1. Anthropometrics I
Rad Zdero, Ph.D.
University of Guelph

2. Outline Anatomical Frames of Reference What is “Anthropometrics”?
Static Dimensions
Dynamic (Functional) Dimensions
Measurement of Dimensions

3. Anatomical Frames of Reference
Planes of Motion
Transverse Plane
Frontal Plane
Sagittal Plane

4. Top View (Transverse Plane)
Relative Position
Posterior
Lateral
Lateral
Medial
Medial
Anterior
Top View (Transverse Plane)

5. Relative Position Point A is Proximal to point BC
Relative Position
Point A is Proximal to point B
Point B is Proximal to point C
Point A is Proximal to point C
Point C is Distal to point B
Point B is Distal to point A
Point C is Distal to point A

6. What is “Anthropometrics”?
The application of scientific physical measurement techniques on human subjects in order to design standards, specifications, or procedures.
“Anthropos” (greek) = person, human being
“Metron” (greek) = measure, limit, extent
“Anthropometrics” = measurement of people

7. Static Dimensions
Definition: “Measurements taken when the human body is in a fixed position, which typically involves standing or sitting”.
Types
Size: length, height, width, thickness
Distance between body segment joints
Weight, Volume, Density = mass/volume
Circumference
Contour: radius of curvature
Centre of gravity
Clothed vs. unclothed dimensions
Standing vs. seated dimensions

8. Static Dimensions
[Source: Kroemer, 1989]

9. Static Dimensions
Static Dimensions are related to and vary with other factors, such as …
Age
Gender
Ethnicity
Occupation
Percentile within Specific Population Group
Historical Period (diet and living conditions)

10. Static Dimensions AGE Lengths and Heights 0 10 20 30 40 50 60 70 80
Age (years)

11. Static Dimensions
GENDER
[Sanders &
McCormick]

12. Static Dimensions
ETHNICITY
[Sanders &
McCormick]

13. Static Dimensions OCCUPATION
e.g. Truck drivers are taller & heavier than general population
e.g. Underground coal miners have larger circumferences (torso, arms, legs)
Reasons
Employer imposed height and weight restrictions
Employee self-selection for practical reasons
Amount and type of physical activity involved

14. Static Dimensions PERCENTILE within Specific Population Group
Normal or Gaussian
Data Distribution
No. of
Subjects
5th percentile =
5 % of subjects
have “dimension”
below this value
50 %
95 %
Dimension
(e.g. height,
weight, etc.)

15. (Europe, US, Canada, Australia)
Static Dimensions
HISTORICAL PERIOD
(Europe, US, Canada, Australia)
Decade
Increase in
Average
Adult
Height
(inches)
4 inch increase in 8 decades

16. Dynamic (Functional) Dimensions
Definition: “Measurements taken when the human body is engaged in some physical activity”.
Types: Static Dimensions (adjusted for movement), Rotational Inertia, Radius of Gyration
Principle 1 - Estimating
Conversion of Static Measures for Dynamic Situations
e.g. dynamic height = 97% of static height
e.g. dynamic arm reach = 120% of static arm length
Principle 2 - Integrating
The entire body operates together to determine the value of a measurement parameter
e.g. Arm Reach = arm length + shoulder movement + partial trunk rotation and + some back bending + hand movement

17. Dynamic (Functional) Dimensions
[Source: North, 1980]

18. Measurement of Anthropometric Dimensions

19. Segment Lengths: Link/Hinge Model
Segments are modeled as rigid mechanical links of known physical shape, size, and weight.
Joints are modeled as single-pivot hinges.
Standard points of reference on human body are defined in the scientific literature and are not arbitrarily used in ergonomics
Less than 5% error by this approximation L
Joint or Hinge
Segment

20. Segment Lengths: Link/Hinge Model

21. D = M / V = (W/g) / V Segment Density where
D = density [g/cm3 or kg/cm3]
M = mass [g or kg]
V = volume [cm3 or m3]
W = weight [N or pounds]
g = gravitational acceleration = 9.8 m/s2

22. Segment Density Double-tank system for measuring displaced volume
of human body
segments on living
or cadaver subjects.
Using standardized
density tables, the mass can then be calculated using
D = M / V.
[source: Miller & Nelson, 1976]

23. Segment Center-of-Gravity
[Kreighbaum & Barthels, 1996]
Segment
C-of-G
Important to know the location of the effective center of gravity (or mass) of segments
Gravity actually pulls on every particle of mass, therefore giving each part weight
For the body, each segment is treated as the smallest division of the body
Can obtain C-of-G for individual segments or group of segments
C-of-G usually slightly closer to the “thicker” end of the segment

24. Force Different weight or mass distributions distance9 6 3
distance
Force 30 20 10
Different weight
or mass distributions
can have the same
C-of-G
C-of-G Line 30 20 10 9 6 3
Force
distance
[adapted from
Kreighbaum & Barthels, 1996]

25. Segment Centers-of-Gravity shown as percentage of segment lengths [Dempster, 1955].

26. Segment Center-of-Gravity
Balance Method
Weight (force of gravity) & vertical reaction force at the fulcrum (axis) must lie in the same plane.
C-of-G line
[Kreighbaum & Barthels, 1996]

27. Segment Center-of-Gravity
Reaction Board Method 1 – Individual Segments O W2 L2
Sum all moments around pivot point ‘O’ for both cases:
-WX – SL – W2L2 = 0
-WX’ – S’L – W2L2 = 0
Subtract equations and rearrange to obtain the exact location (X) of C-of-G for the shank/foot system:
X = {L(S - S’)/W + X’}
[LeVeau, 1977]

28. Segment Center-of-Gravity
Reaction Board Method 2 – Group of Segments
Weigh Scales
C-of-G
Support Point
[Hay and Reid, 1988]

29. Segment Center-of-Gravity
Suspension Method
Determine pivot point which balances the object in 2D plane
Use frozen human cadaver segments
[Hay & Reid, 1988]

30. Segment Center-of-Gravity
Multi-Segment Method
Imagine a body composed of three segments, each with the C-of-G and mass as indicated
sum of Moments of each segment mass about the origin = Moment of the total body mass about the origin
mathematically: SMO = MA + MB + MC = MA+B+C O 4 6 8 2
30 N
10 N
5 N A B C
distance

31. Multi-Segment Method Example – Leg at 90 deg
A leg of is fixed at 90 degrees. The table gives CGs and weights (as % of total body weight W) of segments 1, 2, and 3. Determine coordinates (xCG, yCG) of Centre of Gravity of leg system.
Step 1 - sum of moments of each segment about origin ‘O’ as in Figure 5.39.
SMO=xCG{W1+W2+W3}=x1W1+x2W2+ x3W3
xCG = {x1W1 +x2W2 + x3W3}/(W1+W2+W3)
= {17.3(0.106W) (0.046W) +
45(0.017W)}/(0.106W W W)
xCG = 26.9 cm O O
[Oskaya & Nordin, 1991]

32. Step 2 - rotate leg to obtain the yCG and repeat the same procedure as Step 1.
SMO = yCG{W1 + W2 + W3}
SMO = y1W1 + y2W2 + y3W3
yCG = {y1W1 + y2W2 + y3W3}
/(W1 + W2 + W3)
= {51.3(0.106W) (0.046W) +
3.3(0.017W)}/(0.106W W +
0.017W)
yCG = 41.4 cm O
C-of-G

33. Segment Rotational Inertia
Rotational Inertia, I (Mass Moment of Inertia)
real bodies are not point masses; rather the mass is distributed about an axis or reference point
resistance to angular motion and acceleration
depends on mass of body & how far mass is distributed from the axis of rotation
specific to a given axis

34. Rotational Inertia, I I = rotational inertia m = mass
[Miller & Nelson, 1976]
Rotational Inertia, I
I = rotational inertia
m = mass
r = distance to axis or point of interest
Rotational inertia can be
calculated around any
axis of interest. Distance
from axis (r2) has more
effect than mass (m)

35. k = I/m Radius of Gyration, K
Radius (k) at which a point mass (m) can be located to have the same rotational inertia (I) as the body (m) of interest
measures the “average” spread of mass about an axis of rotation; k = “average r”
not same as C-of-G
k is always a little larger than the radius of rotation (which is the distance from C-of-G to reference axis)
[Hall, 1999]

36. k = I/m Example - Radius of Gyration, k Smaller k Smaller I
Faster Spin
k = I/m
Larger k
Larger I
Slower Spin

37. I = WL / 2f2 L f Measuring Rotational Inertia, I Pendulum Method
use frozen cadaver segments
frictionless, free swing, pivot system
measure rotational resistance to swing
pivot
C-of-G f L
I = WL / 2f2
I = rotational inertia (kg.m2)
W = segment weight (N)
L = distance from C-of-G to pivot axis (m)
f = swing frequency (cycles/s)
[see Lephart, 1984]

38. Measuring Rotational Inertia, I
[Peyton, 1986]
Oscillating Beam Method
use live subjects
forced oscillation system
measure resistance to
forced rotation
I = R/(2f)2 = Rp2/2
I = rotational inertia (kg.m2)
R = spring constant (N.m/rad)
p = period (sec)
f = freq. of oscillation (cycles/sec)

39. Sources Used Chaffin et al., Occupational Biomechanics, 1999.
Dempster, Space Requirements of the Seated Operator, 1955.
Hay and Reid, 1988.
Kroemer, “Engineering Anthropometry”, Ergonomics, 32(7): , 1989
Lephart, “Measuring the Inertial Properties of Cadaver Segments”, J.Biomechanics, 17(7): , 1984.
LeVeau, Biomechanics of Human Motion, 1977.
Peyton, “Determination of the Moment of Inertia of Limb Segments by a Simple Method”, J.Biomechanics, 19(5): , 1986.
Sanders and McCormick, Human Factors in Engineering and Design, 1993.
Moore and Andrews, Ergonomics for Mechanical Design, MECH 495 Course Notes, Queens Univ., Kingston, Canada, 1997.

40. Hall, Basic Biomechanics, 1999.
Miller and Nelson, Biomechanics of Sport, 1976.
Kreighbaum & Barthels, Biomechanics: A Qualitative Approach for Studying Human Movement, 1996.
North, “Ergonomics Methodology”, Ergonomics, 23(8): , 1980.
Oskaya & Nordin, Fundamentals of Biomechanics, 1991.
Webb Associates, Anthropometric Source Book, 1978.