The computation of angular acceleration of a rigid body from measured linear accelerations is a simple procedure, based on well-known kinematic principles. It can be shown that, in theory, a minimum of six linear accelerometers are required for a complete definition of the kinematics of a rigid body. However, recent attempts in impact biomechanics to determine general three-dimensional motion of body segments were unsuccessful when only six accelerometers were used. This paper demonstrates the cause for this inconsistency between theory and practice and specifies the conditions under which the method fails. In addition, an alternate method based on a special nine-accelerometer configuration is proposed. The stability and superiority of this approach are shown by the use of hypothetical as well as experimental data.

No abstract

No abstract

An anatomically based coordinate system is a useful tool for standardizing the placement of instrumentation on segments of the human body or human surrogate. It is suggested that this system be based upon a fixed set of anatomical landmarks that are easily located by palpation and/or x-ray. A set of coordinate systems for the head, torso and extremities is proposed. Such systems will aid investigators in comparing data acquired at different laboratories involved in impact injury research. These systems can also be used for accurately locating the center of gravity of a body segment and for describing body motion in an impact environment.

No abstract