CN105509776B - The method and apparatus measured using vibrating string type sensor into Mobile state - Google Patents
The method and apparatus measured using vibrating string type sensor into Mobile state Download PDFInfo
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- CN105509776B CN105509776B CN201510835532.1A CN201510835532A CN105509776B CN 105509776 B CN105509776 B CN 105509776B CN 201510835532 A CN201510835532 A CN 201510835532A CN 105509776 B CN105509776 B CN 105509776B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/243—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the phase or frequency of ac
Abstract
The present invention relates to the method and apparatus measured using vibrating string type sensor into Mobile state.This method comprises the following steps：Pumping signal is produced in predetermined period to encourage vibrating string type sensor；Stopping excitation period acquisition inductive signal corresponding with the vibration signal of vibrating string type sensor；The inductive signal is amplified；Analog-digital Converter is carried out to amplified inductive signal, obtains discrete signal R (n)；Hilbert transform is carried out to the discrete signal R (n), and calculates the phase angle theta of Hilbert transform result X (n)n；And the sample frequency f according to the Analog-digital ConvertersAnd the difference delta θ of the phase anglen, draw the instantaneous frequency f of measured signaln=Δ θnfs/ (2 π), wherein, n is integer.The present invention also provides the device for performing the above method.The temporal resolution of measurement can be substantially improved in the present invention in the case where ensureing measurement accuracy than conventional method, so as to be measured suitable for dynamic.
Description
Technical field
The present invention relates to vibrating string type sensor, more particularly to using vibrating string type sensor into the method that Mobile state measure with
Device.
Background technology
Vibrating string type sensor is the resonant transducer using the metallic cord of tensioning as sensing element, using than wide.This
Kind sensor is changed by certain mechanical structure, can be converted into shaking by the various physical quantitys such as displacement, tension force, pressure, stress
The tension force of string.When the length of string is fixed, the change of its eigentone reflects its tension variation.By measuring electricity accordingly
Road, can be converted into electric frequency signal by the tension force of vibratory string and measure, so as to fulfill the measurement to various physical quantitys.
In traditional vibrating string type sensor measuring method, the electric signal after conversion is acquired, is then carried out discrete
Fourier transformation, to obtain accurate frequency information；Alternatively, amplifying shaping to the electric signal after conversion, timer capture is utilized
Signal frequency after shaping, to obtain frequency information.Both modes have the problem of a common, are exactly temporal resolution and frequency
There are serious contradiction for resolution ratio two indices：To improve temporal resolution, then measurement result precision (frequency resolution) must
It is so very poor；To improve measurement accuracy, frequency resolution must be improved, then can lose temporal resolution.
Traditional vibrating string type sensor focuses on measurement accuracy index, it is necessary to improve the frequency discrimination of measurement in use
Rate, thus the temporal resolution of measurement can not be improved.Therefore, traditional vibrating string type sensor measuring method is suitable only for very low
Sample frequency work, for example 1Hz is even lower.However, in the dynamic measurement of such as building structure, it is often desired to sampling frequency
Rate can reach 50Hz even more highs.In this case will be unable to use traditional vibrating string type sensor measuring method, can only be by
In other sensors, such as fiber bragg grating sensor, resistance sensor etc..Compared to other sensors, vibrating string type sensor
There is significant advantage in accuracy, stability, long term drift of measurement etc., measured if it can be overcome to be not useable for dynamic
The defects of, then it can play the effect of bigger.
The content of the invention
To overcome above-mentioned traditional vibrating string type sensor to be not useable for the defects of dynamic measures, the present invention provides a kind of use
The method and apparatus that vibrating string type sensor is measured into Mobile state.
A kind of method measured using vibrating string type sensor into Mobile state according to the present invention is comprised the following steps：Predetermined
Period produces pumping signal to encourage vibrating string type sensor；Stopping the acquisition of excitation period and the vibration signal of vibrating string type sensor
Corresponding inductive signal；The inductive signal is amplified；Analog-digital conversion is carried out to amplified inductive signal, is obtained discrete
Signal R (n)；Hilbert transform is carried out to the discrete signal R (n), and calculates the phase angle of Hilbert transform result X (n)
θn；And the sample frequency f according to the analog-digital conversionsAnd the difference delta θ of the phase anglen, draw measured signal
Instantaneous frequency fn=Δ θnfs/ (2 π), wherein, n is integer.
A kind of device measured using vibrating string type sensor into Mobile state according to the present invention is included：Vibrating string type sensor；
Driver/vibration pickup, for producing pumping signal in predetermined period to encourage vibrating string type sensor, and is obtained in stopping excitation period
Take inductive signal corresponding with the vibration signal of vibrating string type sensor；Amplifier, for the inductive signal to be amplified；Simulation-number
Word converter, for carrying out analog-digital conversion to amplified inductive signal, obtains discrete signal R (n)；And microprocessor
Device, for carrying out Hilbert transform to the discrete signal R (n), calculates the phase angle theta of Hilbert transform result X (n)n, and
And according to the sample frequency f of analogue-to-digital converterssAnd the difference delta θ of the phase anglen, draw the instantaneous frequency of measured signal
fn=Δ θnfs/ (2 π), wherein, n is integer.
The present invention handles the signal of vibrating string type sensor by the way of Hilbert transform, and measurement is used as using instantaneous frequency
As a result, it is thus possible to which, in the case where ensureing measurement accuracy, that is, frequency resolution, the mode than traditional steady frequency is substantially improved
The temporal resolution of measurement, so as to be measured suitable for dynamic.
Brief description of the drawings
The illustrative embodiments of the present invention are described in more detail in conjunction with the accompanying drawings, it is of the invention above-mentioned and
Other purposes, feature and advantage will be apparent.
Fig. 1 is a kind of structure of device measured using vibrating string type sensor into Mobile state according to an embodiment of the invention
Figure.
Embodiment
The preferred embodiment of the present invention is described in more detail below.
According to one embodiment of present invention, a kind of method measured using vibrating string type sensor into Mobile state is included following
Step：
● pumping signal is produced to encourage vibrating string type sensor in predetermined period by driver
Motivational techniques can be any one in pulse excitation, swept frequency excitation, environmental excitation three.The purpose of excitation is to make
The vibration of vibrating string type sensor vibratory string has sufficiently large amplitude, easy to measure.Driver stops swashing in gatherer process is measured
Encourage, vibratory string is in free vibration state.
● stop excitation period by vibration pickup acquisition sensing corresponding with the vibration signal of vibrating string type sensor in driver
Signal
During the vibratory string vibration of vibrating string type sensor, due to magnetoelectric effect, it can produce in the coil of vibration pickup and believe with vibration
Number corresponding inductive signal, such as induced voltage signal.Since vibration signal is very faint, caused induced voltage signal shakes
Width is usually between 100 μ V~10mV.
Assuming that measurand is s (t), wherein t represents time, the signal frequency f (t) that vibration pickup is obtained=F (s
(t)), wherein function F is determined by the mechanical structure and tensioning string principle of vibrating string type sensor, is known function.So, vibration pickup
The signal obtained can be expressed as V0(t)=A (t) sin (θ (t)), whereinA (t) represents letter
Number amplitude.
● the inductive signal is amplified by amplifier
Vibration pickup obtain inductive signal by front-end amplifier amplification, such as signal amplitude can be amplified to 100mV~
Between 3V.Amplified inductive signal can be expressed as V1(t)=KV0(t), wherein K is amplification coefficient.
● amplified inductive signal is AD converted by analog to digital (AD) converter, obtains discrete signal R (n)
Obtained discrete signal R (n) can be expressed as R (n)=V1(n/fs), wherein n is integer, fsFor a/d converter
Sample frequency.
● Hilbert transform is carried out to the discrete signal R (n) by microprocessor, calculates Hilbert transform result X
(n) phase angle thetan, and according to the sample frequency f of a/d convertersAnd the difference delta θ of the phase anglen, draw measured signal
Instantaneous frequency fn=Δ θnfs/(2π)
Hilbert transform is the algorithm known of signal processing technology field, it is necessary to the convolution algorithm of complexity be carried out, to hard
Part requires higher.Since processed signal stream should be counted as Infinite Sequences, (if necessary, measurement process can be straight with one
Row goes down), and Hilbert transform is only applicable to time-limited sequence, therefore segment processing can be carried out to signal, and use
Overlap-add method or overlap-save method eliminate because segmentation and caused by edge effect.
For example, microprocessor can use finite impulse response (FIR) hilbert filter to discrete signal R (n) into
Row Hilbert transform, including carry out the convolution fortune of the system function h (n) and discrete signal R (n) of FIR hilbert filters
Calculate I (n)=h (n) * R (n).In this case, Hilbert transform result
Wherein AnRepresent signal amplitude,
For example, the system function h (n) that can set FIR hilbert filters has following frequency response characteristic：
Wherein,
H (n) is an Infinite Sequences (n values are whole integer space), when real system is realized, can to h (n) into
Row truncation, retains finite length.The sequence increases with n, and value levels off to zero.Assuming that intercepted length is N, (N is
It is usually odd number for the exponent number of FIR hilbert filters), then n value ranges areThe selection of N and meter
It is related to computation complexity to calculate precision.N values are bigger, then FIR hilbert filters more approach ideal performance, but operand
Increase therewith.The selection of N can also influence the accuracy and system delay of Hilbert transform, and system delay is (N+1)/(2fs)。
In addition, the difference delta θ of phase anglenIt can be calculated as below：
Each step of the above method of the present invention can be performed by the corresponding component of device as shown in Figure 1.The device
Including vibrating string type sensor, driver/vibration pickup, amplifier, a/d converter and microprocessor.Driver/vibration pickup is pre-
The timing phase produces pumping signal to encourage vibrating string type sensor, and is stopping the acquisition of excitation period and the vibration of vibrating string type sensor
The corresponding inductive signal of signal.Amplifier amplifies the inductive signal.A/d converter carries out AD to amplified inductive signal and turns
Change, obtain discrete signal R (n), wherein n is integer.Microprocessor carries out Hilbert transform to discrete signal R (n), calculates
The phase angle theta of Hilbert transform result X (n)n, and according to the sample frequency f of a/d convertersAnd the difference delta of the phase angle
θn, draw the instantaneous frequency f of measured signaln=Δ θnfs/(2π)。
In the present invention, with sample frequency fsDiscrete signal R (n) is obtained, and exports instantaneous frequency fnFrequency be equal to sampling
Frequency fs, therefore export instantaneous frequency fnTemporal resolution be Δ T1=1/fs.And in the mode of conventionally employed Fourier transformation
In the method for obtaining signal frequency, frequency resolution fs/ M, corresponding temporal resolution are Δ T2=M/fs, wherein M is quick
The sequence length of Fourier transformation, usual M value ranges are 100~10000.Therefore Δ T1＜ ＜ Δs T2.That is, compared to tradition side
Method, the present invention greatly improve the temporal resolution of measurement, so as to be measured suitable for dynamic.
The embodiment of the present invention is the foregoing described, described above is only exemplary, and nonrestrictive.Based on above stating
Bright, those of ordinary skill in the art are readily apparent that various modifications and change to the embodiment of the present invention, these modifications and change
More it is within.
Claims (4)
1. a kind of method measured using vibrating string type sensor into Mobile state, is comprised the following steps：
Pumping signal is produced in predetermined period to encourage vibrating string type sensor；
Stopping excitation period acquisition inductive signal corresponding with the vibration signal of vibrating string type sensor；
The inductive signal is amplified；
Analog-digital conversion is carried out to amplified inductive signal, obtains discrete signal R (n)；
Hilbert transform is carried out to the discrete signal R (n), and calculates the phase angle theta of Hilbert transform result X (n)n；And
According to the sample frequency f of the analog-digital conversionsAnd the difference delta θ of the phase anglen, draw the instantaneous of measured signal
Frequency fn=Δ θnfs/ (2 π),
Wherein, n is integer.
2. the method according to claim 1, wherein,
The Hilbert transform is realized using finite impulse response hilbert filter；
The Hilbert transform include carrying out the system function h (n) of the finite impulse response hilbert filter with it is described
The convolution algorithm I (n) of discrete signal R (n)=h (n) * R (n)；
The Hilbert transform resultWherein AnRepresent signal amplitude,
3. a kind of device measured using vibrating string type sensor into Mobile state, including：
Vibrating string type sensor；
Driver and vibration pickup, wherein, the driver is used to produce pumping signal in predetermined period to encourage type vibration wire to sense
Device, is stopping excitation period, and the vibration pickup is used to obtain inductive signal corresponding with the vibration signal of vibrating string type sensor；
Amplifier, for the inductive signal to be amplified；
Analogue-to-digital converters, for carrying out analog-digital conversion to amplified inductive signal, obtain discrete signal R (n)；
And
Microprocessor, for carrying out Hilbert transform to the discrete signal R (n), calculates Hilbert transform result X (n)
Phase angle thetan, and according to the sample frequency f of analogue-to-digital converterssAnd the difference delta θ of the phase anglen, draw tested letter
Number instantaneous frequency fn=Δ θnfs/ (2 π),
Wherein, n is integer.
4. device according to claim 3, wherein,
Microprocessor realizes the Hilbert transform using finite impulse response hilbert filter；
The Hilbert transform include carrying out the system function h (n) of the finite impulse response hilbert filter with it is described
The convolution algorithm I (n) of discrete signal R (n)=h (n) * R (n)；
The Hilbert transform resultWherein AnRepresent signal amplitude,
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| CN101038310A (en) * | 2007-02-07 | 2007-09-19 | 北京航空航天大学 | Digital detecting system of resonant transducer sensitive structure frequency characteristic |
| KR101044626B1 (en) * | 2009-07-14 | 2011-06-29 | 주식회사 디에스텍 | System to measure a resonant frequency of a vibrating-wire sensor using a digital counter |
| CN202255617U (en) * | 2011-09-16 | 2012-05-30 | 重庆恩菲斯软件有限公司 | Vibrating wire type data acquisition device |
| CN104764482A (en) * | 2015-04-14 | 2015-07-08 | 上海同磊土木工程技术有限公司 | Multifunctional full-automatic acquisition instrument with vibration wire sensors |
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| Title |
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| 振弦式传感器动态测试机理研究;徐承军等;《仪表技术与传感器》;20111231(第12期);第99-101页 * |
| 振弦式传感器用于动态测试的可行性分析;徐承军等;《武汉理工大学学报（交通科学与工程版）》;20120131;第36卷(第1期);第107-110页 * |
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