Using driver's head movements evolution as a drowsiness indicator

Many studies have been conducted to try to put forward measurable indicators that could help in the design of alerting devices used to reliably monitor severe driver drowsiness. However, most of these indicators are either too sensitive to environment modifications (performance indicators), invasive for the driver (EEG, EOG...) or are complex and expensive to measure (Eye blinks, PERCLOS...). This study aims at proposing a set of indicators related to driver performance and physiology that could be efficient for monitoring driver drowsiness and be easy to measure. Thirty two subjects took part to a long duration simulated highway trip (336 km) during which performance and physiological data were recorded The analysis of these data puts forward two sets of indicators : firstly, a set of performance indicators whose evolutions are consistent with those described in literature. They ensure the detection of drowsiness during the experiment. Secondly, a set of physiological indicators : the head movements dispersion. This has revealed itself to be a very good indicator as it evolves in the same way as the performance ones on long lasting periods while being poorly influenced by the road environment, contrary to most performance indicators.