Doppler laser rapid and accurate meter and length measuring device

Abstract

The invention relates to the field of laser meter counting, and discloses a Doppler laser fast and accurate meter and length measuring device which comprises a bottom plate, a laser emitting device is fixedly connected to one side of the top of the bottom plate, and a light splitting assembly is fixedly connected to the light emitting end of the laser emitting device; the other side of the top of the bottom plate is fixedly connected with a reflecting prism; a light receiving lens is fixedly connected to the front side of the top of the bottom plate, and a light filter is further arranged on the front side of the light receiving lens; a light receiver is arranged on the rear side of the light receiving lens, and the connecting line of the center point of the mirror face of the light receiving lens and the center point of a light receiving opening of the light receiver is perpendicular to the front side of the bottom plate. And the optical receiver is electrically connected with the electric signal processing assembly. The invention relates to an optical speed sensor, which is used for non-contact measurement of one-dimensional surface speed, can measure and collect the speed and moving distance of a measured object in a non-contact manner, and solves the problem of inaccuracy of meter counting.

Description

Technical Field

[0001] The present invention relates to the field of laser length measurement, and specifically to a Doppler laser fast and accurate length measuring device. Background Art

[0002] With the continuous development of the domestic economy and technological means, in the process of industrial production, it is often necessary to measure the length of the products produced, especially the long strip-shaped products. Most traditional length measuring devices calculate the length of the product based on the rolling distance of the pressing rollers. However, since there is a layer of deformable substance attached to the surface of some products, it is impossible to use the pressing rollers to press and measure the length. Therefore, a non-contact length measuring device is required for measurement. A laser length measuring device is an optical speed sensor used for non-contact measurement of one-dimensional surface speed, and can non-contact measure and collect the speed and moving distance of the object to be measured. However, the existing length measuring devices on the market still have the following problems:

[0003] 1. At present, it is difficult to industrialize the laser length measuring device. Currently, optical components and the like cannot be installed by the method of fixing them again at the laser cutting position. The position information accuracy requirements of the components inside the laser length measuring device are high, and a deviation of millimeters will cause a huge error in the length measurement effect.

[0004] 2. The laser length measuring device is generally used for the instantaneous speed of the object moving. In terms of length measurement, it can only measure the objects moving at a uniform speed. However, in industry, due to various conditions of the object conveying device, the instantaneous speed of the object moving will change, which will lead to inaccuracy in length measurement.

[0005] 3. The laser length measuring device based on the Doppler effect is currently monopolized by foreign companies. The price of foreign similar products exceeds that of the laser length measuring device produced based on the present invention, and currently no similar laser length measuring products applied to industry have been found in China.

[0006] 4. Most of the other domestic non-contact length measuring devices are based on computer vision image processing, and such products cannot accurately measure the length and there will be a large deviation.

[0007] As the patent publication number is CN114152169A, the disclosed "Wire Metering Device with Paying-in and Paying-out Functions" includes: a paying-out mechanism, which includes a first tray and a first turntable rotatably arranged on the first tray, and a first fixing component is provided on the first turntable; a paying-in mechanism, which is arranged beside the paying-out mechanism, and the paying-in mechanism includes a second tray and a second turntable rotatably arranged on the second tray, and a second fixing component is provided on the second turntable; a metering mechanism, which is arranged between the paying-out mechanism and the paying-in mechanism; the metering mechanism includes a metering wheel and a sensing component, and the sensing component is linked with the metering wheel to sense the number of rotation cycles of the metering wheel; a pressing mechanism, which is linked with the metering wheel to drive the metering wheel to move up and down; a processor, which is signal-connected with the sensing component. This invention uses a pressing roller to press the object to be measured, and calculates the moving distance of the object to be measured through the rotating distance of the pressing roller, and it cannot achieve contactless metering.

[0008] As the patent publication number is CN111649679A, the disclosed "Non-contact Optical Metering Method and Device" includes: irradiating the surface of the object to be measured, and continuously obtaining the image details of the surface of the object to be measured through a microscopic imaging method; calculating the displacement between two adjacent images; obtaining the length of the object to be measured in standard units according to the displacement between two adjacent images; and obtaining the real-time speed of the object to be measured. This invention is based on computer image recognition technology, but image recognition itself is a probability calculation, that is, the recognition of image details is not an accurate calculation, but a comparison, and it is not applicable to scenarios that require accurate metering.

[0009] Therefore, how to provide a Doppler laser fast and accurate meter and length measurer, which uses the principle of Doppler laser velocity measurement and length measurement, calculates and removes impurities from the detected electrical signals, so as to realize the accurate and fast meter measurement processing of the object to be measured, and the cost of the length measurer is low and the measurement accuracy is high. Summary of the Invention

[0010] In view of the deficiencies of the prior art, the present invention provides a Doppler laser fast and accurate meter and length measurer.

[0011] The present invention is a double-beam laser Doppler metering device that uses the principle and characteristics of optical Doppler, realizes frequency shift through a phase modulator and cooperates with fast Fourier transform to realize frequency detection, and then realizes velocity measurement, removes abnormal data, and calculates the moving distance of the object to be measured.

[0012] The technical solutions adopted by it are as follows:

[0013] A Doppler laser rapid and accurate length measuring device, including a bottom plate, on one side of the top of the bottom plate, a laser emitting device is fixedly connected, and a beam splitting component is fixedly connected at the light emitting end of the laser emitting device; on the other side of the top of the bottom plate, a reflecting prism is fixedly connected; in the front side of the top of the bottom plate, a light receiving lens is fixedly connected, and a filter is also arranged in front of the light receiving lens; behind the light receiving lens, a light receiver is arranged, and the connecting line between the center point of the mirror surface of the light receiving lens and the center point of the light receiving port of the light receiver is perpendicular to the front side of the bottom plate; the light receiver is electrically connected to an electrical signal processing component; the specific length measuring method includes:

[0014] S1, the laser beam emitted by the laser emitting device is perpendicular to the side of the beam splitting component close to the laser emitting device, and the incident point of the selected laser beam incident on the beam splitting component is such that the laser beam is evenly divided into a first detection beam and a second detection beam. The first detection beam is directly incident on the surface of the object to be measured, and the second detection beam is incident on the surface of the object to be measured after being reflected by the reflecting prism, and the incident points of the first detection beam and the second detection beam on the object to be measured coincide;

[0015] S2, the first detection beam and the second detection beam in S1 are reflected by the object to be measured to form reflected beams. After the reflected beams are filtered by the filter to remove stray light, through the focusing effect of the light receiving lens, they are converged and concentrated on the light receiver, and the light receiver converts the optical signal into an electrical signal;

[0016] S3, the electrical signal in S2 includes the frequency shift of the reflected beam relative to the first detection beam. According to the Doppler effect principle, combined with the short-time Fourier transform, the wavelet transform method is used to extract the peak value of the Doppler frequency shift, and the speed of the object to be measured is calculated;

[0017] S4, after the electrical signal processing component removes impurities from the speed of the object to be measured obtained in step S3, a mean value calculation is performed to obtain the average speed of the object to be measured, and the average speed of the object to be measured is multiplied by the movement time of the object to be measured to obtain the movement distance of the object to be measured.

[0018] Preferably, the laser emitting device is a distributed feedback laser, and the laser wavelength emitted by the distributed feedback laser is 620 - 650 nm.

[0019] Preferably, the fixed connection is specifically that the laser emitting device, the beam splitting component, the reflecting prism and the light receiving biconvex lens are adhesively attached to the top of the bottom plate, and preferably, epoxy resin glue is used.

[0020] Preferably, the reflecting prism is a right-angled isosceles triangular prism, the beam splitting component is composed of two right-angled isosceles triangular prisms spliced with the bottom edges as the contact surfaces, and the sizes and materials of the right-angled isosceles triangular prisms of the reflecting prism and the beam splitting component are the same; the beam splitting component, the reflecting prism and the light receiving lens are made of BK7 optical glass or fused quartz; the light receiving lens is a circular biconvex lens.

[0021] Preferably, the beam splitting component forms an angle a with the left side of the bottom plate, with a size of 12 - 14°, and the perpendicular distance from the center point of the beam splitting component to the left side of the bottom plate is 20 - 30 mm; the reflecting prism forms an angle b with the right side of the bottom plate, with a size of 1 - 5°, and the perpendicular distance from the center point of the reflecting prism to the right side of the bottom plate is 15 - 20 mm; the perpendicular distance from the center point of the laser emitting device to the left side of the bottom plate is 20 - 25 mm; the perpendicular distance from the center point of the light receiving lens to the front side of the bottom plate is 10 - 15 mm, and the perpendicular point is located at the center point of the front side of the bottom plate.

[0022] Preferably, in S4, after the electrical signal processing component removes data impurities from the measured object speed obtained in step S3, it performs a mean calculation to obtain the actual speed of the measured object, specifically:

[0023] 1) Collect n measured object speeds: V = {x 1 , x 2 ,... x n}, perform standardization processing on the measured object speed V to obtain V' = {x' 1 , x' 2 ,... x' 3};

[0024] 2) Use the K - means algorithm to cluster V' to obtain the normal value clustering center m 1 ;

[0025] 3) Calculate the distance d i from each measured object speed x i to the normal value clustering center;

[0026] 4) Judge the abnormal d i according to the threshold T and exclude the corresponding measured object speed x i to obtain the measured object speed V” after impurity removal;

[0027] 5) Calculate the average value θ of the measured object speed V” after impurity removal to obtain the actual speed of the measured object.

[0028] The standardization processing in step 1) is specifically:

[0029]

[0030] where u is the mean of the speed data and σ is the standard deviation of the speed data.

[0031] In step 2), using the K - means algorithm to cluster V' specifically makes the objective function value minimized; the objective function is the sum of the squares of the distances from all measured object speeds x i to their respective clustering centers, and its formula is:

[0032]

[0033] Among them, C j represents the j-th cluster, and m j represents the center of the j-th cluster.

[0034] In the step 4), the threshold T = m d - 3σ d , where m d is the mean value of all distances d i , and σ d is the standard deviation of all distances d i .

[0035] Meanwhile, it also has the following beneficial effects:

[0036] 1. Through the optical Doppler formula, the present invention calculates and calibrates the specific position information of each component of the laser metering device of a specific size, and at the same time adopts the adhesive fixing method, improving the metering accuracy of the laser metering device.

[0037] 2. For the messy data caused by the sudden change of the instantaneous speed of the object to be measured due to factors such as temperature, the present invention will automatically eliminate it to ensure the accuracy of the data.

[0038] 3. The Doppler laser fast and accurate metering and length measuring device prepared according to the present invention has a greatly reduced cost, is convenient for measurement and use, and has stable product performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the solutions in the present application, the following will briefly introduce the drawings required for the description of the embodiments of the present application. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts.

[0040] Figure 1 It is a schematic structural diagram of a Doppler laser metering device described in an embodiment of the present invention.

[0041] The marks in the drawings are: 1 - bottom plate, 2 - laser emission device, 3 - beam splitting component, 4 - reflecting prism, 5 - light receiving lens, 6 - filter, 7 - light receiver, 8 - object to be measured, 9 - first detection beam, 10 - second detection beam. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art belonging to the technical field of the present application.

[0043] Embodiment 1

[0044] AsFigure 1 As shown in the figure, Embodiment 1 discloses a Doppler laser metering device, which includes a bottom plate 1. On one side of the top of the bottom plate 1, a laser emission device 2 is adhesively attached using epoxy resin glue, and a beam splitting component 3 is adhesively attached at the light-emitting end of the laser emission device 2; on the other side of the top of the bottom plate 1, a reflecting prism 4 is adhesively attached using epoxy resin glue; on the front side of the top of the bottom plate 1, a light receiving lens 5 is adhesively attached using epoxy resin glue, and a filter 6 is further arranged in front of the light receiving lens 5; a light receiver 7 is arranged behind the light receiving lens 5, and the connecting line between the center point of the mirror surface of the light receiving lens 5 and the center point of the light receiving port of the light receiver 7 is perpendicular to the front side of the bottom plate 1; the light receiver 7 is electrically connected to an electrical signal processing component; preferably, the laser emission device is a distributed feedback laser, and the laser wavelength emitted by the distributed feedback laser is 638 nm. The specific metering method includes:

[0045] S1, the laser beam emitted by the laser emission device 2 is perpendicular to the side of the beam splitting component 3 close to the laser emission device 2, and the incident point of the selected laser beam on the beam splitting component 3 is such that the laser beam is evenly divided into a first detection beam and a second detection beam. The first detection beam is directly incident on the surface of the object to be measured 8, and the second detection beam is incident on the surface of the object to be measured 8 after being reflected by the reflecting prism 4, and the incident points of the first detection beam and the second detection beam on the object to be measured 8 coincide; the object to be measured moves axially parallel to the front side of the bottom plate 1;

[0046] Preferably, the reflecting prism 4 is a right-angled isosceles triangular prism, the beam splitting component 3 is composed of two right-angled isosceles triangular prisms spliced with the bottom edges as the contact surfaces, and the sizes and materials of the right-angled isosceles triangular prisms of the reflecting prism 4 and the beam splitting component 3 are the same, and the length of the right-angled side is 20 mm; the beam splitting component, the reflecting prism, and the light receiving lens are made of BK7 optical glass or fused quartz; the light receiving lens 5 is a circular biconvex lens with a diameter of 30 mm and a thickness of 7 mm. Using epoxy resin glue as the adhesive and selecting BK7 optical glass or fused quartz as the materials of various optical components are to ensure the accuracy during measurement in relatively extreme environments.

[0047] Preferably, the beam splitting component 3 forms an angle a with the left side of the bottom plate, with a size of 13°, and the perpendicular distance from the center point of the beam splitting component 3 to the left side of the bottom plate 1 is 26.36 mm; the reflecting prism 4 forms an angle b with the right side of the bottom plate 1, with a size of 2°, and the perpendicular distance from the center point of the reflecting prism 4 to the right side of the bottom plate 1 is 17.55 mm; the perpendicular distance from the center point of the laser emission device 2 to the left side of the bottom plate 1 is 22.57 mm; the perpendicular distance from the center point of the light receiving lens 5 to the front side of the bottom plate 1 is 13.91 mm, and the perpendicular point is located at the center point of the front side of the bottom plate 1.

[0048] The selection of the above prism and the installation positions of the laser emitting device, the beam splitting component, the reflecting prism, and the light receiving lens enable the laser emitted by the laser emitting device to follow the laser path of S1.

[0049] S2, the first detection beam and the second detection beam in S1 are reflected by the object to be measured to form a reflected beam. After the reflected beam filters out stray light through the filter 6, it is focused by the focusing effect of the light receiving lens 5 and concentrated on the optical receiver 7. The optical receiver 7 converts the optical signal into an electrical signal;

[0050] S3, the electrical signal in S2 includes the frequency shift fp of the reflected beam relative to the first detection beam. According to the principle of the Doppler effect, combined with the short-time Fourier transform, the wavelet transform method is used to extract the peak value of the Doppler frequency shift, and the velocity of the object to be measured 8 is calculated;

[0051] S4, after the electrical signal processing component removes impurities from the velocity of the object to be measured 8 obtained in step S3, it performs a mean calculation to obtain the average velocity of the object to be measured 8, and multiplies the average velocity of the object to be measured 8 by the movement time of the object to be measured to obtain the movement distance of the object to be measured.

[0052] When the lateral velocity of the object to be measured 8 is zero, the frequency of the reflected light is the same as that of the detection light; when the lateral velocity is not zero, the reflected light will have a frequency shift relative to the detection light, fp = (2sinα / λ)·v. From this, we can obtain where v is the lateral movement velocity of the object to be measured, α is the angle formed by the coincidence point of the first detection beam and the second detection beam on the surface of the object to be measured 8 as the vertex, and λ is the wavelength of the detection light;

[0053] After the detection light frequency shift fp is received by the optical receiver 7, since the detection light source is already set, other values are fixed values. From this, the lateral movement velocity v of the object to be measured 8 can be obtained.

[0054] Since the laser emits with a certain frequency, the lateral movement velocity v of the object to be measured 8 detected is also a series of discontinuous data. The K-means algorithm is used because in low-temperature or high-temperature environments, due to factors such as humidity in the air affecting the optical instrument and the surface of the object to be measured, the error of the measurement data has a certain tendency. For example, at low temperatures, the suddenly appearing abnormal data is generally higher than the normal value. According to the data of the abnormal aggregation center, the velocity of the object to be measured can be corrected predictively to a certain extent.

[0055] Preferably, in S4, the electrical signal processing component removes impurities from the velocity of the object to be measured obtained in step S3 and then performs a mean calculation to obtain the actual velocity of the object to be measured. Specifically:

[0056] 1) Collect n velocities of the object to be measured: V = {x 1 ,x 2,...x n}, normalize the speed V of the object under test to obtain V' = {x' 1 , x' 2 ,...x' 3};

[0057] 2) Use the K - means algorithm to cluster V' to obtain the normal value clustering center m;

[0058] 3) Calculate the distance d from each speed x of the object under test i to the normal value clustering center i ;

[0059] 4) Judge the abnormal d according to the threshold T i and exclude the corresponding speed x of the object under test i , to obtain the speed V” of the object under test after removing impurities;

[0060] 5) Calculate the average value θ of the speed V” of the object under test after removing impurities to obtain the actual speed of the object under test.

[0061] The normalization process in step 1) is specifically:

[0062]

[0063] where u is the mean of the speed data and σ is the standard deviation of the speed data.

[0064] The use of the K - means algorithm to cluster V' in step 2) is specifically to minimize the objective function value; the objective function is the sum of the squares of the distances from all speeds x of the object under test i to their respective clustering centers, and its formula is:

[0065]

[0066] where C j represents the j - th cluster, and m j represents the center of the j - th cluster.

[0067] The threshold T in step 4) = m d - 3σ d , where m d is the mean of all distances d i , and σ d is the standard deviation of all distances d i .

[0068] Suppose there are the following speeds V of the object under test: V = {10, 12, 11, 100, 13, 14}:

[0069] Step 1) Normalization process:

[0070] Calculate the mean μ = 26.67 and the standard deviation σ = 34.64. The standardized data is V′ = {-0.48, -0.42, -0.45, 2.12, -0.39, -0.37}.

[0071] Step 2) K-means clustering:

[0072] Initialize the cluster centers m 1 = -0.45 and m 2 = 2.12.

[0073] After iteration, the clustering results are as follows:

[0074] Cluster 1: {-0.48, -0.42, -0.45, -0.39, -0.37}, center m 1 = -0.42.

[0075] Cluster 2: {2.12}, center m 2 = 2.12.

[0076] Step 3) Calculate the distance d i from the speed x of each measured object to the normal value cluster center i :

[0077] Use the 3σ principle to determine the threshold T = 1.5.

[0078] It is found that d 4 = 2.54 > T, so x 4 = 100 is an outlier.

[0079] Step 4) Output the result:

[0080] Obtain the speed V” of the measured object after impurity removal = {10, 12, 11, 100, 13, 14}.

[0081] Perform data accuracy testing on a Doppler laser meter device according to the one described in Embodiment 1. The test environment and test steps are specifically as follows:

[0082] In an environment with a temperature ranging from -30°C to 50°C, build an adjustable-speed belt drive device. The maximum speed of this device is 500 meters per minute, and the length of one rotation is 2.79 meters. Record the number of rotations of this device to obtain the moving meters.

[0083] First, align the laser emission part of the product with the belt to be measured, and adjust the distance between the laser meter and the belt to be measured.

[0084] Secondly, observe whether the light spot of the laser on the belt is a dot to determine whether the distance is appropriate.

[0085] Preferably, start the belt drive device after clearing the laser counter. Record the number of rotations. Measure and record the number of meters at different rotational speeds.

[0086] The following table shows the actual counting accuracy of a Doppler laser fast and precise counter and length measurer described in Example 1:

[0087] Belt rotation speed Actual rotation distance Measured distance in Example 1 10 m / min 260 m 260.08 m 100 m / min 260 m 260.05 m 200 m / min 260 m 260.16 m 300 m / min 260 m 260.35 m

[0088] By analyzing the test data, it can be obtained that the data accuracy is within 0.1%.

Claims

1. A Doppler laser fast and accurate meter and length measuring device, comprising a bottom plate, a laser emitting device is fixedly connected to one side of the top of the bottom plate, and a light splitting component is fixedly connected to the light output end of the laser emitting device; characterized in that: A reflective prism is fixedly connected to the other side of the top of the bottom plate; a light-collecting lens is fixedly connected to the front side of the top of the bottom plate, and a filter is also arranged on the front side of the light-collecting lens; a light receiver is arranged on the rear side of the light-collecting lens, and a connecting line between the center point of the mirror surface of the light-collecting lens and the center point of the light receiving port of the light receiver is perpendicular to the front side of the bottom plate; the light receiver is electrically connected to the electrical signal processing component; The specific methods of measuring length by meter include: S1, the laser beam emitted by the laser emitting device is perpendicular to the side of the beam splitter component close to the laser emitting device, and the incident point of the laser beam incident on the beam splitter component is selected so that the laser beam is evenly divided into a first detection beam and a second detection beam, the first detection beam is directly incident on the surface of the object to be measured, and the second detection beam is incident on the surface of the object to be measured after being reflected by a reflecting prism, and the first detection beam and the second detection beam coincide at the incident point of the object to be measured; S2, the first detection light beam and the second detection light beam in S1 are reflected by the object to be measured to form a reflected light beam, after the reflected light beam is filtered by the filter, the reflected light beam is focused on the light receiver through the focusing effect of the light collecting lens, and the light receiver converts the optical signal into an electrical signal; S3, the electrical signal in S2 includes the frequency shift of the reflected light beam relative to the first detection light beam, and the peak value of the Doppler frequency shift is extracted by wavelet transform method through the principle of Doppler effect and combined with short-time Fourier transform, and the speed of the object under test is calculated; S4, the electrical signal processing component performs data decluttering on the speed of the object under test obtained in step S3, and then performs mean calculation to obtain an average speed of the object under test, and then multiplies the average speed of the object under test by the time the object under test moves to obtain a distance the object under test moves.

2. The Doppler laser fast and accurate meter and length measuring device according to claim 1, characterized in that: The laser emitting device is a distributed feedback laser, and the laser wavelength emitted by the distributed feedback laser is 620-650nm.

3. The Doppler laser fast and accurate meter and length measuring device according to claim 1, characterized in that: The fixing specifically comprises that the laser emitting device, the light splitting component, the reflecting prism and the light collecting biconvex lens are adhered to the top of the bottom plate by using glue.

4. The Doppler laser fast and accurate meter and length measuring device according to claim 1, characterized in that: The reflecting prism is a right-angle isosceles prism, the light splitting component is composed of two right-angle isosceles prisms spliced ​​with the bottom edge as the contact surface, and the reflecting prism and the right-angle isosceles prism of the light splitting component are consistent in size and material; the light splitting component, reflecting prism, and light collecting lens are made of BK7 optical glass or fused quartz; the light collecting lens is a circular biconvex lens.

5. The Doppler laser fast and accurate meter and length measuring device according to claim 1, characterized in that: The splitter component forms an angle a with the left side of the base plate, which is 12-14°, and the vertical distance from the center point of the splitter component to the left side of the base plate is 20-30mm; the reflecting prism forms an angle b with the right side of the base plate, which is 1-5°, and the vertical distance from the center point of the reflecting prism to the right side of the base plate is 15-20mm; the vertical distance from the center point of the laser emitting device to the left side of the base plate is 20-25mm; the vertical distance from the center point of the light collecting lens to the front side of the base plate is 10-15mm, and the vertical point is located at the center point of the front side of the base plate.

6. The Doppler laser fast and accurate meter and length measuring device according to claim 1, characterized in that: The electrical signal processing component in S4 performs data cleaning on the speed of the object under test obtained in step S3 and then performs mean calculation to obtain the actual speed of the object under test, which is specifically: 1) Collect n speeds of the objects under test: , for the speed of the object being measured After standardization, we get ; 2) Use K-means algorithm to Perform clustering to obtain the normal value cluster center ; 3) Calculate the speed of each object being measured Distance to the center of the normal cluster ; 4) According to the threshold Judging abnormal And exclude the corresponding measured object speed , get the speed of the object to be measured after impurities are removed ; 5) Calculate the speed of the object to be measured after impurities are removed The average , and get the actual speed of the object being measured.

7. The Doppler laser fast and accurate meter and length measuring device according to claim 6, characterized in that: The standardization process in step 1) is specifically as follows: ， in, is the mean of the speed data, is the standard deviation of the speed data.

8. The Doppler laser fast and accurate meter and length measuring device according to claim 6, characterized in that: Step 2) uses the K-means algorithm to The clustering is specifically performed to minimize the objective function; the objective function is the speed of all the objects being measured. The sum of the squares of the distances to the cluster center to which it belongs is given by: ， in represents the jth cluster, represents the center of the jth cluster.

9. The Doppler laser fast and accurate meter and length measuring device according to claim 6, characterized in that: Step 4) Threshold ,in All distances The mean of All distances The standard deviation of .

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