CN107357760B - The instantaneous Frequency Estimation method examined based on Roberts operator and PauTa - Google Patents

The instantaneous Frequency Estimation method examined based on Roberts operator and PauTa Download PDF

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CN107357760B
CN107357760B CN201710608127.5A CN201710608127A CN107357760B CN 107357760 B CN107357760 B CN 107357760B CN 201710608127 A CN201710608127 A CN 201710608127A CN 107357760 B CN107357760 B CN 107357760B
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pauta
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mean curve
instantaneous frequency
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林近山
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Weifang University
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    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10Complex mathematical operations
    • G06F17/14Fourier, Walsh or analogous domain transformations, e.g. Laplace, Hilbert, Karhunen-Loeve, transforms
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T5/00Image enhancement or restoration
    • G06T5/50Image enhancement or restoration by the use of more than one image, e.g. averaging, subtraction
    • G06T5/70
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00Image analysis
    • G06T7/10Segmentation; Edge detection
    • G06T7/12Edge-based segmentation
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00Indexing scheme for image analysis or image enhancement
    • G06T2207/20Special algorithmic details
    • G06T2207/20048Transform domain processing

Abstract

The invention discloses the instantaneous Frequency Estimation methods based on Roberts operator and PauTa inspection.Original signal is converted to time-frequency spectrum using Short Time Fourier Transform by this method, a plurality of ridge band is obtained using Roberts detection algorithm, the exceptional value for excluding every vallate band is examined using PauTa, pass through one synthesis ridge band with complete sharp edge of superposition building, the exceptional value for excluding synthesis ridge band is examined using PauTa, calculate the Mean curve of synthesis ridge band, Mean curve is smoothed, calculate the confidence interval of the smooth Mean curve in 95% confidence level, smooth Mean curve and its confidence interval are mapped on target crestal line, obtain the reference line and the part region of search of target crestal line, target crestal line is extracted using non-delayed cost function.The present invention is suitable for estimating the instantaneous frequency of complicated multi -components frequency variation signal, overcomes conventional method in the defects of mechanical oscillation signal instantaneous Frequency Estimation, the accuracy and precision of estimated result is high, is convenient for engineer application.

Description

The instantaneous Frequency Estimation method examined based on Roberts operator and PauTa
Technical field
The present invention relates to condition monitoring for rotating machinery and fault diagnosis field, and in particular to based on Roberts operator and The instantaneous Frequency Estimation method that PauTa is examined.
Background technique
Due to the complexity of working environment, rotating machinery often works under Variable Velocity Condition.Instantaneous Frequency Estimation is assessment Running state of rotating machine and the important prerequisite for carrying out fault diagnosis.Currently used instantaneous Frequency Estimation method is a step cost Function method (one-step cost function).One step cost function method can search for ridge point within the scope of local frequencies, but It is that the central point of local frequencies range depends on the position of a upper ridge point, this leads to a step cost function, and there is delays.This Outside, the width of local frequencies range is rule of thumb arbitrarily arranged, and width at any time is fixed, Bu Nengsui The time change, this causes a step cost function to lack enough adaptivitys.Drawbacks described above leads to a step cost function Method accuracy and precision when estimating instantaneous frequency is lower.
Summary of the invention
The problem to be solved in the present invention is against the above deficiency, to propose to examine based on Roberts operator and PauTa instantaneous Frequency estimating methods.Compared with the conventional method, the present invention is using the smooth Mean curve after mapping as the reference line of target crestal line, Using the confidence interval after mapping as the local search section of target crestal line, therefore the central point of local frequencies search range is disobeyed The position for relying a ridge point, without any delay, local frequencies search range can be set automatically, and search bandwidth can be with The variation of time and change automatically, the accuracy and precision of instantaneous Frequency Estimation result is high.
In order to solve the above technical problems, the present invention provides the instantaneous Frequency Estimation examined based on Roberts operator and PauTa Method, which comprises the following steps:
Step 1: signal x(k) (k=1,2 ..., N) is converted to by time-frequency spectrum, N using Short Time Fourier Transform algorithm The length of representation signal;
Step 2: choosing one piece of regional area having compared with high s/n ratio from time-frequency spectrum, detected and calculated using Roberts The regional area is converted into bianry image by method, and bianry image includes a plurality of ridge band;Regional area refers to including at least two vallates Band, signal-to-noise ratio are greater than the region of 80dB;
Step 3: exceptional value of every vallate with lower edges is excluded using PauTa check algorithm;
Step 4: above-mentioned a plurality of ridge band is added to wherein according to mutual kinematics proportionate relationship, and a profile is most On complete ridge band, one synthesis ridge band with complete sharp edge of building;Kinematics proportionate relationship refers to corresponding to ridge band Machine part between transmission ratio;
Step 5: above-mentioned exceptional value of the synthesis ridge with lower edges is excluded using PauTa check algorithm;
Step 6: calculate the Mean curve of above-mentioned synthesis ridge band, using 5 points three times smoothing algorithm Mean curve is carried out it is flat Sliding processing, obtains smooth Mean curve, calculates the confidence interval of the smooth Mean curve in 95% confidence level;
Step 7: by above-mentioned smooth Mean curve and its confidence interval according to smooth Mean curve and target crestal line to be estimated Between kinematics proportionate relationship be mapped on target crestal line;
Step 8: using the smooth Mean curve after mapping as the reference line of target crestal line, the confidence interval after mapping being made For the local search section of target crestal line;
Step 9: ridge point being searched in the local search section corresponding to each moment using non-delayed cost function, is determined Instantaneous frequency corresponding to each moment finally obtains the instantaneous frequency on entire time interval.
Further, in the step 1 Short Time Fourier Transform algorithm the following steps are included:
1) Short Time Fourier Transform is carried out to signal x(k):
,
TF (t, f) representation signal x(k) Short Time Fourier Transform as a result, t represents time factor, f represents scale factor, Function w (z) represents independent variable as the window function of z;
2) calculate signal x(k) time-frequency spectrum:
,
Spectrogram (t, f) represents x(k) time-frequency spectrum.
Further, in the step 2 Roberts detection algorithm the following steps are included:
1) if f (i, j) represents original image, the gradient value G (i, j) of image f (i, j) is defined as:
,
I-th of time point of parameter i representative image, j-th of Frequency point of parameter j representative image;
2) a suitable threshold value is set, if the gradient value G (i, j) of some point (i, j) is greater than the threshold on image Value, then determine that the point is edge;In the present invention, threshold value is set as 2.76 × 10-6
Further, in the step 3 PauTa check algorithm the following steps are included:
1) estimate signal xnThe standard deviation of (n=1,2 ..., N),
,
Representative sample mean value, σ representative sample standard deviation, N representative sample length;
If 2), then x is rejectedn
Further, in the step 9 non-delayed cost function the following steps are included:
1) local search section FB corresponding to k-th of momentkIt is defined as
,
fk(pmc) value of the smooth Mean curve k-th of moment after representing mapping,It is smooth equal after representing mapping It is worth curve confidence interval in the half of k-th of moment width, m represents the length of target crestal line;
2) non-delayed cost function CF corresponding to k-th of momentkIs defined as:
,
,
fk(i) it represents in FBkThe frequency values taken in range, TF (tk, fk) TF (t, f) is represented k-th moment Value, tkT is represented in the value at k-th of moment, fkF is represented in the value at k-th of moment, ekRepresent weight factor.
Further, relative error≤0.693%, average relative error≤0.059%.
The invention adopts the above technical scheme, compared with prior art, the invention has the following advantages that
1) present invention has real-time: the present invention is mapped as reference line to synthesize the smooth Mean curve of ridge band, can be instant The central point for determining current time local frequencies search range avoids the dependence to previous ridge point, eliminates time delay, With real-time.
2) present invention has adaptivity: the present invention is mentioned using the smooth Mean curve confidence interval mapping of synthesis ridge band The subrange of confession, can adaptively determine local frequencies search range corresponding to each moment, and search bandwidth can be with The variation of time and change automatically, do not need that search bandwidth is by virtue of experience arranged, to eliminate due to artificial origin and generate Error.
3) the results showed that it is opposite accidentally by the maximum between obtained instantaneous Frequency Estimation value of the invention and measured value Difference is 0.693%, average relative error 0.059%;Compared with the result of a step cost function method, maximum relative error is reduced 95.77%, average relative error reduces by 97.24%.
The present invention will be further described with reference to the accompanying drawings and examples.
Detailed description of the invention
Attached drawing 1 is the stream based on Roberts operator and PauTa the instantaneous Frequency Estimation method examined in the embodiment of the present invention Cheng Tu;
Attached drawing 2 is epicyclic gearbox vibration signal in the embodiment of the present invention;
Attached drawing 3 is the time-frequency spectrum of epicyclic gearbox vibration signal in the embodiment of the present invention;
Attached drawing 4 is the regional area with high s/n ratio chosen from time-frequency spectrum in the embodiment of the present invention;
Attached drawing 5 is the edge of the local image region detected in the embodiment of the present invention by Roberts algorithm;
Attached drawing 6 is to eliminate every vallate with the result after abnormal point using PauTa check algorithm in the embodiment of the present invention;
Attached drawing 7 is the synthesis ridge band being formed by stacking in the embodiment of the present invention using the kinematics proportionate relationship between ridge band (undermost ridge band is to synthesize ridge band);
Attached drawing 8 is to eliminate synthesis ridge with the result after abnormal point using PauTa check algorithm in the embodiment of the present invention;
Attached drawing 9 is the mean value smoothing curve and its 95% confidence interval that ridge band is synthesized in the embodiment of the present invention;
Attached drawing 10 is the mean value smoothing curve mapped in the embodiment of the present invention and its confidence interval;
Attached drawing 11 is instantaneous Frequency Estimation value in the embodiment of the present invention.
Specific embodiment
Embodiment, as shown in Figure 1, based on the instantaneous Frequency Estimation method that Roberts operator and PauTa are examined, including with Lower step:
Step 1: signal x(k) (k=1,2 ..., N) is converted to by time-frequency spectrum, N using Short Time Fourier Transform algorithm The length of representation signal;
Step 2: choosing one piece of regional area having compared with high s/n ratio from time-frequency spectrum, detected and calculated using Roberts The regional area is converted into bianry image by method, and bianry image includes a plurality of ridge band;Regional area refers to including at least two vallates Band, signal-to-noise ratio are greater than the region of 80dB;
Step 3: exceptional value of every vallate with lower edges is excluded using PauTa check algorithm;
Step 4: above-mentioned a plurality of ridge band is added to wherein according to mutual kinematics proportionate relationship, and a profile is most On complete ridge band, one synthesis ridge band with complete sharp edge of building;Kinematics proportionate relationship refers to corresponding to ridge band Machine part between transmission ratio;
Step 5: above-mentioned exceptional value of the synthesis ridge with lower edges is excluded using PauTa check algorithm;
Step 6: calculate the Mean curve of above-mentioned synthesis ridge band, using 5 points three times smoothing algorithm Mean curve is carried out it is flat Sliding processing, obtains smooth Mean curve, calculates the confidence interval of the smooth Mean curve in 95% confidence level;
Step 7: by above-mentioned smooth Mean curve and its confidence interval according to smooth Mean curve and target crestal line to be estimated Between kinematics proportionate relationship be mapped on target crestal line;
Step 8: using the smooth Mean curve after mapping as the reference line of target crestal line, the confidence interval after mapping being made For the local search section of target crestal line;
Step 9: ridge point being searched in the local search section corresponding to each moment using non-delayed cost function, is determined Instantaneous frequency corresponding to each moment finally obtains the instantaneous frequency on entire time interval.
Short Time Fourier Transform algorithm in step 1 the following steps are included:
1) Short Time Fourier Transform is carried out to signal x(k):
,
TF (t, f) representation signal x(k) Short Time Fourier Transform as a result, t represents time factor, f represents scale factor, Function w (z) represents independent variable as the window function of z;
2) calculate signal x(k) time-frequency spectrum:
,
Spectrogram (t, f) represents x(k) time-frequency spectrum.
Roberts detection algorithm in step 2 the following steps are included:
1) if f (i, j) represents original image, the gradient value G (i, j) of image f (i, j) is defined as:
,
I-th of time point of parameter i representative image, j-th of Frequency point of parameter j representative image;
2) a suitable threshold value is set, if the gradient value G (i, j) of some point (i, j) is greater than the threshold on image Value, then determine that the point is edge;In the present invention, threshold value is set as 2.76 × 10-6
PauTa check algorithm in step 3 the following steps are included:
1) estimate signal xnThe standard deviation of (n=1,2 ..., N),
,
Representative sample mean value, σ representative sample standard deviation, N representative sample length;
If 2), then x is rejectedn
Non-delayed cost function in step 9 the following steps are included:
1) local search section FB corresponding to k-th of momentkIt is defined as
,
fk(pmc) value of the smooth Mean curve k-th of moment after representing mapping,It is smooth equal after representing mapping It is worth curve confidence interval in the half of k-th of moment width, m represents the length of target crestal line;
2) non-delayed cost function CF corresponding to k-th of momentkIs defined as:
,
,
fk(i) it represents in FBkThe frequency values taken in range, TF (tk, fk) TF (t, f) is represented k-th moment Value, tkT is represented in the value at k-th of moment, fkF is represented in the value at k-th of moment, ekRepresent weight factor.
The performance of algorithm of the present invention is verified using blower turbine epicyclic gearbox vibration data.
Vibration data is acquired from the gearbox-case of planetary gear train, data length N=2736825, sample frequency fs= 5000 Hz。
Collected epicyclic gearbox vibration data is as shown in Figure 2.
Epicyclic gearbox vibration data shown in Fig. 2 is converted to by time-frequency spectrum using Short Time Fourier Transform algorithm, is obtained The time-frequency spectrum arrived is as shown in Figure 3.
The regional area with high s/n ratio, obtained regional area such as Fig. 4 institute are chosen from time-frequency spectrum shown in Fig. 3 Show.
Edge detection is carried out to regional area as shown in Figure 4 using Roberts detection algorithm, obtained image border is such as Shown in Fig. 5.
The abnormal point of each vallate band in Fig. 5 is eliminated using PauTa check algorithm, obtained result is as shown in Figure 6.
Each vallate band is added to the wherein most complete ridge band of a profile according to the kinematics proportionate relationship between ridge band On, constructed synthesis ridge band is as shown in Figure 7 (undermost ridge band is to synthesize ridge band).
The abnormal point of synthesis ridge band is eliminated using PauTa check algorithm, as a result as shown in Figure 8.
The smooth Mean curve of synthesis ridge band and its 95% confidence interval are calculated, as a result as shown in Figure 9.
According to the kinematics proportionate relationship between smooth Mean curve and target crestal line by smooth Mean curve and its confidence On Interval Maps to target crestal line, the results are shown in Figure 10.
Using the ridge point of non-delayed cost function search target crestal line, obtained instantaneous frequency profile is as shown in figure 11.
Show through many experiments by the maximum relative error between obtained instantaneous Frequency Estimation value of the invention and measured value It is 0.693%, average relative error 0.059%, and the instantaneous Frequency Estimation value and actual measurement for using a step cost function method to obtain Maximum relative error between value is 16.39%, and average relative error 2.14%, maximum relative error of the present invention reduces 95.77%, average relative error reduces by 97.24%.
According to experimental result, think after analysis:
1) a traditional step cost function needs to rely on when determining the central point in current search section a upper ridge point Position, there is time delay phenomenon, the present invention can be determined immediately using the smooth Mean curve after mapping as reference line The center in current search section does not depend on a ridge point completely, therefore has real-time.
2) a traditional step cost function method lacks adaptivity, needs artificially to be arranged the region of search, and search width It is fixed, thus inevitably brings error, the present invention is using the smooth Mean curve confidence interval after mapping come automatic Determine local search section, search bandwidth can change automatically with the variation of time, not need manually to participate in, therefore have Adaptivity.
3) compared with a traditional step cost function method, accuracy of the present invention and accuracy are high.
One skilled in the art would recognize that the above specific embodiments are only exemplary, it is to make ability Field technique personnel can better understand the content of present invention, should not be construed as limiting the scope of protection of the present invention, as long as Technical solution improvements introduced according to the present invention each falls within protection scope of the present invention.

Claims (3)

1. the rotating machinery instantaneous Frequency Estimation method examined based on Roberts operator and PauTa, which is characterized in that including with Lower step:
Step 1: rotating machinery signal x(k) k=1,2 ..., N are converted to by time-frequency spectrum using Short Time Fourier Transform algorithm, N represents the length of rotating machinery signal;
Step 2: one piece of regional area having compared with high s/n ratio is chosen from time-frequency spectrum, it will using Roberts detection algorithm The regional area is converted into bianry image, and bianry image includes a plurality of ridge band;
Step 3: exceptional value of every vallate with lower edges is excluded using PauTa check algorithm;
Step 4: above-mentioned a plurality of ridge band is most complete according to the mutual kinematics proportionate relationship wherein profile that is added to Ridge band on, synthesis ridge band of the building one with complete sharp edge;
Step 5: above-mentioned exceptional value of the synthesis ridge with lower edges is excluded using PauTa check algorithm;
Step 6: calculate the Mean curve of above-mentioned synthesis ridge band, using 5 points three times smoothing algorithm Mean curve is smoothly located Reason, obtains smooth Mean curve, calculates the confidence interval of the smooth Mean curve in 95% confidence level;
Step 7: by above-mentioned smooth Mean curve and its confidence interval according between smooth Mean curve and target crestal line to be estimated Kinematics proportionate relationship be mapped on target crestal line;
Step 8: using the smooth Mean curve after mapping as the reference line of target crestal line, using the confidence interval after mapping as mesh Mark the local search section of crestal line;
Step 9: ridge point being searched for using non-delayed cost function in the local search section corresponding to each moment, is determined each Instantaneous frequency corresponding to moment finally obtains the instantaneous frequency on entire time interval;
Non-delayed cost function in the step 9 the following steps are included:
1) local search section FB corresponding to k-th of momentkIt is defined as
,
fk(pmc) value of the smooth Mean curve k-th of moment after representing mapping,Smooth mean value after representing mapping is bent For line confidence interval in the half of k-th of moment width, m represents the length of target crestal line;
2) non-delayed cost function CF corresponding to k-th of momentkIs defined as:
,
,
fk(i) it represents in FBkThe frequency values taken in range, TF (tk, fk) TF (t, f) is represented in the value at k-th of moment, tk T is represented in the value at k-th of moment, fkF is represented in the value at k-th of moment, ekRepresent weight factor.
2. the rotating machinery instantaneous Frequency Estimation side according to claim 1 examined based on Roberts operator and PauTa Method, which is characterized in that Short Time Fourier Transform algorithm in the step 1 the following steps are included:
1) Short Time Fourier Transform is carried out to signal x(k):
,
TF (t, f) representation signal x(k) Short Time Fourier Transform as a result, t represents time factor, f represents scale factor, function W (z) represents independent variable as the window function of z;
2) calculate signal x(k) time-frequency spectrum:
,
Spectrogram (t, f) represents x(k) time-frequency spectrum.
3. the rotating machinery instantaneous Frequency Estimation side according to claim 1 examined based on Roberts operator and PauTa Method, which is characterized in that
PauTa check algorithm in the step 3 the following steps are included:
1) estimate signal xnThe standard deviation of n=1,2 ..., N,
,
Representative sample mean value, σ representative sample standard deviation, N representative sample length;
If 2), then x is rejectedn
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