Applied Anthropometry and the Workplace

1. Applied Anthropometry and the Workplace • Anthropometry • A. Description of the physical variation in humans by measurement; a basic technique of physical anthropology. • B. The measurement of the • dimensions and certain other • physical characteristics of the • body.

2. Measuring Types • A. Static (structural) - taken while the body is in a static position • 1. Skeletal dimensions - joint-to-joint measurement • 2. Maximum body width • 3. Data available on most • characteristics of the body • NASA Anthropometric Source • Book. (vol 2, 1978)

3. Measuring Types • B. Dynamic (functional) • 1. Measurements taken while the body is engaged in some kind of activity • a. Driving a car • b. Working at a desk / VDT terminal

4. Applications • Principles • 1. Design for extremes of individuals (or the population) • a. Maximum: automobile interiors, escape hatches, doorway • b. Minimum: applied force, reach distances • c. Most designs cover 5th • through 95th percentile

5. Principles • 2. Design with an adjustable range • a. Design should "fit" 5th through 95th percentile of relevant population • b. Involves a trade-off with cost/complexity • 3. Design for the average • - vs. design for the extreme • (seat height, counter tops, • letter height)

6. Principles • 4. Variability of population - • Anthropomorphic measurements are a functionof age, gender, nationality, user type and several other factors

7. Applications of Design Principles • A. Bittner • Taking 13 dimensions between 5th and 95th percentile excluded 52% of the population • B. Body dimensions are not perfectly correlated • Short legs with a long torso • in automobile design

8. Applications of Design Principles • C. Physical modeling • 1. Computer programs to model human movement • 2. Dummies are used to represent specific percentiles • - crash tests for autos

9. General Approach for Design Evaluation • A. Determine the body dimensions which will be important in the use of the system • B. Define the relevant (user) population • C. Which design principle • will be used

10. General Approach for Design Evaluation • D. What percentage of the population it is to be designed for • E. Determine the relevant value from the anthropomorphic tables • F. Add appropriate allowances for special situations • 1. Bulky clothing worn in • cold weather • 2. Protective clothing worn by • hazardous duty personnel

11. Work Spaces (Envelopes) • A. Work Space Envelope • Defined as the 3-dimensional space around an individual in which it is reasonably optimal for persons to perform some type of manual activity • B. Seated personnel • 1. Most important factor in this position is arm reach • a. direction ofreach • b. task to be performed (grasp, fingertip operation) • c. type of reaching motion (restricted/unrestricted)

12. Work Spaces (Envelopes) • 2. Design for the minimum (5th percentile) - Makes it useful for 95% of the population • 3. Consider apparel worn • C. Standing Personnel • 1. vs. seated • a. Larger workspace is defined • (due to ability to bend/reach) • b. Workspace is dynamic • (moves as the person moves)

13. Work Spaces (Envelopes) • D. Clearance Requirements • workers need to fit into awkward or restrictive spaces sometimes. • i.e. maintenance or emergency hatches.

14. Work Surfaces • A. Horizontal Surfaces (tables, desks, counters) • 1. Normal area - area covered by sweep of the forearm while the upper arm remains in a natural position • 2. Maximum area - area which • can be reached by extending • the arm from the shoulder

15. Work Surfaces • B. Slanted Surfaces • vs. horizontal • a. Eastman and Kodat (use of slanted surfaces, 12-24 degrees, gives better posture, less fatigue/discomfort • b. Drafting tables, computer keyboards • C. Height of Work Surfaces

16. Work Surfaces • Guidelines • a. Make it adjustable where possible (legs/feet, slant) • b. Forearm should be level of slightly down with shoulders relaxed (not hunched) • c. Allow for a "straight" spine (posture) to reduce strain and fatigue in the back muscles/spine • d. Adjustable for type of activity • to be performed

17. Work Surfaces • 2. For Standing Personnel • a. Precision work (work level even with or slightly above elbow height) • b. Light / Heavy work (work level should be below elbow height)

18. Seating • Principles of Seat Design • 1. Back support should be used • a. Lower support most critical to reduce fatigue and eliminate back pain • b. Lordotic (concave) preferred over Kyphotic (convex)

19. Seating • 2. Seat height and slope • a. Generally, seat height should • be low enough so as to reduce • pressure on the underside of • the thigh (reduces blood flow • to the legs) • b. Common to design seats for • minimum (5th percent)

20. Seating • 3. Seat depth and width • a. For public seating, depth should be designed for a minimum while the width should be designed for the maximum • b. Spacing between seats • should be at least 20 inches

21. Guidelines for Seat Design • A. Seat back should provide support for lumbar (lower) area • B. Seat back should have moderate inclination (10-30 degrees) • C. Seat pan should slope back slightly • D. Angle between seat pan • and back is 95-120 degrees

22. Guidelines for Seat Design • E. Seat height and backrest should be adjustable • F. Seat height designed for small people, width for large people • G. Use moderately contoured seat pan for weight distribution

23. Guidelines for Seat Design: ANSI Standard • Seat Height and Slope: • - fixed height: 18 - 19” • - adjustable height: 16 - 20.5” • - slope: 0 - 10o backward tilt • Seat Depth and Width: • - depth: 15 - 17” • - width: 18.2”

24. Guidelines for Seat Design: ANSI Standard • Contour and Cushioning: • - contour: tradeoffs between even weight distribution vs. restricting movement and postural fixity. • - cushion: 1.5 - 2” thick. • Seat Back: • - angle: minimum 90 - 105o with respect to the seat pan. Up to 120o prefered. • - width: minimum 12” in the lumbar region. • - height: minimum 19.5”. • - lumbar support: 6 - 9” high, 12” wide, positioned 6 - 10” above seat reference point, and protrude ~ 2” from back rest.