

Which methods are easier?

Can an individual perform a job safely?

How should jobs be ranked (for wage-salary purposes and for work-rest cycle purposes)?

It provides the “Science” to resolve legal disputes.

Who actually does this? 



Many different professions contribute to implementing physiology techniques in the workplace (MD, OHN, IE, IH, etc…).

Typically, most workplace physiological evaluations will be performed by:   

Industrial Engineers Exercise Physiologists Occupational Health Nurses

Summary  Primary focus of physiology is the

system  Differences between work / exercise physiology  Value of work physiology  Who typically applies these techniques

Success Stories  http://www.osha.gov/SLTC/ergonomics/suc

cess_stories.html  http://www.osha.gov/dcsp/compliance_ass istance/success_stories.html