Biomedical Engineering Reference
In-Depth Information
Right eyes
r
eye
Midpoint
θ
Left eyes
r
vision
Box center
FIGURE 8.7
Vision constraint.
r
t
r
handle
r
n
r
box
Hand
Box edge
FIGURE 8.8
Hand-orientation constraint.
Note that the orientation constraints are imposed in such a way that the hand
normal vector is parallel to the box edge vector, r
box
, and the hand tangential vec-
tor is parallel to the box handle vector, r
handle
.
8.5.3.3
Collision avoidance
There are many methods for detecting and avoiding collision during the calcula-
tion process. A fast and efficient method is to fill objects in the scene with
spheres, including the human body. The size of the spheres will determine the
accuracy of the collision detection/avoidance algorithm.
Specifically, the ankle, knee, hip, shank, thigh, chest, and neck are filled with
spheres of various radii to represent the body dimensions. The distances between
the box edge and all sphere centers are calculated to impose collision avoidance
as shown in
Figure 8.9
. Collision avoidance is considered in the current formula-
tion to prevent penetration of the box in the body.
5
k
r
body
3
r
edge
k
k
r
edge
k
l
r
(8.22)
$
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