Systems and methods for filtering signals corresponding to sensed parameters

• US 7,825,721 B2
• Filed: 10/17/2008
• Issued: 11/02/2010
• Est. Priority Date: 10/17/2008
• Status: Active Grant

• Current Assignee: Rtx Corporation
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Vanderleest, Ruurd A., Marples, Brett
• Primary Examiner(s): Donovan; Lincoln
• Assistant Examiner(s): ROJAS, DANIEL E
• Application Number:
  US12/253,329
• Publication Number:
  US 20100097132A1
• Time in Patent Office: 746 Days
• Field of Search: 327/551
• US Class Current: 327/551
• CPC Class Codes: H03H 17/0261 Non linear filters

Abstract

Systems and methods for filtering analog signals corresponding to sensed parameters are provided. In this regard, a representative method includes: sampling the analog signal to acquire a sequential series of data points; determining a first cumulative change in value with respect to a first of the data points relative to at least two subsequent data points in the series, the subsequent data points including a second of the data points; determining a second cumulative change in value with respect to the second of the data points relative to at least two data points adjacent to the second of the data points in the series, the at least two adjacent data points including an immediately preceding and an immediately succeeding one of the data points relative to the second of the data points; comparing the first cumulative change and the second cumulative change to respective data thresholds; and outputting a filtered analog signal based, at least in part, on results of the comparing.

Claims

1. A method for filtering a signal corresponding to a sensed parameter comprising:

a controller determining a first cumulative change in value of the parameter with respect to consecutively sensed pairs of samples of the parameter, a first of the pairs of the samples comprising, in time-sampled order, a first previous value and a second, previous value, a second of the pairs of the samples comprising the first previous value and a current value;

said controller determining a second cumulative change in value of the parameter with respect to the first of the pairs of the samples and a third of the pairs of the samples, the third of the pairs of samples comprising the second previous value and the current value;

said controller outputting a filtered signal, the filtered signal containing information corresponding to the second previous value if the first cumulative change and the second cumulative change are within respective predetermined out-of-bounds limits;

said controller maintaining output of the filtered signal with the information corresponding to the second previous value if at least one of the first cumulative change and the second cumulative change is not within the respective predetermined out-of-bounds limits; and

said controller modifying the output of the filtered signal such that the filtered signal contains information corresponding to a subsequent second previous value if a corresponding subsequent first cumulative change and a corresponding subsequent second cumulative change are within respective predetermined in-bounds limits, the in-bounds limits being more restrictive than the out-of-bounds limits.

2. The method of claim 1, wherein the out-of-bounds limits are dynamically set.

3. The method of claim 2, wherein the in-bounds limits are dynamically set.

4. The method of claim 1, further comprising said controller sampling an analog signal to obtain the samples of the parameter.

5. The method of claim 1, wherein the filtered signal is an analog signal.

6. The method of claim 1, wherein the first previous value immediately precedes the current value in the time-sampled order.

7. The method of claim 6, wherein the second previous value immediately precedes the first previous value in the time-sampled order.

8. The method of claim 1, further comprising said controller iteratively performing the steps of determining the first cumulative change, determining the second cumulative change and outputting the filtered signal with respect to subsequently sensed samples of the parameter such that, at a next iteration, the second previous value is replaced by the first previous value, the first previous value is replaced by the current value, and the current value is replaced by a next current value.

9. The method of claim 1, wherein determining the first cumulative change in value comprises:

subtracting the second previous value from the first previous value to generate a first difference;

subtracting the current value from the first previous value to generate a second difference;

adding the first difference and the second difference to generate a first sum; and

computing the absolute value of the first sum.

10. The method of claim 1, wherein the parameter is a temperature.

11. The method of claim 1, wherein the parameter is associated with a speed of a device.

12. The method of claim 11, wherein:

the device is a gas turbine engine; and

the speed is a rotational speed of a portion of the gas turbine engine.

13. A method for filtering an analog signal corresponding to a sensed parameter comprising:

a controller sampling the analog signal to acquire a sequential series of data points;

said controller determining a first cumulative change in value with respect to a first of the data points relative to at least two subsequent data points in the series, the subsequent data points including a second of the data points;

said controller determining a second cumulative change in value with respect to the second of the data points relative to at least two data points adjacent to the second of the data points in the series, the at least two adjacent data points including an immediately preceding and an immediately succeeding one of the data points relative to the second of the data points;

said controller comparing the first cumulative change and the second cumulative change to respective data thresholds; and

said controller outputting a filtered analog signal based, at least in part, on results of the comparing.

14. The method of claim 13, wherein outputting the filtered analog signal comprises maintaining a previous value on the filtered analog signal responsive to at least one of the first cumulative change and the second cumulative change failing to correspond to the respective data thresholds.

15. The method of claim 14, wherein the data thresholds are dynamically set based, at least in part, on predetermined values of the data points.

16. A system for filtering an analog signal corresponding to a parameter comprising:

a signal processor operative to;

receive information corresponding to samples of the analog signal;

determine a first cumulative change in value of the parameter with respect to consecutive pairs of the samples of the parameter, a first of the pairs of the samples comprising, in time-sampled order, a first previous value and a second previous value, a second of the pairs of the samples comprising the first previous value and a current value;

determine a second cumulative change in value of the parameter with respect to the first of the pairs of the samples and a third of the pairs of the samples, the third of the pairs of samples comprising the second previous value and the current value; and

control output of a filtered analog signal corresponding to the parameter, an analog value being carried by the filtered analog signal being selected based, at least in part, on comparison of the first cumulative change and the second cumulative change to respective predetermined out-of-bound limits such that, responsive to at least one of the first cumulative change and the second cumulative change being outside the respective predetermined out-of-bounds limits, the information being carried by the filtered analog signal is maintained at a previous analog value.

17. The system of claim 16, further comprising a sensor operative to obtain information corresponding to the parameter.

18. The system of claim 17, wherein the sensor is a speed sensor.

19. The system of claim 17, wherein the sensor is a temperature sensor.

20. The system of claim 17, further comprising an analog-to-digital converter operative to receive an analog signal from the sensor and to provide a corresponding digital signal, containing the information corresponding to the samples, to the signal processor.