Sleepiness detecting device

Patent metadata

Field	Value
Publication number	US-2016304099-A1
Application number	US-201615085121-A
Country	US
Kind code	A1
Filing date	Mar 30, 2016
Priority date	Apr 18, 2015
Publication date	Oct 20, 2016
Grant date	—

Abstract

A device for detecting the sleepiness of a driver driving a vehicle is designed to determine if the resetting of threshold values for detection of sleepiness is performed based upon its necessity when an interruption of the driving occurs. The inventive device computes successively an eyelid opening/closing characteristic amount from time intervals between transitions between an opened state and a closed state of an eyelid detected successively; sets threshold values using the eyelid opening/closing characteristic amounts obtained in a predetermined period; and judges the driver feels sleepiness when the eyelid opening/closing characteristic amount deviates from a range defined with the threshold values. In restarting the driving after its interruption, it is judged if the resetting of the threshold values is to be performed based on the driver's condition till then, and the resetting is performed, using eyelid opening/closing characteristic amounts obtained after the restarting of the driving.

First claim

1 . A device for detecting sleepiness of a subject driving a vehicle, comprising:
an eyelid state detector which detects an opened/ closed state of an eyelid of the subject; a time interval detector which detects sequentially a time interval between transitions between an opened state and a closed state of the eyelid; an eyelid opening/closing characteristic amount computer which computes an eyelid opening/closing characteristic amount successively from time series data of the time intervals between transitions between an opened state and a closed state of the eyelid, a threshold value setter which sets threshold values for the eyelid opening/closing characteristic amount using the eyelid opening/closing characteristic amount obtained in a predetermined period; and a sleepiness judging device which judges that the subject feels sleepiness when the eyelid opening/closing characteristic amount deviates from a range defined with the threshold values after lapse of the predetermined period; wherein the threshold value setter judges whether or not the threshold values are to be reset based on a condition of the subject before the restarting of the driving in restarting the driving of the vehicle after an interruption of the driving of the vehicle, and resets the threshold values for the eyelid opening/closing characteristic amount using eyelid opening/closing characteristic amounts obtained in the predetermined period after the restarting of the driving when it is judged that the threshold values are to be reset.

2 . The device of claim 1 , wherein the threshold value setter judges that the threshold values are to be reset when sleepiness of the subject is detected before the interruption of the driving of the vehicle.

3 . The device of claim 1 , wherein the threshold value setter judges that the threshold values are to be reset when a time length of the interruption of the driving of the vehicle is longer than a predetermined time length.

4 . The device of claim 1 , wherein, until the threshold value setter has completed the setting of the threshold values with the eyelid opening/closing characteristic amounts obtained in the predetermined period, the sleepiness judging device judges whether or not the subject feels sleepiness, using threshold values being set using time series data of time intervals between transitions between the opened state and closed state of the eyelid obtained before the predetermined period.

5 . The device of claim 1 , wherein the threshold value setter sets a plurality of threshold values having mutually different magnitudes, and the sleepiness judging device judges which stage a degree of the sleepiness of the subject falls into among two or more stages based on relationships in magnitude of the eyelid opening/closing characteristic amount to the respective plural threshold values.

6 . The device of claim 1 , wherein the sleepiness judging device judges that the subject feels sleepiness when a time length in which the eyelid opening/closing characteristic amount has deviated from the range defined with the threshold values exceeds beyond a predetermined length or when a number of times that the eyelid opening/closing characteristic amount deviates from the range defined with the threshold values exceeds beyond a predetermined number of times.

7 . The device of claim 1 , wherein the threshold value setter sets an upper threshold value and a lower threshold value lower than the upper threshold value, and the sleepiness judging device judges that the subject feels sleepiness when the eyelid opening/closing characteristic amount deviates from the range between the upper threshold value and the lower threshold value.

8 . The device of claim 1 , wherein the time interval between transitions between the opened state and the closed state of the eyelid is either of a time interval from a transition from the closed state to the opened state of the eyelid to a transition from the opened state to the closed state, a time interval from a transition from the opened state to the closed state to a next transition from the opened state to the closed state and a time interval from a transition from the closed state to the opened state to a next transition from the closed state to the opened state

9 . The device of claim 1 , wherein the eyelid opening/closing characteristic amount is an index value representing a statistical change of the time intervals between the transitions between the opened state and the closed state of the eyelid.

10 . The device of claim 9 , wherein the eyelid opening/closing characteristic amount is a standard deviation of the time intervals between transitions between the opened state and a closed state of the eyelid.

11 . The device of claim 1 , wherein the threshold values are values obtained by multiplying a positive number smaller than one and a positive number larger than one to an average value of the eyelid opening/closing characteristic amounts obtained in the predetermined period, respectively.

12 . The device of claim 1 , wherein the eyelid state detector judges the opened/closed state of the eyelid based on a camera image of the eyelid or an ocular potential signal of the subject.

Assignees

• Toyota Motor Co Ltd

Inventors

• Hatakeyama Yoshiyuki

Classifications

• B60W2040/0827

  due to sleepiness · CPC title

• A61B5/18

  for vehicle drivers {or machine operators} · CPC title

• A61B5/4809

  Sleep detection, i.e. determining whether a subject is asleep or not · CPC title

• A61B5/1103

  Detecting muscular movement of the eye, e.g. eyelid movement · CPC title

• A61B3/14

  Arrangements specially adapted for eye photography · CPC title