CN100359284C - Measurement of long-distance and wireless transmission displacement - Google Patents

Abstract

The present invention discloses a displacement measuring method via long-distance and wireless transmission. The method utilizes a laser beam emitting unit, a photo detector, a radio frequency or light emitter, a radio frequency or light receiver, a signal and data processing unit. In the process of displacement measurement, the photo detector is arranged at a measuring point, and the laser beam points to the photo detector; analog signal outputted from the photo detector is directly modulated onto a radio frequency or a light carrier, or is modulated onto a radio frequency or a light carrier after analog/digital conversion; the radio frequency or light receiver receives the radio frequency or the light carrier signal and obtains the transmitted analog or digital signal that is outputted from the photo detector after demodulation; during the measurement, analog or digital signal outputted from the photo detector in the deformation process of the measured object is collected, a processing unit processes the received pixel grey scale signal of the photo detector via related algorithms and Gauss Curve Fitting so as to determine the peak position of cross correlation coefficient, and thereby, the displacement of the laser light spot on the photo detector is obtained. The present invention has the characteristic of high measuring precision.

Description

The method of long-distance and wireless transmission Displacement Measurement

Technical field

The present invention relates to a kind of method of long-distance and wireless transmission Displacement Measurement, belong to the photoelectricity test technical field of displacement.

Background technology

It all is crucial that the accurate measurement of displacement is used many engineerings.For example in the construction and use of heavy construction (as bridge), need monitor in real time its deformation and vibration under various carrying conditions.This deformation is called amount of deflection again in many engineerings are used, and is key parameter and the important evidence of estimating building safety state such as bridge.The measurement of amount of deflection and vibration all can realize by the displacement of measuring a certain relatively object of reference of measured object.The measuring method and the technology of existing displacement and amount of deflection comprise: (1) mechanical means: adopt dial gauge or displacement meter directly to measure, or adopt the method for communicating pipe and Level Detection.It is simple that mechanical means has an instrument and equipment, can directly obtain the advantages such as measured value of displacement and amount of deflection, wastes time and energy but measure, and can't realize the measurement of dynamic displacement and amount of deflection, more can't carry out automatic measurement.(2) optical means: grid target or other sign are placed the measured point, adopt the image of camera or camera record sign, obtain the measured value of displacement and amount of deflection through Flame Image Process.Optical means is a kind of remote, contactless measurement, can carry out multiple spot and detect simultaneously.(3) photoelectric method: lasing light emitter is fixed on witness mark (or measured point), and photodetector is installed in measured point (or witness mark).Directly or through imaging len be radiated on the photodetector through the collimated laser light bundle, the relative displacement between witness mark and the measured point can be obtained by the output of photodetector.Adopt photoelectric method can realize long-range contactless displacement and deflection metrology, have high-speed real-time, can obtain the advantages such as kinetic measurement value of displacement and amount of deflection, be easy to realize the robotization and the long term monitoring of measuring process simultaneously.Because These characteristics, laser displacement and deflection metrology technology and surveying instrument are developed rapidly, and are applied on engineering.

Existing laser displacement and deflection metrology system adopt semiconductor laser to make light source more, and as photodetector, displacement and amount of deflection are to obtain by the change in location of detection laser hot spot on photodetector with linear array or area array CCD device.Therefore, accurately obtaining the position of laser facula on photodetector is vital for accurate Displacement Measurement and amount of deflection.Theoretically, the position of laser facula on photodetector can obtain by the position of determining hot spot maximum intensity or hot spot edge.But because there is the angle of divergence in laser beam, light beam is after a segment distance is particularly grown the transmission of distance, and it is big that laser spot diameter becomes, and intensity weakens, and produce diffraction and speckle phenomena, so will adopt some particular algorithms in the actual measurement accurately to obtain the position of laser facula on photodetector.Existing technology is to adopt pixel grey scale Distribution calculation glossing up center the position on photodetector of gravity model appoach by laser facula.Adopt this method can obtain the precision of several pixel magnitudes.It is very difficult further improving precision.In addition, in distance displacement and deflection metrology, distinct issues are transmission of signal and measurement data.All adopt wire transmission in existing laser displacement and the deflection metrology system, make troubles to practical application.

Summary of the invention

The method that the purpose of this invention is to provide a kind of long-distance and wireless transmission Displacement Measurement.This method has the high characteristics of measuring accuracy.

The present invention is realized by following technical proposals.A kind of method of long-distance and wireless transmission Displacement Measurement, this method adopts the laser beam transmitter unit that is made of semiconductor laser and beam-expanding collimation device, laser beam input ccd array photodetector irradiation measured object behind collimation, again through radio frequency or optical transmitting set and radio frequency or optical receiver and signal data processing unit, obtain the displacement of laser facula on the ccd array photodetector, thereby realize the telemeasurement displacement, it is characterized in that comprising following process:

1. the laser beam that places the semiconductor laser of witness mark to send is launched behind beam-expanding collimation, and the ccd array photodetector is installed in the measured point, and laser beam is pointed to the ccd array photodetector.

2.CCD the simulating signal of array photodetectors output directly is modulated on radio frequency or the light carrier, or through being modulated to after mould/number conversion on radio frequency or the light carrier.

3. radio frequency or optical receiver be at witness mark received RF or optical carrier, the analog or digital signal of the ccd array photodetector output that obtains being transmitted through demodulation.

4. when measuring beginning, the analog or digital signal that at first writes down a width of cloth ccd array photodetector is as hot spot benchmark or reference position, begins to gather the analog or digital signal of ccd array photodetector output in the deformation process of measured object then.The displacement that produces in the deformation process of measured object is relative this reference position with amount of deflection.

5. the signal data processing unit of receiving end adopts the cross correlation algorithm that describes below to handle to the grey scale signal of the pixel of the ccd array photodetector received.For M pixel line array CCD, if the gray scale of establishing with reference to hot spot m pixel is f ₀(m), the gray scale of other respective pixel constantly is f _d(m).Calculate f by following formula ₀(m) and f _d(m) cross-correlation coefficient $c_d\left(m\right)=\frac{\underset{i}{\mathrm{\Σ}}{f}_0\left(i\right)f_d(i+m)}{{\left(\underset{i}{\mathrm{\Σ}}{f}_0^2\left(i\right)\underset{i}{\mathrm{\Σ}}{f}_d^2\left(i\right)\right)}^{1/2}}.$ By the distribution of cross-correlation coefficient, determine the peak of cross-correlation coefficient to obtain the displacement of laser facula on the ccd array photodetector with this by gaussian curve approximation; For M * N area array CCD, the gray scale of establishing with reference to the capable n row of light spot image m pixel is f ₀(m, n), the gray scale of other respective pixel constantly is f _d(m, n).Calculate f by following formula ₀(m, n) and f _d(m, cross-correlation coefficient n) $c_d(m,n)=\frac{\underset{i}{\mathrm{\Σ}}\underset{j}{\mathrm{\Σ}}{f}_0(i,j)f_d(i+m,j+n)}{{\left(\underset{i}{\mathrm{\Σ}}\underset{j}{\mathrm{\Σ}}{f}_0^2(i,j)\underset{i}{\mathrm{\Σ}}\underset{j}{\mathrm{\Σ}}{f}_d^2(i,j)\right)}^{1/2}},$ By cross-correlation coefficient c _d(m, distribution n) are determined the peak of cross-correlation coefficient to obtain the displacement of laser facula on the ccd array photodetector with this by gaussian curve approximation.

The invention has the advantages that, adopt said method can Wireless transmission mode to realize kinetic measurement to remote ohject displacement and amount of deflection, measuring accuracy compared with prior art is significantly increased, and can make the measuring error of laser facula displacement be reduced to yardstick less than a pixel.

Description of drawings

Fig. 1 is for realizing the apparatus structure block diagram of method of the present invention.Among the figure: 101 is the laser beam transmitter unit that is made of semiconductor laser and beam-expanding collimation device; 102 are the laser beam behind the collimation; 103 is the ccd array photodetector; 104 is measured object; 105 is radio frequency or optical transmitting set; 106 is radio frequency or optical receiver; 107 is the signal data processing unit.

Embodiment

Below in conjunction with accompanying drawing the specific embodiment of the present invention is elaborated.As shown in Figure 1, the laser beam of being sent by semiconductor laser and beam-expanding collimation device unit 101 102 directly projects on the ccd array photodetector 103.The power of semiconductor laser is 5mW, and wavelength is 670nm.Photodetector is the line array CCD of 2700 pixels, and its pixel dimension is 7 microns, and driving frequency is 4MHz.The carrier frequency of radiofrequency launcher 105 is 2.4GHz, can transmit the signal of three different channels simultaneously, is respectively applied for to transmit pixel synchronizing signal, line synchronizing signal and CCD analog output signal.Radio frequency receiver 106 reverts to the signal output identical with transmitting terminal with the signal demodulation of above-mentioned three channels.Signal data processing unit 107 carries out mould/number conversion with the CCD analog output signal, adopts then $c_d\left(m\right)=\frac{\underset{i}{\mathrm{\Σ}}{f}_0\left(i\right)f_d(i+m)}{{\left(\underset{i}{\mathrm{\Σ}}{f}_0^2\left(i\right)\underset{i}{\mathrm{\Σ}}{f}_d^2\left(i\right)\right)}^{1/2}}$ Carry out cross correlation process, and calculate the variable quantity of relative hot spot benchmark of laser facula or reference position, obtain the displacement and the deflection metrology value of measured target object thus.Measurement data can show in real time, and form storage that can data file, or links by data-interface and computing machine or miscellaneous equipment.

Except that adopting above-mentioned is the embodiment of carrier wave with the radio frequency, and the present invention can also light be the measurement that carrier wave is realized long-distance and wireless transmission displacement and amount of deflection.Also the CCD analog output signal can be carried out mould/number conversion earlier in addition, by wireless transmission method data be transmitted receiving end again.

Claims (1)

1. the method for a long-distance and wireless transmission Displacement Measurement, this method adopts the laser beam transmitter unit that is made of semiconductor laser and beam-expanding collimation device, laser beam input ccd array photodetector irradiation measured object behind collimation, again through radio frequency or optical transmitting set and radio frequency or optical receiver and signal data processing unit, obtain the displacement of laser facula on the ccd array photodetector, thereby realize the telemeasurement displacement, it is characterized in that comprising following process:

1) laser beam that places the semiconductor laser of witness mark to send is launched behind beam-expanding collimation, and the ccd array photodetector is installed in the measured point, and laser beam is pointed to the ccd array photodetector;

2) simulating signal of ccd array photodetector output directly is modulated on radio frequency or the light carrier, or through being modulated to after mould/number conversion on radio frequency or the light carrier;

3) radio frequency or optical receiver be at witness mark received RF or optical carrier, the analog or digital signal of the ccd array photodetector output that obtains being transmitted through demodulation;

4) when measuring beginning, the analog or digital signal that at first writes down a width of cloth ccd array photodetector is as hot spot benchmark or reference position, begin to gather the analog or digital signal of ccd array photodetector output in the deformation process of measured object then, the displacement that produces in the deformation process of measured object is relative this reference position with amount of deflection;

5) the signal data processing unit of receiving end adopts the cross correlation algorithm that describes below to handle to the grey scale signal of the pixel of the ccd array photodetector received, for M pixel line array CCD, if the gray scale of establishing with reference to hot spot m pixel is f ₀(m), the gray scale of other respective pixel constantly is f _d(m), calculate f by following formula ₀(m) and f _d(m) cross-correlation coefficient $c_d\left(m\right)=\frac{\underset{i}{\mathrm{\Σ}}{f}_0\left(i\right)f_d(i+m)}{{\left(\underset{i}{\mathrm{\Σ}}{f}_0^2\left(i\right)\underset{i}{\mathrm{\Σ}}{f}_d^2\left(i\right)\right)}^{1/2}},$ By the distribution of cross-correlation coefficient, determine the peak of cross-correlation coefficient to obtain the displacement of laser facula on the ccd array photodetector with this by gaussian curve approximation; For M * N area array CCD, the gray scale of establishing with reference to the capable n row of light spot image m pixel is f ₀(m, n), the gray scale of other respective pixel constantly is f _d(m n), calculates f by following formula ₀(m, n) and f _d(m, cross-correlation coefficient n) $c_d(m,n)=\frac{\underset{i}{\mathrm{\Σ}}\underset{j}{\mathrm{\Σ}}{f}_0(i,j)f_d(i+m,j+n)}{{\left(\underset{i}{\mathrm{\Σ}}\underset{j}{\mathrm{\Σ}}{f}_0^2(i,j)\underset{i}{\mathrm{\Σ}}\underset{j}{\mathrm{\Σ}}{f}_d^2(i,j)\right)}^{1/2}},$ By cross-correlation coefficient c _d(m, distribution n) are determined the peak of cross-correlation coefficient to obtain the displacement of laser facula on the ccd array photodetector with this by gaussian curve approximation.

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