Wakefulness maintaining apparatus and method of maintaining wakefulness

• US 20080180257A1
• Filed: 11/30/2007
• Published: 07/31/2008
• Est. Priority Date: 01/29/2007
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Omi, Takuhiro, Nagai, Fumiya
• Granted Patent: US 7,982,618 B2
• Time in Patent Office: Days
• US Class Current: 340/575
• CPC Class Codes: B60K 28/06 responsive to incapacity of 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 2050/143 Alarm means
• CPC Class Codes: B60W 2420/403 Image sensing, e.g. optical camera
• CPC Class Codes: B60W 50/14 Means for informing the driver, warning the driver or prompting a driver intervention
• CPC Class Codes: B60W 50/16 Tactile feedback to the driver, e.g. vibration or force feedback to the driver on the steering wheel or the accelerator pedal
• CPC Class Codes: G08B 21/06 indicating a condition of sleep, e.g. anti-dozing alarms

Abstract

A wakefulness maintaining apparatus includes an event detecting part, a drowsiness level determining part, a threshold setting part, and a stimulus supplying part. The event detecting part detects an event related to a drowsiness of a person. The drowsiness level determining part determines a drowsiness level that changes in accordance with a strength of the drowsiness. The threshold setting part sets a threshold value to divide the drowsiness level into a first level range and a second level range in such a manner that the first level range is equal to or lower than the threshold value and the second level range is higher than the threshold value. The stimulus supplying part supplies a stimulus having an awaking effect to the person when the drowsiness level is in the second level range and the event is detected.

Claims

1. A wakefulness maintaining apparatus, comprising:

an event detecting part for detecting an event related to a drowsiness of a person, wherein the event includes at least one of an action, an appearance, and a biologic signal of the person, and a movement of a vehicle driven by the person;

a drowsiness level determining part for determining a drowsiness level of a person that changes in accordance with a strength of a drowsiness;

a threshold setting part for setting a first threshold value to divide the drowsiness level into a first level range and a second level range, wherein the first level range is equal to or lower than the first threshold value and the second level range is higher than the first threshold value;

a level range determining part for determining the level range of the drowsiness level determined by the drowsiness level determining part;

an event determining part for determining whether the event detecting part detects the event; and

a stimulus supplying part for supplying a stimulus having an awaking effect to the person when the level range determining part determines that the drowsiness level is in the second level range and the event determining part determines that the event detecting part detects the event.

2. The wakefulness maintaining apparatus according to claim 1, wherein:

the stimulus supplying part supplies no stimulus to the person when the level range determining part determines that the drowsiness level is in the first level range, even when the event detecting part detects the event.

3. The wakefulness maintaining apparatus according to claim 1, wherein:

the threshold setting part further sets a second threshold value that is higher than the first threshold value, for defining a third level range;

wherein;

the second level range is equal to or lower than the second threshold value and the third level range is higher than the second threshold value; and

the stimulus supplying part supplies the stimulus to the person when the level range determining part determines that the drowsiness level is in the third level range, even when the event detecting part detects no event.

4. The wakefulness maintaining apparatus according to claim 3, wherein:

the stimulus supplying part supplies no stimulus for a predetermined time since a last stimulus is supplied to the person when the level range determining part determines that the drowsiness level is in one of the second level range and the third level range.

5. The wakefulness maintaining apparatus according to claim 4, wherein:

the predetermined period is set to an increasing trend period when the drowsiness level is on an increasing trend; and

the predetermined period is set to a decreasing trend period that is longer than the increasing trend period when the drowsiness level is on a decreasing trend.

6. The wakefulness maintaining apparatus according to claim 5, further comprising:

a decreasing rate determining part for determining a decreasing rate of the drowsiness level; and

a period controlling part for controlling a length of the decreasing trend period in accordance with the decreasing rate.

7. The wakefulness maintaining apparatus according to claim 6, further comprising:

a memory part for storing an event related to a habit of the person that includes at least one of an action and appearance of the person; and

a habit determining part for determining whether the event detected by the event detecting part corresponds to the event stored in the memory part, wherein;

the stimulus supplying part supplies no stimulus to the person when the habit determining part determines that the event detected by the event detecting part corresponds to the event stored in the memory part, even when the level range determining part determines that the drowsiness level is in the second level range.

8. The wakefulness maintaining apparatus according to claim 1, wherein:

the stimulus supplying part provides information on the drowsiness level of the person to an outside of the vehicle when the stimulus supplying part supplies the stimulus to the person.

9. A wakefulness maintaining apparatus, comprising:

a drowsiness level determining part for determining a drowsiness level of a person that changes in accordance with a strength of the drowsiness; and

a stimulus supplying part for supplying a stimulus having an awaking effect to the person when the drowsiness level is higher than a predetermined value, wherein;

the stimulus supplying part supplies no stimulus for a predetermined period since a last stimulus is supplied;

the predetermined period is set to an increasing trend period when the drowsiness level is on an increasing trend and is set to a decreasing trend period when the drowsiness level is on a decreasing trend; and

the increasing trend period is shorter than the decreasing trend period.

10. The wakefulness maintaining apparatus according to claim 9, further comprising:

a decreasing rate determining part for determining a decreasing rate of the drowsiness level; and

a period controlling part for controlling a length of the decreasing trend period to be longer as the decreasing rate increases.

11. A method of maintaining a wakefulness of a person, comprising:

detecting an event related to a drowsiness, wherein the event includes at least one of an action, an appearance, and a biologic signal of the person, and a movement of a vehicle driven by the person;

determining a drowsiness level that changes in accordance with a strength of the drowsiness;

setting a first threshold value to divide the drowsiness level into a first level range and a second level range, wherein the first level range is equal to or lower than the first threshold value and the second level range is higher than the first threshold value;

determining a level range of the drowsiness level; and

generating a stimulus having an awaking effect when the drowsiness level is in the second level range and the event is detected.

12. The method of according to claim 11, wherein:

no stimulus is generated when the drowsiness level is in the first level range, even when the event is detected.

13. The method of according to claim 11, further comprising:

setting a second threshold value that is higher than the first threshold value, for defining a third level range, wherein the second level range is equal to or lower than the second threshold value and the third level range is higher than the second threshold value; and

generating the stimulus when the drowsiness level is in the third level range, even when no event is detected.

14. The method of according to claim 13, wherein:

the generating the stimulus is restricted for a predetermined time since a last stimulus is generated when the drowsiness level is in one of the second level range and the third level range.

15. The method according to claim 14, further comprising:

determining a trend of the drowsiness level;

setting the predetermined period to an increasing trend period when the drowsiness level is on an increasing trend; and

setting the predetermined period to a decreasing trend period that is longer than the increasing trend period when the drowsiness level is on a decreasing trend.

16. The method according to claim 15, further comprising:

determining a decreasing rate of the drowsiness level; and

controlling a length of the decreasing trend period to be longer as the decreasing rate increases.

17. The method according to claim 11, further comprising:

storing an event related to a habit of the person that includes at least one of an action and an appearance of the person; and

determining whether the detected event related to the drowsiness corresponds to the event related to the habit, wherein;

the supplying the stimulus is restricted when the detected event corresponds to the event related to the habit, even when the drowsiness level is in the second level range.

18. The method according to claim 11, further comprising:

outputting information on the drowsiness level of the person to an outside of the vehicle.