The HIC (Head Injury Criterion) calculation sounds simple — integrate the acceleration signal over time. In practice, getting a valid HIC number from a head impact test requires careful attention to signal conditioning, filtering, and sampling rate. Here's the technical detail.

Sensor Setup

The standard headform accelerometer setup per ECE 22.06, FMVSS 208, and related standards:

Triaxial accelerometer at headform centre of gravity (CG)

Accelerometer range: ±2000g (motorcycle) or ±500g (industrial)

Sensitivity: 1–2 mV/g typical

Natural frequency: >10 kHz (to avoid mechanical resonance in measurement band)

Mount the accelerometer with minimal mass adapter — any added mass shifts the CG and invalidates the test.

Signal Conditioning Chain

Accelerometer → Charge Amplifier → Anti-alias Filter → ADC → DAQ

Specifications: - Charge amplifier: <0.1% linearity, bandwidth DC to 10kHz - Anti-alias filter: 4th order Butterworth, fc = 1650Hz (per SAE J211 channel class 1000) - ADC: 16-bit minimum, ≥10kHz sample…