CN107167080B - Moire frange signal of grating reconstructing method - Google Patents
Moire frange signal of grating reconstructing method Download PDFInfo
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- CN107167080B CN107167080B CN201710402052.5A CN201710402052A CN107167080B CN 107167080 B CN107167080 B CN 107167080B CN 201710402052 A CN201710402052 A CN 201710402052A CN 107167080 B CN107167080 B CN 107167080B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
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Abstract
The invention discloses a kind of moire frange signal of grating reconstructing methods, comprising the following steps: a. Signal Pretreatment: photoelectric conversion is carried out to optical grating Moire fringe, by filtering and obtaining the sine voltage signal that two paths of signals difference is about 90 ° after calculation processWith;B. the linearisation reconstruct of signal: to the signal obtained in step aWithLinearisation reconstruct is carried out, and introduces auxiliary function, finally reconstructed to obtain linearized function;C. the metering being displaced: using number N complete cycle of cycle rate counter record Moire fringe variation, it is for pitchIncrement type optical grid line displacement sensor, be by the obtained shift value x of its metering.By the above-mentioned means, moire frange signal of grating reconstructing method of the present invention, enables to signal reconstruction function insensitive to the amplitude variation of original signal, and have the good linearity and finally realize displacement measurement.
Description
Technical field
The present invention relates to photoelectric measurement fields, more particularly to a kind of moire frange signal of grating reconstructing method.
Background technique
Grating displacement sensor is widely used in displacement monitoring in recent years, is become with Moire fringe as reason
The most typically of the measuring technique of opinion represents.Grating displacement sensor must be surveyed comprising a pair of of optical grating pair, one of grating scale
It measures benchmark to use, which is known as scale grating (or key light grid), and another piece of grating scale is then known as indication grating.When two pieces of grating faces
Opposite overlapping, Moire fringe will be generated, when two gratings along performed relative motion perpendicular to grid line direction when, Moire fringe just along
It correspondingly moves in direction identical with grid line direction.The light intensity of variation is converted to using photoelectric cell the electric signal of variation, and
By the filter shape and calculation process of electronic component, corresponding shift value can be obtained.Under normal circumstances, in order to realize
Sensing and further subdivision, it is necessary to which, the moire frange signal by photoelectric cell conversion, being processed into two-way phase difference is about
90 ° of sine voltage signal.
Currently, domestic foreign minister's grating pitch is mostly 4 μm or more, in practical applications, grating pitch itself is only relied on
Resolution ratio is generally unable to reach the requirement of accurate measurement.That is, it is necessary to which light is improved using the subdivision technology of Moire fringe
The resolution ratio of grid measuring system.
However, can have the following problems, if directly carrying out sampling subdivision to original two-way sinusoidal signal to signal
Sampling is carried out when comparing, due to just, the linearity of cosine signal it is bad, in one cycle, electricity corresponding to same displacement difference
Pressure amplitude value difference is different, and especially when voltage magnitude is close to peak value, grating scale needs mobile one biggish displacement just generation one
A small voltage change, so original signal must be reconstructed.
Common restructing algorithm mainly linearizes restructing algorithm, including arc tangent algorithm, sine and cosine absolutely subtract each other (approximation
Triangular wave), sine and cosine it is absolute after be divided by (absolute value of tangent, approximate triangular wave) and 8 close classifications are (using sine and cosine approximation line
The partial reconstructed signal of property).Although these algorithms can obtain linear reconstruction function, usually all the amplitude of signal is changed
The more sensitive and linearity is to be improved.
Summary of the invention
The invention mainly solves the technical problem of providing a kind of moire frange signal of grating reconstructing methods, enable to
Signal reconstruction function is insensitive to the amplitude variation of original signal, and has the good linearity and finally realize displacement measurement.
In order to solve the above technical problems, one technical scheme adopted by the invention is that: a kind of optical grating Moire fringe letter is provided
Number change reconstructing method, which comprises the following steps: a. Signal Pretreatment: to optical grating Moire fringe carry out photoelectric conversion,
By filtering and obtaining the sine voltage signal that two paths of signals difference is about 90 ° after calculation processWith;B. signal
Linearisation reconstruct: to the signal obtained in step aWithLinearisation reconstruct is carried out, the first linearized function is constructed,
, and introduce
Auxiliary function,, finally reconstructed to obtain
Second linearized function,;C. it the metering being displaced: utilizes
Cycle rate counter records number N complete cycle of Moire fringe variation, the increment type optical grid line displacement sensor for being d for pitch,
It is by the shift value x that its metering obtains, wherein
。
In a preferred embodiment of the present invention, voltage signal in the step aWith, in ideal state
Under be expressed as,, it is expressed as in the case where physical presence error,, wherein A1And A2Representation signal
Amplitude, B1And B 2The phase of representation signal, C1And C2The DC component of representation signal.
In a preferred embodiment of the present invention, the sgn function in the step b is sign function, for sgn function,
Have
For symbol, indicate a kind of nonequivalence operation, i.e., forIf the value of Y and Z is identical, calculated result
It is 0, if the value of Y and Z is different, calculated result is 1, for linearized function, with real ideal linearity triangular wave
Deviation be the restructing algorithm theoretical error, be defined as
,For ideal triangular wave,
Have, theoretical maximum error is。
In a preferred embodiment of the present invention, the θ in the c, unit are rad(radian), for d and x, unit
It is μm (micron).
The beneficial effects of the present invention are: moire frange signal of grating reconstructing method of the present invention, enables to signal reconstruction
Function is insensitive to the amplitude variation of original signal, and has the good linearity and finally realize displacement measurement.
Detailed description of the invention
To describe the technical solutions in the embodiments of the present invention more clearly, make required in being described below to embodiment
Attached drawing is briefly described, it should be apparent that, drawings in the following description are only some embodiments of the invention, for
For those of ordinary skill in the art, without creative efforts, it can also be obtained according to these attached drawings other
Attached drawing, in which:
Fig. 1 is the working principle flow diagram of moire frange signal of grating reconstructing method of the present invention;
Fig. 2 is signal waveforms of the invention;
Fig. 3 is the Lisaru circle figure of Fig. 2;
Fig. 4 is the waveform diagram of grating forward motion of the invention;
Fig. 5 is the heterodromous waveform diagram of grating of the invention;
Specific embodiment
The technical scheme in the embodiments of the invention will be clearly and completely described below, it is clear that described implementation
Example is only a part of the embodiments of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, this field is common
Technical staff's all other embodiment obtained without making creative work belongs to the model that the present invention protects
It encloses.
Referring to Fig. 1, a kind of moire frange signal of grating reconstructing method, comprising the following steps:
A. the pretreatment of signal: the signal input signal pretreatment circuit board of grating scale output is filtered, number is used
It is acquired according to capture card PCI-8757 and passes through pretreated two-way voltage signal.
B. the linearisation reconstruct of signal: as figure one will be acquired by data collecting card PCI-8757 and Labview software
To voltage value input server in real time and obtain the voltage value sequence of two paths of signalsWith.What calling wove
Labview program, the voltage value sequence inputted with following equation Real-time ReconstructionWith, form new reconstruction of function:
The function reconstructed, as shown in Figure 2.
C. the metering being displaced: using number N complete cycle of labview software programming record Moire fringe variation, and with such as
Lower formula real time measure goes out shift value x,
In formula, d=20 μm, the unit of θ is radian (rad).
Further, when pass through the collected two paths of signals of data collecting card PCI-8757 are as follows:
When
For the theoretical maximum error of this restructing algorithm, have。
Regulated and controled by using server and labview, and in practice in order to improve speed, can also use FPGA and
Related corollary equipment, the pitch of used increment type optical grid line displacement sensor are 20 microns, can also to have it is smaller or
The grating of bigger pitch carries out linearisation reconstruct and metering, other specific equipment also can be according to required settings.
Moire frange signal of grating reconstructing method of the present invention, enables to signal reconstruction function to the amplitude of original signal
Change insensitive, and has and the good linearity and finally realize displacement measurement.
It is different from the prior art, moire frange signal of grating reconstructing method of the present invention enables to signal reconstruction function
It is insensitive to the amplitude variation of original signal, and there is the good linearity and finally realize displacement measurement.
The above description is only an embodiment of the present invention, is not intended to limit the scope of the invention, all to utilize this hair
Equivalent structure or equivalent flow shift made by bright description is applied directly or indirectly in other relevant technology necks
Domain is included within the scope of the present invention.
Claims (4)
1. a kind of moire frange signal of grating reconstructing method, which comprises the following steps:
A. Signal Pretreatment: carrying out photoelectric conversion to optical grating Moire fringe, by obtaining two paths of signals after filtering and calculation process
The sine voltage signal that about 90 ° of differenceWith;
B. the linearisation reconstruct of signal: to the signal obtained in step aWithCarry out linearisation reconstruct, construction the
One linearized function,,
And introduce auxiliary function,, finally through weight
Structure obtains the second linearized function,;
C. number N complete cycle of cycle rate counter record Moire fringe variation, the increasing for being d for pitch the metering being displaced: are utilized
Amount formula optical grid line displacement sensor, measuring obtained shift value x by it is, wherein
。
2. moire frange signal of grating reconstructing method according to claim 1, which is characterized in that electric in the step a
Press signalWith, it is expressed as in an ideal case,, in physical presence
It is expressed as in the case where error,,
Wherein A1And A2The amplitude of representation signal, B1And B 2The phase of representation signal, C1And C2The DC component of representation signal.
3. moire frange signal of grating reconstructing method according to claim 1, which is characterized in that in the step b
Sgn function has sgn function for sign function
For symbol, indicate a kind of nonequivalence operation, i.e., forIf the value of Y and Z is identical, calculated result is 0, if
The value of Y and Z is different, then calculated result is 1, for linearized function, and the deviation of real ideal linearity triangular wave
For the theoretical error of the restructing algorithm, it is defined as
,For ideal triangular wave,
Have, theoretical maximum error is。
4. moire frange signal of grating reconstructing method according to claim 1, which is characterized in that in the step c
θ, unit are rad(radian), for d and x, unit is μm (micron).
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Citations (3)
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CN101813463A (en) * | 2010-04-20 | 2010-08-25 | 重庆理工大学 | Soft subdivision method of moire frange signal of grating |
CN103604373A (en) * | 2013-11-20 | 2014-02-26 | 沈阳工业大学 | Raster Moire striped wavelet fine dividing method and raster displacement measuring apparatus |
CN106556342A (en) * | 2016-11-11 | 2017-04-05 | 深圳市太赫兹科技创新研究院 | A kind of grating subdivision device and method based on FPGA |
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CN101813463A (en) * | 2010-04-20 | 2010-08-25 | 重庆理工大学 | Soft subdivision method of moire frange signal of grating |
CN103604373A (en) * | 2013-11-20 | 2014-02-26 | 沈阳工业大学 | Raster Moire striped wavelet fine dividing method and raster displacement measuring apparatus |
CN106556342A (en) * | 2016-11-11 | 2017-04-05 | 深圳市太赫兹科技创新研究院 | A kind of grating subdivision device and method based on FPGA |
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