Table 2 Features characterizing driving fatigue in literature
Id | Feature descriptions |
|---|---|
\(\hbox {F}_{1}\) | PERCLOS (\(\hbox {F}_{1}\) ) (Bergasa and Nuevo 2006; Ji et al. 2004; Jin et al. 2013; Kong et al. 2015; Friedrichs and Yang 2010; Darshana et al. 2015; Sun et al. 2017): represents the percentage of eyelid closure at 75%: \( \text{PERCLOS}_{75}=\frac{N_{\text{closure}75}}{N} \) |
\(F_{2}\) | Eye closure duration (ECD) (\(F_{2}\)) (Azim et al. 2014; Bergasa and Nuevo 2006; Kong et al. 2015; Sun et al. 2017, 2015): represents the number of frames where the eye is totally closed. \(\text{ECD}=\sum N_{\text{Total closure}}\) |
\(F_{3}\) | Pupil diameter (PupilDiam) (\(F_{3}\)) (Miyaji and Kawanaka 2010): represents the diameter of eye iris contour. \(\text{PupilDiam}=\text{average}(P\_\text{diam}_{\text{l}},P\_\text{diam}_{\text{r}})\) |
\(F_{4}\) | Percentage of saccade (Persac) (\(F_{4}\)) (Ji et al. 2004; Liang et al. 2007): represents the percentage of eye pupil saccade |
\(F_{5}\) | Average eye closure speed (AECS) (\(F_{5}\)) (Bergasa and Nuevo 2006; Ji et al. 2004; Friedrichs and Yang 2010): represents the number of frames where the eye changed its state (opened/closed) \(\text{AECS}=\frac{N_{\text{Total closure}}+ N_{\text{Total opening}}}{N_{\text{Transition}}}\) |
\(F_{6}\) | Microsleep (\(F_{6}\)) (Friedrichs and Yang 2010): Microsleep during 30 s \(\text{Microsleep}=\sum N_{\text{Total closure}}/N\) |
\(F_{7}\) | Eye opened (EOP) (\(F_{7}\)) (Sun et al. 2017, 2015): eye opened during 30 s \(\text{EOP}=\sum N_{\text{Total opening}}/N\) |
\(F_{8}\) | Gaze angle distribution (\(\text{Gaz}_{\text{dis}}\)) (Ji et al. 2004; Engström et al. 2005; Jin et al. 2013; Darshana et al. 2015; Miyaji and Kawanaka 2010): \(\text{Gaze}= \sqrt{\varphi ^{2}+\psi ^{2}}\) |
\(F_{9}\) | Gaze angle variation (\(\text{Gaz}_{\text{var}}\)) (Ji et al. 2004): \(\text{Gaz}_{\text{var}}=\sigma (\text{Gaze}_{\text{dis}})\) |
\(F_{10}\) | FixedGaze (Bergasa and Nuevo 2006; Liang et al. 2007): it is a Boolean variable, if \(\text{Gaze}_{\text{dis}}\) is stable during 30 s \(\text{FixedGaze}= 1\), otherwise \(\text{FixedGaze}= 0\) |
\(F_{11}\) | Blink frequency (\(\text{Blink}_{\text{freq}}\)) (Bergasa and Nuevo 2006; Jin et al. 2013; Friedrichs and Yang 2010; Sun et al. 2017, 2015): \(\text{Blink}_{\text{freq}}=\frac{N_{\text{Total closure}}}{N}\) |
\(F_{12}\) | Blink duration (Blink-dur) (Friedrichs and Yang 2010; Hu and Zheng 2009) : represents the blink time amount |
\(F_{13}\) | Distribution of head tilt angle (Head-tilts-dis) (Bergasa and Nuevo 2006; Ji et al. 2004): \(\text{HeadTilts}= \sqrt{\varphi _{\text{head}}^{2}+\psi _{\text{head}}^{2}}\) |
\(F_{14}\) | Variation of head tilt angle (Head-tilts-var) (Bergasa and Nuevo 2006): \(\text{HeadTiltsVar}=\sigma (\text{HeadTilts}) \) |
\(F_{15}\) | Head nodding frequency (Head-nod-freq) (Bergasa and Nuevo 2006; Ji et al. 2004): represents the number of peaks in the head tilt angle distribution |
\(F_{16}\) | FacePose (Bergasa and Nuevo 2006): represents the number of frames where driver head is in frontal position \(\sum N_{\text{head frontal position}}\) |
\(F_{17}\) | Steering wheel movement (SWM) (Engström et al. 2005; Joly et al. 2018; Thiffault and Bergeron 2003; Sahayadhas et al. 2012; Ingre et al. 2006): represents the variability in steering wheel movements |