Biomedical Engineering Reference
In-Depth Information
Figure 3.1
Spatial coordinate system for all data and analyses.
An example taken from the data on a human subject during walking will
illustrate the convention. The kinematics of the right leg segment (as viewed
from the right side) and its center of mass were analyzed as follows:
14
.
29 rad/s
2
,
ω
=−
2
.
34 rad/s,
α
=
υ
x
=
0
.
783 m/s
9
.
27 m/s
2
,
0
.
31 m/s
2
a
x
=−
υ
y
=
0
.
021 m/s,
a
y
=−
This means that the leg segment is rotating clockwise but is decelerating
(accelerating in a counterclockwise direction). The velocity of the leg's center
of mass is forward and very slightly upward, but it is decelerating in the
forward direction and accelerating downward.
3.1.2 Total Description of a Body Segment in Space
The complete kinematics of any body segment requires 15 data variables, all
of which are changing with time:
1. Position (x, y, z) of segment center of mass
2. Linear velocity (
x
,
˙
y
,
˙
˙
z
) of segment center of mass
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