In many studies MADYMO has been used to simulate the behaviour of the human body in -mainly- impa... more In many studies MADYMO has been used to simulate the behaviour of the human body in -mainly- impact conditions. Besides mathematical models describing crash dummies, models directly based on the human body have been applied. Such biomechanical models are discussed. (A) For the covering abstract of the conference see IRRD 875886.
Background: Motion sickness (MS) as an area of scientific inquiry has mostly seen experimental wo... more Background: Motion sickness (MS) as an area of scientific inquiry has mostly seen experimental work. A range of models attempt to predict MS, but have not been validated for a broad selection of sickening motion stimuli. By doing so this study aims to identify models that lead to better sickness predictions. Lastly, the study will also elaborate on the effects of vision, a key factor in motion sickness of automated driving in particular. Methods: Three models of spatial orientation are compared, the TNO model, the Newman model and the probalistic particle filter model. The models are tuned and validated with respect to the perceptual responses to earth-vertical axis rotation, off-vertical axis rotation and centrifugation. Internal conflict terms are used as a proxy for sickness prediction. Sickness responses are evaluated for five motion paradigms: pure roll, pure lateral and vertical acceleration, off-vertical axis rotation and cross-coupled coriolis stimulation. MS susceptibility as a function of frequency is derived for 3D acceleration and rotation for 3 different visual conditions; internal vision, external vision and darkness. Results: Preliminary results show that models do not adequately explain differences in sickness response observed between motion paradigms. For the TNO model, MS susceptibility as function of frequency matches experiments for vertical acceleration in darkness, but not for horizontal plane acceleration. The inclusion of vision shifts the center frequency from 0.2 Hz to 0.1 Hz for vertical acceleration, but does not affect the horizontal response. The Newman model predictions are the least accurate due to a direct coupling between state estimates and conflict terms. The particle filter model shows promise in that parameter variations approximately reproduce the MS susceptibility observed for lateral accelerations. However unlike the TNO & Newman models, it cannot account for vertical motion sickness as by design its predictions are based on the somatogravitic illusion.Intelligent VehiclesControl & Simulatio
Introduction: Reflex modulation has been extensively reported during posture maintenance in respo... more Introduction: Reflex modulation has been extensively reported during posture maintenance in response to task instructions, and to perturbation type, bandwidth and amplitude. For the head-neck system the modulation of the vestibulocollic (VCR) and cervicocollic (CCR) reflexes is essential to maintain upright head posture during unexpected disturbances. Previous studies have estimated that VCR and CCR contribute equally during perturbations in the sagittal plane; however, their modulation with respect to the properties of the disturbance remains unclear. This study seeks to establish how neck reflexes are modulated during perturbations with varying properties and how each reflex contributes to stabilization behavior. We hypothesized that VCR and CCR (a) modulate according to the perturbation bandwidth, (b) are unaffected by the perturbation amplitude and (c) increase when performing a visual acuity task. Methods: Twelve subjects were perturbed via the torso while restrained in a seated position on a motion platform. The anterior-posterior perturbations varied in bandwidth from 0.3 Hz to a maximum frequency of 1.2, 2.0, 4.0 and 8.0 Hz, at three different amplitudes, and with eyes open and closed. Results: Head kinematics and neck muscle EMG demonstrated significant (P < 0.05) changes due to bandwidth, which through modeling and closed loop identification were attributed to modulation of VCR and CCR gains. VCR and CCR demonstrated dominant contributions to stabilization during high (8.0 Hz) and low bandwidth (1.2 and 2.0 Hz) perturbations respectively, and equivalent contributions during mid bandwidth perturbations (4.0 Hz). However both were attenuated when perturbations exceeded the systems natural frequency (~2-3 Hz). Amplitude had an effect only for the lowest amplitude relative to other conditions attributed to thresholding properties of the semicircular canals. With eyes closed reflex gains decreased, attributed to the reduced ability to discriminate self-motion without vision. Conclusions: To maintain head-upright posture adaptations of neck reflexes are observed to occur due to perturbation frequency and visual task conditions but not amplitude. Estimation of reflex contributions demonstrates that previous literature has underestimated the contribution of CCR, particularly during low frequency perturbations.
Mathematical modelling is widely used for crash-safety research and design. However, most occupan... more Mathematical modelling is widely used for crash-safety research and design. However, most occupant models used in crash simulations are based on crash dummies and thereby inherit their apparent limitations. This paper describes a mathematical model of the real human body for impact loading. A combination of modelling techniques is applied using rigid bodies for most body segments, but describing the thorax as a flexible structure. The skin is described using an arbitrary surface consisting of triangular facets to simulate contact with structures like seats, belts and airbags. The model allows simulation of global injury criteria like chest deflection, acceleration, and neck loads. For a more detailed analysis, submodels can easily be integrated into the current whole body model. As an example a detailed neck model including muscles with reflex activation has been included, and results are compared to those of the standard neck model.
In many studies MADYMO has been used to simulate the behaviour of the human body in -mainly- impa... more In many studies MADYMO has been used to simulate the behaviour of the human body in -mainly- impact conditions. Besides mathematical models describing crash dummies, models directly based on the human body have been applied. Such biomechanical models are discussed. (A) For the covering abstract of the conference see IRRD 875886.
Background: Motion sickness (MS) as an area of scientific inquiry has mostly seen experimental wo... more Background: Motion sickness (MS) as an area of scientific inquiry has mostly seen experimental work. A range of models attempt to predict MS, but have not been validated for a broad selection of sickening motion stimuli. By doing so this study aims to identify models that lead to better sickness predictions. Lastly, the study will also elaborate on the effects of vision, a key factor in motion sickness of automated driving in particular. Methods: Three models of spatial orientation are compared, the TNO model, the Newman model and the probalistic particle filter model. The models are tuned and validated with respect to the perceptual responses to earth-vertical axis rotation, off-vertical axis rotation and centrifugation. Internal conflict terms are used as a proxy for sickness prediction. Sickness responses are evaluated for five motion paradigms: pure roll, pure lateral and vertical acceleration, off-vertical axis rotation and cross-coupled coriolis stimulation. MS susceptibility as a function of frequency is derived for 3D acceleration and rotation for 3 different visual conditions; internal vision, external vision and darkness. Results: Preliminary results show that models do not adequately explain differences in sickness response observed between motion paradigms. For the TNO model, MS susceptibility as function of frequency matches experiments for vertical acceleration in darkness, but not for horizontal plane acceleration. The inclusion of vision shifts the center frequency from 0.2 Hz to 0.1 Hz for vertical acceleration, but does not affect the horizontal response. The Newman model predictions are the least accurate due to a direct coupling between state estimates and conflict terms. The particle filter model shows promise in that parameter variations approximately reproduce the MS susceptibility observed for lateral accelerations. However unlike the TNO &amp; Newman models, it cannot account for vertical motion sickness as by design its predictions are based on the somatogravitic illusion.Intelligent VehiclesControl & Simulatio
Introduction: Reflex modulation has been extensively reported during posture maintenance in respo... more Introduction: Reflex modulation has been extensively reported during posture maintenance in response to task instructions, and to perturbation type, bandwidth and amplitude. For the head-neck system the modulation of the vestibulocollic (VCR) and cervicocollic (CCR) reflexes is essential to maintain upright head posture during unexpected disturbances. Previous studies have estimated that VCR and CCR contribute equally during perturbations in the sagittal plane; however, their modulation with respect to the properties of the disturbance remains unclear. This study seeks to establish how neck reflexes are modulated during perturbations with varying properties and how each reflex contributes to stabilization behavior. We hypothesized that VCR and CCR (a) modulate according to the perturbation bandwidth, (b) are unaffected by the perturbation amplitude and (c) increase when performing a visual acuity task. Methods: Twelve subjects were perturbed via the torso while restrained in a seated position on a motion platform. The anterior-posterior perturbations varied in bandwidth from 0.3 Hz to a maximum frequency of 1.2, 2.0, 4.0 and 8.0 Hz, at three different amplitudes, and with eyes open and closed. Results: Head kinematics and neck muscle EMG demonstrated significant (P < 0.05) changes due to bandwidth, which through modeling and closed loop identification were attributed to modulation of VCR and CCR gains. VCR and CCR demonstrated dominant contributions to stabilization during high (8.0 Hz) and low bandwidth (1.2 and 2.0 Hz) perturbations respectively, and equivalent contributions during mid bandwidth perturbations (4.0 Hz). However both were attenuated when perturbations exceeded the systems natural frequency (~2-3 Hz). Amplitude had an effect only for the lowest amplitude relative to other conditions attributed to thresholding properties of the semicircular canals. With eyes closed reflex gains decreased, attributed to the reduced ability to discriminate self-motion without vision. Conclusions: To maintain head-upright posture adaptations of neck reflexes are observed to occur due to perturbation frequency and visual task conditions but not amplitude. Estimation of reflex contributions demonstrates that previous literature has underestimated the contribution of CCR, particularly during low frequency perturbations.
Mathematical modelling is widely used for crash-safety research and design. However, most occupan... more Mathematical modelling is widely used for crash-safety research and design. However, most occupant models used in crash simulations are based on crash dummies and thereby inherit their apparent limitations. This paper describes a mathematical model of the real human body for impact loading. A combination of modelling techniques is applied using rigid bodies for most body segments, but describing the thorax as a flexible structure. The skin is described using an arbitrary surface consisting of triangular facets to simulate contact with structures like seats, belts and airbags. The model allows simulation of global injury criteria like chest deflection, acceleration, and neck loads. For a more detailed analysis, submodels can easily be integrated into the current whole body model. As an example a detailed neck model including muscles with reflex activation has been included, and results are compared to those of the standard neck model.
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