Measurement of Hybrid III Head Impact Kinematics Using an Accelerometer and Gyroscope System in Ice Hockey Helmets

Abstract

Helmet-based instrumentation is used to study the biomechanics of concussion. The most extensively used systems estimate rotational acceleration from linear acceleration, but new instrumentation measures rotational velocity using gyroscopes, potentially reducing error. This study compared kinematics from an accelerometer and gyroscope-containing system to reference measures. A Hybrid III (HIII) adult male anthropometric test device head and neck was fit with two helmet brands, each instrumented with gForce Tracker (GFT) sensor systems in four locations. Helmets were impacted at various speeds and directions. Regression relationships between GFT-measured and reference peak kinematics were quantified, and influence of impact direction, sensor location, and helmet brand was evaluated. The relationship between the sensor output and the reference acceleration/velocity experienced by the head was strong. Coefficients of determination for data stratified by individual impact directions ranged from 0.77 to 0.99 for peak linear acceleration and from 0.78 to 1.0 for peak rotational velocity. For the data from all impact directions combined, coefficients of determination ranged from 0.60 to 0.80 for peak resultant linear acceleration and 0.83 to 0.91 for peak resultant rotational velocity. As expected, raw peak resultant linear acceleration measures exhibited large percent differences from reference measures. Adjustment using regressions resulted in average absolute errors of 10-15% if regression adjustments were done by impact direction or 25-40% if regressions incorporating data from all impact directions were used. Average absolute percent differences in raw peak resultant rotational velocity were much lower, around 10-15%. It is important to define system accuracy for a particular helmet brand, sensor location, and impact direction in order to interpret real-world data.

A Review of Instrumented Equipment to Investigate Head Impacts in Sport

“…A strong correlation ( R 2 = 0.94) was also found between raw peak rotational velocity measured by the GFT and the Hybrid III ATD headform data. Campbell et al [104] supported the conclusions of Allison et al [101] regarding helmet brand-specific correction algorithms.…”

“…Allison et al [101] evaluated the accuracy of the GFT using a linear impactor, at speeds ranging from 1.5 to 5.0 m/s, to impact a hockey helmet mounted on a Hybrid III ATD head-neck system at various sites: facemask, side, rear-oblique, and rear. Relative to the peak linear acceleration data from the Hybrid III ATD headform, the raw data from the GFT demonstrated large differences of up to 150%, which was attributed to the lack of algorithm to transform the data to the centre of gravity of the head.…”

“…Mean absolute errors for angular velocity did not vary substantially by helmet brand, impact direction, sensor location, or impact severity. Allison et al [101] recommended that helmet brand-specific correction algorithms be developed to transform the raw linear acceleration data obtained from the GFT to represent the kinematics of the centre of gravity of the head.…”

White matter alterations over the course of two consecutive high‐school football seasons and the effect of a jugular compression collar: A preliminary longitudinal diffusion tensor imaging study

“…The authors acknowledge the potential for spurious head impact measurement based on accelerometry of the helmet, and not the head (e.g., pounding helmet on ground while not on head) despite the effort in standardizing head impact measurement between study groups. While prior studies have indicated that GForce Tracker affixed in helmets can provide suitable impact‐monitoring, the authors acknowledge the potential for up to 10–40% error as has been suggested in the literature in accelerometry measures with GForce Tracker [Allison et al, ; Campbell et al, ]. Further efforts to achieve technology development and algorithmic solutions to accelerometry measurement error, for example, combining and synchronizing video information with wearable sensor recording to cross‐verify head impact events [Cortes et al, ], are needed in future studies.…”

Helmets, head injury and concussion in sport

“…Because of these findings, new helmet-based instrumentation systems, such as the gForce Tracker (Markham, ON), have been developed that use gyroscopes in combination with accelerometers to more accurately measure rotational kinematics. Preliminary studies show decreased errors when measured with ATD modeling [30].…”