Applied Anthropometry and the Workplace 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.

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)

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

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

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)

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

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

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

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

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

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)

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)

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

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

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

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

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)

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)

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)

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

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

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

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”

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.