ABSTRACT
This chapter considers a representation or model of the human body, which is a finite-segment (or lumped-mass) model with the segments representing the major limbs of the human frame. It explores ways of simplifying the expressions for the inertia torque. The chapter investigates the properties of the triple vector product and shows that they may be expressed in terms of the inertia dyadic of a typical body relative to the mass center. Biological bodies are generally not homogeneous (nor are they isotropic). Nevertheless, for gross dynamic modeling, it is often reasonable to represent the limbs of a model (a human body model) by homogeneous bodies with simple shapes (structures of cones and ellipsoids). In such cases, it is occasionally convenient to use the concept of radius of gyration defined simply as the square root of the moment of inertia=mass ratio.
