Civil Engineering Reference
In-Depth Information
Erector Spinae
Rectus Abdom
Int. Oblique
Ext. Oblique
Lat. Dorsi
Trans. Abdom.
Psods
Quad. Lumborum
15 cm
POSTERIOR VIEW
RIGHT-SIDE VIEW
FIGURE 48.5 Muscle geometry illustrated for a 50th percentile male. Muscles are treated as point-wise connections
from origin to insertion (see text). An imaginary cutting plane, which bisects the L3
L4 motion segment, is also
shown. (From Nussbaum, M.A. and Chaffin, D.B. 1996. Clin. Biomech. 11(1):25-34. With permission.)
/
These have been referred to as the University of Michigan's Two-Dimensional and Three-Dimensional
Static Strength Prediction Programs
TM
(i.e., 2DSSPP
TM
and 3DSSPP
TM
). Currently only one version is
available, 3DSSPP, which includes both the sagittal plane and 3D low-back models as well as the strength
model. The University of Michigan's Office of Technology Transfer has granted over 2500 individual
licenses for use of these programs since 1984.
The 3DSSPP program requires more input data than the previous 2D version. 3D exertions often
involve two hand forces, which can act in any direction. Also, a model of the human body in 3D has
12 body links (some with three postural angles). The main window of the 3DSSPP program is depicted
in Figure 48.7. The input values (posture, hand forces, and anthropometry) are entered in dialogs avail-
able from the pull-down menus. Postures can be entered manually by specifying body link angles, by spe-
cifying hand locations and using the posture prediction feature, or graphically by selecting and dragging
joints using a mouse entry device. The posture prediction feature uses an inverse kinematic model with
preferred postural prediction capability and is included to allow the user to easily manipulate the figure.
Orthogonal stick figures depicting the body posture, the hand location, and the hand force directions are
provided across the top of the window. An oblique-view enfleshed hominoid, which along with the stick
figures assist with the entry and adjustment of the posture, is provided in the lower-left area of the
window and can be manipulated to appear in the same orientation as a photo, video, or digital
image. The use of the 3D hominoid was found by Beck and Chaffin (1992) to allow postures to be accu-
rately entered and represented in a computer.
Summary analysis results, including the predicted percent of the population having sufficient strength
to perform the designated exertion, back compression, and balance status, are shown in tabular form in
the lower right quadrant of the main window. From inspection of the percent capable predictions shown
in Figure 48.7 for the analysis of a 50th percentile male lifting a 44-lb stock reel, it is obvious that hip
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