Parametric Evaluation of Head Center of Gravity Acceleration Error From Rigid Body Kinematics Assumptions Used in Environmental Sensors

Abstract

Environmental sensors (ES) are a proposed way to identify potentially concussive events using Rigid Body Kinematics (RBK) to get motion at the head CG. This study systematically investigated the extent that errors in RBK assumptions including sensor orientation (SO), head CG position (HCGP), and exposure severity contribute to errors in sensor readings of predicted peak resultant linear acceleration (PRLA) at the head CG. Simulated sensor readings were defined by idealized representations of head motion [extension, lateral bending and axial rotation] using a half sine pulse for linear and angular acceleration. Peak magnitudes of linear acceleration ranged from 12.5 to 100 Gs and peak magnitudes of angular acceleration ranged from 1250 to 10000 rad/s/s. Durations of linear and angular accelerations ranged between 5 and 30 ms. Simulated HCGP variations ranged from −10% to 10% radius of the head (assumed to be a sphere) in each direction and SO variations ranged from −20 to 20 degrees about each axis. True head CG response was calculated using zero error for SO and HCGP. Mean (+/− standard deviation) of calculated errors for maximum percent error (MaxPE) of a given head exposure was 30.3% (+/−9.71). 50% and 38% of all simulated exposures had MaxPE associated with maximum SO and HCGP offset, respectively. MaxPE was likely due to user error, ES form factor, and anthropometric variation.