Method for detecting fault of vehicle motion sensors

• US 6,202,009 B1
• Filed: 12/22/1998
• Issued: 03/13/2001
• Est. Priority Date: 12/22/1998
• Status: Expired due to Term

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Tseng, Hongtei Eric
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Beaulieu, Yonel
• Application Number:
  US09/218,285
• Time in Patent Office: 812 Days
• Field of Search: 701/34, 701/35, 701/124, 701/80, 701/82, 701/72, 701/73, 701/63, 180/197, 180/199, 303/122, 303/122.05
• US Class Current: 701/34
• CPC Class Codes: B60T 2210/22 Banked curves
• CPC Class Codes: B60T 8/171 Detecting parameters used in the regulation; Measuring values used in the regulation
• CPC Class Codes: B60T 8/885 using electrical circuitry

Abstract

A method for detecting fault in vehicle motion sensors for a motor vehicle includes providing a measured lateral acceleration signal and yaw rate signal. The method further includes calculating, respectively, a first and second road bank angle estimate based on these signals. Also included is determining a first and second maximum road bank angle based on the first and second road bank angle, respectively, and calculating a first and second threshold based on these values. The method further includes comparing whether the first and second road bank angles exceeds the second and first thresholds, respectively, and if so, indicating either one or both a lateral acceleration signal fault or yaw rate signal fault.

Claims

1. A method for detecting a signal fault in a motion sensor for a motor vehicle, the method comprising:

providing a lateral acceleration signal for the motor vehicle;

determining a first estimated value for road bank angle based on the lateral acceleration signal and at least one additional non-yaw rate vehicle motion signal;

providing a yaw rate signal for the motor vehicle;

determining a second estimated value for road bank angle based on the yaw rate signal and at least one additional non-lateral acceleration vehicle motion signal;

determining a first maximum estimated value based on the first estimated value;

determining a second maximum estimated value based on the second estimated value;

calculating a first threshold based on the first maximum estimated value;

calculating a second threshold based on the second maximum estimated value;

comparing whether the first estimated value exceeds the second threshold, and if so, indicating a lateral acceleration signal fault; and

comparing whether the second estimated value exceeds the first threshold, and if so, indicating a yaw rate signal fault.

2. The method of claim 1 wherein:

determining the maximum first estimated value includes calculating a rolling maximum first estimated value which is continuously updated in a predetermined time period; and

determining the maximum second estimated value includes calculating a rolling maximum second estimated value which is continuously updated in a predetermined time period.

3. The method of claim 1 further comprising:

providing a steering wheel angle signal; and

calculating the first and second estimated values using the steering wheel angle signal.

4. The method of claim 1 further comprising:

determining whether the vehicle is stable by a function characterized as a product of (a) the difference between a front slip angle and a rear slip angle and (b) its time rate of change, wherein the vehicle is determined to be stable when the product is less than a calibrated threshold.

5. The method of claim 1 wherein:

comparing whether the first estimated value exceeds the second threshold includes generating a first counter increment when the first estimated value exceeds the second threshold, and indicating a lateral acceleration signal fault when the first counter exceeds a predetermined first counter threshold; and

wherein, comparing whether the second estimated value exceeds the first threshold includes generating a second counter increment when the second estimated value exceeds the first threshold, and indicating a yaw rate signal fault when the second counter exceeds a predetermined second counter threshold.

6. The method of claim 1 wherein the measured lateral acceleration signal is provided by a lateral acceleration sensor, and wherein the measured yaw rate signal is provided by a yaw rate sensor.

7. A method for fault based detection of vehicle motion sensors for a motor vehicle comprising:

determining a first signal corresponding to a lateral acceleration signal;

determining an estimated first road bank value in accordance with said first signal;

determining a second signal corresponding to a yaw rate signal;

determining an estimated second road bank value in accordance with said second signal;

storing a maximum first road bank value determined from said estimated first road bank value;

storing a maximum second road bank value determined from said estimated second road bank value;

calculating a first threshold using the maximum first road bank value, the first threshold for performing a check of the second signal;

calculating a second threshold using the maximum second road bank value, the second threshold for performing a check of the lateral first signal;

determining whether the estimated first road bank value is greater than the second threshold, and if so, increasing a first counter thereby increasing the possibility of a lateral acceleration signal fault;

determining whether the estimated second road bank value is greater than the first threshold, and if so, increasing a second counter thereby increasing the possibility of a yaw rate signal fault;

indicating the lateral acceleration signal fault if said first counter is greater than a predetermined first counter threshold; and

indicating the yaw rate signal fault if said second counter is greater than a predetermined second counter threshold.

8. The method of claim 7 further comprising:

determining whether a vehicle is stable by a function characterized as a product of (a) the difference between a front slip angle and a rear slip angle and (b) its time rate of change, wherein the vehicle is determined to be stable if the product is less than a calibrated threshold.

9. The method of claim 7 wherein storing the maximum first estimated road bank value includes calculating a rolling maximum second road bank value which is continuously verified and updated in a predetermined time period;

and

storing the maximum second estimated road bank value includes calculating a rolling maximum second road bank value which is continuously verified and updated in a predetermined time period.

10. The method of claim 7 wherein the lateral acceleration signal is provided by a lateral acceleration sensor, and wherein the yaw rate signal is provided by a yaw rate sensor.

11. A method for fault based detection of vehicle motion sensors for a motor vehicle comprising:

generating a first signal corresponding to a lateral acceleration signal of the motor vehicle;

calculating a first estimated value dependent on the first signal, the first estimated value corresponding to an estimated first road bank angle;

generating a second signal corresponding to a yaw rate signal of the motor vehicle;

calculating a second estimated value dependent on the second signal, the second estimated value corresponding to an estimated second road bank angle;

storing a first rolling maximum estimated value of the calculated first estimated value which is updated in a first predetermined time interval;

storing a second rolling maximum estimated value of the calculated second estimated value which is updated in a second predetermined time interval;

calculating a first threshold using the first rolling maximum, the first threshold for detecting fault in the yaw rate signal;

calculating a second threshold using the second rolling maximum, the second threshold for detecting fault in the lateral acceleration signal;

determining whether the first estimated value is greater than the second threshold, and if so, generating an incremental signal to a first counter thereby increasing the possibility of a lateral acceleration signal fault;

determining whether a vehicle is stable by a function characterized as a product of (a) the difference between a front slip angle and a rear slip angle and (b) its time rate of change, wherein the vehicle is determined to be stable when the product is less than a calibrated stability threshold;

indicating the lateral acceleration signal fault if said first counter has a value which is greater than a predetermined first counter threshold and if the vehicle is determined to be stable;

determining whether the second estimated value is greater than the first threshold, and if so, generating an increment to a second counter thereby increasing the possibility of a yaw rate signal fault; and

indicating the yaw rate signal fault if said second counter has a value greater than a predetermined second counter threshold.

12. The method of claim 11 wherein the lateral acceleration signal is provided by a lateral acceleration sensor, and wherein the yaw rate signal is provided by a yaw rate sensor.