Effects of a Motion Seat System on Driver's Passive Task-Related Fatigue: An On-Road Driving Study

Cardiac indices of driver fatigue across in-lab and on-road studies

Driver fatigue is a major contributor to road accidents. Therefore, driver assistance systems (DAS) that would monitor drivers' states may contribute to road safety. Such monitoring can potentially be achieved with input from ECG indices (e.g., heart rate). We reviewed the empirical literature on responses of cardiac measures to driver fatigue and on detecting fatigue with cardiac indices and classification algorithms. We used meta-analytical methods to explore the pooled effect sizes of different cardiac indices of fatigue, their heterogeneity, and the consistency of their responses across studies. Our large pool of studies (N = 39) allowed us to stratify the results across on-road and simulator studies. We found that despite the large heterogeneity of the effect sizes between the studies, many indices had significant pooled effect sizes across the studies, and more frequently across the on-road studies. We also found that most indices showed consistent responses across both on-road and simulator studies. Regarding the detection accuracy, we found that even on-road classification could have been as accurate as 70% with only 2-min of data. However, we could only find two on-road studies that employed fatigue classification algorithms. Overall, our findings are encouraging with respect to the prospect of using cardiac measures for detecting driver fatigue. Yet, to fully explore this possibility, there is a need for additional on-road studies that would employ a similar set of cardiac indices and detection algorithms, a unified definition of fatigue, and additional levels of fatigue than the two fatigue vs alert states.

Reducing passive driver fatigue through a suitable secondary motor task by means of an interactive seating system

OBJECTIVE

The primary objective of the study was to evaluate the effect of a secondary motor task induced by an interactive seating system (IASS) on passive driver fatigue in a monotonous simulated driving task. The effect was compared to that of a state-of-the-art massage seating system (MS), which may reduce monotony through additional tactile stimuli. The secondary objective was to compare the user experience of both systems.

METHOD

The independent variables were three conditions: one with the IASS, another with the MS, and a control without intervention. The study included seven dependent variables in total: a rating of subjective fatigue, three parameters measuring lane keeping ability, and three parameters reflecting fatigue-related eye movements. The duration of the simulator ride was 40 min in each condition. The study included thirty-five subjects.

RESULTS

The assessment of subjective fatigue and lane keeping showed that the use of the IASS resulted in significantly lower passive driver fatigue compared to the massage and control conditions. The alerting effects of the IASS were also reflected by an increased eyelid distance. Frequency and duration of blinks, however, showed no clear patterns of fatigue over time in any of the conditions. Thus, both parameters did not seem be suitable to capture passive driver fatigue in this study. Regarding user experience, the subjects preferred the IASS over the MS as well.

CONCLUSION

The IASS showed a strong potential as an effective measure against passive driver fatigue within monotonous driving situations. The MS, on the other hand, induced no measurable effects.

Drivers’ subjective perceptions of the contextual factors influencing fatigue: A qualitative study of suburban bus drivers in Iran

BACKGROUND: Drivers’ drowsiness is a significant issue globally known as a contributing factor to crashes in various transportation operations. Although there is evidence that suburban bus drivers experience drowsy driving, most previous studies are quantitative, which means that drivers experiencing drowsiness have not had the opportunity to explain their direct views and thoughts. OBJECTIVES: This qualitative exploratory study subjectively investigates the contextual factors influencing fatigue among suburban bus drivers. METHODS: Collecting data was conducted through 14 in-depth interviews with suburban bus drivers working in Tehran province’s transportation system, Iran. The interview recording was transcribed by the research team and entered into the qualitative data analysis software. Two independent coders with qualitative content analysis and thematic analysis approach analyzed transcripts. RESULTS: Four themes emerged, including human factors (with categories of individual characteristic and lifestyle), vehicle factors (with categories of design and performance), job factors (with categories of task requirement, quantity and quality of sleep, and circadian rhythm,) and environmental factors (with categories of the physical and economic environment). We found a more significant number of codes and categories and thus more contextual factors associated with job factors. The participants emphasized the importance of sleep deprivation, long driving hours, and even time of the day as factors influencing fatigue. CONCLUSIONS: The study results can provide beneficial information for both ergonomists and car manufacturers in developing more accurate fatigue detection models and effective educational and technical interventions to maintain road user’s health and reduce road accidents and mortality rates due to drowsiness.

Electrophysiological frequency domain analysis of driver passive fatigue under automated driving conditions

With the continuous improvement of automated vehicles, researchers have found that automated driving is more likely to cause passive fatigue. To explore the impact of automation and scenario complexity on the passive fatigue of a driver, we collected electroencephalography (EEG), detection-response task (DRT) performance, and the subjective report scores of 48 drivers. We found that in automated driving under monotonic conditions, after 40 min, the alpha power of the driver’s EEG indicators increased significantly, the accuracy of the detection reaction task decreased, and the reaction time became slower. The receiver characteristic curve was used to calculate the critical threshold of the alpha power during passive fatigue. The determination of the threshold further clarifies the occurrence time and physiological characteristics of passive fatigue and improves the passive fatigue theory.

Effects of a seat-integrated mobilization system during passive driver fatigue

OBJECTIVE

The aim of this study is to evaluate the effectiveness of a seat-integrated mobilization system for maintaining vigilance under monotonous driving situations.

METHOD

For this purpose, vigilance indicators were compared intra-individually in a test condition with mobilization (seat-integrated stimulation) and a placebo condition under standardized conditions in a real driving study (N = 31). During a monotonous two-hour ride, physiological (brain activity by the EEG alpha spindle rate), performance-based (reaction times) and subjective indicators were recorded.

RESULTS

The necessary precondition for the paradigm of inducing fatigue through monotony was confirmed by a significant increase in the EEG alpha spindle rate and the subjective vigilance indices. The mobilization system had a significant impact on the most fatigue-sensitive parameter of the alpha spindle rate, whereas the other parameters of vigilance did not reflect a significant effect of mobilization.

CONCLUSION

The Mobilization Seat is an effective measure to prevent drivers' fatigue during monotonous situations.