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Objective: For driver state estimation, physiological features might be promising input parameters. As cable-bound sensing of these parameters is impractical for ubiquitous monitoring, the measurement certainly has to be based on unobtrusive and contact-free technologies. In this work, unobtrusive methods for heart rate (HR) and respiration rate (RR) monitoring, including a hybrid imaging approach, are evaluated under simulated and real driving conditions. Methods: The feasability of unobtrusive methods was tested by comparing measurements from unobtrusive sensors to reference sensors. Under laboratory conditions, magnetic induction and photoplethysmography, both integrated into the seat belt, and hybrid imaging, combining visual and thermal imaging, were evaluated for RR sensing. In real driving, creating an urban and a rural scenario, sensing of RR by hybrid imaging and sensing of HR by a seat-integrated capacitive ECG were evaluated. Results: Under laboratory conditions, a reliable RR detection was possibly using all three sensor technologies. In real-world driving, a reliable HR and RR detection was possible during the rural scenario. In the urban scenario, only the RR detection was feasible. Due to motion artifacts, the capacitive ECG was disturbed and the HR detection impaired. Conclusion: The evaluated unobtrusive measurement systems can monitor physiological parameters during e.g. long-time driving on highways, but may not yet be feasible for monitoring during agile inner-city driving situations, due to motion artifacts. Therefore, future work should focus on artifact reduction. Significance: Physiological features might be used as input parameters for driver state estimation systems. This work presents unobtrusive sensing methods for these parameters. [ABSTRACT FROM AUTHOR]

A driving study was performed to induce stress with 24 participants performing different inducement tasks (n-back task, Sing-a-Song Stress Test and noise exposure). Both performance-based measures (Tactile Detection Response Task) as well as subjective measures were recorded to assess the driver state. Subjective ratings indicate that stress was most successfully induced on a group level with the n-back task with high inter-individual variation. The average response times doubled during the n-back task for a simultaneously performed tactile detection response task compared to baseline response times. Sympathetic nervous activation resulting in the increase of heart rate, respiration rate and decrease in heart rate variability (RMSSD) was found as a physiological reaction on stress-inducing secondary tasks. The most prominent physiological responses were found during the modified Sing-a-Song Stress Test. Subjective ratings on the perceived stress level and physiological response rarely correlated. This study provided reference data for driver state algorithm development in the EU-funded project ADAS&ME. [ABSTRACT FROM AUTHOR]

Objective: This study aims to compare the informative value of a capacitively coupled electrocardiogram (cECG) to a conventional galvanic reference ECG (rECG) in patients after a major cardiac event under simulated driving conditions. Addressed research questions are the comparison and coherence of cECG and rECG by means of the signal quality, the artifact rate, the rate of assessable data for differential diagnosis, the visibility of characteristic ECG structures in cECG, the precision of ECG time intervals, and heart rate (in particular, despite possible waveform deformations due to the cardiac preconditions). Methods: In a clinical trial, cECG and rECG data were recorded from ten patients after a major cardiac event. The cECG and rECG data were blindly evaluated by two cardiologists with regard to signal quality, artifacts, assessable data for differential diagnosis, visibility of ECG structures, and ECG time intervals. The results were statistically compared. Results: The cECG presented with more artifacts, an inferior signal quality, and less assessable data. However, when the data were assessable, determination of the ECG interval lengths was coherent to the one obtained from the rECG. Conclusion: When the signal quality is sufficient, the cECG yields the same informative value as the rECG. Significance: For certain scenarios, cECG might replace rECG systems. Hence, it is an important research question whether a similar amount of information can be obtained using a cECG system. [ABSTRACT FROM AUTHOR]