Traditionally, occupant safety research has centered on passive safety systems such as seatbelts, airbags, and energy-absorbing vehicle structures, all designed under the assumption of a nominal occupant posture at the moment of impact. However, with increasing deployment of active safety technologies such as Forward Collision Warning (FCW) and Autonomous Emergency Braking (AEB), vehicle occupants are exposed to pre-crash decelerations that alter their seated position before the crash. Although AEB mitigates the crash severity, the induced occupant movement leads to out-of-position behavior (OOP), compromising the available survival space phase and effectiveness of passive restraint systems during the crash. Despite these evolving real-world conditions, global regulatory bodies and NCAP programs continue to evaluate pre-crash and crash phases independently, with limited integration. Moreover, traditional Anthropomorphic Test Devices (ATDs) such as Hybrid III dummies, although highly repeatable, lack the bio-fidelity necessary to capture human-like kinematics during pre-crash braking events involving low g. ATDs do not simulate the spinal articulation, posture adjustments and active muscle contraction that occur during emergency maneuvers or pre-crash scenarios. To overcome these limitations, researchers have increasingly turned to Human Body Models (HBMs) such as Total Human Model for Safety (THUMS) and Global Human Body Model Consortium (GHBMC). These models enable high-fidelity finite element (FE) simulations with anatomical realism, allowing for the inclusion of active musculature and posture changes.
This study aims to quantify the occupant forward excursion under pre-crash phase (due to AEB) and explore the possibility of an integrated simulation framework that evaluates occupant safety across both pre-crash and crash events. For this, the approach was to carry out full vehicle braking tests (1g braking pulse) with adult male (AM50) volunteers at different speeds to measure forward head excursion during pre-crash. These scenarios were replicated in LS-Dyna using THUMS HBM, showing strong agreement with experimental data. The resulting excursed postures were then used in crash simulations with ATDs to evaluate the effect on injury outcomes. Overall, the findings demonstrate effect of forward excursion on occupant injuries and the effectiveness of HBMs in capturing occupant kinematics, during pre-crash events.