Characterisation of driver drowsiness induced by vibration
Creators: name: BHUIYAN, Mohammed
Publisher: name: RMIT University
Year: 2024
Subjects: classificationCode: 400204
subject: Automotive safety engineering

description: Since driver drowsiness is a significant factor in many motor vehicle accidents and fatalities, drowsiness detection and alerting systems are attracting attention from both researchers and the business sector. Among the numerous factors that can contribute to driver drowsiness, vehicle vibration is one that has received comparatively little attention. Vehicle vibrations are transmitted to the driver through the various interfaces such as the floor, seat, backrest, steering wheel and accelerator pedal. Vehicle vibration can induce a driver to fall asleep behind the wheel. The fact that transmitted vibration influences drowsiness is demonstrated by marked changes in driver physiological, psychological and cognitive parameters. The study provides an overview of the earlier studies that have investigated interrelationships between the various components of vibration exposure and driver drowsiness.

Vibration is an oscillatory motion characterised by frequency, acceleration, direction, waveform and amplitude. Vehicle occupants generally experience random, non-periodical, multi-frequency vibrations that occur simultaneously in different planes (vertical, longitudinal and transverse). Shocks or temporary vibration are also perceived due to the bumpy roads or potholes. International standards regulate the limits of vibration exposure, yet these standards aim to ensure passenger comfort rather than curtailing driver drowsiness. Indeed, little is known about the parameters of vibration (e.g. frequency and amplitude) that influence driver drowsiness. The current studies demonstrated that low frequency (&lt;10 Hz) whole-body vibration, in particular, the vibrations of 4-10 Hz are most effective at inducing drowsiness, while vibration amplitude and duration of exposure are also important factors.

The present laboratory-based study aimed to advance our understanding of the effect of vibration amplitudes on driver drowsiness. Three vibration amplitudes (rms acceleration) were selected, based on drivers' perceptions from real road conditions. These vibration amplitudes corresponded to the lower level (0.05 ms-2), mid-level (0.1 ms-2), and higher-level (0.2 ms-2) of vibrations in the vertical plane that are regularly experienced in a motor vehicle. In all experiments, the vibration frequency was restricted to a random 4 to 7 Hz as this band is common in motor vehicles and has previously been shown to induce drowsiness. The experiments were conducted on four different days; three days for each of the three levels of vibration and one day for the control condition (without vibration). Both physiological and subjective measures were used to evaluate driver drowsiness levels. Heart rate variability (HRV) was used to assess autonomic nervous system (ANS) activity, which is an objective indicator of the level of psychological alertness, while participants' self-reported drowsiness provided a subjective measure, the Karolinska Sleepiness Scale (KSS), subjective drowsiness score (SDS) and NASA TLX subjective workload score. Differences between treatment groups were assessed with repeated measures one-way ANOVA and Bonferroni's multiple comparison tests. The findings of subjective and objective measure indicate that exposure to vibration amplitudes are more likely to cause drowsiness than the control (CTRL) condition. Collectively, the results indicate that different vibration amplitudes showed a different level of drowsiness. However, low amplitudes of vibration (L1) induced more drowsiness than higher amplitudes (L2 and L3).The outcomes of the study will assist to control the whole-body vibration exposure associated with underground mine operations. In the interests of safety, manufacturers of motor vehicles should aim to minimise the vibrational factors in the future vehicle design that cause drowsiness.