Vehicle rollover detection method based on differential z-axis acceleration

• US 20060184300A1
• Filed: 02/11/2005
• Published: 08/17/2006
• Est. Priority Date: 02/11/2005
• Status: Abandoned Application

• Current Assignee: Charles A. Cluff, David B. Rich, Gregory J. Manlove, James H. Brogoitti, John William Robertson, Peter J. Schubert
• Original Assignee: Charles A. Cluff, David B. Rich, Gregory J. Manlove, James H. Brogoitti, John William Robertson, Peter J. Schubert
• Inventors: Robertson, John William, Brogoitti, James H., Cluff, Charles A., Schubert, Peter J., Rich, David B., Manlove, Gregory J.
• Application Number:
  US11/056,682
• Publication Number:
  US 20060184300A1
• Time in Patent Office: Days
• US Class Current: 701/45
• CPC Class Codes: B60R 16/0233 Vehicle tilting, overturning or roll over
• CPC Class Codes: B60R 2021/0018 Roll-over
• CPC Class Codes: B60R 2021/01322 comprising variable thresholds, e.g. depending from other collision parameters
• CPC Class Codes: B60R 2021/01325 Vertical acceleration
• CPC Class Codes: B60R 21/0133 by integrating the amplitude of the input signal
• CPC Class Codes: B60R 21/01336 using filtering
• CPC Class Codes: B60R 21/0134 responsive to imminent contact with an obstacle , e.g. using radar systems

Abstract

Impending rollover events are detected based on differential z-axis (i.e., vertical) acceleration. Vertical or z-axis acceleration measured at laterally opposite sides of the vehicle are filtered and differenced, and the differential acceleration is processed and compared to a calibrated threshold to detect impending rollover. Separate algorithms are employed to detect different categories of rollover events, and a sum of the z-axis acceleration measurements is used as a safing signal.

Claims

1. A method of detecting an impending rollover event of a vehicle, comprising the steps of:

measuring a first z-axis acceleration at a first location of said vehicle and a second z-axis acceleration at a second location of said vehicle that is laterally displaced from said first location;

determining a difference between said first z-axis acceleration and said second z-axis acceleration; and

detecting an impending rollover event of said vehicle based on said difference.

2. The method of claim 1, including the step of:

high pass filtering the measured first and second z-axis accelerations before determining said difference.

3. The method of claim 1, where the step of detecting an impending rollover event includes the steps of:

low pass filtering the measured first and second z-axis accelerations to attenuate acceleration components above a specified frequency before determining said difference.

4. The method of claim 3, wherein said specified frequency is in a range of approximately 10 Hz to 20 Hz to identify an acceleration difference characteristic of a rollover event triggered by a ditch drift condition.

5. The method of claim 3, wherein said specified frequency is in a range of approximately 50 Hz to 100 Hz to identify an acceleration difference characteristic of a rollover event triggered by a free rotation condition.

6. The method of claim 1, wherein the step of determining a difference between said first z-axis acceleration and said second z-axis acceleration includes the steps of:

buffering samples of said first z-axis acceleration and samples of said second z-axis acceleration; and

determining a correlation between the buffered samples of said first z-axis acceleration and the buffered samples of said second z-axis acceleration.

7. The method of claim 6, wherein the step of detecting an impending rollover event includes the step of:

comparing said correlation to a calibrated threshold.

8. The method of claim 1, wherein the step of detecting an impending rollover event includes the steps of:

integrating said difference to determine a roll rate of said vehicle; and

detecting an impending rollover event when the determined roll rate exceeds a calibrated threshold.

9. The method of claim 8, including the step of:

high pass filtering at least one of said difference and said determined roll rate to remove bias errors due to non-roll related excursions of said difference.

10. The method of claim 1, wherein the step of detecting an impending rollover event includes the step of:

computing a moving average of said difference over a predefined time interval; and

detecting an impending rollover event if said moving average exceeds a calibrated threshold.

11. The method of claim 1, including the steps of:

determining a sum of said first z-axis acceleration and said second z-axis acceleration; and

detecting an impending rollover event of said vehicle based on said difference only if said sum also exceeds a calibrated threshold for at least a predetermined period of time.

12. The method of claim 1, including the steps of:

twice integrating said difference to determine a roll angle of said vehicle; and

detecting an impending rollover event when the determined roll angle exceeds a calibrated threshold.

13. The method of claim 1, including the steps of:

twice integrating said difference to determine a roll angle of said vehicle; and

inhibiting the step of detecting an impending rollover event when the determined roll angle is characteristic of a fall-back event following a near rollover of said vehicle.

14. The method of claim 1, including the steps of:

carrying out a plurality of rollover detection algorithms that individually process said difference to recognize different types of impending rollover events; and

detecting an impending rollover event when an impending rollover event is recognized by at least one of said rollover detection algorithms.

15. The method of claim 14, including the step of:

determining a sum of said first z-axis acceleration and said second z-axis acceleration; and

detecting an impending rollover event of said vehicle based on said difference only if said sum is characteristic of a rollover event.

16. The method of claim 14, wherein said different types of impending rollover events comprise rollover events triggered by different operating conditions of said vehicle.

17. The method of claim 16, wherein said different operating conditions comprise a ditch drift condition, a free rotation condition and a trip-over condition.

18. The method of claim 1, wherein said first and second locations are laterally disposed about a center of mass of said vehicle.

19. The method of claim 18, wherein said first and second locations are symmetrically disposed about said center of mass.