Methods and apparatus for determining the condition of a sensor and identifying the failure thereof

• US 20040098228A1
• Filed: 11/19/2002
• Published: 05/20/2004
• Est. Priority Date: 11/19/2002
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (General Motors Company)
• Inventors: Hartrey, Timothy John
• Granted Patent: US 7,228,249 B2
• Time in Patent Office: Days
• US Class Current: 702/184
• CPC Class Codes: F02D 11/106 Detection of demand or actuation
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Methods and apparatus are provided which generate an error signal if a sensor is either anticipated to fail or fails. At least two sensors provide input signals having magnitudes that approximately correspond to a sensed event. A processor calculates an actual correlation error for the two signals. A processor then further calculates an estimated new correlation value based on the difference of a stored initial correlation value and the actual correlation error. After a predetermined number of estimated correlation values are calculated, the error signal is generated if the difference between an estimated correlation value and the actual correlation error exceeds a predetermined threshold.

Claims

1. An apparatus for generating an error signal, including in combination:

at least two sensors providing control signals having magnitudes that approximately correspond to a sensed event, said magnitudes being unequal to each other;

memory means storing an initial correlation value;

processor means coupled to said sensors and to said memory means, said processor means calculating an actual correlation error for said control signals;

said processor means further calculating a first new estimated correlation value based on the difference between said initial correlation value and said actual correlation error;

said processor means additionally calculating a second new estimated correlation value based on the difference between said first new correlation value and said actual correlation error;

said processor means comparing the difference between a new correlation value and said actual correlation error to a threshold value; and

said processor means providing the error signal if the difference exceeds a predetermined threshold.

2. The apparatus of claim 1 wherein said processor means is configured to store said new correlation values in said memory means in place of said initial correlation value.

3. The apparatus of claim 1 wherein said initial correlation value is a maximum correlation value.

4. The apparatus of claim 1 wherein said processor calculates a predetermined number of said new estimated correlation values before comparing said difference to said threshold to thereby provide a predetermined amount of delay to enable said processor to evaluate said difference signals.

5. The apparatus of claim 1 further comprised of means using said error signal to determine if any of the sensors is failing.

6. The apparatus of claim 1 wherein:

said magnitudes of said control signals correspond to the positions of an accelerator control device for an engine having an electronically controlled throttle; and

each of said magnitudes further corresponding to a desired amount of airflow through said electronically controlled throttle.

7. The apparatus of claim 6 wherein:

at least one of said sensors has a movable member whose positions correspond to said positions of said accelerator control device;

said magnitudes of said control signals varying with said positions of said movable members; and

said memory means being configured to have predetermined breakpoints corresponding to said magnitudes of said control signals and to store said initial correlation value at said predetermined breakpoints.

8. The apparatus of claim 7 wherein at least one of said sensors include a potentiometer having said movable member.

9. The apparatus of claim 7 wherein said processor means compares a sensor position value to the table breakpoints to determine which breakpoint is closest to the sensor position.

10. The apparatus of claim 7 wherein said processor means determines the proximity of the position of said movable member to said corresponding break point.

11. The apparatus of claim 10 wherein said processor means calculates said new correlation error by utilizing said proximity of said movable member to said corresponding breakpoint.

12. The method of claim 11 wherein said processor means squares said proximity value to give more weighting to correlation errors that are closer to said breakpoints.

13. A method for determining the condition of at least one of a plurality of sensors and for generating an error signal if the sensor is failing, comprising:

receiving input signals from at least two of the sensors, said input signals having different magnitudes that approximately correspond to a sensed event;

calculating an actual correlation error relating to said different magnitudes of said two sensor signals;

storing an initial correlation value;

determining the difference value between said actual correlation error and said initial correlation value;

using said difference value to calculate a new estimated correlation value;

storing said new correlation value in place of said initial correlation value;

repeating said steps of determining, using and storing to calculate a predetermined number of said new correlation values; and

generating the error signal if a selected one of said difference values exceeds a predetermined threshold.

14. The method of claim 13 further comprised of using said error signal to determine if a sensor is failing.

15. The method of claim 13 wherein said initial correlation value is a maximum correlation value.

16. The method of claim 13 wherein said repeating said steps enables the method to provide a predetermined amount of delay enabling the evaluation of said difference values.

17. The method of claim 13 wherein said sensors have a movable member having positions corresponding to the sensed event and further comprised of:

reserving memory locations for a table of break points corresponding to said movable member positions; and

reserving memory locations for a table of estimated correlation errors corresponding to said movable member position breakpoints.

18. The method of claim 17 wherein:

said sensed event is the position of an accelerator control device for an engine; and

said method being further comprised of mechanically coupling said movable members to said accelerator control device.

19. The method of claim 17 further comprised of:

calculating the proximity value of sad movable member positions to a breakpoint; and

using said proximity value, said difference value and the previous said estimated correlation value to calculate a new correlation value.

20. The method of claim 19 wherein said proximity values are squared to give more weighting to correlation values that are closer to said breakpoints.