CN105157820A - Harmonic frequency identifying and rejecting method based on spectroscopic derivative and frequency hurdle seam - Google Patents
Harmonic frequency identifying and rejecting method based on spectroscopic derivative and frequency hurdle seam Download PDFInfo
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- CN105157820A CN105157820A CN201510197209.6A CN201510197209A CN105157820A CN 105157820 A CN105157820 A CN 105157820A CN 201510197209 A CN201510197209 A CN 201510197209A CN 105157820 A CN105157820 A CN 105157820A
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Abstract
The invention discloses a harmonic frequency identifying and rejecting method based on spectroscopic derivatives and frequency hurdle seams. The method is characterized by including the following steps: calculating a first order derivative or second order derivative of a vibration signal power spectrum G([Omega]), and obtaining a spectrum abrupt change degree ab([Omega]) or a quickness ag([Omega]); setting thresholds of the spectrum abrupt change degree or the quickness as ab-max and ag-max respectively; finding a frequency point [Omega]i in an ab([Omega]i)=ab-max position or ag([Omega]i)=ag-max position; finding a frequency point [Omega]j the first spectrum abrupt change degree of which is negative or the third quickness of which is negative after the frequency point [Omega]i, the frequency point [Omega]j being a harmonic frequency [Omega]h; and building frequency hurdle seams and rejecting all harmonic frequencies through the identified harmonic frequency [Omega]h, and obtaining the real inherent frequency of a mechanical structure. The method is high in detection accuracy, is capable of obtaining the inherent frequency of a mechanical structure when the mechanical structure is in a working state, and provides a powerful means for identifying and monitoring a mechanical structure on-line and identifying structural damage of a mechanical structure.
Description
Technical field
The invention belongs to the dynamic analysis field of mechanized equipment structure, more specifically, relating to a kind of harmonics frequency identification and elimination method based on composing derivative and frequency fence seam.
Background technology
The dynamics of physical construction, for raising vibration resistance, improves its serviceability most important.During ONLINE RECOGNITION physical construction dynamics, usually can be subject to the severe jamming of the periodic signals such as power supply power frequency component, rotary part, thus the natural frequency of mechanism itself is flooded.At present, process for these periodic signals is all carry out special filtering to the original signal gathered usually, thus filter periodic signal, but when the natural frequency of structure and the fundamental frequency of periodic signal or its frequency multiplication close to time, the natural frequency of structure also filters out by filtering method possibly, thus causes the loss of structural dynamic characteristics.In addition, the rotating speed of rotary part may change in the course of the work, and the fundamental frequency of its periodic vibration signal produced and frequency multiplication thereof also can change thereupon, are difficult to automatic identification.
Therefore, be necessary to propose a kind of new method, with under the prerequisite of unknown vibration signal frequency content, identify automatically and accurately and reject the harmonics frequency of undesired signal, preserving the natural frequency information of physical construction simultaneously.
Summary of the invention
For above-mentioned shortcoming and/or the Improvement requirement of prior art, the invention provides a kind of harmonics frequency identification and elimination method based on composing derivative and frequency fence seam, it realizes accurate identification and the rejecting of harmonics frequency in conjunction with the mode that frequency fence stitches by employing spectrum derivative, can correspondingly obtain lathe in working order under true natural frequency, thus be particularly useful in unknown vibration signal frequency content, and harmonics frequency signal is when often changing, the occasions such as the true natural frequency of Obtaining Accurate mechanism.
For achieving the above object, the present invention proposes a kind of harmonics frequency identification and elimination method based on composing derivative and frequency fence seam, it is characterized in that, comprise the steps:
Step (1): to the physical construction as measuring object, test its vibration response signal to obtain vibration response signal power spectrum G (ω), then calculate first order derivative or the second derivative of this vibration response signal power spectrum G (ω), obtain spectrum sudden change degree a thus
b(ω) or prompt degree a
g(ω), identify the natural frequency ω of all mode of physical construction simultaneously
j, then utilize spectrum sudden change degree a
b(ω) or prompt degree a
g(ω) from vibration response signal power spectrum G (ω), identify the harmonics frequencies omega of undesired signal
h, wherein ω represents frequency;
Step (2): by the harmonics frequencies omega identified
hbuild frequency fence seam and carry out following operation specifically:
Step (2-1): the centre frequency that frequency fence stitches is preset as ω
ref, frequency domain width is 2 Δ ω;
Step (2-2): build frequency fence seam [ω
ref– Δ ω, ω
ref+ Δ ω], wherein ω
ref=n ω
h, n is positive integer;
Step (2-3): the frequency fence seam built by step (2-2) is to all described natural frequency ω identified in step (1)
jperform filtration treatment, obtain the filter result of the true natural frequency reflecting described physical construction.
As further preferably, described step (1) comprises following sub-step:
Step (1-1): the first order derivative or the second derivative that calculate vibration signal power spectrum G (ω), obtains spectrum sudden change degree a
b(ω) or prompt degree a
g(ω), as follows:
Step (1-2): the threshold value of setting spectrum sudden change degree or prompt degree is respectively a
b-maxand a
g-max, wherein, obtain described spectrum sudden change degree a
b(ω) or prompt degree a
g(ω) standard deviation of each numerical value at each Frequency point place on frequency domain axle, described a
b-maxor a
g-maxbe set to 3 times of respective above-mentioned standard deviation;
Step (1-3): find spectrum sudden change degree a
b(ω
i)=a
b-maxor prompt degree a
g(ω
i)=a
g-maxthe Frequency point ω at place
i;
Step (1-4): find described Frequency point ω
irear first spectrum sudden change degree be negative value or Frequency point ω
irear 3rd prompt degree is the Frequency point ω of negative value
j, this Frequency point ω
jbe harmonics frequencies omega
h.
As further preferably, described Δ ω is preferably set to 0.25Hz.
In general, the above technical scheme conceived by the present invention compared with prior art, mainly possesses following technological merit:
1. first, the invention solves in on-line measurement, measuring-signal is often subject to AC power frequency signal and the humorous wave interference of periodic motion parts and causes model analysis to occur the problem of false mode, can in unknown vibration signal frequency content, and the harmonics in signal is when often changing, accurate identification the harmonics frequency rejected in vibration signal, in effective weakening on-line measurement process, AC power frequency signal and rotary part periodic vibration signal are to the interference of Modal Parameter Identification, improve the accuracy of model analysis.
Secondly, this invention removes the personal error that operating personnel rely on experience to reject harmonics frequency to cause, detection efficiency is high, can obtain physical construction in working order under structural modal natural frequency, for physical construction ONLINE RECOGNITION and monitoring, and structural damage identification etc. provides strong instrument.
Accompanying drawing explanation
Fig. 1 is vibration signal power spectrum, spectrum sudden change degree and prompt degree schematic diagram;
Fig. 2 is frequency fence seam schematic diagram;
Fig. 3 is vibration signal power spectrum under lathe operating mode, spectrum sudden change degree and prompt degree instance graph.
Embodiment
In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.In addition, if below in described each embodiment of the present invention involved technical characteristic do not form conflict each other and just can mutually combine.
A kind of harmonics frequency identification and elimination method based on composing derivative and frequency fence seam of the present invention, the method calculates first order derivative (being referred to as spectrum sudden change degree) or the second derivative (being referred to as prompt degree) of the power spectrum of vibration original signal, near the harmonics frequency of periodic signal, the feature of extreme value is there is according to spectrum sudden change degree or prompt degree, can accurately locate harmonics Frequency point, as Fig. 1; Then occur the characteristic of spike at the fundamental frequency of periodic signal and integral multiple (i.e. frequency multiplication) place thereof according to the power spectrum of vibration original signal, the frequency fence arranging frequency domain narrower in width stitches, and the harmonics frequency that integral filter identifies, as Fig. 2; As seen from Figure 1, near the harmonic frequency such as 3.2,4,5,8 and 12Hz, the sudden change degree of response signal power spectrum presents " N " shape, there will be significantly positive and negative two kurtosis, and harmonic frequency is just in time that between two spikes, first sudden change degree is the point of negative value, this is because the power spectral value of several point suddenly increases before harmonic frequency, therefore the power spectrum first order derivative at these some places is the positive number maximum value of local, and harmonic frequency place is the starting point that power spectrum suddenly diminishes, therefore the first order derivative at this some place is the first negative value after positive number maximum value; And the power spectral value of several point still to reduce rapidly and the Amplitude Ratio harmonic frequency point place reduced is also large after harmonic frequency, therefore the negative maximum value in current situation portion can be pointed out at these.And the prompt degree of power spectrum presents " M " shape near harmonic frequency, analysis is carried out to the change of prompt degree known, harmonic frequency be first spike after the 3rd prompt degree be the point of negative value.And at other Frequency point places, power spectrum change is little, sudden change degree and prompt degree are all average level.As can be seen here, the sudden change degree near harmonic frequency is obviously different from other Frequency point places with Jie Du, and sudden change degree presents " N " shape, and prompt degree presents " M " shape.The essence of this phenomenon is that forced vibration response (or AC power power frequency component) does not have damping characteristic, and cause power spectrum to present the spike of sudden change at fundamental frequency and frequency multiplication place thereof, therefore, this rule has popularity and certainty.Meanwhile, the position of harmonic frequency point in sudden change degree and prompt degree is determined again, the first negative value point namely after " N " shape sudden change degree first spike, and after " M " shape victory degree first spike, the 3rd prompt degree is the point of negative value.Therefore, can according to these rules and characteristic, the harmonic frequency point in location response power spectrum signal is carried out by spectrum sudden change degree or prompt degree, realize when without automatically search when pre-known information frequency fence stitch centre frequency, coordinate frequency fence seam to filter the harmonics frequency identified simultaneously, can reach under the prerequisite of unknown vibration signal frequency content, the object of storage configuration natural frequency information while of identifying automatically and accurately and reject the harmonics frequency of undesired signal.
Embodiment 1:
The harmonics frequency identification of stitching based on spectrum sudden change degree and frequency fence and an elimination method, comprise the following steps:
(1) measure the X of lathe under machining state and the vibration response signal of Y-direction, obtain the vibration signal power spectrum G (ω) of X and Y-direction, wherein, signal sampling frequency is 1024Hz; And identify the natural frequency ω of all mode
j, utilize spectrum sudden change degree to identify harmonics frequencies omega from vibration signal power spectrum G (ω)
h;
(1-1) calculate the first order derivative of the vibration signal power spectrum G (ω) of lathe under machining state, namely compose sudden change degree a
b(ω), as Fig. 3, its frequency domain section is identical with the frequency domain section of vibration signal power spectrum G (ω), is the half of signal sampling frequency;
(1-2) the threshold value a of setting spectrum sudden change degree
bmaxequal each frequency point spectrum sudden change degree a
b(ω) 3 times of standard deviation;
(1-3) spectrum sudden change degree a is found
b(ω
i)=a
b-maxthe frequencies omega at place
i;
(1-4) frequencies omega is found
irear first spectrum sudden change degree is the Frequency point ω of negative value
j, it is respectively 0.25,5.25,16.75,33.25,200,300 and 321Hz, and these frequencies are harmonics frequencies omega
h;
(2) the harmonics frequencies omega by identifying
hbuild frequency fence seam and reject all harmonics frequencies
(2-1) the frequency domain width 2 Δ ω of setpoint frequency fence seam is 3Hz;
(2-2) frequencies omega centered by the harmonics frequency identified in step (1-4) respectively
ref, build frequency fence seam [ω
ref– Δ ω, ω
ref+ Δ ω], wherein ω
ref=n ω
h, n=1,2,3
(2-3) filter with the frequency fence seam built all natural frequency ω identified
j, the true natural frequency of structure can be obtained.
Embodiment 2:
The harmonics frequency identification of stitching based on Jie Du and frequency fence and an elimination method, comprise the following steps:
(1) measure the X of lathe under machining state and the vibration response signal of Y-direction, obtain the vibration signal power spectrum G (ω) of X and Y-direction, wherein, signal sampling frequency is 1024Hz; And identify the natural frequency ω of all mode
j, utilize prompt degree to identify harmonics frequencies omega from vibration signal power spectrum G (ω)
h;
(1-1) second derivative of the vibration signal power spectrum G (ω) of lathe under machining state is calculated, i.e. prompt degree a
g(ω), as Fig. 3, its frequency domain section is identical with the frequency domain section of vibration signal power spectrum G (ω), is the half of signal sampling frequency;
(1-2) the threshold value a of prompt degree is set
g-maxequal each Frequency point victory degree a
g(ω) 3 times of standard deviation;
(1-3) prompt degree a is found
g(ω
i)=a
g-maxthe frequencies omega at place
i;
(1-4) ω is found
irear 3rd prompt degree is the point of negative value, is respectively 0.25,5.25,16.75,33.25,200,300 and 321Hz, and these frequencies are harmonics frequencies omega
h;
(2) the harmonics frequencies omega by identifying
hbuild frequency fence seam and reject all harmonics frequencies:
(2-1) setpoint frequency fence seam half-breadth Δ ω is 1.5Hz;
(2-2) frequencies omega centered by the harmonics frequency identified in (1-4) respectively
h, build frequency fence seam [ω
ref– Δ ω, ω
ref+ Δ ω], wherein: ω
ref=n ω
h, n=1,2,3
(2-3) filter with the frequency fence seam built all natural frequency ω identified
jthe true natural frequency of structure can be obtained.
Those skilled in the art will readily understand; the foregoing is only preferred embodiment of the present invention; not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.
Claims (3)
1., based on harmonics frequency identification and an elimination method of composing derivative and frequency fence seam, it is characterized in that, comprise the steps:
Step (1): to the physical construction as measuring object, test its vibration response signal to obtain vibration response signal power spectrum G (ω), then calculate first order derivative or the second derivative of this vibration response signal power spectrum G (ω), obtain spectrum sudden change degree a thus
b(ω) or prompt degree a
g(ω), identify the natural frequency ω of all mode of physical construction simultaneously
j, then utilize spectrum sudden change degree a
b(ω) or prompt degree a
g(ω) from vibration response signal power spectrum G (ω), identify the harmonics frequencies omega of undesired signal
h, wherein ω represents frequency;
Step (2): by the harmonics frequencies omega identified
hbuild frequency fence seam and carry out following operation specifically:
Step (2-1): the centre frequency that frequency fence stitches is preset as ω
ref, frequency domain width is 2 Δ ω;
Step (2-2): build frequency fence seam [ω
ref– Δ ω, ω
ref+ Δ ω], wherein ω
ref=n ω
h, n is positive integer;
Step (2-3): the frequency fence seam built by step (2-2) is to all described natural frequency ω identified in step (1)
jperform filtration treatment, obtain the filter result of the true natural frequency reflecting described physical construction.
2. as claimed in claim 1 a kind of based on spectrum derivative and frequency fence seam harmonics frequency identification and elimination method, it is characterized in that, described step (1) comprises following sub-step:
Step (1-1): the first order derivative or the second derivative that calculate vibration signal power spectrum G (ω), obtains spectrum sudden change degree a
b(ω) or prompt degree a
g(ω), as follows:
or
Step (1-2): the threshold value of setting spectrum sudden change degree or prompt degree is respectively a
b-maxand a
g-max, wherein, obtain described spectrum sudden change degree a
b(ω) or prompt degree a
g(ω) standard deviation of each numerical value at each Frequency point place on frequency domain axle, described a
b-maxor a
g-maxbe set to 3 times of respective above-mentioned standard deviation;
Step (1-3): find spectrum sudden change degree a
b(ω
i)=a
b-maxor prompt degree a
g(ω
i)=a
g-maxthe Frequency point ω at place
i;
Step (1-4): find described Frequency point ω
irear first spectrum sudden change degree be negative value or Frequency point ω
irear 3rd prompt degree is the Frequency point ω of negative value
j, this Frequency point ω
jbe harmonics frequencies omega
h.
3. as claimed in claim 1 or 2 a kind of based on spectrum derivative and frequency fence seam harmonics frequency identification and elimination method, it is characterized in that, described Δ ω is preferably set to 0.25Hz.
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Cited By (1)
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| CN105628185A (en) * | 2015-12-28 | 2016-06-01 | 江西飞尚科技有限公司 | Vibration wire sensor triple-frequency shielding method |
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2015
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| US20080010039A1 (en) * | 2000-11-06 | 2008-01-10 | Nsk Ltd | Anomaly diagnosis apparatus and method of machine installation |
| CN101354315A (en) * | 2008-09-05 | 2009-01-28 | 爱立迈科（宁波）计测仪器有限公司 | Device and method for tracking and detecting engine state based on vibration signal |
| CN104198031A (en) * | 2014-07-30 | 2014-12-10 | 东风康明斯发动机有限公司 | Torsional vibration signal detection method and device for engine crankshaft |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105628185A (en) * | 2015-12-28 | 2016-06-01 | 江西飞尚科技有限公司 | Vibration wire sensor triple-frequency shielding method |
| CN105628185B (en) * | 2015-12-28 | 2018-11-06 | 江西飞尚科技有限公司 | A kind of vibrating wire sensor frequency tripling screen method |
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| CN105157820B (en) | 2018-01-26 |
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