A method for intra-experimental validation of head impact acceleration measurements

Abstract

Methods of measuring head kinematics during short duration impacts include the so-called 3-2-2-2 method [1]. The method uses an array of linear accelerometers to estimate linear and angular acceleration of the head. The use of these and similar arrays in PMHS and animal models can be problematic because non-rigid effects can drastically affect the measurement of angular acceleration [2]. Problems include non-rigid attachment of the array to the head. One must also consider whether or not the rigid body is actually rigid, and to what extent the surface to which the array is attached is likely to exhibit non-rigid behaviour [3]. However, if the acceleration of a rigid body is known, the acceleration at any point on the rigid body can be calculated. Therefore it is possible to quantify the validity of the acceleration measurement using the output of one or more reference accelerometers. An accelerometer placed on the skull can record the acceleration experienced by a single point on the head during the impact. The output of the array can be used to predict the acceleration of that point. The degree of correlation between the prediction of the array and the acceleration measured by the reference accelerometer provides a statistical measure of the validity of the acceleration measurement in any given impact. If the predicted and measured acceleration correlate well, one can have increased confidence that the array successfully measured the rigid body motion of the head.