CN108444591A - The method that residual periodic sampling determines shake table vibration level - Google Patents
The method that residual periodic sampling determines shake table vibration level Download PDFInfo
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- CN108444591A CN108444591A CN201810060713.5A CN201810060713A CN108444591A CN 108444591 A CN108444591 A CN 108444591A CN 201810060713 A CN201810060713 A CN 201810060713A CN 108444591 A CN108444591 A CN 108444591A
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- vibration level
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H17/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves, not provided for in the preceding groups
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Abstract
The invention discloses the methods that residual periodic sampling determines shake table vibration level, are sampled to shake table output waveform and obtain sampled data, and sampling duration is less than a cycle, the current vibration level for carrying out Amplitude Estimation by sampled data, obtaining shake table.The present invention carries out residual periodic sampling when vibration level is tested to vibration level, and ultralow frequency sinusoidal signal amplitude is quickly estimated using sampled data, obtains current vibration level, saves the sampling time.
Description
Technical field
The present invention relates to a kind of determination methods to shake table vibration level.
Background technology
In numerous methods of vibration-measuring sensor Calibration of Dynamic, single-frequency steady-state advocate approach has calibration accuracy height, school
Quasi- wide frequency range, the advantages of facilitating realization to automatically control, various countries generally vibrate benchmark according to this method building national.Single-frequency
Steady stimulation method is usually to generate vibration source with electromagnetic vibration generator system, while detection is previously installed at the sensor on vibration table surface
Output voltage signal and laser interferometer output signal (absolute method) or standard transducer output signal (relative method),
And the relevant parameter of sensor is calculated by machine solution.It is referred to electromagnetic vibration generator system since electromagnetic vibration generator system generates vibration source
Drive the specified amplitude under assigned frequency, and in view of reasons such as shake table transient response and degree of regulation, cannot a step arrive
It is adjusted to position target vibration level, but should gradually control the amplitude of excitation acceleration, until vibration level is met the requirements.But it is right
In the calibration of ultralow frequency vibration-measuring sensor, the signal period is long, time the lengthening with the signal period of vibration level adjustment
It lengthens again, seriously affects the calibration efficiency of ultralow frequency vibration-measuring sensor.And the test of vibration level is in conventional vibration level method of adjustment
First vibration level is waited for stablize, then test method complete cycle is used to be tested, and when testing low frequency, the period is longer, complete cycle
Sampling needs a large amount of time, seriously affects testing efficiency, reduces the working efficiency of tester.
Invention content
It is that can determine to shake that the purpose of the present invention is to provide one kind by carrying out residual periodic sampling to shake table output signal
The method of grade.
The method that residual periodic sampling determines shake table vibration level, it is characterised in that：Shake table output waveform is adopted
Sample data, sampling duration are less than a cycle, the current vibration level for carrying out Amplitude Estimation by sampled data, obtaining shake table.
Further, the amplitude that current period is estimated in such a way that data are by solution inconsistent equation group, is currently shaken
Grade.
Further, every time for estimate that the sampled data of vibration level occupies when a length of vibration period 10%~30%.
Further, the displacement signal of sampled data isWherein,c3=d, x (k) are the displacement that sampling obtains
Waveform, k indicate that k-th of sampled point, A are the vibration displacement amplitude of shake table, and f is vibration frequency, fsFor sample frequency,For phase
Position, d is DC quantity, if total sampling number is N, N<(fs/ f), the value range of k is 0,1,2,3 ..., N-1, wherein x (k) sequences
It is classified as test gained, fsIt is user's setting value with f, is known quantity.
Feedback control technology, waveform distortion very little, so sampling are introduced when ultralow frequency is tested based on shake table
To displacement signal (sampled data) sinusoidal waveform in residual period can be regarded as, it is assumed that be
In formula, x (k) is the displacement waveform that sampling obtains；K indicates k-th of sampled point；A is the vibration displacement width of shake table
Value；F is vibration frequency；fsFor sample frequency；For phase；D is DC quantity.If total sampling number is N, N<(fs/ f), k's takes
Value ranging from 0,1,2,3 ..., N-1.Wherein, x (k) sequences are test gained, fsIt is user's setting value with f, as known quantity,
Amplitude A, phaseIt is amount to be asked with DC quantity d.
Formula (1) is melted into following form
In formula,c3=d.Formula (2) is converted to matrix form to obtain
In formula, frequency f and sample rate fsFor known quantity, i.e. left side first item is known terms, is calculated as matrix K；The left side second
Item is item to be asked, and is calculated as vectorial C；The right is the sequence that sampling obtains, and is also known quantity, is calculated as vectorial X, then can write a Chinese character in simplified form above formula
For
KC=X, (4)
It is 3 column matrix of N rows by K, inverse matrix is not present, can obtain
C=(KTK)-1KTX. (5)
After acquiring C, can acquire A,It is respectively with d
The present invention carries out residual periodic sampling when vibration level is tested to vibration level, and ultralow frequency sine is quickly estimated using sampled data
Signal amplitude obtains current vibration level, saves the sampling time.
Description of the drawings
Fig. 1 is the evaluated error under different cycles ratio.
Fig. 2 is the evaluated error under the different wave distortion factor.
Fig. 3 is the evaluated error under out of phase.
Fig. 4 is the evaluated error under different opposite DC quantities.
Specific implementation mode
The method that residual periodic sampling determines shake table vibration level samples shake table output waveform and obtains sampled data, sampling
Duration is less than a cycle, the current vibration level for carrying out Amplitude Estimation by sampled data, obtaining shake table.
The maximum amplitude of current period is estimated in such a way that data are by solution inconsistent equation group, which is to work as
Preceding vibration level.
Every time for estimate that the sampled data of vibration level occupies when a length of vibration period 10%~30%.
The displacement signal of sampled data isWherein,c3=d, x (k) are the displacement that sampling obtains
Waveform, k indicate that k-th of sampled point, A are the vibration displacement amplitude of shake table, and f is vibration frequency, fsFor sample frequency,For phase
Position, d is DC quantity, if total sampling number is N, N<(fs/ f), the value range of k is 0,1,2,3 ..., N-1, wherein x (k) sequences
It is classified as test gained, fsIt is user's setting value with f, is known quantity.
Feedback control technology, waveform distortion very little, so sampling are introduced when ultralow frequency is tested based on shake table
To displacement signal (sampled data) sinusoidal waveform in residual period can be regarded as, it is assumed that be
In formula, x (k) is the displacement waveform that sampling obtains；K indicates k-th of sampled point；A is the vibration displacement width of shake table
Value；F is vibration frequency；fsFor sample frequency；For phase；D is DC quantity.If total sampling number is N, N<(fs/ f), k's takes
Value ranging from 0,1,2,3 ..., N-1.Wherein, x (k) sequences are test gained, fsIt is user's setting value with f, as known quantity,
Amplitude A, phaseIt is amount to be asked with DC quantity d.
Formula (1) is melted into following form
In formula,C3=d.Formula (2) is converted to matrix form to obtain
In formula, frequency f and sample rate fsFor known quantity, i.e. left side first item is known terms, is calculated as matrix K；The left side second
Item is item to be asked, and is calculated as vectorial C；The right is the sequence that sampling obtains, and is also known quantity, is calculated as vectorial X, then can write a Chinese character in simplified form above formula
For
KC=X, (4)
It is 3 column matrix of N rows by K, inverse matrix is not present, can obtain
C=(KTK)-1KTX. (5)
After acquiring C, can acquire A,It is respectively with d
The present invention is not passive when vibration level is tested blindly to wait for vibration level to stablize, and is adopted to the vibration level progress residual period
Sample quickly estimates ultralow frequency sinusoidal signal amplitude using sampled data, obtains current vibration level, saves the sampling time.
The simulation analysis of residual period ultralow frequency sinusoidal signal amplitude method for quick estimating is as follows：
Based on the residual period ultralow frequency sinusoidal signal Amplitude Estimation method of solution inconsistent equation group, can be used for underestimating one
The parameters such as the amplitude of sinusoidal signal of a periodic sampling time.In order to verify the validity of this method, following emulation point is carried out
Analysis.
For one section of sinusoidal waveform, waveform length, waveform distortion, DC quantity and phase etc. may be to estimating matter
Amount has an impact, and waveform length here refers to that time span, same time span are all for different frequency signals
Issue is different, for example 10s time spans are only ten/a cycle for 0.01Hz signals, and then for 0.1Hz signals
A cycle, therefore it is nonsensical directly to investigate influence of the absolute time length to predicted magnitude, it should with waveform time with
The ratio of whole cycle time indicates, referred to as period proportional, is indicated with percentage；Waveform distortion refers to total harmonic distortion rate
(THD, Total Harmonic Distortion) indicates that a signal deviates the degree of single frequency sinusoidal signal, can be in addition to base
Outside wave all harmonic energies and square root with the ratio of fundamental wave energy calculate, for the distortion factor emulation herein by
A certain amount of white noise is added in sinusoidal signal to realize, waveform distortion is also denoted as percentage；Equally, DC quantity absolute magnitude
It to indicate also without practical significance, therefore is indicated with the ratio of DC quantity and actual magnitude, referred to as with respect to DC quantity.What phase referred to
It is the initial phase of waveform to be measured, unit expenditure indicates.
The present embodiment carries out numerical simulation using LabVIEW softwares to this method, mainly has studied period proportional, waveform loses
The influences of the factors to evaluated error such as true degree, phase, opposite DC quantity, the evaluated error amplitude resolved and setting amplitude
Between the ratio of difference and setting amplitude indicate that and take percentage, it is more accurate that value indicates to resolve closer to " 0 ".
(1) period proportional
Influence of the emulation cycle ratio to estimated accuracy first keeps other parameters constant, i.e. wave using control variate method
The shape distortion factor takes 0.05%, and phase takes 60 °, and opposite DC quantity takes 10%, only changes period proportional, the then change of recording error
Change.Since this paper is tested mainly for the amplitude of a cycle time following sinusoidal signal, period proportional takes 0~100%,
Simulation result is as shown in Figure 1.It can be seen from the figure that the period proportional of waveform has a significant effect to evaluated error, especially in week
When phase ratio is less than 10%, calculated error is larger；When period proportional reaches 10%, error can meet within 1%
The required precision quickly tested.
(2) waveform distortion
Influence of the waveform distortion to estimated accuracy is studied, using control variate method, keeps other parameters constant, i.e. the period
Ratio takes 10%, and phase takes 60 °, and opposite DC quantity takes 10%, only changes waveform distortion, the then variation of recording error.Wave
The shape distortion factor is emulated from 0% to 1%, and simulation result is as shown in Figure 2.It can be seen from the figure that waveform distortion and calculating
The error gone out is substantially proportional to relationship, and waveform distortion is bigger, and error is also bigger.Under conditions of having feedback, shake table is low
The displacement distortion factor of frequency range generally 0.05% hereinafter, according to simulation result, the displacement distortion factor at 0.05% error 1% with
It is interior, the required precision quickly tested can be met.
(3) phase
Influence of the phase to estimated accuracy is emulated, using control variate method, keeps other parameters constant, i.e., period proportional takes
10%, waveform distortion takes 0.05%, and opposite DC quantity takes 10%, only changes phase, then the situation of change of recording error.Phase
Position ° is emulated from 0 ° to 360, and simulation result is as shown in Figure 3.It can be seen from the figure that the phase of waveform and the relationship of error
Substantially it is in SIN function relationship, is maximized respectively in 60 ° and 240 ° and minimum value, but error is within 1%, Ke Yiman
The required precision that foot is quickly tested.
(4) opposite DC quantity
Opposite influence of the DC quantity to estimated accuracy of emulation, also uses control variate method, keeps other parameters constant, i.e., all
Phase ratio takes 10%, waveform distortion that 0.05%, phase is taken to take 60 °, only changes opposite DC quantity, the then change of recording error
Change.It is 0-1 to take opposite DC quantity according to actual conditions, and simulation result is as shown in Figure 4.It can be seen from the figure that with relatively straight
The variation of flow, calculated error do not have significant change, illustrate that opposite DC quantity does not have shadow to the result of calculation of this method
It rings.
In conclusion this method can utilize the sine wave signal of 10% period proportional, under lower waveform distortion
The amplitude of sinusoidal signal is estimated, averaged power spectrum error is better than 1%, therefore this method can be used for the test of ultralow frequency vibration level
In.
Content described in this specification embodiment is only enumerating to the way of realization of inventive concept, protection of the invention
Range is not construed as being only limitted to the concrete form that embodiment is stated, protection scope of the present invention is also and in art technology
Personnel according to present inventive concept it is conceivable that equivalent technologies mean.
Claims (4)
1. the method that residual periodic sampling determines shake table vibration level, it is characterised in that：Sampled data is obtained to shake table waveform sampling,
It samples duration and is less than a cycle, the current vibration level that Amplitude Estimation is carried out by sampled data, obtains shake table.
2. the method that residual periodic sampling as described in claim 1 determines shake table vibration level, it is characterised in that：Passed through using data
The mode of solution inconsistent equation group estimates the maximum amplitude of current period, which is current vibration level.
3. the method that residual periodic sampling as claimed in claim 1 or 2 determines shake table vibration level, it is characterised in that：Sample duration
More than the 10% of the vibration period.
4. the method that residual periodic sampling as claimed in claim 3 determines shake table vibration level, it is characterised in that：The position of sampled data
Shifting signal isWherein,
c3=d, x (k) are the displacement waveform that sampling obtains, and k indicates that k-th of sampled point, A are the vibration displacement amplitude of shake table, and f is to shake
Dynamic frequency, fsFor sample frequency,For phase, d is DC quantity, if total sampling number is N, N<(fs/ f), the value range of k is
0,1,2,3 ..., N-1, wherein x (k) sequences are test gained, fsIt is user's setting value with f, is known quantity.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0124136B1 (en) * | 1983-05-03 | 1989-03-15 | Alfons Dr.-Ing. Schmidt | Process and device for steering, controlling and regulating vibrating and quality control test stands |
| CN102230821A (en) * | 2011-04-11 | 2011-11-02 | 浙江大学 | Method for rapidly adjusting vibration level of ultralow-frequency vibration table |
| CN105628189A (en) * | 2016-01-08 | 2016-06-01 | 中国航空工业集团公司上海航空测控技术研究所 | Helicopter body vibration signal adaptive processing method |
| CN106768757A (en) * | 2016-12-06 | 2017-05-31 | 中国人民解放军国防科学技术大学 | Shake table ultralow frequency sine sweep signal amplitude recognition methods based on variable sampling rate sampling |
-
2018
- 2018-01-22 CN CN201810060713.5A patent/CN108444591A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0124136B1 (en) * | 1983-05-03 | 1989-03-15 | Alfons Dr.-Ing. Schmidt | Process and device for steering, controlling and regulating vibrating and quality control test stands |
| CN102230821A (en) * | 2011-04-11 | 2011-11-02 | 浙江大学 | Method for rapidly adjusting vibration level of ultralow-frequency vibration table |
| CN105628189A (en) * | 2016-01-08 | 2016-06-01 | 中国航空工业集团公司上海航空测控技术研究所 | Helicopter body vibration signal adaptive processing method |
| CN106768757A (en) * | 2016-12-06 | 2017-05-31 | 中国人民解放军国防科学技术大学 | Shake table ultralow frequency sine sweep signal amplitude recognition methods based on variable sampling rate sampling |
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| 梁志国等: "残周期正弦波形的四参数拟合", 《计量学报》 * |
| 王志鹏等: "基于专家系统的振动台振级调整算法研究", 《振动与冲击》 * |
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Application publication date: 20180824 |