Table 1.

State transition process model parameters. These parameters are estimated using LS method and they are assumed to be constant for all of the driving tests. In other words, state transition process of PERCLOS (Equation 1) has the same parameters in different driving tests.

Parameter	Meaning	Value
${\sigma }_{ϵ}^2$	Noise variance of state transition process model	0.03
a	The slope of the linear regression in Equation (4)	3.93
b	The intercept of the linear regression in Equation (4)	−1.79