Doze detection method and apparatus thereof

• US 9,286,515 B2
• Filed: 09/04/2012
• Issued: 03/15/2016
• Est. Priority Date: 09/05/2011
• Status: Expired due to Fees

• Current Assignee: National University Corporation University of Toyama
• Original Assignee: TOYAMA PREFECTURE
• Inventors: Nakamura, Kiyomi, Takano, Hironobu
• Primary Examiner(s): Shah, Utpal
• Assistant Examiner(s): Zohrabyan, Narek
• Application Number:
  US14/342,720
• Publication Number:
  US 20140205149A1
• Time in Patent Office: 1,288 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: A61B 5/0077 Devices for viewing the surface of the body, e.g. camera, magnifying lens
• CPC Class Codes: A61B 5/1103 Detecting eye twinkling
• CPC Class Codes: A61B 5/163 by tracking eye movement, gaze, or pupil change
• CPC Class Codes: A61B 5/18 for vehicle drivers or machine operators
• CPC Class Codes: A61B 5/4809 Sleep detection, i.e. determining whether a subject is asleep or not
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: B60K 28/066 actuating a signalling device B60K28/063 takes precedence
• CPC Class Codes: G06V 40/19 Sensors therefor
• CPC Class Codes: G08B 21/06 indicating a condition of sleep, e.g. anti-dozing alarms

Abstract

A doze detection method, which accurately detects a blink burst and improves speed and accuracy of doze detection, includes measuring a state where the eye is substantially open as an open eye time and another state as a closed eye time, defining a time shorter than an average blink interval of a healthy adult in an alert state as a first threshold time; defining a time longer than an average closed eye time of a healthy adult in an alert state as a second threshold time; and defining blinks as a blink burst when detecting an eye opening equal to or shorter than the first threshold time. A doze state is determined when the closed eye time of a blink among the blinks during the blink burst reaches at least the second threshold time, the blink occurring after an open eye time equal to at most the first threshold time.

Claims

1. A doze detection method comprising:

measuring an open eye time and a closed eye time of a human eye, the open eye time being a state in which the eye is open among states between an eye closure to an eye opening thereof, and the closed eye time being a state other than the state in which the eye is open;

setting a first threshold time, the first threshold time being shorter than an average open eye time of a healthy adult in an alert state;

setting a second threshold time, the second threshold time being longer than an average closed eye time of a healthy adult in an alert state;

making a first doze state determination in which existence of a doze state is immediately determined when (i) the measured open eye time is determined to be equal to or shorter than the first threshold time and (ii) the measured closed eye time of a blink occurring immediately after the measured open eye time determined to be equal to or shorter than the first threshold time reaches the second threshold time or more;

setting a third threshold time, the third threshold time being a closed eye time that is longer than the second threshold time; and

making a second doze state determination to again determine the existence of the doze state when a closed eye time of a blink reaches the third threshold time or more, the blink occurring after an open eye time equal to or shorter than the first threshold time.

2. The doze detection method according to claim 1, further comprising immediately determining the existence of the doze state at an end of a measured open eye time equal to or shorter than the first threshold time, when a closed eye time of a blink occurring immediately before the open eye time equal to or shorter than the first threshold time is determined to be equal to or longer than the second threshold time.

3. A doze detection method comprising:

measuring an open eye time and a closed eye time of a human eye, the open eye time being a state in which the eye is open among states between an eye closure to an eye opening thereof, and the closed eye time being a state other than the state in which the eye is open;

setting a first threshold time, the first threshold time being shorter than an average open eye time of a healthy adult in an alert state;

setting a second threshold time, the second threshold time being longer than an average closed eye time of a healthy adult in an alert state;

making a first doze state determination in which existence of a doze state is immediately determined when (i) the measured open eye time is determined to be equal to or shorter than the first threshold time and (ii) the measured closed eye time of a blink occurring immediately after the measured open eye time determined to be equal to or shorter than the first threshold time reaches the second threshold time or more;

setting another threshold time, the another threshold time being a closed eye time that is longer than the second threshold time;

in measuring the open eye time, when detecting an eye opening being longer than the first threshold time and an open eye time immediately before occurrence of a blink immediately preceding the eye opening also being longer than the first threshold time, setting the immediately-preceding blink as an isolated blink; and

making another doze state determination to immediately determine the existence of the doze state by an end of the eye opening after the isolated blink when a closed eye time of the isolated blink is equal to or longer than the another threshold time.

4. A doze detection method comprising:

measuring an open eye time and a closed eye time of a human eye, the open eye time being a state in which the eye is open among states between an eye closure to an eye opening thereof, and the closed eye time being a state other than the state in which the eye is open;

setting a first threshold time, the first threshold time being shorter than an average open eye time of a healthy adult in an alert state;

setting a second threshold time, the second threshold time being longer than an average closed eye time of a healthy adult in an alert state;

making a first doze state determination in which existence of a doze state is immediately determined when (i) the measured open eye time is determined to be equal to or shorter than the first threshold time and (ii) the measured closed eye time of a blink occurring immediately after the measured open eye time determined to be equal to or shorter than the first threshold time reaches the second threshold time or more;

setting another threshold time, the another threshold time being a closed eye time that is longer than the second threshold time; and

making a another doze determination to immediately determine the existence of the doze state, when detecting an eye opening longer than the first threshold time in detecting the open eye time and when a closed eye time of a blink immediately after the eye opening reaches the another threshold time or more.

5. A doze detection apparatus comprising:

a memory; and

a processor configured to execute a program stored in the memory to perform functions comprising;

detecting states from an eye closure to an eye opening of a human eye by recognizing a position of the human eye;

measuring an open eye time and a closed eye time of the human eye, the open eye time being a state in which the eye is open, and the closed eye time being a state other than the state in which the eye is open;

setting (i) a first threshold time which is shorter than an average open eye time of a healthy adult in an alert state, and (ii) a second threshold time which is longer than an average closed eye time of a healthy adult in an alert state;

immediately determine existence of a doze state when (i) the measured open eye time is determined to be equal to or shorter than the first threshold time and (ii) the measured closed eye time of a blink occurring immediately after the measured open eye time determined to be equal to or shorter than the first threshold time reaches the second threshold time or more;

setting a third threshold time as a closed eye time that is longer than the second threshold time; and

determining the existence of the doze state when a closed eye time of a blink reaches the third threshold time or more, the blink occurring after an open eye time equal to or shorter than the first threshold time.

6. The doze detection apparatus according to claim 5, wherein the functions performed by the processor further comprise immediately determining the existence of the doze state at an end of the measured open eye time that is determined to be equal to or shorter than the first threshold time, when a closed eye time of a blink occurring immediately before the open eye time equal to or shorter than the first threshold time is determined to be equal to or longer than the second threshold time.

9. The doze detection apparatus according to claim 5, wherein the functions performed by the processor further comprise performing control to issue a doze alert when the existence of the doze state is determined.

10. A vehicle comprising the doze detection apparatus according to claim 5.

11. The doze detection apparatus according to claim 5, wherein detecting the states from the eye closure to the eye opening of the human eye includes measuring respective areas of the iris and pupil of the human eye.

7. A doze detection apparatus comprising:

a memory; and

a processor configured to execute a program stored in the memory to perform functions comprising;

detecting states from an eye closure to an eye opening of a human eye by recognizing a position of the human eye;

measuring an open eye time and a closed eye time of the human eye, the open eye time being a state in which the eye is open, and the closed eye time being a state other than the state in which the eye is open;

setting (i) a first threshold time which is shorter than an average open eye time of a healthy adult in an alert state, and (ii) a second threshold time which is longer than an average closed eye time of a healthy adult in an alert state;

immediately determine existence of a doze state when (i) the measured open eye time is determined to be equal to or shorter than the first threshold time and (ii) the measured closed eye time of a blink occurring immediately after the measured open eye time determined to be equal to or shorter than the first threshold time reaches the second threshold time or more;

setting another threshold time as a closed eye time that is longer than the second threshold time;

when an eye opening that is longer than the first threshold time is detected and an open eye time immediately before occurrence of a blink immediately preceding the eye opening that is also longer than the first threshold time, setting the immediately-preceding blink as an isolated blink; and

immediately determining the existence of the doze state by an end of the eye opening after the isolated blink when a closed eye time of the isolated blink is equal to or longer than the another threshold time.

8. A doze detection apparatus comprising:

a memory; and

a processor configured to execute a program stored in the memory to perform functions comprising;

detecting states from an eye closure to an eye opening of a human eye by recognizing a position of the human eye;

measuring an open eye time and a closed eye time of the human eye, the open eye time being a state in which the eye is open, and the closed eye time being a state other than the state in which the eye is open;

setting (i) a first threshold time which is shorter than an average open eye time of a healthy adult in an alert state, and (ii) a second threshold time which is longer than an average closed eye time of a healthy adult in an alert state;

immediately determine existence of a doze state when (i) the measured open eye time is determined to be equal to or shorter than the first threshold time and (ii) the measured closed eye time of a blink occurring immediately after the measured open eye time determined to be equal to or shorter than the first threshold time reaches the second threshold time or more;

setting another threshold time as a closed eye time that is longer than the second threshold time; and

immediately determining the existence of the doze state, when an eye opening longer than the first threshold time is measured and when a closed eye time of a blink immediately after the eye opening reaches the another threshold time or more.