Driver's arousal level estimating apparatus for vehicle and method of estimating arousal level

• US 20020097160A1
• Filed: 11/20/2001
• Published: 07/25/2002
• Est. Priority Date: 11/24/2000
• Status: Active Grant

• Current Assignee: Subaru Corp.
• Original Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Inventors: Oyama, Hajime
• Granted Patent: US 6,686,845 B2
• Time in Patent Office: Days
• US Class Current: 340/576
• CPC Class Codes: A61B 5/18 for vehicle drivers or machine operators
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: B60K 28/066 actuating a signalling device B60K28/063 takes precedence
• CPC Class Codes: B60W 2520/125 Lateral acceleration
• CPC Class Codes: G08B 21/06 indicating a condition of sleep, e.g. anti-dozing alarms

Abstract

A driver'"'"'s arousal level estimating apparatus for a vehicle includes a FFT signal processing section for obtaining respective frequency component powers by applying a frequency conversion to displacement quantities successively detected of the vehicle, an evaluation value calculating section for calculating an evaluation value from a ratio of an average value of the respective calculated frequency powers and a maximum value of frequency component powers in a specified frequency domain containing a predetermined lateral fluctuation frequency characteristic of a lowered arousal level, and a judging section for judging a driver'"'"'s arousal level based on said evaluation value.

Claims

1. An arousal level estimating apparatus for estimating an arousal level of a driver of a vehicle comprising:

a power calculating means for calculating a frequency component power by applying a frequency conversion method to a lateral displacement quantity detected successively;

a first evaluation value calculating means for calculating a first evaluation value based on a sum of said frequency component power calculated by said power calculating means;

a second evaluation value calculating means for calculating a maximum value of frequency component power in a specified frequency domain including a fluctuation frequency as a second evaluation value;

an evaluation value calculating means for calculating an evaluation value from a ratio of said first evaluation value and said second evaluation value; and

a judging means for judging a driver'"'"'s arousal level based on said evaluation value.

2. The apparatus according to claim 1, wherein

said frequency component powers are subjected to a leveling process.

3. The apparatus according to claim 2, wherein

said leveled frequency component power is obtained by multiplying said frequency component power by a frequency raised to n power.

4. The apparatus according to claim 3, wherein

said exponent n is a value not more than 3 and not less than 2.

5. The apparatus according to claim 1, wherein

said first evaluation value is obtained based on said frequency component powers excluding a maximum one from said respective frequency component powers calculated by said power calculating means.

6. The apparatus according to claim 1, wherein

said evaluation calculating means calculates said evaluation value in time sequence and said judging means increases or decreases a counter value according to said evaluation value and when said counter value reaches a judging value, judges that a warning should be raised to a driver of said vehicle.

7. The apparatus according to claim 6, wherein

said judging means changes said counter value according to said evaluation value.

8. An arousal level estimating method, comprising the steps of:

calculating a frequency component power by applying a frequency conversion method to a lateral displacement quantity detected successively;

calculating a first evaluation value based on a sum of said frequency component power calculated by said power calculating means;

calculating a maximum value of frequency component power in a specified frequency domain including a fluctuation frequency as a second evaluation value;

calculating an evaluation value from a ratio of said first evaluation value and said second evaluation value; and

judging a driver'"'"'s arousal level based on said evaluation value.

9. The method according to claim 8, wherein

Said step of calculating said first evaluation value is obtaining said first evaluation value based on said frequency component powers excluding a maximum one from said respective frequency component powers calculated by said step of calculating said frequency component power.

10. The method according to claim 8, wherein

said step of calculating said evaluation value is calculating said evaluation value in time sequence and said step of judging is increasing or decreasing a counter value according to said evaluation value and when said counter value reaches a judging value, is judging that a warning should be raised to a driver of said vehicle.