Development and plausibility assessment of an active human body model in numerical cyclist to vehicle collision simulations based on real-life accident data

Finite element (FE) human body models (HBMs) have been used in the past to investigate injury biomechanics of road users in simulations based on accident data and were validated with postmortem human subject data. Recent HBM developments increasingly implement activatable musculature in both occupant and pedestrian applications because they show a significant difference in kinematics and injury biomechanics compared to passive HBMs (PHBMs). In this study, an active FE HBM (AHBM) was developed by incorporating 658 controlled Hill-type muscles adapted from a scalable muscle driven multibody HBM into the Total HUman Model for Safety (THUMSTM) V4.02 AM50 Pedestrian, allowing for stabilisation of the pre-impact position and for the assessment of muscle injuries. Using a previously developed method, multiple accident cases were replicated numerically and model prediction of kinematics, collision points and injuries were compared to the accident case documentation and to the PHBM results. The AHBM results agreed very well with the accident data overall, but not as well as the PHBM in terms of injury prediction. Strain-based injury assessment for the pelvis further suggests that the femoral head’s position in the acetabulum is not entirely physiologically valid, which should be considered in future HBM and AHBM development.