Vehicle control and drowsiness - VTI

Example 3, subject number 1Figure 19 Lateral position, SDLP and estimated drowsiness for subjectnumber 1. The lateral position is measured with 10 Hz. The SDLP window is setto 30 seconds. The drowsiness was estimated every five minutes.It is much harder to see any effect of SDLP and estimated drowsiness on thedriving behaviour of subject number 1. The SDLP does not fluctuate much even ifthe subject uses the whole KSS and becomes very tired at the end of the drivingperiod, looking at the estimated drowsiness. The estimated drowsiness can varywithout any variation in the SDLP. This is how it looks in most of the caseswhether the subject is from the tired group or not. Subject number two and 17 areexceptions that have higher and clearer values when it comes to lateral position.The correlation between estimated drowsiness and SDLP seems to be low. So isSDLP a bad indicator of drowsiness or is the rating scale a bad indicator ofdrowsiness? The KSS is validated, but is it useful as reference value fordrowsiness in this context?50 VTI meddelande 922A