Applied Anthropometry and the Workplace

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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.
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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)
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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

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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
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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)
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Principles

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

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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
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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

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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
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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
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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)

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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)
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Work Spaces (Envelopes)

• D. Clearance Requirements
• workers need to fit into awkward or restrictive
  spaces sometimes.
• i.e. maintenance or emergency hatches.

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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
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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

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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
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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)

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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)

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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)
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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
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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
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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

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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

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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.