Automatic stencil generation system and method

• US 6,236,950 B1
• Filed: 10/30/1998
• Issued: 05/22/2001
• Est. Priority Date: 10/30/1998
• Status: Expired due to Term

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Grichnik, Anthony J.
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Bui, Bryan
• Application Number:
  US09/183,622
• Time in Patent Office: 935 Days
• Field of Search: 702/56, 702/66, 702/75-77, 702/183, 736/59--60, 736/02, 324/76.19, 324/76.21, 324/76.22, 324/772
• US Class Current: 702/66
• CPC Class Codes: G01M 13/02 Gearings; Transmission mechanisms
• CPC Class Codes: G01M 13/045 Acoustic or vibration analysis
• CPC Class Codes: G01M 7/025 Measuring arrangements

Abstract

A stencil generator for automatically constructing a stencil representative of signals having similar characteristics includes a boundary extractor and a component generator. The boundary extractor is operable to (i) receive a frequency spectrum of a signal, and (ii) obtain from the received frequency spectrum a plurality of characteristic frequency boundaries for the signal. The component generator is coupled to the boundary extractor and is operable to (i) receive the frequency spectrum, (ii) receive the plurality of characteristic frequency boundaries from the boundary extractor, and (iii) define a plurality of stencil components based upon the plurality of characteristic frequency boundaries and the frequency spectrum.

Claims

1. A method of automatically constructing a stencil representative of signals having similar characteristics, comprising the steps of:

obtaining from a frequency spectrum for a signal, a plurality of characteristic frequency boundaries that define a plurality of characteristic frequency intervals for said signal; and

generating said stencil representative of signals having similar characteristics by defining a plurality of stencil components based upon said plurality of characteristic frequency intervals and said frequency spectrum.

2. The method of claim 1, wherein said generating step comprises the step of:

defining a rectangular stencil component for each characteristic frequency interval of said plurality of characteristic frequency intervals.

3. The method of claim 1, wherein said generating step comprises the step of:

defining a curved stencil component for each characteristic frequency interval of said plurality of characteristic frequency intervals.

4. The method of claim 1, wherein said generating step comprises the steps of:

combining characteristic frequency intervals of said plurality of characteristic frequency intervals with adjacent characteristic frequency intervals of said plurality of characteristic frequency intervals to form a group of combined frequency intervals in which each combined frequency interval represents a frequency interval greater than a threshold frequency interval;

defining a rectangular stencil component for each characteristic frequency interval of said plurality of characteristic frequency intervals that is not included in said group of combined frequency intervals; and

defining a curved stencil component for each combined frequency interval of said plurality of characteristic frequency interval.

5. The method of claim 1, wherein said generating step comprises the steps of:

defining a rectangular stencil component for each characteristic frequency interval of said plurality of characteristic frequency intervals; and

replacing a group of adjacent rectangular stencil components with a curved stencil component if a first rectangular stencil component of said group of adjacent rectangular stencil components represents a characteristic frequency interval of said plurality of characteristic frequency intervals that is less than a threshold frequency interval.

6. The method of claim 1, wherein said obtaining step comprises the steps of:

calculating an accumulative spectral power plot of said frequency spectrum;

fitting a first line to said accumulative spectral power plot; and

selecting for a first characteristic frequency boundary of said plurality of characteristic frequency boundaries, a first frequency that corresponds to a first point of said accumulative spectral power plot which deviates from said first line by more than a threshold amount.

7. The method of claim 1, wherein said obtaining step comprises the steps of:

selecting said characteristic frequency boundaries based upon variations in an accumulative spectral power plot of said frequency spectrum.

8. A stencil generator for automatically constructing a stencil representative of signals having similar characteristics, comprising:

a boundary extractor that is operable to (i) receive a frequency spectrum of a signal, and (ii) obtain from said received frequency spectrum a plurality of characteristic frequency boundaries for said signal that define a plurality of characteristic frequency intervals; and

a component generator coupled to said boundary extractor, said component generator operable to (i) receive said frequency spectrum, (ii) receive said plurality of characteristic frequency boundaries from said boundary extractor, and (iii) define a plurality of stencil components based upon said frequency spectrum and said plurality of characteristic frequency intervals defined by said plurality of characteristic frequency intervals.

9. The stencil generator of claim 8, wherein:

said component generator comprises a template generator that is operable to generate a maximum spectral magnitude for each characteristic frequency interval of said plurality of characteristic frequency intervals.

10. The stencil generator of claim 8, wherein:

said component generator comprises an envelope generator that is operable to generate a separate maximum spectral magnitude for each spectral component included in a combined frequency interval comprising at least two characteristic frequency intervals of said plurality of characteristic frequency intervals.

11. The stencil generator of claim 8, wherein said component generator comprises:

an envelope generator that is operable to generate a separate maximum spectral magnitude for each spectral component included in a combined frequency interval comprising (i) a second characteristic frequency interval of said plurality of characteristic frequency intervals that is less than a threshold frequency interval, and (ii) a third characteristic frequency interval of said plurality of characteristic frequency intervals that is adjacent to said second characteristic interval.

12. The stencil generator of claim 8, wherein said boundary extractor comprises:

an integrator that is operable to (i) receive said frequency spectrum, and (ii) generate an accumulative sum signal that is representative of the accumulative spectral power of said frequency spectrum; and

a linear regression component that is operable to (i) receive said accumulative sum signal, (ii) fit a first line to said accumulative sum signal, and (iii) cause a first frequency to be included in said plurality of characteristic boundary frequencies in response to a first accumulative spectral power value of said accumulative sum signal deviating from said first line by more than a threshold amount.

13. The stencil generator of claim 8, wherein said boundary extractor comprises:

an accumulative summing component that is operable to (i) receive said frequency spectrum, and (ii) generate an accumulative sum signal that is representative of a magnitude sum of said frequency spectrum over frequency; and

a linear regression comparator that is operable to (i) receive said accumulative sum signal, (ii) fit a first line to said accumulative sum signal from (a) magnitude sums corresponding to higher frequencies of said accumulative sum signal to (b) magnitude sums corresponding to lower frequencies of said accumulative sum signal, and (iii) cause a first frequency to be included in said plurality of characteristic boundary frequencies in response to a first magnitude sum of said accumulative sum signal deviating from said first line by more than a threshold amount.

14. A stencil generator for automatically constructing a stencil representative of signals having similar characteristics, comprising a processor coupled to a memory device having stored therein a plurality of instructions which when executed by said processor cause said processor to:

obtain from a frequency spectrum for a signal, a plurality of characteristic frequency boundaries that define a plurality of characteristic frequency intervals for said signal; and

generate said stencil representative of signals having similar characteristics by defining a plurality of stencil components based upon said plurality of characteristic frequency intervals and said frequency spectrum.

15. The stencil generator of claim 14, wherein said plurality of instructions when executed by said processor further causes said processor to:

define a rectangular stencil component for each characteristic frequency interval of said plurality of characteristic frequency intervals.

16. The stencil generator of claim 14, wherein said plurality of instructions when executed by said processor further causes said processor to:

define a curved stencil component for each characteristic frequency interval of said plurality of characteristic frequency intervals.

17. The stencil generator of claim 14, wherein said plurality of instructions when executed by said processor further causes said processor to:

combine characteristic frequency intervals of said plurality of characteristic frequency intervals with adjacent characteristic frequency intervals of said plurality of characteristic frequency intervals to form a group of combined frequency intervals in which each combined frequency interval represents a frequency interval greater than a threshold frequency interval;

define a rectangular stencil component for each characteristic frequency interval of said plurality of characteristic frequency intervals that is not included in said group of combined frequency intervals; and

define a curved stencil component for each combined frequency interval of said plurality of characteristic frequency interval.

18. The stencil generator of claim 14, wherein said plurality of instructions when executed by said processor further causes said processor to:

define a rectangular stencil component for each characteristic frequency interval of said plurality of characteristic frequency intervals; and

replace a group of adjacent rectangular stencil components with a curved stencil component if a first rectangular stencil component of said group of adjacent rectangular stencil components represents a characteristic frequency interval of said plurality of characteristic frequency intervals that is less than a threshold frequency interval.

19. The stencil generator of claim 14, wherein said plurality of instructions when executed by said processor further causes said processor to:

calculate an accumulative spectral power plot of said frequency spectrum;

fit a first line to said accumulative spectral power plot; and

select for a first characteristic frequency boundary of said plurality of characteristic frequency boundaries, a first frequency that corresponds to a first point of said accumulative spectral power plot which deviates from said first line by more than a threshold amount.

20. The stencil generator of claim 14, wherein said plurality of instructions when executed by said processor further causes said processor to:

calculate an accumulative spectral power plot of said frequency spectrum;

fit a first line to said accumulative spectral power plot from said higher frequencies of said accumulative spectral power plot toward said lower frequencies of said accumulative spectral power plot; and

select for a first characteristic frequency boundary of said plurality of characteristic frequency boundaries, a first frequency corresponding to a first point of said accumulative spectral power plot which deviates from said first line by more than a threshold amount.