Ergonimics at workplace consildated.pptx

ergonimics at workplace

1. Introduction to Ergonomics

2. At the end of this lecture, student will be able to: - Explain Ergonomics and its application In design -Describe the significance of Ergonomics Lecture Objectives

3. P r e f ace Why do we face problems in operating day today things in and around us? Why do some car seats leave you aching after a long journey? Why do some computer workstations confer eyestrain and muscle fatigue? Such human irritations and inconveniences are not inevitable – ergonomics is an approach which puts human needs and capabilities at the focus of designing technological systems. The aim is to ensure that humans and technology work in complete harmony, with the equipment and tasks aligned to human characteristics

4. Ergonomics The word ergonomics comes from two Greek words: ERGO: meaning work NOMOS: laws or principles Ergonomics is a science focused on the study of human fit, and decreased fatigue and discomfort through product design. Ergonomics applied to office furniture design requires that we take into consideration how the products we design fit the people that are using them. At work, at school, or at home, when products fit the user, the result can be more comfort, higher productivity, and less stress.

5. Ergonomics Ergonomics can be an integral part of design, manufacturing and use. Knowing how the study of anthropometry, posture, repetitive motion, and workspace design affects the user is critical to a better understanding of ergonomics as they relate to end-user needs. In the design of work and everyday-life situations, the focus o f ergonomics is man. Unsafe, unhealthy, uncomfortable or inefficient situations at work or in everyday life are avoided by taking account of the physical and psychological capabilities and limitations of humans.

6. Ergonomics A large number of factors play a role in ergonomics; these include body posture and movement (sitting, standing, lifting, pulling and pushing), environmental factors (noise, vibration, illumination, climate, chemical substances), information and operation (information gained visually or through other senses, controls, relation between displays and control), as well as work organization (appropriate tasks, interesting jobs) These factors determine to a large extent safety, health, comfort and efficient performance at work and in everyday life Ergonomics draws its knowledge from various fields in the human sciences and technology, including anthropometrics, biomechanics, physiology, psychology, toxicology, mechanical engineering, industrial design, information technology and industrial management

7. Ergonomics In applying this knowledge, specific methods and techniques are used Ergonomics differs from other fields by its interdisciplinary approach and applied nature. The interdisciplinary character of the ergonomic approach means that it relates to many different human facets As a consequence of its applied nature, the ergonomic approach results in the adaptation of the workplace or environment to fit people, rather than the other way round

8. History of Ergonomics Ergonomics developed into a recognized field during the Second World War, when for the first time, technology and the human sciences were systematically applied in a co-ordinated manner. Physiologists, psychologists, anthropologists, medical doctors, work scientists and engineers together addressed the problems arising from the operation of complex military equipment. The results of this inter-disciplinary approach appeared so promising that the cooperation was pursued after the war, in industry. Interest in the approach grew rapidly, especially in Europe and the United States, leading to the foundation in England of the first ever national ergonomics society in 1949, which is when the term ‘ergonomics’ was adopted.

9. Social Significance of Ergonomics Ergonomics can contribute to the solution of a large number of social problems related to safety, health, comfort and efficiency Daily occurrences such as accidents at work, in traffic and at home, as well as disasters involving cranes, aeroplanes and nuclear power station scan often be attributed to human error From the analysis of these failures it appears that the cause is often a poor and inadequate relationship between operators and their task The probability of accidents can be reduced by taking better account of human capabilities and limitations when designing work and every day-life environments

10. Ergonomics Many work and everyday-life situations are hazardous to health. D iseases of the musculoskeletal system (mainly lower back pain) and psychological illnesses (for example, due to stress) constitute the most important cause of absence due to illness, and of occupational disability . These conditions can be partly ascribed to poor design of equipment, technical systems and tasks Here, too, ergonomics can help reduce the problems by improving the working conditions. Ergonomics can contribute to the prevention of inconveniences and also, to some considerable degree, can help improve performance. In the design of complex technical systems such as process installations, (nuclear) power stations and aircraft, ergonomics has become one of the most important design factors in reducing operator error.

11. General and Individual ergonomics An important ergonomic principle is that equipment, technical systems and tasks have to be designed in such a way that they are suited to every user The variability within populations is such that most designs, in the first instance, are suited to only 95 per cent of the population. This means that the design is less than optimum for five per cent of the users, who then require special, individual ergonomic measures Examples of groups of users, who from an ergonomic perspective require additional attention, are short or tall persons, overweight people, the physically challenged , the old, the young, and pregnant women

12. The Components of Ergonomics Ergonomics deals with the interaction of technological and work situations with the human being. The basic human sciences involved are anatomy , physiology and psychology , Thes e scie nc e s a r e applied b y t he e r g on o m i s t t o w a r d s t w o m a in objectives: The most productive use of human capabilities. The maintenance of human health and well being

13. An a t o m y The contribution of basic anatomy lies in improving physical ‘fit’ between people and the things they use, ranging from hand tools to aircraft cockpit design. The science of anthropometrics provides data on dimensions of the human body, in various postures. Biomechanics considers the operation of the muscles and limbs, and ensures that working postures are beneficial, and that excessive forces are avoided.

14. Physiology Our knowledge of human physiology supports two main technical areas. Work physiology -addresses the energy requirements of the body and sets standards for acceptable physical work rate and work load, and for nutrition requirements. E n vi r onme n t al p h y si o l o g y - anal y s e s the imp a ct o f p h y si c al w or k ing conditions Thermal Noise Vibration Lighting

15. Psychology It is concerned with human information processing and decision-making capabilities. Relevant topics are Sensory processes Perception Long- and short-term memory Decision making Action

16. Ergonomics in Practice Planning Design E v alu a ti o n Tasks Jobs Products Organizations E n vi r onme n ts Systems Needs Abilities Limi ta tions In order to make them compatible with Of of people Practitioners of ergonomics contribute in

17. P r act i cing e r g on o mics sh o ul d h a v e a b r oa d unde rs t and i n g o f the following factors Physical Cognitive Organizational Social Environmental Out of these the fields which are of concentration from the design point of view are Ergonomics in Practice

18. Physical Ergonomics Is concerned with human anatomical, anthropometric, physiological and biomechanical characteristics, as they relate to physical activity. Relevant topics include; Working postures Sitting and standing postures Physical workloads Manual material handling Repetitive motion and repetitive stress Work-related musculoskeletal disorders Workplace layout Vibration stress Countermeasures Safety, health and the prevention of injures

19. Cognitive Ergonomics Is concerned with mental processes, such as perceptions, habits, memory, reasoning and motor responses, as they pertain to interactions among humans and the other elements of a total system. Relevant topics include, Mental workloads Decision-making Skilled performance Human-computer interaction Human reliability Work stress Countermeasures

20. Environmental Ergonomics Is concerned with human interaction with the environment. The physical environment is characterized by: Climate Temperature Pressure Vibration Light

21. Organizational Ergonomics It is concerned with optimization of sociotechnical systems Organizational structures Policies Processes The relevant topics in this may include Communication Crew Resource Management Work Design Design of Working Times Teamwork Participatory Design Community ergonomics Cooperative work New work paradigms Organizational culture Virtual organizations Telework Quality management

22. A n th r opom e t r y Anthropometry: an·thro·pom·e·try (nthr-pm-tr) - The study of human body measurement for use in anthropological classification and comparison. an·thro·pom·e·trics - The comparative study of human body measurements and properties.

23. E r g onomics “we bear in mind that the object we are working on is going to be ridden In, sat upon, looked at, talked into activated, operated or in some other way Used by people” “if the point of contact between the product and the people becomes a point of friction, then the designer has failed.” “On the other hand, if people are made safer, more efficient, more comfortable…or just plain happier… by contact with the product, then the designer has succeeded.” --Henry Dreyfuss

24. Ergonomics - Synonyms Ergonomics in general Human Engineering in Military Engineering Psychology by Psychologist

25. Anthropometri c Specification Specifies the user population and the levels of attributes required to be accommodated. Defines the performances required of the users and The equipment, as well as the effects of the design on the people in the Environment. Take each phase of the life cycle of the machine or workspace in turn,e.g manufacture/ assembly, setting up; use, including loading. Unloading and servicing; maintenance; dismantling/ disposal. Review proposed design under each of the above headings; assess.

26. Whether people’s capacities are able to achieve the objectives in each phase. Redesign to reduce miss- matches. Specify users in terms of sex, age, language, skill/ training. Set limits, Or angles for human and for machine performance. Anthropometri c Specification

27. Task Analysis Pri o r to designin g equipm e n t, the designe r ne e d s a cl e a r understanding of how people will use it, build it, maintain it or even misuse it. The procedure for defining people’s activities with equipment is known as Task analysis. Information form task analysis will be relevant in a number of different areas Task analysis seeks to identify all the various sub-tasks required to achieve the system’s objectives. Th e v arious s o u r c e s of i n f orm a ti o n, r equi r e d b y the use r s a r e identified, as are the actions they are required to take, the postures and movements needed and the working conditions under which the work will be done.

28. Task Analysis The better the quality of information, the more readily can the designer meet the demands of the specification. The use of a relatively formal Procedure is advised, so that the subsequent data can be assessed and Verified by users, others in the design team and by the system purchaser. The procedure involves three closely linked stages: Information Collection Recording Data Analysis

29. Information Collection Be specific : F ocu s o n t h e anal y sis , e . g . . s t ar t - up p r ocedu r e s , O pe r a ting or maintenance. Choose the most effective information- gathering procedures, video recording may be effective if after hours of analysis it yields little data on the points of concern. Comm o nly used m et h o ds a r e : E x i s t ing d ocume nt a t io n : o pe r a ting manuals, training manuals, safety, reports, previous analyses. Observation: recording what people do in the specified situations. Study the effects of the various possible circumstances, unlikely as well as likely events Q u e s t i o nin g : L i n k o b s e r v a ti o n methods with questioning . Ask people To describe what they do, how they do it, what information they use and How they tell if a task has been carried out satisfactorily.

30. Get them to review the results of observations. Questioning can be formal or informal ,But should usually be confidential and anonymous, particularly if error Or accident information is needed. Recording : Voice, Photographic or Video techniques are useful, although Voice and video can require hours of analysis. But they can be re- assessed by others and repeatedly studied. The selection of techniques depends on the information needed and the Circumstances of the investigation. Field studies are usually the most Effective, but simulators, even simple simulators, can be useful. Results from task analysis should be verified by others expert in the field. People being studied should have agreed to take part, should see the Results, be fully aware of the purposes of the studies and be assured of Personal confidentiality Information Collection

31. Use of Anthropometric Data Anthropometry measures the physical characteristics of the human body. Anthropometry is also concerned with heights, weights, inertial properties, volumes and centers of gravity. There are two primary types of measurement: Static measurement Dynamic Measurement ( Functional)

32. Use of Anthropometric Data Dynamic (functional) dimensions are not solely the result of individual static measurements, but a function of the interaction of body parts ( e.g..., reaching forward). More static data is predominantly available than dynamic data and no good method is available for converting from dynamic data to static data. Anthropometric data should be used that is appropriate for the specific target population. Design for adjustability is usually most desirable, but designing for the average or extreme may also be necessary or desirable. Examples: Designing a bike seat, a bus seat, a doorway, a spoon, clothing, etc.

33. Use of Anthropometric Data

34. Use of Anthropometric Data

35. What is it that you are aiming for with your Design examples: Examples of measurements to consider: Users that your design should accommodate: Easy reach Vehicle dashboards, Shelving Arm length, Shoulder height Smallest user: 5th percentile Adequate clearance to avoid unwanted contact or trapping Manholes, Cinema seats Largest user: 95th percentile A good match between the user and the product opera t ed from hazard 95th percentile © Ramaiah University of Applied Sciences A comfortable and safe posture Seats, Cycle helmets, Pushchairs Lawnmowers, Monitor positions, Work surface heights Maximum range: 5th to 95th percentile Maximum range: 5th to 95th percentile Easy operation To ensure that an item can't be reached or Screw bottle tops, Door handles, Light switches Machine guarding mesh, Distance of railings Shoulder or hip width, Thigh length Knee-floor height, Head circumference, Weight Elbow height, Sitting eye height, Elbow height (sitting or standing?) Grip strength, Hand width, Height Finger width Arm length Smallest or weakest user: 5th percentile Smallest user: 5th percentile Largest user: Use of Anthropometric Data

36. General Approach to Anthropometrical Design Determine critical body dimensions: e.g.-sitting height in automobile. D e f i n e the d esi g n popu l a t i o n: e . g . - ci v i l i ans, mi l i t a r y pe r s o n s , di f f e r e n t a g e groups, race difference etc. Determine the principles to apply: e.g.-design for extreme, for average Select the % of the population to accommodate Refer to the appropriate percentile of the selected population percentage Lo c a t e t h e a pp r opri a t e t a bl e s o r d a t a, o r c ollec t the d a t a f r o m the t a r g e t population Account for special clothing or environments, and when possible, build a full- scale mock-up for testing.

37. Ergonomics in Hand Injury and Disorder

38. Lecture Objectives At the end of this lecture, student will be able to Explain Hand injury and disorder for any give hand tools Describe various design principles applied for hand tool design

39. Ou t line 3 Hand Anatomy & Injury Design Principles Shape Orientation Size Weight Grip Strength Vibration Texturing and Gloves

40. Traumatic “One Time” Injuries impact, crush, cut 9 % of all work-related injuries 260,000 hand tool related injuries in U.S. each year $ 400 million associated medical costs 21% of hand injuries are power tool related Most common: knives, wrenches, and hammers Mostly “one time” traumatic injuries (U.S. Statistics by Aghazadeh & Mital, 1987) 4 Hand Injury and Disorder

41. Hand Injury and Disorder 5 Repetitive Injuries 4.8 % of workers in meat packing industry suffer from repetitive injuries (Bureau of Labor Stats, 1986) 13 repetitive injuries per 200,000 work hours in poultry processing plant (Armstrong et al., 1982) Often go unreported but show up as … reduced worker output poor quality work increased absence from work “one time” trauma injuries

42. Hand Injury and Disorder 6 Carpal Tunnel Syndrome hand held in fixed position for prolonged time repetitive exertion with flexed or hyperflexed wrist with low or high forces pressure at base of palm vibration Tendinitis repetitive motion, especially in combination with ulnar deviation with fixed thumb Hammer Syndrome vibration, push, twist, hand hammering, catching

43. Hand Injury and Disorder 7 Trigger Finger excessive flexion and extension of digits overuse of finger with pistol airtool Gamekeeper’s Thumb thumb abduction/extension with force Pronator Teres Syndrome repeated gripping and grasp tight gripping, turning of tools forceful flexion with finger flexion and/or elbow extension

44. Factors to Minimize Soft tissue, artery, and nerve compression Grip/Finger/Torque/Push/Pull strength required to perform task successfully Vibration levels Temperature changes (+/- 2 degrees) Repetitive motion Prolonged performance of task Prolonged maintenance of “fixed position” Angle deviation away from “neutral” hand position Pinching, sharp corners, edges Cost 8 Design Principles

45. Factors to Maximize General feeling of “comfort” Adjustability of design Ease of use Factors to Consider Depending on Use Weight of tool Texturing, gloves, bracing/support, padding Size of tool and hand anthropometrics Subgroups: Lefthanders, women, physically impaired, young, elderly Safety and protection features (e.g. flange, safety latch, plastic guard, etc.) Material selection – What’s it made of? Why? Power Specs: Manual vs. powered, Battery vs. plug-in, Design Principles

46. Design Principles 10 47

47. Design Principles 11 48

48. Summary 12 Weight of tool may work against task performance e.g. torque or moment around arm joints may eventually cause muscle fatigue, etc Increase the general feeling of comfort in any hand tool using cushion and straps

49. 50 Ergonomics in Human hand tool and Shape

50. Lecture Objectives 51 At the end of this lecture, student will be able to Explain shape restriction for design of hand tool Describe Hand Orientation for determining Hand tool shape

51. Shape A conventional paint scraper that presses on the ulnar artery and a modified handle which rests o n the tough tissues between thumb and the index finger, this preventing pressure on the critical areas of the hand. Source ( Tichauer , 1967) 3 52

52. [Lewis and Narayan, 1993] 4 53 Shape

53. Shape 5 54

54. Shape 6 55

55. Shape 7 56

56. Comparison of two groups of trainees using different pilers. Shows percent of workets with tenosynovitis, epicondylitis ( tennis elbow), and carpal tunnel irritation. (Source: adapted from Tichauer, 1976. Reprinted with permission from Industrial Engineering Magazine, 1976, copyright American Institute of Industrial Engineerg, Inc,.25 Technology Park/ Atlanta, Norcross, GA 30092 Shape 8 57

57. Orientation 9 58

58. Orientation 10

59. Thumb-operated and finger strip operated pneumatic tool. Thumb operation results in over extension of the thumb. Figure strip control aloows all the fingers to share the load and the thumb to grip and guide the tool. 11 Orientation

60. Orientation 12

61. Orientation 13

62. Orientation 14

63. Orientation 15

64. Orientation 16 65 Faculty of Art and Design © Ramaiah University of Applied Sciences

65. [Chaffin et al., 1999] Orientation 17 66 Faculty of Art and Design © Ramaiah University of Applied Sciences

66. + T Arm Weight Tool Weight (W ) Tool-to-Elbow Length (L) Bicep Muscle Force T ool Total Elbow Torque, T [N-m] } To = Net Torque on Elbow without tool Tool Weight (W T ) [N] Added Torque from Tool Weight 18 18 Weight W e i g h t o f t o o l m a y w ork A GAIN S T t ask per f or m an c e e . g. t o r qu e o r mom e n t a r ou n d arm joi n ts m a y e v e n tu a l l y c ause muscle fatigue, etc Orientation

67. Weight of tool may work FOR task performance; E.g. less pushing force required in using a chain e l ec t r i c s a n d e r , s a w , dri l l, T ool W ei g ht ( W T ) [N] Required Total Push Force Needed For Task, P [N] Po = Net Push Force without Tool weight hammer, etc. Tool Weight (W T ) Arm Weight and Push Force Orientation 19

68. Grip Strength 20

69. Vibration Weighted hand –arm vibration accelerations in various toold used in car body reapir work. This illusturates the wide range of vibration levels both between and within classis of power tools. (Source: Adapted from Hansson, Eklund, Kihlberg, and Ostergern,1987). 22

70. Skin Temperature of the fourth finger of the left hand during thermal resting of a group of workers occupationally exposed to hand vibration and a control group not exposed. (Source: Koradecka,1977) 23 Vibration

71. Sum m a r y 26 Comparison of two groups of trainees using different pilers, to understand which group of shape of pliers are easier to work with Skin Temperature of the fourth finger of the left hand during thermal resting of a group of workers occupationally exposed to hand orientation greatly determines the shape of the hand tool