Poincaré plot indices of heart rate variability for monitoring driving fatigue

To evaluate the effects of driver fatigue on the autonomic nervous system (ANS), Poincare plot indices of heart rate variability (HRV) were investigated. A total of 20 volunteers were recruited to perform a 60-min duration driving experiment on a high-fidelity driving simulator with ECG recorded. The Poincare plot derived from RR intervals of ECG was quantified by measuring SD1, SD2, SD2/SD1, and S. The results showed that all four indices increased significantly (Mann-Whitney U test, p < 0.01) in fatigue state compared to an alert state. Poincare plot indices seem able to distinguish drivers' mental state and have potential prospective in ECG based driving fatigue detection systems.