Implementation and Calibration of Active Reflexive Cervical Muscles on Female Head-Neck Model
Konferensbidrag (offentliggjort, men ej förlagsutgivet), 2019

Problem outline
ViVA OpenHBM is an open source human body model that represents the 50th percentile female
population for assessing whiplash protection systems in car. ViVA OpenHBM was developed with
intention to fill the gap of current available HBMs which excluded the average female size although
injury statistics since 1960s have shown that females have three times higher risk to sustain whiplash
injury compared to males. In this study, the current model is being enhanced by implementing active
muscles as previous studies have shown that cervical muscles could alter the head and neck kinematics
of the occupant during low-speed rear- crashes.
Study objectives
The first goal of this study was to implement a Proportional Integral Derivative (PID) feedback control
mechanism adding to the Finite Element models of cervical muscles. The second goal was to calibrate
the PID control gains by conducting an optimization-based parameter identification with publishedvolunteer data and to analyze the effects of three calibration objectives to the head and cervical
kinematics of the model.
The VIVA OpenHBM head-neck model, previously validated to PMHS data, was used. To represent the
34 cervical muscles, 129 beam elements with Hill-type material models were implemented. A closedloop control strategy was applied to activate these muscles mimicking the human body’s vestibular
system. Calibration studies of head and cervical spine kinematics were conducted by comparing the
model against published-volunteer responses to identify reasonable gain values for the controller. Three
different calibrations were conducted with three different objectives: head kinematics in linear and
angular direction, head and cervical spine kinematics in angular direction, and head and cervical spine
kinematics in linear and angular direction.
Results and Conclusion
The simulation results show that the reflexive feedback control was numerically stable and able to
control model muscle’s activation. Gain values of the implemented muscle control strategies were able
to be identified from calibration simulations. Muscle activation changed the head kinematics by reducing
peak linear and angular displacements, as compared to the model without muscle activation. The
agreement of specific kinematic variables such as head kinematic and cervical spine angular
displacement was dependent on the controller calibration objectives. Best agreement of head
kinematics was observed in the model that calibrated against only volunteer head kinematics. However,
in the vertical and angular direction there was a discrepancy of head response caused by anteriorposterior buckling of the cervical spine. In the model that was calibrated against head and cervical spine
in angular direction, less contraction of cervical muscles was observed. As the result, good agreement
was obtained in the cervical spine angular kinematics but not in the head kinematics. The best
agreement was obtained by the model that calibrated against both linear and angular displacement of
volunteer head and cervical spine kinematics although reduced the agreement of head kinematics
compared to the model that was calibrated against only volunteer head kinematics. This was because
of different calibration objectives that opposing each other.

Finite element model



Active Muscles

Volunteer test


I Putu Alit Putra


Johan Iraeus


Robert Thomson


Mats Svensson


15th Annual Injury Biomechanics Symposium-The Ohio State University
Columbus, Ohio, USA,

Virtual Vehicle Safety Assessment Step 2: Open Source Human Body Models and Crash Testing (Viva II)

VINNOVA, 2017-01-01 -- 2019-06-30.


Hållbar utveckling



Hälsa och teknik


Annan medicinteknik




Grundläggande vetenskaper


C3SE (Chalmers Centre for Computational Science and Engineering)

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