Enhancing a Multibody Model of a 6-year-old - Controller Implementation

Abstract

The number of children injured or disabled each year as a result of road traffic crashes has been estimated at around 10 millions around the world. Avoiding those fatalities and protecting car occupants are a goal many researchers are actively working toward. One of the fields involved in this effort is the modelling of the behavior of the human body (HBM) in pre‐crash and crash situations using computer‐aided simulations. The aim of this study is to improve an active 6‐year‐old HBM with more realistic and biofidelic movements to understand its behavior in pre‐crash events. More specifically, steering events will be analyzed. The thesis at hand recreates a child’s movements using a HBM modelled in MADYMO. The active 6‐year‐old HBM consists of an active spine, which is necessary to keep the body in an upright position during long simulations. Rigid bodies simulate the vertebrae of the spine and the addition of controllers implemented in the joints between the vertebrae maintains the HBM’s posture. The first step to improve the model was testing different reference systems for measuring vertebral angles. When these reference systems were defined, it was taken into account how the body moves trying to keep the balance. Secondly, the sensitivity of the spinal gains was studied to understand how it affected the movement of the active 6‐year‐old HBM when loaded with a lateral acceleration. The results point to the fact that the gains for lateral bending for the cervical, thoracic and lumbar spine were the most influential when a lateral acceleration was applied. In addition to that, it was revealed that the model for which all spinal joints are measured by taking the vertebral angles relative to the global coordinate system, fits in the volunteer corridors. Hence, this model can be useful to evaluate child restraint systems. However, further validations compared to other experimental data and with other child restraints are recommended. In addition to that, an improved model of the 6‐year‐old HBM – after further validation‐ could be used to optimize restraints and for seat assessment.