Drowsy driver detection system

• US 5,900,819 A
• Filed: 04/21/1998
• Issued: 05/04/1999
• Est. Priority Date: 04/21/1998
• Status: Expired due to Fees

• Current Assignee: Meritor Heavy Vehicle Systems, LLC (Meritor, Inc. (Nevada))
• Original Assignee: Meritor Heavy Vehicle Systems, LLC (Meritor, Inc. (Nevada))
• Inventors: Kyrtsos, Christos T.
• Primary Examiner(s): MULLEN, THOMAS J
• Application Number:
  US09/063,574
• Time in Patent Office: 378 Days
• Field of Search: 340/576, 340/575, 340/669, 340/439, 701/70, 180/272, 180/282, 73/514.01, 280/5.508
• US Class Current: 340/576
• CPC Class Codes: B60G 2600/04 Means for informing, instructing or displaying
• CPC Class Codes: B60G 2800/012 Rolling condition
• CPC Class Codes: B60G 2800/24 Steering, cornering
• CPC Class Codes: B60G 2800/70 Estimating or calculating vehicle parameters or state variables
• CPC Class Codes: B60G 2800/704 predicting unorthodox driving conditions for safe or optimal driving
• CPC Class Codes: B60G 2800/9124 Roll-over protection systems, e.g. for warning or control
• CPC Class Codes: G08B 21/06 indicating a condition of sleep, e.g. anti-dozing alarms

Abstract

A system for detecting a drowsy driver includes an axle with a sensor for measuring the movement of the axle and for producing an axle signal. The sensor typically measures any or all of the following: the lateral acceleration of the axle, the fore-aft acceleration of the axle, or the vehicle speed. A central processing unit compares the axle signal derived from the sensor measurements to a pre-determined drowsy threshold and an indicator indicates to the driver that drowsiness has been detected when the axle signal exceeds the pre-determined drowsy threshold.

Claims

1. A method for detecting a drowsy driver of a vehicle comprising the steps of:

1) providing at least one axle having a sensor;

2) measuring movement of the axle with the sensor;

3) producing an axle signal in response to measuring the movement of the axle;

4) comparing the axle signal to a pre-determined drowsy threshold; and

5) indicating to the driver that drowsiness has been detected if the axle signal exceeds the pre-determined drowsy threshold.

2. A method as recited in claim 1 further including the steps of:

providing an accelerometer as the sensor;

producing an acceleration signal in response to measuring the acceleration of the axle; and

deriving the axle signal from the acceleration signal.

3. A method as recited in claim 2 further including the steps of

measuring the lateral acceleration of the axle to produce a lateral acceleration signal,

comparing the lateral acceleration signal to a pre-determined lateral acceleration threshold, and

producing the acceleration signal if the lateral acceleration signal exceeds the lateral acceleration threshold.

4. A method as recited in claim 3 further including the steps of

measuring a plurality of lateral accelerations of the axle over a pre-determined lateral acceleration time interval,

determining a lateral acceleration time density by counting the number of times the measured lateral accelerations exceed the pre-determined lateral acceleration threshold during the pre-determined lateral acceleration time interval, and

producing the lateral acceleration signal if the lateral acceleration time density exceeds a lateral time density threshold.

5. A method as recited in claim 3 further including the steps of

measuring the fore-aft acceleration of the axle to produce a fore-aft acceleration signal,

comparing the fore-aft acceleration signal to a pre-determined fore-aft acceleration threshold, and

producing the acceleration signal if the lateral acceleration signal exceeds the lateral acceleration threshold or the fore-aft acceleration signal exceeds the fore-aft acceleration signal.

6. A method as recited in claim 5 further including the steps of

measuring a plurality of fore-aft accelerations of the axle over a pre-determined fore-aft acceleration time interval,

determining a fore-aft acceleration time density by counting the number of times the measured fore-aft accelerations exceed the pre-determined fore-aft acceleration threshold during the pre-determined fore-aft acceleration time interval, and

producing the fore-aft acceleration signal if the fore-aft acceleration time density exceeds a fore-aft time density threshold.

7. A method as recited in claim 5 further including the steps of

producing a speed signal based on vehicle speed,

comparing the speed signal to a pre-determined speed threshold, and

producing the acceleration signal if the lateral acceleration signal exceeds the lateral acceleration threshold, the fore-aft acceleration signal exceeds the fore-aft acceleration signal, or the speed signal exceeds the speed threshold.

8. A method as recited in claim 7 further including the steps of

measuring a plurality of vehicle speeds over a pre-determined speed time interval,

determining a standard deviation of the vehicle speed for the pre-determined speed time interval, and

producing the speed signal if the standard deviation of the vehicle speed exceeds a speed standard deviation threshold.

9. A method as recited in claim 7 further including the step of producing a drowsy count by incrementing a drowsy counter each time the lateral acceleration signal exceeds the lateral acceleration threshold, the fore-aft acceleration signal exceeds the fore-aft acceleration signal, or the speed signal exceeds the speed threshold.

10. A method as recited in claim 9 further including the steps of incrementing a loop counter each time the lateral acceleration, fore-aft acceleration, and vehicle speed is measured to produce a loop count, comparing the loop count to a pre-determined minimum requirement, and deriving the axle signal from the acceleration signal if the loop count exceeds or equals the pre-determined minimum requirement.

11. A method as recited in claim 10 further including the step of taking an additional set of measurements for the lateral acceleration, fore-aft acceleration, and vehicle speed each time the loop count is less than the pre-determined minimum requirement.

12. A method as recited in claim 10 further including the steps of producing the axle signal by determining a ratio of the drowsy count to the loop count, comparing the ratio to the pre-determined drowsy threshold, and indicating to the driver that drowsiness has been detected if the ratio exceeds the pre-determined drowsy threshold.

13. A method as recited in claim 1 further including the steps of:

measuring a plurality of vehicle speeds over a pre-determined speed time interval with the sensor,

determining a standard deviation of the vehicle speed for the predetermined speed time interval,

producing a speed signal if the standard deviation of the vehicle speed exceeds a speed standard deviation threshold; and

eriving the axle signal from the speed signal.

14. A method as recited in claim 13 further including the steps of

providing an accelerometer as the sensor,

producing a lateral acceleration signal in response to measuring the lateral acceleration of the axle;

comparing the lateral acceleration signal to a pre-determined lateral acceleration threshold; and

deriving the axle signal from the speed and lateral acceleration signals.

15. A method as recited in claim 14 further including the steps of

producing a fore-aft acceleration signal in response to measuring the fore-aft acceleration of the axle;

comparing the fore-aft acceleration signal to a pre-determined fore-aft acceleration threshold; and

deriving the axle signal from the speed, lateral acceleration, and fore-aft signals.

16. A method as recited in claim 15 further including the step of producing a drowsy count signal by incrementing a drowsy counter each time the speed signal exceeds the speed standard deviation threshold, the lateral acceleration signal exceeds the pre-determined lateral acceleration threshold, or the fore-aft acceleration signal exceeds the pre-determined fore-aft acceleration threshold.

17. A method as recited in claim 16 further including the steps of

producing a loop count signal by incrementing a loop counter each time the lateral acceleration, fore-aft acceleration, and vehicle speed is measured,

comparing the loop count signal to a pre-determined minimum requirement, and

comparing the axle signal to the pre-determined drowsy threshold if the loop count signal exceeds or equals the pre-determined minimum requirement.

18. A method as recited in claim 17 further including the steps of

producing the axle signal by determining a ratio of the drowsy count signal to the loop count signal,

comparing the axle signal to the pre-determined drowsy threshold, and

indicating to the driver that drowsiness has been detected if the axle signal exceeds the pre-determined drowsy threshold.

19. A system for detecting a drowsy driver of a vehicle comprising:

at least one axle;

at least one sensor for measuring the movement of said axle and producing an axle signal;

a processor for comparing said axle signal to a pre-determined drowsy threshold; and

an indicator for indicating to a driver that drowsiness has been detected when said axle signal exceeds said pre-determined drowsy threshold.

20. A system as recited in claim 19 wherein said sensor is an accelerometer for measuring the accelerations of said axle.

21. A system as recited in claim 19 wherein said axle includes an axle center, said sensor being supported on said axle adjacent said axle center.

22. A system as recited in claim 19 wherein said axle is a steering axle.

23. A system as recited in claim 19 wherein at least one axle is comprised of a plurality of axles, each supporting a sensor for measuring the movement of said respective axle and producing a respective axle signal.

24. A system as recited in claim 19 wherein said indicator is a visual display.

25. A system as recited in claim 24 wherein said indicator additionally includes an audio component.