System and method for fuzzy-logic based fault diagnosis

• US 20070078576A1
• Filed: 10/04/2005
• Published: 04/05/2007
• Est. Priority Date: 10/04/2005
• Status: Abandoned Application

• Current Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: Salman, Mutasim, Quet, Pierre-Francois
• Application Number:
  US11/243,058
• Publication Number:
  US 20070078576A1
• Time in Patent Office: Days
• US Class Current: 701/29
• CPC Class Codes: G07C 5/0808 Diagnosing performance data testing of vehicles G01M17/00; testing of electrical installation on vehicles G01R31/005
• CPC Class Codes: G07C 5/085 using electronic data carriers

Abstract

A system and method for monitoring the state of health of sensors, actuators and sub-systems in an integrated vehicle control system. The method includes identifying a plurality of potential faults, identifying a plurality of measured values, and identifying a plurality of estimated values based on models in the control system. The method further includes identifying a plurality of residual error values as the difference between the estimated values and the measured values. The method also defines a plurality of fuzzy logic membership functions for each residual error value. A degree of membership value is determined for each residual error value based on the membership functions. The degree of membership values are then analyzed to determine whether a potential fault exists.

Claims

1. A method for detecting a fault in a vehicle control system, said method comprising:

identifying a plurality of potential faults;

identifying a plurality of measured values in the control system;

identifying a plurality of estimated values based on models in the control system;

identifying a plurality of residual error values as the difference between the estimated values and the measured values;

defining a plurality of membership functions for each residual error value;

determining a degree of membership value for each residual error value based on the degree of membership functions; and

determining whether a fault exists by analyzing the degree of membership values.

2. The method according to claim 1 wherein identifying a plurality of potential faults includes identifying faults related to a lateral acceleration sensor, a yaw rate sensor, road wheel angle sensors and wheel speed sensors.

3. The method according to claim 1 wherein identifying a plurality of measured values includes identifying a vehicle yaw rate, a vehicle lateral acceleration and a road wheel angle difference between a front wheel of the vehicle and a rear wheel of the vehicle.

4. The method according to claim 1 wherein identifying a plurality of residual error values includes defining four residual error values as a difference between a measured vehicle lateral acceleration signal and an estimated lateral acceleration signal, a measured yaw rate signal and an estimated yaw rate signal, a measured road wheel angle difference and an estimated road wheel angle difference and a combined signal for all of the vehicle wheel speeds.

7. The method according to claim 1 wherein determining whether a fault exists includes determining whether a particular set of degree of membership values exceeds a predetermined threshold in a certain pattern.

5. The method according to claim I wherein defining a plurality of membership functions includes defining at least three membership functions for each residual error value.

6. The method according to claim I wherein determining a degree of membership value for each residual error value includes assigning-one of the degree of membership values to each residual for each potential fault.

8. The method according to claim I further comprising putting the vehicle in a fail-safe mode of operation if a fault is detected.

9. A method for detecting a fault in a vehicle control system, said method comprising:

identifying a plurality of potential faults;

identifying a plurality of measured values in the control system;

identifying a plurality of estimated values based on models in the control system;

identifying a plurality of residual error values as the difference between the estimated values and the measured values;

defining at least three membership functions for each residual error value;

determining a degree of membership value for each residual error value including assigning one of the degree of membership values to each residual for each potential fault; and

determining whether a fault exists by analyzing the degree of membership values, wherein determining whether a fault exists includes determining whether a particular set of degree of membership values exceeds a predetermined threshold in a certain pattern.

10. The method according to claim 9 wherein identifying a plurality of potential faults includes identifying faults related to a lateral acceleration sensor, a yaw rate sensor, road wheel angle sensors and wheel speed sensors.

11. The method according to claim 10 wherein identifying a plurality of measured values includes identifying a vehicle yaw rate, a vehicle lateral acceleration and a road wheel angle difference between a front wheel of the vehicle and a rear wheel of the vehicle.

12. The method according to claim 11 wherein identifying a plurality of residual error values includes defining four residual error values as a difference between a measured vehicle lateral acceleration signal and an estimated lateral acceleration signal, a measured yaw rate signal and an estimated yaw rate signal, a measured road wheel angle difference and an estimated road wheel angle difference and a combined signal for all of the vehicle wheel speeds.

13. A system for detecting a fault in a vehicle control system, said system comprising:

means for identifying a plurality of potential faults;

means for identifying a plurality of measured values in the control system;

means for identifying a plurality of estimated values based on models in the control system;

means for identifying a plurality of residual error values as the difference between the estimated values and the measured values;

means for defining a plurality of degree of membership functions for each residual error value;

means for determining a degree of membership value for each residual error value based on the membership functions; and

means for determining whether a fault exists by analyzing the degree of membership values.

14. The system according to claim 13 wherein the means for identifying a plurality of potential faults includes means for identifying faults related to a lateral acceleration sensor, a yaw rate sensor, road wheel angle sensors and wheel speed sensors.

15. The system according to claim 13 wherein the means for identifying a plurality of measured values includes means for identifying a vehicle yaw rate, a vehicle lateral acceleration and a road wheel angle difference between a front wheel of the vehicle and a rear wheel of the vehicle.

16. The system according to claim 13 wherein the means for identifying a plurality of residual error values includes means for defining four residual error values as a difference between a measured vehicle lateral acceleration signal and an estimated lateral acceleration signal, a measured yaw rate signal and an estimated yaw rate signal, a measured road wheel angle difference and an estimated road wheel angle difference and a combined signal for all of the vehicle wheel speeds.

17. The system according to claim 13 wherein the means for defining a plurality of membership functions includes means for defining at least three membership functions for each residual error value.

18. The system according to claim 13 wherein the means for determining a membership value for each residual error value includes means for assigning one of the degree of membership values to each residual for each potential fault.

19. The system according to claim 13 wherein the means for determining whether a fault exists includes means for determining whether a particular set of degree of membership values exceeds a predetermined threshold in a certain pattern.

20. The system according to claim 13 further comprising means for putting the vehicle in a fail-safe mode of operation if a fault is detected.

21. The system according to claim 13 wherein the vehicle is a by-wire vehicle.