Vestibulocollic and Cervicocollic Muscle Reflexes in a Finite Element Neck Model During Multidirectional Impacts

Abstract

Active neck musculature plays an important role in the response of the head and neck during impact and can affect the risk of injury. Finite element Human Body Models (HBM) have been proposed with open and closed-loop controllers for activation of muscle forces; however, the controllers in many current models are often calibrated to specific experimental loading cases, without considering the intrinsic role of physiologic muscle reflex mechanisms under different loading conditions. The goal of this study was to develop a closed-loop controller for a contemporary male HBM to represent muscle activation mechanisms based on the vestibulocollic and cervicocollic reflexes. Dual PID controllers were implemented, with head rotation and muscle stretch used for input.Controller parameters were optimized using volunteer data and then independently assessed across twelve impact conditions. The kinematics from the closed-loop controller simulations showed good average correlations to the experimental data (0.699) for the impacts. Compared to a previous optimized open-loop activation strategy, the average difference was less than 9%. The incorporation of the reflex mechanisms using a closedloop controller can provide robust performance for a range of impact directions and severities, which is critical to improving HBM response under a larger spectrum of automotive impact simulations.

Analysis of control strategies for VIVA OpenHBM with active reflexive neck muscles

“…Another important difference between the present study and previous studies (Ólafsdóttir et al 2019b;Kleinbach 2019;Correia et al 2021;Larsson et al 2019) was that previous studies did not conduct any evaluations of intervertebral rotations of the cervical spine or use the intervertebral rotations as objectives in the optimization process to derive controller gains. The correct prediction of intervertebral rotation in the cervical spine is vital if a model will be used to study head-neck kinematics in whiplash-type motions.…”

“…When the activation signals of each controller were compared (Online Resource 2), the combined control always had the highest magnitude and was active earlier than the other strategies. This high magnitude could be because combining a vestibular inspired and muscle spindle feedback inspired controller was unsuitable using In the closed-loop controller of Correia et al (2021), the CCR-like controller was only implemented for the Trapezius and SCM muscle groups. In the present work, the CCR-like controller was implemented into all neck muscles (combined-control approach) or only deep muscles (distributedcontrol approach).…”

“…In the present work, the CCR-like controller was implemented into all neck muscles (combined-control approach) or only deep muscles (distributedcontrol approach). In previous work (Correia et al 2021), the maximum contribution of a CCR-like controller was only 10% of the total muscle force (based on Correia et al (2020) defined using optimization). On the other hand, the CCRlike controller could activate 100% of the muscle forces in the present study.…”

“…An active HBM (AHBM) with a closed-loop approach can generally be used in a broader range of applications than those with an open-loop control method as the latter is defined a-priori for specific load cases. AHBMs with closed-loop muscle control have been successfully used to study occupant kinematics in different loading conditions (Östh et al 2012a , 2014b , 2014a ; Iwamoto and Nakahira 2015 ; Kleinbach 2019 ; Devane et al 2019 ; Martynenko et al 2019 ; Putra et al 2019 , 2020 ; Correia et al 2021 ).…”

Role of Rotated Head Postures on Volunteer Kinematics and Muscle Activity in Braking Scenarios Performed on a Driving Simulator

“…Virtual Human Body Models (HBMs) can be used in such investigations and can help to create a better understanding of the injury mechanism in WAD. 7,19,30,32 Because the HBMs allows the measurements of intrinsic values like ligament strain, muscle state, or pressure in the intervertebral discs, which are almost impossible to obtain in human experiments due to ethical aspects. Volunteer tests play an essential role in the calibration and validation process of HBMs, as they allow matching the controlled HBM kinematics with observed human behavior.…”