Wakefulness estimating apparatus and method

• US 20050065663A1
• Filed: 08/24/2004
• Published: 03/24/2005
• Est. Priority Date: 08/26/2003
• Status: Active Grant

• Current Assignee: Subaru Corp.
• Original Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Inventors: Oyama, Hajime
• Granted Patent: US 7,084,773 B2
• Time in Patent Office: Days
• US Class Current: 701/1
• CPC Class Codes: A61B 5/18 for vehicle drivers or machine operators
• CPC Class Codes: G08B 21/06 indicating a condition of sleep, e.g. anti-dozing alarms

Abstract

When a steering angle dakaku is equal to or smaller than ±15° (S22), the steering angle dakaku is integrated to calculate an integrated value dakaku_sum (S24). When the integrated value dakaku_sum is within a set range (S25, S26), a road-shape-based wakefulness correction coefficient R_hosei is set at 0.5 (S28). Any erroneous determination of wakefulness attributable to a road shape is prevented by correcting wakefulness H for evaluating wakefulness by decreasing it using the road-shape-based wakefulness correction coefficient R_hosei.

Claims

1. An apparatus for estimating wakefulness of a driver comprising:

a frequency analyzing process unit, for calculating an average value of a quantities of the frequency power components as a quantity of high frequency components, wherein the quantities of the frequency power components are calculated by performing frequency transformation of displacements of a vehicle in the width direction detected as a time series, and for calculating a maximum value of the quantities of frequency power components within a predetermined frequency range as a quantity of low frequency components, wherein the predetermined frequency range includes a stagger frequency exposed when the driver is at a low level of wakefulness;

an estimated wakefulness value calculation unit for calculating an estimated value of wakefulness from the ratio of the quantity of the high frequency components to the quantity of the low frequency components; and

a road-shape-based wakefulness value correction unit for correcting the estimated value of wakefulness according to a road condition,

wherein the road-shape-based wakefulness value correction unit includes;

a steering angle integration unit, for determining a magnitudes of steering angles based on steering angles detected by a steering angle sensor, and for integrating steering angles determined to be small angle; and

a steering angle determination unit for determining whether the integrated value of the steering angles is within a set range of steering angles, and

wherein the estimated value of wakefulness is corrected when the integrated value of the steering angles is within the set range of steering angles.

2. The apparatus for estimating wakefulness of a driver according to claim 1, wherein the road-shape-based wakefulness value correction unit corrects the estimated value of wakefulness by decreasing it by 50%.

3. The apparatus for estimating wakefulness of a driver according to claim 1, further comprising:

a lane recognition unit for recognizing left and right lane markings located ahead the vehicle in the traveling direction; and

a lane recognition result correction unit for detecting the displacements of the vehicle in the width direction based on a recognized lane width obtained from the difference between the positions of the left and right lane markings recognized by the lane recognition unit.

4. The apparatus for estimating wakefulness of a driver according to claim 1, further comprising a personal difference correction unit for correcting the estimated value of wakefulness according to a personal difference between the drivers.

5. A method of estimating wakefulness of a driver comprising:

a first step for calculating quantities of frequency power components by performing frequency transformation of displacements of a vehicle in the width direction detected as a time series;

a second step for calculating an average value of the quantities of the frequency power components calculated by a signal processing unit as a quantity of high frequency components;

a third step for calculating a maximum value of the quantities of frequency power components within a predetermined frequency range including a stagger frequency exposed when the driver is at a low level of wakefulness, the maximum value being calculated as the quantity of low frequency components;

a fourth step for calculating an estimated value of wakefulness from the ratio of the quantity of the high frequency components to the quantity of the low frequency components;

a fifth step for determining the magnitudes of steering angles based on steering angles detected by steering angle sensor and integrating steering angles determined to be small angles;

a sixth step for determining whether the integrated value of the steering angles is within a set range of steering angles; and

a seventh step for correcting the quantity of the low frequency components when the integrated value of steering angles is within the set range of steering angles by decreasing the quantity of the low frequency components.

6. The method of estimating wakefulness of a driver according to claim 5, wherein, at the seventh step, the quantity of the low frequency components is corrected by decreasing it by 50%.