R-R interval measurement system for car drivers that allows measurement while the driver is driving with one hand has been developed. This system is intended for analysis of R-R interval fluctuation which is related to drowsiness and stress. R-R interval is the interval between R-waves in electrocardiogram (ECG). Our goal is to detect changes in R-R interval fluctuation and alert the driver to prevent drowsy driving. ECG was measured with a contact electrode on the steering wheel and a capacitive coupling electrode on the driver’s seat. ECG measurement with capacitive coupling is very sensitive to body motion. Baseline fluctuation can be as large as hundred times of the R-wave. In order to utilize differential amplification to reduce the fluctuation, an additional seat electrode was placed on top of the seat electrode with a paper insulator in between the two electrodes. The outputs of the upper seat electrode and the steering wheel electrode showed similar baseline fluctuation with respect to the lower seat electrode, while R-waves appeared only in the signal from the steering wheel electrode. Baseline fluctuation was reduced by taking the difference between the two signals. The proposed measurement method was evaluated in a real car. The system was capable of measuring R-waves of a passenger who held an electrode in the hand to simulate one hand driving while driving on a highway.
Financed by the National Centre for Research and Development under grant No. SP/I/1/77065/10 by the strategic scientific research and experimental development program:
SYNAT - “Interdisciplinary System for Interactive Scientific and Scientific-Technical Information”.