Head motions using nine accelerometer package and angular rate sensors.

This study compared linear and angular accelerations and angular velocities of the head using two systems. The first sensor was a custom-developed pyramid nine accelerometer package (PNAP) in 3-2-2-2 configuration. The three corners of the base contained two biaxial accelerometers in the 2-2-2 array, and the vertex contained the tri-axial accelerometer. The second sensor was a recently available angular rate sensor. Both sensors were mounted on the periphery of the head of an intact post mortem human cadaver specimen (PMHS), exposed to impact loading. Using the dynamic equations of equilibrium and geometric properties of the head of the PMHS, linear location-specific acceleration data from the PNAP device were transformed to head angular accelerations and velocities and linear accelerations at its center of gravity. Using recorded angular velocity data from the rate sensor, angular and linear accelerations were obtained. A comparative evaluation of these data indicated that the angular rate sensor is preferable for rotational velocities and the PNAP device for angular accelerations. A combination of angular velocity data from the rate sensor and angular acceleration data from the PNAP device produced the most preferable temporal linear acceleration data at the center of gravity of the head. It may be prudent to use both sensors to obtain linear and angular acceleration and rotational velocity data from impact tests.