SLEEPINESS ASSESSMENT APPARATUS

• US 20120078122A1
• Filed: 05/26/2010
• Published: 03/29/2012
• Est. Priority Date: 06/08/2009
• Status: Active Grant

• Current Assignee: Public University Corporation Nagoya City University
• Original Assignee: Public University Corporation Nagoya City University
• Inventors: Yokoyama, Kiyoko, Takahashi, Issei, Ohashi, Hayato, Tabata, Genki
• Granted Patent: US 8,979,761 B2
• Time in Patent Office: Days
• US Class Current: 600/484
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/18 for vehicle drivers or machine operators
• CPC Class Codes: A61B 5/6887 mounted on external non-worn devices, e.g. non-medical devices
• CPC Class Codes: B60K 28/02 responsive to conditions relating to the driver
• CPC Class Codes: B60K 28/066 actuating a signalling device B60K28/063 takes precedence
• CPC Class Codes: B60W 2040/0827 due to sleepiness
• CPC Class Codes: B60W 2540/22 Psychological state; Stress level or workload
• CPC Class Codes: B60Y 2400/902 giving haptic or tactile signals

Abstract

A sleepiness assessment value P1 is set to be an average heart rate HR (S130). A sleepiness assessment value P2 is set to be a standard deviation σ of a respiration interval RespI for one minute (S150). A sleepiness assessment value P3 is set to be a value that is obtained by dividing, by one minute, an integrated value of a square of an average heartbeat interval RRIavg in a case where a variation in which a heartbeat interval RRI increases occurs (in a case where an RRI count value Xi is a value of one) (S190). A sleepiness assessment value P4 is set to a value that is obtained by averaging a variation ratio in a case where a variation in which the respiration interval RespI increases occurs (in a case where an RRI count value Yi is a value of one) (S210). A sleepiness assessment value P is set to be a value obtained by summing values that are obtained by multiplying the individual sleepiness assessment values P1 to P4 by weight coefficients a to d, each of which is set for a corresponding one of the sleepiness assessment values P1 to P4 (S220). When the sleepiness assessment value P is smaller than a value of zero, it is determined that a person is highly alert (S240), and, when the sleepiness assessment value P is equal to or larger than the value of zero, it is determined that the person is less alert (S250).

Claims

1. A sleepiness assessment apparatus for determining whether or not a subject is sleepy, the sleepiness assessment apparatus comprising:

a respiration-interval acquisition unit for acquiring a respiration interval of the subject; and

a sleepiness assessment unit for determining, in a case where a variation in which the acquired respiration interval increases occurs, by using a degree of the variation as a sleepiness assessment parameter, whether or not the subject is sleepy.

2. The sleepiness assessment apparatus according to claim 1,

wherein the sleepiness assessment parameter is a parameter that is, in the case where a variation in which the acquired respiration interval increases occurs, obtained on the basis of a ratio obtained by the variation.

3. The sleepiness assessment apparatus according to claim 1,

wherein the sleepiness assessment parameter is a parameter that is obtained on the basis of a standard deviation of the acquired respiration interval.

4. The sleepiness assessment apparatus according to claim 1,

wherein the sleepiness assessment parameter includes a plurality of sleepiness assessment parameters, and the sleepiness assessment unit determines, by using the plurality of sleepiness assessment parameters and weights, whether or not the subject is sleepy, each of the weights being set for a corresponding one of the plurality of sleepiness assessment parameters.

5. The sleepiness assessment apparatus according to claim 1, further comprising

a heartbeat-interval acquisition unit for acquiring a heartbeat interval of the subject,

wherein the sleepiness assessment unit calculates an average value of the acquired heartbeat interval, and determines, in a case where a variation in which the acquired heartbeat interval decreases occurs, by using a frequency of the variation and the calculated average value of the heartbeat interval as the sleepiness assessment parameter, whether or not the subject is sleepy.

6. The sleepiness assessment apparatus according to claim 5,

wherein the sleepiness assessment parameter is a parameter that is, every time a variation in which the acquired heartbeat interval decreases occurs, obtained by multiplying the calculated average value of the heartbeat interval by a value which is obtained by dividing the acquired heartbeat interval by the number of heartbeats per unit time.

7. The sleepiness assessment apparatus according to claim 6,

wherein the sleepiness assessment parameter is a parameter that is, every time a variation in which the acquired heartbeat interval decreases occurs, obtained by integrating a square of the calculated average value of the heartbeat interval to obtain an integrated value, and by dividing the integrated value by a unit time.