Simulating 3D Human Postural Stabilization in Vibration and Dynamic Driving

Abstract

In future automated vehicles we will often engage in non-driving tasks and will not watch the road. This will affect postural stabilization and may elicit discomfort or even motion sickness in dynamic driving. Future vehicles shall accommodate this by properly designed seats and interiors whereas comfortable vehicle motion shall be achieved with smooth driving styles and well de-signed (active) suspensions. To support research and development in dynamic comfort, this paper presents validation of a multi-segment full body human model including visuo-vestibular and muscle spindle feedback for postural stabilization. Dynamic driving is evaluated using a “sicken-ing drive” including a 0.2 Hz 4 m/s2 slalom. Vibration transmission is evaluated with compliant automotive seats, applying 3D platform motion and evaluating 3D translation and rotation of pelvis, trunk and head. The model matches human motion in dynamic driving and reproduces fore-aft, lateral and vertical oscillations. Visuo-vestibular and muscle spindle feedback are shown to be essential in particular for head-neck stabilization. Active leg muscle control at the hips and knees is shown to be essential to stabilize the trunk in the high amplitude slalom condition but not in low amplitude horizontal vibrations. However, active leg muscle control can strongly affect 4-6 Hz vertical vibration transmission. Compared to the vibration tests, the dynamic driving tests show enlarged postural control gains to minimize trunk and head roll and pitch, and to align head yaw with the driving direction. Human modelling can create the required insights to achieve breakthrough comfort enhance-ments while enabling efficient development for a wide range of driving conditions, body sizes and other factors. Hence, modelling human postural control can accelerate innovation of seats and vehicle motion control strategies for (automated) vehicles.

Effects of seat back height and posture on 3D vibration transmission to pelvis, trunk and head

“…An exposure of 60 seconds per motion condition as in Mansfield et al (2006) was found sufficient to obtain coherent and consistent results from 0.34 Hz. Results below this frequency, as well as the significant effects of amplitude, will be evaluated in the time domain using 3D nonlinear models of human seat interaction (Mirakhorlo, Kluft, Irmak, Shyrokau and Happee, 2021). Such biomechanical models can also address cross-axis nonlinearity as demonstrated by Zheng, Qiu and Griffin (2019).…”

“…Future research shall explore contributions of translational and rotational motion to comfort perception in particular for the head. To achieve this we are currently integrating models of sensory integration (Oman, 1982) and postural stabilization (Happee, de Bruijn, Forbes and van der Helm, 2017) in full body biomechanical models (Mirakhorlo et al, 2021).…”