Sleepiness signal detector
A sleepiness sign detection apparatus, includes: a head movement detection unit configured to detect a head movement to generate a head movement data; an eye movement detection unit configured to detect an eye movement to generate an eye movement data; an ideal eye movement angular velocity calculation unit configured to calculate an ideal eye movement angular velocity based on the head movement data generated by the head movement detection unit; an eye-rotation angular velocity calculation unit configured to calculate an eye-rotation angular velocity based on the eye movement data generated by the eye movement detection unit; and a sleepiness sign detection unit configured to detect vestibule-ocular reflex (VOR) from the ideal eye movement angular velocity and the eye-rotation angular velocity, and determine a sign of sleepiness based on the vestibule-ocular reflex.
1. A sleepiness sign detection apparatus, comprising:
a head movement detection unit configured to detect a head movement to generate a head movement data;
an eye movement detection unit configured to detect an eye movement to generate an eye movement data;
an ideal eye movement angular velocity calculation unit configured to calculate an ideal eye movement angular velocity based on the head movement data generated by the head movement detection unit;
an eye-rotation angular velocity calculation unit configured to calculate an eye-rotation angular velocity based on the eye movement data generated by the eye movement detection unit; and
a sleepiness sign detection unit configured to detect vestibule-ocular reflex (VOR) from the ideal eye movement angular velocity and the eye-rotation angular velocity, and determine a sign of sleepiness based on the vestibule-ocular reflex.
2. The sleepiness sign detection apparatus according to claim 1 , wherein
the sleepiness sign detection unit
calculates a VOR gain defined by G and a decrease rate of the VOR gain, the G obtained by approximating the eye-rotation angular velocity by a linear equation of the ideal eye movement angular velocity:
e ( t )= G·h ( t −τ)+ dc +ε( t ),
where e(t) represents eye-rotation angular velocity; G represents VOR gain; h(t) represents ideal eye movement angular velocity; τ represents delay time of eye movement with respect to head movement; dc represents constant term; and ε(t) represents residual of regression model, and
determines a sign of sleepiness, when the decrease rate of the VOR gain exceeds a threshold value set in advance.
3. The sleepiness sign detection apparatus according to claim 1 , wherein
the sleepiness sign detection unit
calculates an approximation residual defined by ε(t) and a residual standard deviation, the ε(t) obtained by approximating the eye-rotation angular velocity by a linear equation of the ideal eye movement angular velocity:
e ( t )= G·h ( t −τ)+ dc +ε( t ),
where e(t) represents eye-rotation angular velocity; G represents VOR gain; h(t) represents ideal eye movement angular velocity; τ represents delay time of eye movement with respect to head movement; dc represents constant term; and ε(t) represents residual of regression model, and
determines a sign of sleepiness, when an increase rate of the residual standard deviation exceeds a threshold value set in advance.
4. The sleepiness sign detection apparatus according to claim 2 , wherein
the sleepiness sign detection unit
calculates an approximation residual defined by ε(t) and a residual standard deviation, the ε(t) obtained by approximating the eye-rotation angular velocity by a linear equation of the ideal eye movement angular velocity:
e ( t )= G·h ( t −τ)+ dc+ε ( t ),
where e(t) represents eye-rotation angular velocity; G represents VOR gain; h(t) represents ideal eye movement angular velocity; τ represents delay time of eye movement with respect to head movement; dc represents constant term; and ε(t) represents residual of regression model, and
determines a sign of sleepiness, when an increase rate of the residual standard deviation exceeds a threshold value set in advance.
5. The sleepiness sign detection apparatus according to claim 1 , wherein
the sleepiness sign detection apparatus is a sleepiness detection apparatus installed in a vehicle, and
the ideal eye movement angular velocity is calculated on the basis of outputs of an acceleration sensor and a gyro sensor provided in the vehicle as the head movement detection unit.
6. The sleepiness sign detection apparatus according to claim 2 , wherein
the sleepiness sign detection apparatus is a sleepiness detection apparatus installed in a vehicle, and
the ideal eye movement angular velocity is calculated on the basis of outputs of an acceleration sensor and a gyro sensor provided in the vehicle as the head movement detection unit.
7. The sleepiness sign detection apparatus according to claim 3 , wherein
the sleepiness sign detection apparatus is a sleepiness detection apparatus installed in a vehicle, and
the ideal eye movement angular velocity is calculated on the basis of outputs of an acceleration sensor and a gyro sensor provided in the vehicle as the head movement detection unit.
8. The sleepiness sign detection apparatus according to claim 4 , wherein
the sleepiness sign detection apparatus is a sleepiness detection apparatus installed in a vehicle, and
the ideal eye movement angular velocity is calculated on the basis of outputs of an acceleration sensor and a gyro sensor provided in the vehicle as the head movement detection unit.