Anthropometric application and workspace design

1. BMFP3553 Industrial Ergonomics Anthropometric application and workspace design Group Members: Chan Yun Kim Rosalina Rashidi Noor Azureen Mohd Zulhilmi Mohd Nor Hafiz Yusnurahman

2. 4.1 INTRODUCTION

3. What is anthropometry? • Measurement of the human body.

4. Anthropometric information describes the dimensions of the human body, usually through the use of bony landmarks to which height, breadths, depths, distances, circumferences and curvatures are measured.

5. Anthropometry and its uses • Body size and proportion vary greatly between different population and racial groups-a fact which designers must never lose sight of when designing for international market.

6. Importance of anthropometric considerations in design If a piece of equipment… Would fit roughly • 25% of Thais • - 10% of Vietnamese

7. It is usually impracticable and expensive to design products individually to suit the requirements of every user. • Mass-produced and designed to fit a wide range of users-the custom tailor, dressmaker, and cobbler are perhaps the only remaining examples of truly user-oriented designers in western industrial societies.

8. Availability of anthropometric data • Anthropometry of military populations is usually well documented and is used in the design of everything from cockpits to ranges and sizes of boots and clothing. • Data are available for U.S., British, and other European groups, as well as Japanese citizens. • Pheasant (1986) provides a useful and well-illustrated collection of anthropometric data and a method of estimating unknown anthropometric dimensions from data on stature. • Problems with much of the anthropometric data from the United States and Europe are the age of the data and the lack of standardization across surveys.

9. 4.2 designing for population of users

10. INTRODUCTION

11. What is Population ?

12. Engineering Anthropometry for Design • Design Idea • Accommodate the body characteristics of the population • Universal operability is 90-95% of the population • Build in adjustment to meet objectives • Some dimensions only require one set of dimensions • Example: 95% reach

13. Human Variability • Is there a Average Human? • Humans vary in dimensions based on • Gender • Ethnic groups • Nationalities • Etc. • Over 300 anthropometric measurements on the body • It is hard to say that any one person is 50%-tile on all measurements • Factors affecting Anthropometric data • Age – body dimensions begin to increase with age and then decrease around 40 • Gender – men are generally larger than women at any given percentile and body dimensions except hips and thighs • Ethnic differences cause further differences • Body Position • Posture affect size • Clothing – clothing adds to body size plus restricts movement

14. Design and Use of Anthropometric Data • Design for the Extreme -- An attempt to accommodate all (or nearly all) of the population • Design for the maximum – if maximum value accommodates all (e.g., height of door, escape hatch in airplane) • Design for the minimum – if minimum value determines if all are accomodated (e.g., distance to control button from the operator (reach); amount of force to press a button) • Design for Adjustable Range – design to accommodate all (e.g., office chairs, desk height, key board height) • Range typically is 5th percentile of females to the 95th percentile of males in relevant characteristics • Design for the Average – there is no average human • There are times when the average may be acceptable (e.g., counter height at grocery store)

15. Design and Use of Anthropometric Data • Design Principles Discussion • Setting limits to 5th and 95th percentiles can eliminate a fairly high percentage of population • Bittner (1974) – looked at 5th and 95th percentiles on 13 dimensions • Would have excluded 52% of population instead of 10% implied by percentiles • Why? – body measurements are not perfectly correlated • Short arms  short legs • To derive composite measures taking into account imperfect correlations requires regression analysis

16. Percentile Covered • Herman Miller found that chairs theoretically designed to fit the 5th-percentile female to the 95th-percentile male actually fit far fewer people (Dowell, 1995a). Source: Herman Miller Workplace Researchhttp://www.hermanmiller.com/research/essays/aeronessay2/essay2.html

17. Design and Use of Anthropometric Data • General approach • Determine body dimensions important in the design Example: chair popliteal height (lower leg length), seat depth (buttock to popliteal length) hip breadth, midshoulder sitting height (back height), elbow height, lumbar height lumbar depth • Define population (e.g., adult - male, adult - female, children) • Determine what principle should be applied • Select % of population to be accommodated • Locate anthropometric tables appropriate for the population • If special clothing worn – add allowances • Build prototype and test using representative tasks • Anthropometric data • Structural dimensions – taken in standard & still positions • Functional dimensions – obtained in various work postures

18. POSSIBLE CONSEQUENCES

19. 4.3 Anthropometry and its uses

20. The approach of ergonomics is to consider product dimensions in human terms in view of the constraints placed on their design by body size variability. • example:- a seat should be no higher than popliteal the height of a short user and no deeper than the distance from the buttocks to the knees.

21. Types of anthropometric data • Structural anthropometric data are measurements of the bodily dimensions of subjects in fixed (static) positions. • Some examples of the use of structural anthropometric data are to specify furniture dimensions and ranges of adjustment and to determine ranges of clothing sizes.

22. Limitations on the use of structural data • Structural data may be used for design in situations where people are adopting static postures • Caution should be used when applying these data to design problems that involve movement, particularly skilled movement.

23. Functional anthropometric data • Functional anthropometric data are collected to describe the movement of a body part with respect to a fixed reference point • example, data are available concerning the maximum forward reach of standing subjects • Functional anthropometric data are useful for designing workspaces and positioning objects within them, particularly in the design of aircraft cockpits, crane cabs, vehicle interiors and complex control panels in the process industries

24. 4.4 PRINCIPLES OF APPLIED ANTHROPOMETRY

25. Applying statistics to design • the designer has to analyze in what ways (if any) anthropometric mismatches might occur • decide which anthropometric data might be appropriate to the problem

26. In many design applications, mismatches occur only at one extreme (only very tall or very short people are affected) and the solution is to select either a maximum or a minimum dimension • If the design accommodates people at the appropriate extreme of the anthropometric range, less-extreme people will be accommodated

29. Using Percentiles • Since most body dimensions are normally distributed, follows a symmetric bell curve • Percentiles tell you how well/bad you are doing, compared to the rest of the population.

30. Using Percentiles It bears repeating that percentiles are a comparison score. The number of a percentile represents how well or how poorly you did as compared to other students. It does not represent the number of questions you answered correctly. If you score in the 70th percentile, you scored better than 70 out of 100 people who took the test. If you score in the 50th, read this as better than 50 people who took the test.*

31. Determine Single Point Select desired percentile Determine k Calculate P Determine Range Select upper and lower percentile Determine kmax and kmin Calculate Pmax and Pmin Range = Pmax - Pmin Using Percentiles

32. Anthropometry Problem #1 • The instructor’s height is 170 cm. What percentile is his stature among US Adult males? US stature mean = 175.6 cm, SD = 6.7 cm. • Use the formula p= m + k (SD) • Solve for k = -0.8358 • Find the corresponding value of k in the z table. • That would be your answer : 0.2005 = 20th percentile. • This means, I am taller than 20% of the US adult males.

33. Anthropometry Problem #2 • What is the stature of a 85th percentile female? Mean stature : 1629 mm, SD = 64 mm. • My popliteal height is 38.5cm. What percentile is my popliteal height among the US population? Mean popliteal height : 434 mm, SD = 25 mm.

34. Minimum dimensions • A door handle must not be lower than the highest standing knuckle height in a population so that all users can open the door without stooping

35. The width of a chair must be no narrower than the hip breadth of a large woman

36. The height of a doorway must be no lower than the stature of a tall man (plus an allowance for clothing and shoes).

37. Maximum dimensions • A door lock must be no higher than the maximum vertical reach of a small person.

38. Seat heights and depths must not exceed the maximum height and buttock–knee lengths of small users

39. Steps to Apply Anthropometric Data • Select those anthropometric measures that directly relate to defined design dimensions. • Examples : hand length related to handle size. 2. For each of these pairings, determine whether the design must fit only one given percentile (minimal or maximal) of the body dimension, or a range along that body dimension. • Examples : the escape hatch must be big enough to accommodate the largest extreme value of shoulder breadth and hip breadth, considering clothing and equipment worn;

40. Steps to Apply Anthropometric Data 3. Combine all selected design values in a careful drawing, mock-up, or computer model to ascertain that they are compatible. • For example: the required leg-room clearance height, needed for sitting persons with long lower legs, may be very close to the height of the working surface determined from elbow height.

41. Steps to Apply Anthropometric Data 4. Determine whether one design will fit all users. If not, several sizes or adjustment must be provided to fit all users. • Examples are: one extra large bed size fits all sleepers; gloves and shoes must come in different sizes; seat heights of office chairs are adjustable.

42. Designing to fit the body • Normal distribution often used to describe certain measures (depends on sample size) • Central Limit Theorem • There is no true average human • Use the following steps • Select measurements that relate to the design • Determine if design is to fit a certain percentile or a range • Combine values to ascertain compatibility • Determine if one design will fit all users

43. 4.5 designing for everyone

44. Designing for everyone

45. 1. Make different sizes • Design same product with several different sizes. • Use anthropometry data to determine a minimum number of different sizes and the dimensions of each size that accommodate all users. • Example: hand tool--- screw driver or chopsticks

46. Example: screwdriver • Research: to evaluate the effects of the length of the chopsticks on the food-serving performance of adults and children The results showed that the food-pinching performance was affected by the length of the chopsticks, and that chopsticks of about 240 and 180 mm long were optimal for adults and pupils, respectively. Longer chopsticks require greater effort to exert same pinch force at tip than shorter chopsticks.

47. 2.Design adjustable products • Alternative approach to manufacture product whose critical dimensions can be adjusted by users. • Steps:

48. Seat work Desk • The seat height should not higher than popliteal height of user so that both feet can rested firmly on the floor to support the weight of the lower legs. • Desk height should coincide with the user’s sitting elbow height.

49. EXAMPLE:

50. 3. Anthropometry and personal space • Defined as the area immediately around the body. • 2 important issues: (1) volume of space regarded as personal territory (2) consequences of an invasion of this space by others • Design decisions regarding: (1) the sizes and spacing of seats in public areas (2) the proximity of desks (3) take account of people’s space requirements (4) particular social context. • Minimum separation of desks and benches approximately 1.2m is thought to be needed in workplace.