Comparison of different criteria for evaluating fatigue prediction

Accident research is highly concerned with the danger to fall asleep at the wheel.. To develop a driver support system that is able to measure the state of the driver a reliable criterion for fatigue has to be found. Several approaches have been made in the past, but the difficulty to operationalise fatigue remains. 75 subjects drove on a monotonous route on highway in a vibro-acoustic simulator provided by the Volkswagen AG. To designate the changing state of the driver in respect to his fatigue level different criteria were applied. Participants were asked every 30 minutes to estimate their own alertness level on a 10-point rating scale. Experts [t1]rated the probands' facial expressions and behaviour on a 4point rating scale in one minute intervals. EEG-data was collected throughout the experiment and an index calculated from the occurence of alpha-spindels was compute to diagnose fatigue states. Other measures like blinking behaviour and driving behaviour can be related to all three kinds of fatigue criteria. The study shows the advantages and disadvantages of all three criteria. We compare the explanatory power of the criteria and discuss future approaches. We would like to thank the Volkswagen AG (Wolfsburg, Germany) for providing the means and financing this project.