Anthropometrics

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Anthropometrics Ergonomics
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Anthropometrics Ergonomics
Anthropometrics- The study of measuring the
various sizes and proportions of the human
body. Data is represented in units of
measurements from one point of a body part to
another (e.g. elbow joint to shoulder joint is
275mm) Greek Antrho- Man
Metrics- Measurement Ergonomics- The study
of the relationship between man and their
environment. This is more concerned with the
shape and texture of the product. (e.g. groovy
shaped mobile phone case and buttons to make it
user friendly and comfortable to
use) Greek Ergon- work
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Anthropometrics Ergonomics
Using the Ergonome to estimate shape, size and
proportions of chair- it is also a useful aid to
visualise the comfort of the seating position of
the chair
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Anthropometrics Ergonomics
Seating People sit down in a number of ways and
for a variety, of reasons, like writing, resting
and watching TV. When sitting people change
positions often to stop parts of the body getting
too tired. A good chair design will allow people
to move about like this. Seats can be
badly designed in a number of ways. Seat A is
too high. The front of the seat presses into the
back of the thigh at X. The thigh is not meant to
bear a lot of weight and will soon get tired.
Seat B is too low. The legs either slide forward
or the body has to crouch. Both positions soon
become uncomfortable.
Seat C is
too long. Either the sitter has no back support
or has to lean back too far. Both positions can
cause back ache.
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Anthropometrics Ergonomics
How can you decide upon seating size and
shape? First you must decide exactly what the
seats purpose is. An easy chair will have to be
very different from a desk chair. (2) Then you
must take measurements of the relevant parts of
the body (or use anthropometric data). (3) In
complex cases you should use a test rig, or
prototype model, to test your design.
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Anthropometrics Ergonomics
What needs to be measured?
1 Seat height depends upon the distance
between the lower heel and the back of the knee.
In adult men there is a range between about 370
mm and 470 mm. For women the range is 355 mm to
455 mm. Therefore, overall the range is between
355 mm and 470 mm. An ideal solution would be a
seat with an adjustable height. If you cannot
make this, a reasonable height for, say, a dining
chair would be between 390 and 420 mm. The ideal
height would be lower for an easy chair.
2 Seat width is not so critical, unless the chair
has arm rests. The seat needs to be wide enough
to hold the spread of the buttocks. It must also
allow for small changes of position. For long
periods of sitting a minimum width is 435 mm.
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Anthropometrics Ergonomics
3 Seat depth depends on the distance between the
back of the knee and the buttocks. The minimum
for adult women is about
405 mm and the maximum for an adult man is about
505 mm. A common work chair seat depth is 380
mm, which will be suitable angle for both men
and women.
4 Seat angle usually slopes
down towards the back of the chair. 5
Seat hardness needs to be soft enough for comfort
but firm enough to support the body. For short
periods of sitting the seat can be hard, but for
longer periods some sort of padding has to be
provided.
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Anthropometrics Ergonomics
6 Backrests are generally used for chairs in
which a person is to be seated for more than a
short time. A rest which tilts backwards is more
comfortable than a perfectly upright rest. The
angle of tilt varies. A leisure chair will tilt
more than a work chair, for example. Why do you
think this is? A good back rest will support both
the lumbar region and the shoulder blades. For
working chairs, the shoulders are normally free
and only the lumbar region supported.
Ergonomics Investigation Tasks
(1) Find three
different kinds of chair as you can. State their
main purpose. Try them out, measure their height,
depth, angle and so on and Describe how
successful you think they are. (2) Find an
adjustable chair, Study it until you understand
how it works. How could you improve the design?