CN107063545B - Cable force motion detector based on correction FFT algorithm and algorithm thereof - Google Patents
Cable force motion detector based on correction FFT algorithm and algorithm thereof Download PDFInfo
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- CN107063545B CN107063545B CN201611182472.9A CN201611182472A CN107063545B CN 107063545 B CN107063545 B CN 107063545B CN 201611182472 A CN201611182472 A CN 201611182472A CN 107063545 B CN107063545 B CN 107063545B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/04—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring tension in flexible members, e.g. ropes, cables, wires, threads, belts or bands
- G01L5/10—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring tension in flexible members, e.g. ropes, cables, wires, threads, belts or bands using electrical means
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- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
- Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
Abstract
The invention relates to a cable force motion detector based on a correction FFT algorithm and an algorithm thereof, belongs to the field of civil engineering, and is applied to the structural safety and health monitoring industry. The system comprises a vibration sensor, an anti-aliasing filter, an ADC (analog to digital converter), an embedded processor, a keyboard, an RTC (real time clock) real time clock, a power management module, an LCD (liquid crystal display) and a DSP (digital signal processor); the vibration sensor is connected with the anti-aliasing filter, the anti-aliasing filter is connected with the ADC converter, and the ADC converter is connected with the embedded processor; the keyboard, RTC real-time clock, LCD display and DSP processor are all connected with the embedded processor. The invention obtains accurate actual frequency value by utilizing the modified FFT algorithm, so that the frequency value accuracy of the force value measurement through the modified FFT algorithm is within five parts per million, the frequency accuracy after the conventional FFT calculation is only about 2% at most, and the error is larger along with the frequency reduction.
Description
Technical Field
The invention relates to a cable force motion detector based on a correction FFT algorithm and an algorithm thereof, belongs to the field of civil engineering, and is applied to the structural safety and health monitoring industry.
Background
The prior art comprises the following steps: although the traditional cable force test system is subjected to time domain sampling and FFT (fast Fourier transform) conversion into a frequency domain, due to the limitation of the number of sampling points and the computing capability of a device processor, the frequency accuracy cannot be quite high, and the tested object is a bridge cable and belongs to a low-frequency signal, and the influence of the frequency accuracy on the measurement accuracy is quite large, so that the cable force measurement error is quite large.
Such as the frequency resolution formula af=sf/N for conventional FFT calculations, where SF is the sampling rate, N is the number of samples, assuming a sampling rate of 200Hz, the number of samples is 500,then Δf=0.4 Hz, the frequency error is 0.2Hz at maximum, and the calculation formula is based on the cable force(n is the frequency order, defaults to 1,4 ml) 2 Constant), assuming that the measured frequency of the measured cable is 2.4Hz and the actual frequency is 2.2Hz, the force value error will be (5.76-4.84)/4.84=19%, so the accuracy of the frequency measurement will have a very large impact on the final force value.
Disclosure of Invention
The invention aims to provide a cable force motion detector based on a correction FFT algorithm and an algorithm thereof, wherein the FFT spectrum is discrete spectrum transformation with windowing and cutting, so that leakage phenomenon can be generated, the actual frequency f value is reversely deduced by the FFT spectrum, the influence of a window function is considered, the size of f is considered, namely the position of the frequency on the FFT spectrum is considered, after FFT conversion is carried out on a time domain signal, the influence of the position of the signal frequency on the FFT is utilized to find out the algorithm of FFT correction, the frequency measurement precision of the cable force motion detector is greatly improved, and the cable force measurement precision is improved, so that the use value of equipment is further improved.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a cable force motion detector based on a correction FFT algorithm comprises a vibration sensor, an anti-aliasing filter, an ADC (analog-to-digital converter), an embedded processor, a keyboard, an RTC (real time clock), a power management module, an LCD (liquid crystal display) and a DSP (digital signal processor);
the vibration sensor is connected with the anti-aliasing filter, the anti-aliasing filter is connected with the ADC converter, and the ADC converter is connected with the embedded processor;
the keyboard, RTC real-time clock, LCD display and DSP processor are all connected with the embedded processor.
A modified FFT algorithm for the cable force tester:
after the time domain signal is subjected to FFT conversion, an FFT correction algorithm is obtained on the influence of the position of the signal frequency in the FFT on leakage, and the specific calculation method comprises the following steps: setting the amplitude of the fundamental frequency signalDegree of A n Frequency f n The amplitudes of the first two points and the last two points of the fundamental frequency signal on the FFT spectrum are A respectively n-2 、A n-1 ，A n+1 、A n+2 When A is n-2 2 + A n-1 2 Greater than A n+2 2 + A n+1 2 I.e. when the sum of the powers of the first two points of the fundamental frequency signal is greater than the sum of the powers of the second two points of the fundamental frequency signal, the modified frequency value is equal to fx=f n +[1-（A n-2 2 + A n-1 2 ）/（A n-2 2 + A n-1 2 + A n 2 + A n+2 2 + A n+1 2 ）]；
Equivalent A n-2 2 + A n-1 2 Less than A n+2 2 + A n+1 2 I.e. the sum of the powers of the two points before the fundamental frequency signal is smaller than the sum of the powers of the two points after the fundamental frequency, the modified frequency value is equal to fx=f n +[1+（A n+2 2 + A n+1 2 ）/（A n-2 2 + A n-1 2 + A n 2 + A n+2 2 + A n+1 2 ）]Thus, a high-precision corrected frequency value is obtained;
then through classical cable force calculation formulaCalculating to obtain a cable force value, wherein l is the cable length, m is the cable weight per unit length, and f n Is the nth order vibration frequency.
The invention realizes the principle: since the fundamental frequency, the second order, the third order and the like of the cable force are all obtained by obtaining the maximum amplitude value of the frequency point, after the FFT transformation, all the points such as fundamental frequency, Δf=sf/N, which are only points with equal interval frequency resolution of the FFT, are only points with integral multiple sampling, the actual frequency falls on the points with the FFT frequency resolution, which is basically not used in practice, because the actual frequency is random and real, if the actual frequency is required to obtain high-precision frequency resolution, the sampling rate needs to be reduced and the sampling point needs to be increased, but both the measures are difficult to operate in practice, the sampling rate may not meet the sampling theorem, and the sampling point needs to be increased, so that the processor of the device has strong operation capability, and can be realized without loss in cost.
The invention has the beneficial effects that:
the invention obtains accurate actual frequency value by utilizing the modified FFT algorithm, so that the frequency value accuracy of the force value measurement through the modified FFT algorithm is within five parts per million, the frequency accuracy after the conventional FFT calculation is only about 2% at most, and the error is larger along with the frequency reduction.
Drawings
FIG. 1 is a block diagram of the structure of the present invention;
fig. 2 is a flowchart of the algorithm of the present invention.
Detailed Description
The invention is described in detail below with reference to fig. 1 and 2:
a cable force motion detector based on a correction FFT algorithm comprises a vibration sensor 1, an anti-aliasing filter 2, an ADC (analog-to-digital converter) converter 3, an embedded processor 4, a keyboard 5, an RTC (real time clock) 6, a power management module 7, an LCD (liquid crystal display) 8 and a DSP (digital signal processor) 9;
the vibration sensor 1 is connected with the anti-aliasing filter 2, the anti-aliasing filter 2 is connected with the ADC converter 3, and the ADC converter 3 is connected with the embedded processor 4;
the keyboard 5, the RTC real time clock 6, the LCD display 8 and the DSP processor 9 are all connected to the embedded processor 4.
The embedded processor 4 carries out FFT conversion and correction on the time domain signals acquired by the ADC 3 by the DSP 9 to obtain high-precision cable force values, and the high-precision cable force values are displayed by the LCD 8.
The DSP processor 9 uses a modified FFT algorithm to obtain a frequency value of high accuracy.
A modified FFT algorithm of the cable force motion detector is used:
after the time domain signal is subjected to FFT conversion, the frequency of the signal is in FFTThe algorithm for FFT correction is obtained by the influence of the position on leakage, and the specific calculation method is as follows: let the amplitude of the fundamental frequency signal be A n Frequency f n The amplitudes of the first two points and the last two points of the fundamental frequency signal on the FFT spectrum are A respectively n-2 、A n-1 ，A n+1 、A n+2 When A is n-2 2 + A n-1 2 Greater than A n+2 2 + A n+1 2 I.e. when the sum of the powers of the first two points of the fundamental frequency signal is greater than the sum of the powers of the second two points of the fundamental frequency signal, the modified frequency value is equal to fx=f n +[1-（A n-2 2 + A n-1 2 ）/（A n-2 2 + A n-1 2 + A n 2 + A n+2 2 + A n+1 2 ）]；
Equivalent A n-2 2 + A n-1 2 Less than A n+2 2 + A n+1 2 I.e. the sum of the powers of the two points before the fundamental frequency signal is smaller than the sum of the powers of the two points after the fundamental frequency, the modified frequency value is equal to fx=f n +[1+（A n+2 2 + A n+1 2 ）/（A n-2 2 + A n-1 2 + A n 2 + A n+2 2 + A n+1 2 ）]Thus, a high-precision corrected frequency value is obtained;
then through classical cable force calculation formulaCalculating to obtain a cable force value, wherein l is the cable length, m is the cable weight per unit length, and f n Is the nth order vibration frequency.
Examples:
in the implementation process of the invention, the embedded processing area uses a processor with a Cortex-A8 kernel of TI company, which can meet the functions of LCD graphic display, man-machine interaction interface, report making, printing, man-machine interface and the like. The DSP processor adopts a C55XX series processor of TI company, is used for FFT calculation and correction of FFT algorithm, and can display spectrum patterns in real time. The ADC converter adopts AD7190 of ADI company, has sampling rate of 4.8Ksps and 24-bit resolution, and can meet the testing requirements of cable force bandwidth and precision. The antialiasing filter generally adopts an active filter design, the cut-off frequency is selected to be 100Hz, and for samples lower than 100Hz, an oversampling decimation mode is used in order to meet the sampling theorem. In the operation executing process of the system, after FFT calculation is carried out on the acquired time domain signal data according to the configured cable and sampling parameters, according to manually selected fundamental frequency, when a cursor is placed on the selected frequency, a high-precision calculation button is selected, at the moment, the system can use a correction FFT algorithm according to the current frequency to obtain a high-precision frequency value, and finally a high-precision cable force value is obtained.
Comparison parameter table:
Claims (1)
1. a modified FFT algorithm of a cable force motion detector is characterized in that:
after the time domain signal is subjected to FFT conversion, an FFT correction algorithm is obtained on the influence of the position of the signal frequency in the FFT on leakage, and the specific calculation method comprises the following steps: let the amplitude of the fundamental frequency signal be A n Frequency f n The amplitudes of the first two points and the last two points of the fundamental frequency signal on the FFT spectrum are A respectively n-2 、A n-1 ，A n+1 、A n+2 When A is n-2 2 +A n-1 2 Greater than A n+2 2 +A n+1 2 I.e. when the sum of the powers of the first two points of the fundamental frequency signal is greater than the sum of the powers of the second two points of the fundamental frequency signal, the modified frequency value is equal to fx=f n +[1-(A n-2 2 +A n-1 2 )/(A n-2 2 +A n-1 2 +A n 2 +A n+2 2 +A n+1 2 )]；
Equivalent A n-2 2 +A n-1 2 Less than A n+2 2 +A n+1 2 I.e. the sum of the powers of the two points before the fundamental frequency signal is smaller than the sum of the powers of the two points after the fundamental frequency, the modified frequency value is equal to fx=f n +[1+(A n+2 2 +A n+1 2 )/(A n-2 2 +A n-1 2 +A n 2 +A n+2 2 +A n+1 2 )]Thus, a high-precision corrected frequency value is obtained;
and then through classical cable force calculation formula T=4ml 2 f n 2 /n 2 Calculating to obtain a cable force value, wherein l is the cable length, m is the cable weight per unit length, and f n Is the nth order vibration frequency.
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101201282A (en) * | 2007-12-20 | 2008-06-18 | 宁波大学 | Fundamental frequency identification method for detecting cord force of cable-stayed bridge |
| CN101368860A (en) * | 2008-09-12 | 2009-02-18 | 江苏工业学院 | Method for correcting FFT data in stayed-cable force of stayed-cable bridge detected by frequency method |
| KR20100052264A (en) * | 2008-11-10 | 2010-05-19 | 주식회사 엠디티 | Method of maximizing accuracy of measurement for saw type tpms sensor |
| CN103217248A (en) * | 2013-04-28 | 2013-07-24 | 清华大学 | Method for detecting tensile force of bridge steel cable |
| CN105527047A (en) * | 2015-12-30 | 2016-04-27 | 中交路桥技术有限公司 | Magnetic flux cable force detecting device based on MEMS (Micro Electro Mechanical System) acceleration sensor correction |
| CN206450357U (en) * | 2016-12-20 | 2017-08-29 | 江西飞尚科技有限公司 | A kind of Suo Li dynamic testers |
-
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- 2016-12-20 CN CN201611182472.9A patent/CN107063545B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101201282A (en) * | 2007-12-20 | 2008-06-18 | 宁波大学 | Fundamental frequency identification method for detecting cord force of cable-stayed bridge |
| CN101368860A (en) * | 2008-09-12 | 2009-02-18 | 江苏工业学院 | Method for correcting FFT data in stayed-cable force of stayed-cable bridge detected by frequency method |
| KR20100052264A (en) * | 2008-11-10 | 2010-05-19 | 주식회사 엠디티 | Method of maximizing accuracy of measurement for saw type tpms sensor |
| CN103217248A (en) * | 2013-04-28 | 2013-07-24 | 清华大学 | Method for detecting tensile force of bridge steel cable |
| CN105527047A (en) * | 2015-12-30 | 2016-04-27 | 中交路桥技术有限公司 | Magnetic flux cable force detecting device based on MEMS (Micro Electro Mechanical System) acceleration sensor correction |
| CN206450357U (en) * | 2016-12-20 | 2017-08-29 | 江西飞尚科技有限公司 | A kind of Suo Li dynamic testers |
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