Introduction to Ergonomics and Human Factors PDF

Introduction to Ergonomics and Human Factors Prepared by: Ezrha C. Godilano MSIE, CIE [email protected] Ergonomics An applied scientific discipline that is concerned with how humans interact with the tools and equipment they use while per...

Introduction to Ergonomics and Human Factors Prepared by: Ezrha C. Godilano MSIE, CIE [email protected] Ergonomics An applied scientific discipline that is concerned with how humans interact with the tools and equipment they use while performing tasks and other activities Interface between humans and equipment is a common focus It is also concerned with the physical and social environment in which the tasks and activities are performed and how humans and machines interact with the environment Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p565-579 Ergonomics Derived from the Greek word “ergon” which means work and “nomos” which means rules or laws. A term used in place of ergonomics is human factors. Human Factors is commonly used in the United States, while ergonomics was the preferred term in Europe. Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p565-579 Ergonomics vs Human Factors Ergonomics emphasized work physiology and anthropometry while human factors emphasized experimental psychology and systems engineering. Ergonomics in Europe was more on the industrial work systems, while Human Factors in the United States was more on military systems. Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p565-579 Overview of Ergonomics The main objective of ergonomics is to improve the performance of systems consisting of people and equipment. Methods Engineering and Ergonomics are closely related and their general objectives are: § Improve the performance of existing systems and § To design a new systems for optimum performance Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p565-579 Overview of Ergonomics Ergonomics has a wide variety of applications, and these can be classified into two main areas: § Work system design: interaction between the worker and equipment used in the workplace. Safety, accident avoidance, and related performance attributes are the objectives. Includes consideration of factors related to the work environment such as lighting and noise levels § Product design: deals with the design of products that are safer, more comfortable, and more user-friendly and mistake-proof. Issue is product liability lawsuits and their avoidance through consideration of ergonomics Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p565-579  “Fitting the job to the person” vs “Fitting the person to the job” If you are to choose, which is better? Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p565-579 The ergonomic approach is diametrically opposite of FPJ. The philosophy is “fitting the job to the person”. WHY? Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p565-579  “Fitting the job to the person” § Is designing the job so that nearly any member of the workplace can perform it. “Fitting the person to the job” § Recommends that workers be selected on the basis of their mental aptitudes and physical characteristics for a particular job opening. Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p565-579 Human-Machine Systems Definition Human-Machine Systems is the basic model in ergonomics. It is defined as a combination of humans and equipment interacting to achieve some desired result. Can be classified into three basic categories: 1. Manual Systems § The system involves a person using some hand tool or other nonpowered implement to perform an activity. 2. Mechanical Systems § The system refers to one or more humans using powered equipment to accomplish some job and the function of the human is to control the equipment Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p565-579 Definition Human-Machine Systems is the basic model in ergonomics. It is defined as a combination of humans and equipment interacting to achieve some desired result. Can be classified into three basic categories: 3. Automated Systems § Involves the performance of a job with minimum of human attention. The ergonomic objective in Human-Machine Systems is to optimize the performance of the system by making interactions between the human and the equipment as seamless as possible while the system operates in its environment. Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p565-579 Human-Machine Interactions Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p565-579 Components of Human-Machine Systems Human Components Machine Components Environment Components Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p565-579 Human Components § Human Senses: includes the five basic human senses. They are the sensors by which humans are able to be aware of where they are and what is happening around them. § Human Brain: the brain can be considered as a data- and information- processing unit, analogous in some ways to the operation of a computer. § Human Effectors: an effector is a body part such as muscle group of muscles that actuates in response to some stimulus. Principal human effectors are the fingers, hands, feet, and voice. These are supported by the musculoskeletal system of the body, and the stimulus is provided by the information processing occurring in the human brain. Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p565-579 Machine Components § The process: refers to the function or operation performed by the human-machine system, such as digging a hole, driving a car, etc. § Displays: this function is accomplished by the worker observing the process as it is being performed. It can be mental or artificial display is needed. § Controls: these can be operated by the human effectors, usually the fingers and the hands. Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p565-579 Environmental Components § Physical Environment: includes the immediate area of the human- machine system, separated from the system by a defined boundary. Usually include the location and surrounding lighting, noise, temperature, and humidity. § Social Environment: this is determined by coworkers and colleagues, immediate supervisors, organizational culture, and the work organization. Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p565-579 Topic Areas in Ergonomics Topic Areas in Ergonomics § Physical Ergonomics: it is mostly about manual labor. ü Physiology ü Anthropometry § Cognitive Ergonomics: concerned with the capabilities and limitations of the human brain and sensory system while performing activities that include a significant amount of information processing ü Sensory system ü Perception ü Memory ü Response selection and execution Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p565-579 Topic Areas in Ergonomics § Physical Work Environment: work is performed in an environment that includes both physical and social aspects. ü Visual environment ü Auditory environment ü Climate § Occupational Safety and Health: constitutes an important national issue that affects virtually every person who works. Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p565-579  Industrial Accidents and Injuries Definitions § Occupational Safety: concerned with the avoidance of industrial accidents and in particular accidents that cause injury or fatality. § Occupational Health: concerned with avoiding diseases and disorders that are induced by exposures to materials or conditions in the workplace. Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p668-684 Industrial Accidents and Injuries ü Industrial Accident: an unexpected or unintentional event that disrupts work procedures and has the potential to cause damage to property and injury or death to workers. ü hazard: a condition or a set of conditions that has the potential for causing an accident or other harmful outcome. ü danger: is the relative exposure or liability to injury, death, and/or damage from that hazard. Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p668-684 Industrial Accidents Factors § Human errors. These factors relate to the worker or workers who are responsible for the operation and make mistakes that are sometimes the direct cause of an industrial accident. § Job factors. This category refers to the kinds of tasks, methods, materials, equipment, and so on that are used in the operation. Some jobs are more dangerous than others. § Environmental conditions. Lighting, noise, temperature and other conditions that surround the operation. Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p668-684 Human Error and Accidents § Human error is often identified as the cause of an industrial accident. § Human error can be defined as an improper and or inadvertent human act or decision that has the effect or the potential to reduce effectiveness or safety in the workplace. Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p668-684 Human Error Classifications § Errors of omission occur when a worker fails to take some action that is called for. § Errors of commission occur when a worker takes an action that is incorrect. § Factors that correlate with accident rates are: ü Age ü Time on the job ü Fatigue ü Stress Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p668-684 Job Factors § Methods. It can be manual, mechanized, or automated, or there may be combinations of these categories for certain tasks. § Equipment. The equipment used by a worker can be a source of hazards in a job. § Materials. Materials that cause hazards to humans can be classified into three categories: ü Corrosive materials ü Toxic or irritant materials ü Flammable materials Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p668-684 Job Factors § Corrosive materials are usually acidic or caustic substances that can burn or damage human tissue. Exposure ca occur due to skin contact or inhalation. § Toxic or irritant materials are poisons that disrupt the normal body processes. They include liquids, gases and solids. Toxicology is the science that studies poisons and their effects and problems. Effects may include: ü Cancerous tumors and other tumors ü Embryo damage ü Irritation to the skin, eyes, or respiratory tract ü Reduction in mental alertness ü Altered behavior ü General decline in health ü Reduction of sexual function ü Other short term and long term illnesses Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p668-684 Job Factors § Flammable materials are those that present hazards or fire or explosions. Three ingredients are needed to ignite a flammable material: ü An oxidizer ü Heat ü A chain chemical reaction Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p668-684 Environmental Conditions § These are the factors that are in the immediate surroundings of an operation. These include: ü Physical factors ü Social or psychological factors Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p668-684 Occupational Disorders and Diseases Overuse Disorder These are types of disorders that take years before their effects are evident. These are also known as repetitive-motion disorders because they are caused by repeated use of certain tendons and nerves, such as those in the fingers, wrist, forearm, upper arm, and shoulder. Different terms have been used to describe injuries stemming from repetitive motion such as : ü occupational overuse disorder (or injury or syndrome) ü regional or work-related musculoskeletal disorder (MSD) ü repetitive motion or stress or stress injury (RSI) ü Osteoarthrosis rheumatic disease ü Cumulative trauma disorder (CTD) Source: Kroemer, Karl et al. (2001). Ergonomics: How to Design for Ease and Efficiency 2nd ed. Pearson-Prentice Hall. P384-394 Occupational Disorders and Diseases § Repetitiveness ü High repetitiveness is defined by Silverstein in 1985 as a cycle of less than 30 seconds’ duration, or as more than 50 percent of the cycle time spent performing the same fundamental action. § Forcefulness ü According to Silverstein, high force exerted with the hand (e.g more than 45 N) § Tension related to posture ü Static muscle tension, often generated to maintain body posture, is stressful when high enough. Source: Kroemer, Karl et al. (2001). Ergonomics: How to Design for Ease and Efficiency 2nd ed. Pearson-Prentice Hall. P384-394 Occupational Activities and Related Disorders § “Seven Sins” ü These are seven conditions in particular that need to be avoided: 1. Activities with many repetitions 2. Any activity that requires prolonged or repetitive exertion of more than about one-third of the operator’s static muscular strength available for the activity 3. Putting body segments into extreme positions 4. Making a person maintain the same body position for a long time 5. Pressure from tools or work equipment on tissues (skin, muscles, or tendons), nerves, or blood vessels 6. A tool vibrating the body or part of the body 7. The exposure of working body segments to cold, including airflow from pneumatic tools Source: Kroemer, Karl et al. (2001). Ergonomics: How to Design for Ease and Efficiency 2nd ed. Pearson-Prentice Hall. P384-394 Common ODs (Type of Disorder: N-nerve, T-tendon, M-muscle, V-vessel) § Carpal Tunnel Syndrome (writer’s cramp, neuritis, median neuritis) (N) ü The result of compression of the median nerve in the carpal tunnel under the wrist. This tunnel is an opening under the carpal ligament on the palmar side of the carpal bones. ü Tingling, numbness, or pain in all digits but the little finger. Source: Kroemer, Karl et al. (2001). Ergonomics: How to Design for Ease and Efficiency 2nd ed. Pearson-Prentice Hall. P384-394 Common ODs (Type of Disorder: N-nerve, T-tendon, M-muscle, V-vessel) § Cubital Tunnel Syndrome (N) ü Compression of the ulnar nerve below the notch of the elbow, ü Tingling, numbness, or pain radiating into ring or little finger Source: Kroemer, Karl et al. (2001). Ergonomics: How to Design for Ease and Efficiency 2nd ed. Pearson-Prentice Hall. P384-394 Common ODs (Type of Disorder: N-nerve, T-tendon, M-muscle, V-vessel) § DeQuervain’s syndrome or disease (T) ü A special case of tendosynovitis that occurs in the abductor and extensor tendons of the thumb, where they share a common sheath. ü The condition often results from combined forceful gripping and hand twisting, as in screw driving. Source: Kroemer, Karl et al. (2001). Ergonomics: How to Design for Ease and Efficiency 2nd ed. Pearson-Prentice Hall. P384-394 Common ODs (Type of Disorder: N-nerve, T-tendon, M-muscle, V-vessel) § Epicondylitis or “tennis elbow” (T) ü This condition is often the result of the impact of jerky throwing motions, repeated supination and pronation of the forearm, and forceful wrist extension movements. ü The condition is well known among tennis players, pitchers, bowlers, and people hammering. ü A similar irritation of the tendon attachments on the inside of the elbow is called medical epicondylitis, also known as “golfer’s elbow” Source: Kroemer, Karl et al. (2001). Ergonomics: How to Design for Ease and Efficiency 2nd ed. Pearson-Prentice Hall. P384-394 Common ODs (Type of Disorder: N-nerve, T-tendon, M-muscle, V-vessel) § Ganglion (T) ü The affected area swells and causes a bump under the skin, often on the dorsal or radial side of the wrist. Source: Kroemer, Karl et al. (2001). Ergonomics: How to Design for Ease and Efficiency 2nd ed. Pearson-Prentice Hall. P384-394 Common ODs (Type of Disorder: N-nerve, T-tendon, M-muscle, V-vessel) § Neck tension syndrome (M) ü An irritation of the muscles of the neck, commonly occurring after repeated or sustained overhead work. Source: Kroemer, Karl et al. (2001). Ergonomics: How to Design for Ease and Efficiency 2nd ed. Pearson-Prentice Hall. P384-394 Common ODs (Type of Disorder: N-nerve, T-tendon, M-muscle, V-vessel) § Pronator (teres) syndrome (N) ü Result of the compression of the median nerve in the distal third of the forearm, often where it passes through the two heads of the pronator teres muscle in the forearm, common with strenuous flexion of elbow and wrist. Source: Kroemer, Karl et al. (2001). Ergonomics: How to Design for Ease and Efficiency 2nd ed. Pearson-Prentice Hall. P384-394 Common ODs (Type of Disorder: N-nerve, T-tendon, M-muscle, V-vessel) § Shoulder tendonitis (T) ü Irritation and swelling of the tendon or bursa are often caused by continuous muscle and tendon effort to keep the arm elevated. Source: Kroemer, Karl et al. (2001). Ergonomics: How to Design for Ease and Efficiency 2nd ed. Pearson-Prentice Hall. P384-394 Common ODs (Type of Disorder: N-nerve, T-tendon, M-muscle, V-vessel) § Tendonitis or Tendinitis (T) ü Inflammation of the tendon that is often associated with repeated tension, motion, bending, being in contact with a hard surface, or vibration. Source: Kroemer, Karl et al. (2001). Ergonomics: How to Design for Ease and Efficiency 2nd ed. Pearson-Prentice Hall. P384-394 Common ODs (Type of Disorder: N-nerve, T-tendon, M-muscle, V-vessel) § Tenosynovitis(T) ü This is a disorder of the tendons that are inside synovial sheaths. ü The tendon surfaces can become irritated, rough, and bumpy. Source: Kroemer, Karl et al. (2001). Ergonomics: How to Design for Ease and Efficiency 2nd ed. Pearson-Prentice Hall. P384-394 Common ODs (Type of Disorder: N-nerve, T-tendon, M-muscle, V-vessel) § Thoracic outlet (V, N) ü A disorder resulting from the compression of nerves and blood vessels between the clavicle and the first and second ribs, at the brachial plexus. ü This ischemic condition makes the arm numb and limits muscular activities. Source: Kroemer, Karl et al. (2001). Ergonomics: How to Design for Ease and Efficiency 2nd ed. Pearson-Prentice Hall. P384-394 Common ODs (Type of Disorder: N-nerve, T-tendon, M-muscle, V-vessel) § Trigger finger (T) ü A special case of tendosynovitis wherein the tendon wherein the tendons becomes nearly locked, so that its forced movement is not smooth, but occurs in a snapping or jerking manner. Source: Kroemer, Karl et al. (2001). Ergonomics: How to Design for Ease and Efficiency 2nd ed. Pearson-Prentice Hall. P384-394 Common ODs (Type of Disorder: N-nerve, T-tendon, M-muscle, V-vessel) § White finger or “dead finger”, Reynaud’s syndrome, vibration syndrome (V) ü Stems from insufficient blood supply and brings about a noticeable blanching. Finger turns cold, gets numb, tingles, and sensation and control of finger movement may be lost. ü A common cause is continued forceful gripping of vibrating tools, particularly in a cold environment. Source: Kroemer, Karl et al. (2001). Ergonomics: How to Design for Ease and Efficiency 2nd ed. Pearson-Prentice Hall. P384-394 Avoiding Industrial Accidents and Injuries Hand Postures *From ”Cumulative Trauma Disorders”; Taylor & Friends ©1988  Grips power grip pinch grip  Wrist Flexion & Extension Extension v Look for wrist fully deviated. Flexion  Wrist Radial & Ulnar Deviation Radial v Look for wrist fully deviated. Ulnar  Pinch Grip Force - Risk Level Total Counts Forces (lbs, kg) Per Day High Medium Low 1– 10 >20 lbs 9.0 kg 17– 20 lbs 7 – 9kg 12– 16 lbs 5.5 – 7.2 kg 11 – 100 >10 lbs 4.5 kg 9 – 10 lbs 4 – 4.5 kg 6 – 8 lbs 2.7 – 3.6 kg 101– 500 > 6 lbs 3.0 kg 5.1 – 6 lbs 2.3 – 2.7 kg 3.5 – 5 lbs 1.6 – 2.3 kg 501– 2000 > 4 lbs 2.0 kg 3.3 – 4 lbs 1.5 – 1.8 kg 2.5 – 3.2 lbs 1.1 – 1.5 kg 2001 – 5000 >3lbs 1.3kg 2.6 – 3lbs 1.2 – 1.4kg 1.7 – 2.5lbs 0.8 – 1.1kg Wrist Radial & Ulnar Deviation – Wrist Posture versus Grip Strength  Forearm Rotation v Look for palms up”. Elbow Height Shoulder Posture - Flexion Shoulder Posture Shoulder Postures Neck Flexion/Extension Neck Flexion Posture Avoid tilting the upper body more than 20 degrees  Posture - Before & After pistol handle grip before & after *”The UAW-Ford Ergonomics Process”; UAW-Ford Joint Committee ©1990  Posture - Before & After handle grip before & after pistol grip and tool balancer *”The UAW-Ford Ergonomics Process”; UAW-Ford Joint Committee ©1990  Posture - Before & After pistol handle grip before & after *”The UAW-Ford Ergonomics Process”; UAW-Ford Joint Committee ©1990 Posture - Before & After  Posture - Before & After before before after Jigs should be located and oriented so that parts can be assembled without flexing the wrist or limiting visual contact  Posture - Before & After before after  Posture - Before & After before after Shoulder Abduction  Posture - Before & After before after Shoulder Abduction  Posture - Before & After before after Shoulder  Pressure Eliminate direct pressure on the body  Pressure Eliminate handles with sharp edges and corners which press on small joints *”The UAW-Ford Ergonomics Process”; UAW-Ford Joint Committee ©1990 Pressure Reaching - Before & After Bending - Before & After  Bending poor improved Avoid bending over continually  Bending poor improved Design for Neutral Posture  Reaching before Minimize reach distances after  Twisting Don’t twist your back  Pushing Don’t pull Pulling large objects can be as hard on your back as lifting. Instead, be sure to push. Stay close to the load, without leaning forward Tighten your stomach muscles as you push Push with both arms, keeping your elbows bent Pushing Push it Be sure that you can see over the top  Lifting Techniques Think Bend Knees Load Close to Body Lift with Legs  Lifting Lift between shoulder & knuckle height Occupational Safety and Health Laws and Agencies Occupational Safety and Health Act § It is also known as the Williams-Steiger Act § It was signed into law in late 1970 and became effective in April 1971. § OSHAct created several new agencies within various departments of the federal government: ü OSHA ü OSHRC ü NIOSH § The following are the purpose of this law: 1. To ensure so far as possible that every working man and woman will be provided with safe and healthful working conditions 2. To preserve the nation’s human resources Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p668-684 Occupational Safety and Health Administration § It enforces the provisions of the OSHAct. § Its responsibilities are the following: 1. Implement safety and health programs 2. Establish mandatory occupational safety and health standards 3. Enforce the standards in industry by conduction inspections and assessing penalties for violations 4. Define responsibilities and rights for employers and employees to promote better safety and health conditions 5. Maintain a reporting system and database of occupational injuries and illnesses 6. Work with states in the development and support of state occupational safety and health programs Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p668-684 Occupational Safety and Health Review Commission § This reviews citations and proposed penalties when employers or employees contest enforcement actions of OSHA § It is a three-member quasi-judicial panel that is responsible for holding hearings and reviewing alleged violations of OSHA standards and the penalties for these violations Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p668-684 National Institute for Occupational Safety and Health § This engages in research, training, and education in the area of occupational safety and health § It is an institute that was established within the U.S Department of Health and Human Resources by the OSHAct to conduct research and make recommendations for the prevention of work-related injuries and illnesses. § Its major objectives are as follows: Conduct research to reduce work-related injuries and illnesses Promote safe and healthful workplaces, through standards, recommendations, and interventions Improve global workplace safety and health through collaborations in the international community. Source: Groover, Mikell P. (2007). Work Systems and the Methods, Measurement, and the Management of Work. Pearson-Prentice Hall. p668-684