EXPONENTIALLY WEIGHTED MOVING AVERAGING FILTER WITH ADJUSTABLE WEIGHTING FACTOR

• US 20140122020A1
• Filed: 10/16/2013
• Published: 05/01/2014
• Est. Priority Date: 10/25/2012
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Kowalkowski, Janean E., Anilovich, Igor, Chung, Jason J.
• Granted Patent: US 9,501,452 B2
• Time in Patent Office: Days
• US Class Current: 702/179
• CPC Class Codes: F01N 11/00 Monitoring or diagnostic devices for exhaust-gas treatment apparatus , e.g. for catalytic activity safety, indicating or supervising devices for internal combustion engines F02B77/08; testing of machines G01M13/00
• CPC Class Codes: F01N 2560/026 for measuring or detecting NOx
• CPC Class Codes: F02D 2041/1432 the system including a filter, e.g. a low pass or high pass filter
• CPC Class Codes: F02D 41/146 the characteristics being an NOx content or concentration
• CPC Class Codes: F02D 41/222 relating to the failure of sensors or parameter detection devices
• CPC Class Codes: G06F 17/18 for evaluating statistical data , e.g. average values, frequency distributions, probability functions, regression analysis forecasting specially adapted for a specific administrative, business or logistic context G06Q10/04
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A method of increasing a weighting factor of an exponentially weighted moving averaging (“EWMA”) filter is provided. The method includes monitoring a data stream containing raw data values, and determining an EWMA value based on the data stream by an electronic control module. The method includes determining if the EWMA value is between a predetermined maximum fault threshold value and a predetermined minimum fault threshold value. The method includes increasing the weighting factor of the EWMA filter to more heavily weigh incoming raw data values of the data stream based on the difference between the first raw data value and a previously calculated filtered value exceeding the calibration value.

Claims

1. A method of increasing a weighting factor of an exponentially weighted moving averaging (“

EWMA”

) filter, comprising;

monitoring a data stream containing raw data values and determining an EWMA value based on the data stream by an electronic control module including operative logic;

determining if the EWMA value is between a predetermined maximum fault threshold value and a predetermined minimum fault threshold value; and

increasing the weighting factor of the EWMA filter to an adjusted weighting factor to more heavily weigh incoming raw data values of the data steam based on the difference between the first raw data value and a previously calculated filtered data value exceeding the calibration value.

2. The method of claim 1, wherein the EWMA filter determines an adjusted filter value based on the formula EWMA(t0)=λ

′

Y_t0+(1−

λ

′

)(EWMA)<sub>t−

1</sub> . . . (1−

λ

′

)(EWMA)<sub>t−

n</sub>.

3. The method of claim 1, further comprising:

passing the adjusted filter value to a diagnostic module.

4. The method of claim 3, further comprising:

comparing the maximum fault threshold value and the minimum fault threshold value to the adjusted filter value.

5. The method of claim 3, further comprising:

issuing a passing signal if the adjusted filter value is less than the minimum fault threshold value.

6. The method according to claim 1, further comprising:

providing a worst performing acceptable (WPA) maximum level, and a WPA minimum level for the EWMA filter to a WPA module.

7. The method of claim 1, further comprising:

comparing the raw data values to the WPA maximum level and the WPA minimum level; and

generating a rapid healing logic signal if the raw values are greater than the WPA minimum level and less than the WPA maximum level, the rapid heaing logic signal indicating existence of a potential corrective action.

8. A diagnostic system comprising:

a sensor;

an exponentially weighted moving averaging (“

EWMA”

) filter operatively connected to the sensor; and

a control module operatively connected to the EWMA filter, the control module being configured and disposed to increase the weighting factor of the EWMA filter to an adjusted weighting factor to more heavily weigh incoming raw data values of the data stream.

9. The diagnostic system according to claim 8, wherein the EWMA filter is configured and disposed to establish an adjusted filtered value based on the formula EWMA(t0)=λ

′

Y_t0(1−

λ

)(EWMA)<sub>t−

1</sub> . . . (1−

λ

′

)(EWMA)<sub>t−

n</sub>.

10. The diagnostic system according to claim 8, further comprising:

a diagnostic module operatively connected to the control module, the diagnostic module being configured and disposed to determine if the adjusted filtered value is between a predetermined maximum fault threshold value and a predetermined minimum fault threshold value.

11. The diagnostic system according to claim 8, wherein the diagnostic module is configured and disposed to compare the adjusted filtered value to a maximum fault threshold value and a minimum fault threshold value.

12. The diagnostic system according to claim 8, further comprising:

a worst performing acceptable (WPA) module operatively connected to the control module, the WPA module including aWPA maximum level, and a WPA minimum level for the EWMA filter.

13. The diagnostic system according to claim 11, wherein the WPA module is configured and disposed to generate a rapid healing logic signal if raw data values passing to the EWMA filter are greater than the WPA minimum level and less than the WPA maximum level, the rapid healing logic signal indicating the existence of a potential corrective action of the sensor.

14. The diagnostic system according to claim 8, wherein the sensor comprises a NOx sensor.

15. An exhaust gas treatment system comprising:

an exhaust gas conduit;

a sensor operatively connected to the exhaust gas conduit;

an exponentially weighted moving averaging (“

EWMA”

) filter operatively connected to the sensor; and

a control module operatively connected to the EWMA filter, the control module being configured and disposed to increase the weighting factor of the EWMA filter to an adjusted weighting factor to more heavily weigh incoming raw data values of the data stream.

16. The exhaust gas treatment system according to claim 15, wherein the EWMA filter is configured and disposed to establish an adjusted filtered value based on the formula EWMA(t0)=λ

′

Y_t0+(1−

λ

′

)(EWMA)<sub>t−

1</sub> . . . (1−

λ

′

)(EWMA)<sub>t−

n</sub>.

17. The exhaust gas treatment system according to claim 16, further comprising:

a diagnostic module operatively connected to the control module, the diagnostic module being configured and disposed to determine if the adjusted filtered value is between a predetermined maximum fault threshold value and a predetermined minimum fault threshold value.

18. The exhaust gas treatment system according to claim 16, wherein the diagnostic module is configured and disposed to compare the adjusted filtered value to a maximum fault threshold value and a minimum fault threshold value.

19. The exhaust gas treatment system according to claim 15, further comprising:

a worst performing acceptable (WPA) module operatively connected to the control module, the WPA module including a WPA maximum level, and a WPA minimum level for the EWMA filter.

20. The exhaust gas treatment system according to claim 19, wherein the WPA module is configured and disposed to generate a rapid healing logic signal if raw data values passing to the EWMA filter are greater than the WPA minimum level and less than the WPA maximum level, the rapid healing logic signal indicating the existence of a potential corrective action of the sensor.