Rh. Crompton et al., SEGMENT INERTIAL PROPERTIES OF PRIMATES - NEW TECHNIQUES FOR LABORATORY AND FIELD STUDIES OF LOCOMOTION, American journal of physical anthropology, 99(4), 1996, pp. 547-570
Studies of the dynamics of locomotor performances depend on knowledge
of the distribution of body mass within and between limb segments. How
ever, these data are difficult to derive. Segment mass properties have
generally been estimated by modelling limbs as truncated cones, but t
his approach fails to take into account that some segments are of elli
ptical, not circular, cross section; and further, the profiles of real
segments are generally curved. Thus, they are more appropriately mode
lled as solids of revolution, described by the rotation in space of co
nvex or concave curves, and the possibility of an elliptical cross sec
tion needs to be taken into account. In this project we have set out t
o develop a general geometric model which can take these factors into
account, and permit segment inertial properties to be derived from cad
avers by segmentation, and from living individuals using linear extern
al measurements. We present a model which may be described by up to fo
ur parameters, depending on the profile and serial cross section (circ
ular or ellipsoidal) of the individual segments. The parameters are ob
tained from cadavers using a simplified complex-pendulum technique, an
d from intact specimens by calculation from measurements of segment di
ameters and lengths. From the parameters, the center of mass, moments
of inertia, and radii of gyration may be derived, using simultaneous e
quations. Inertial properties of the body segments of four Pan. troglo
dytes and a single Pongo were determined, and contrasted to comparable
findings for humans. Using our approach, the mass distribution charac
teristics of any individual or species may be represented by a rigid-l
ink segment model or ''android.'' If this is made to move according to
motion functions derived from a real performance of the individual re
presented, we show that recordings of resulting ground reaction forces
may be quite closely simulated by predictive dynamic modelling. (C) 1
996 Wiley-Liss, Inc.