Cable drawing and pulling speed measuring method based on micro-Doppler effect

Abstract

The invention relates to the technical field of cable manufacturing, in particular to a non-contact high-precision measuring method for the cable drawing and pulling speed based on the micro-Doppler effect. The method comprises the steps that a millimeter wave radar is installed on the side of a cable at a preset pitch angle and an acute angle beta is formed between the millimeter wave radar and the pulling direction of the cable, and it is ensured that radar beams cover the surface of the cable; the radar transmits frequency-modulated continuous waves and receives micro-Doppler modulation echo signals reflected by the surface of the cable; extracting a radial velocity component by separating Doppler frequency shift in echoes; establishing a coordinate system for the radial speed by combining with the accurate geometric position relationship between the radar and the cable, and calculating the axial pulling wire speed of the cable; and finally, outputting a real-time speed value and a motion direction through a data interface. According to the method, high-precision speed measurement can be achieved without contacting a cable, the non-contact measurement precision is improved, and the method can adapt to various measurement environments and conditions and is wide in application range.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable manufacturing, and in particular to a cable pulling speed measurement method based on micro-Doppler effect. BACKGROUND

[0002] In the field of industrial cable manufacturing, the accurate measurement of cable axial speed directly affects product quality and production efficiency. The traditional contact type coding wheel technology has been facing three major bottlenecks for a long time: mechanical wear causes permanent damage of 3-5 μm / km to the cable insulation layer, the slip rate of 2-15% during high-speed operation seriously restricts the measurement accuracy, and industrial environments such as oil and dust are more likely to cause the wheel to slip and fail. Although the non-contact laser speed measurement technology avoids physical contact, it is extremely sensitive to the surface characteristics of the cable - when the roughness of the insulation layer is less than 0.8 μm, the signal-to-noise ratio drops to below 10 dB, and the cost of more than $20,000 per system and the strict optical school qualification requirements (<0.1° installation tolerance) make it difficult to adapt to the working conditions of industrial sites.

[0003] In the patent with the publication number "CN113091733A", a real-time positioning device and method based on millimeter wave radar and IMU fusion are disclosed. The proposed scheme has a principle defect: the vertical installation configuration causes the beam to be orthogonal to the cable axis, which can only capture transverse vibrations and cannot detect axial motion; when the reflectivity of the cable surface exceeds 90%, strong specular reflection will mask the key micro-Doppler features, causing the spectrum analysis to fail. SUMMARY

[0004] The purpose of the present application is to provide a non-contact high-precision cable pulling speed measurement device and method based on micro-Doppler effect, to overcome the problems of existing technologies that cannot accurately measure the axial speed of the cable and fail to analyze the spectrum.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme: a non-contact high-precision cable pulling speed measurement method based on micro-Doppler effect, characterized by comprising the following steps:

[0006] Step one, install two antennas of continuous frequency modulation radar: transmitting antenna and receiving antenna with a preset pitch angle θ t and symmetrically installed above the cable side at an acute angle β (15°≤β≤45°) with the cable pulling direction, adjust the beam direction to form an angle θ with the cable movement direction;

[0007] Step two, set the initial position of the cable center of the device as the origin, obtain the initial geometric position parameters of the radar and the cable through the laser range finder, and the transmitting antenna T x (x t , y t , z treceiving antenna R x (x r , y r , z r ), combined with the geometric position to calculate the radial distance R t of the radar and the trigonometric function to calculate the pitch angle θ t , and the lateral distance, axial distance, vertical distance and installation angle are pre-stored to the processing system;

[0008] Step three, set the radar parameters, including the center frequency, wavelength λ, bandwidth;

[0009] Step four, separate the Doppler shift in the echo, identify the main spectrum peak frequency f d , extract the radial velocity v radial ;

[0010] Step five, take the initial position of the cable center as the coordinate origin, and establish a rectangular coordinate system at the radar position of the pitch angle θ t , combined with the trigonometric function relationship to calculate the cable pulling axial linear velocity υ x .

[0011] Further, the initial geometric position parameters in the above step two, the relationship is:

[0012] x t = x r

[0013] y t = -y r

[0014] z t = z r

[0015] In the formula: y t is the lateral distance; x t is the axial distance; z t is the vertical distance; y r is the lateral distance; x r is the axial distance; z r is the vertical distance.

[0016] Further, the above step two combined with the geometric position to calculate the radial distance R t of the radar and combined with the trigonometric function to calculate the installation pitch angle θ t , the mathematical expression is:

[0017]

[0018] In the formula: y r is the lateral distance; x r is the axial distance; z r is the vertical distance.

[0019] Further, the radial velocity υ in step four is extracted radial The calculation expression is:

[0020]

[0021] In the formula, f d is the main spectral peak frequency; and λ is the wavelength.

[0022] Further, the axial linear velocity υ of the cable in step five is calculated by the trigonometric function relationship x The calculation expression is as follows:

[0023]

[0024] υ radial = υ x cos θ

[0025]

[0026] In the formula, y t is the lateral distance; x t is the axial distance; and z t is the vertical distance.

[0027] Compared with the prior art, the present application has the beneficial effects that:

[0028] 1. The cable microtexture causes scattering and reflection of electromagnetic waves, and a characteristic sidelobe physical phenomenon is generated, through which the present application establishes a 12dB gain mechanism of the signal-to-noise ratio by the acute angle installation configuration (0°< β < 30°); through the unique acute angle installation configuration (0°< β < 30°) and the micro-Doppler characteristic separation algorithm, the interference of the cable micro-mirror reflection on the signal analysis in the non-contact measurement is completely overcome, and the characteristic sidelobe can still be stably captured when the cable surface roughness is extremely low, thereby improving the non-contact measurement precision.

[0029] 2. The present application adopts a radar module, thereby eliminating the maintenance cost of replacing the wear parts every 3 months in the mechanical coding wheel scheme, and effectively reducing the use cost.

[0030] 3. The present application has strong applicability, can adapt to various different measurement environments and conditions, is non-contact to the measurement target, has wide application range, and can be applied to the military field and the civil field. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is the main view of the installation for testing of the present application;

[0032] Figure 2 is the top view of the installation for testing of the present application;

[0033] Figure 3 The installation side view for testing the present application;

[0034] Figure 4 The space vector coordinate system for testing the present application;

[0035] Wherein the reference signs are as follows: 1-transmitting antenna, 2-receiving antenna, 3-cable. DETAILED DESCRIPTION

[0036] The present application will be further clarified by the following examples with reference to the accompanying drawings. The examples are intended to explain the present application, but not to limit the present application.

[0037] The design principle of the present application is: the millimeter wave radar is installed at the side of the cable 3 with a preset pitch angle θ t and an acute angle β with the pulling direction of the cable 3, to ensure that the radar beam covers the surface of the cable 3; the radar transmits a frequency-modulated continuous wave and receives the micro-Doppler-modulated echo signal reflected by the surface of the cable 3; the radial velocity component is extracted by separating the Doppler shift in the echo; the radial velocity is established in a coordinate system combined with the accurate geometric position relationship between the radar and the cable 3 to calculate the axial pulling line speed of the cable 3; and finally the real-time speed value is output through a data interface.

[0038] The present application provides a non-contact high-precision cable pulling line speed measurement method based on micro-Doppler effect, comprising the following steps:

[0039] Step one: install the transmitting antenna 1 and the receiving antenna 2 of the continuous frequency-modulated radar: the transmitting antenna 1 and the receiving antenna 2 are installed at the side of the cable 3 with a preset pitch angle θ t and an acute angle β with the pulling direction of the cable 3, in this embodiment, β is 30°, the beam direction is adjusted to form an angle θ with the movement direction of the cable 3, see Figure 1 .

[0040] Step two: see Figure 2 and Figure 3 , the initial position of the center of the extruded cable 3 is the origin, the initial geometric position parameters of the radar and the cable 3 are obtained by a laser range finder, the transmitting antenna T x (x t , y t , z t ), the receiving antenna R x (x r , y r , z r ), and the relationship is:

[0041] x t = x r

[0042] yt = -y r

[0043] z t = z r

[0044] wherein: y t is the lateral distance (horizontal lateral offset distance from the center of the transmitting radar to the center of the cable); x t is the axial distance (distance along the pulling direction from the center of the transmitting radar to the center of the cable); z t is the vertical distance (vertical longitudinal distance from the center of the transmitting radar to the center of the cable); y r is the lateral distance (horizontal lateral offset distance from the center of the receiving radar to the center of the cable); x r is the axial distance (distance along the pulling direction from the center of the receiving radar to the center of the cable); z r is the vertical distance (vertical longitudinal distance from the center of the receiving radar to the center of the cable);

[0045] The radial distance R of the radar is calculated in combination with the geometric position t and the pitch angle θ is calculated by a trigonometric function t , and the lateral distance, axial distance, vertical distance and installation angle are pre-stored to the processing system, and the relationship and calculation formula are:

[0046]

[0047] wherein: y r is the lateral distance (horizontal lateral offset distance from the center of the radar to the center of the cable 3); x r is the axial distance (distance along the pulling direction from the center of the radar to the center of the cable 3); z r is the vertical distance (vertical longitudinal distance from the center of the radar to the center of the cable 3).

[0048] Step three: set the radar parameters, in the embodiment, the center frequency is selected as 24GHz, the wavelength λ = 0.0125m, the bandwidth is selected as 2GHz, the distance resolution ΔR = c / 2B = 0.075m, the sweep frequency period T c = 1ms; the signal capture collection time length is greater than or equal to 0.5 seconds, 500 sweep frequency periods.

[0049] Step four: separate the Doppler frequency shift in the echo, identify the main spectrum peak frequency f d , and extract the radial velocity υ radial , and the calculation formula is:

[0050]

[0051] wherein: f d is the main spectrum peak frequency; λ is the wavelength.

[0052] Step five: Establishing a rectangular coordinate system with the initial position of the center of the cable 3 as the coordinate origin and the radar position at the pitch angle θ t The axial linear velocity υ of the cable 3 is calculated by combining the trigonometric function relationship, and the calculation formula is as follows: x

[0053]

[0054] υ radial = υ x cosθ

[0055]

[0056] In the formula, y t is the horizontal lateral offset distance from the center of the transmitting radar to the center of the cable 3; x t is the axial distance from the center of the transmitting radar to the center of the cable 3 along the pulling direction; and z t is the vertical longitudinal distance from the center of the transmitting radar to the center of the cable 3.

[0057] The contents not described in detail in the specification belong to the prior art known to those skilled in the art. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or make equivalent replacements for part of the technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.​

Claims

1. A method for non-contact high-precision measurement of cable pulling line speed based on micro-Doppler effect, characterized in that: Comprising the steps of: Step one, install two antennas of continuous frequency modulation radar: transmitting antenna (1) and receiving antenna (2) with preset elevation angle θ t And symmetrically installed on the cable (3) side above with acute angle β (15°≤β≤45°) to the cable pulling direction, adjust the beam direction and the cable (3) movement direction form θ angle; Step two, the equipment extrusion cable (3) center initial position is set as the origin, through the laser range finder to obtain the initial geometric position parameters of radar and cable (3), the transmitting antenna T x (x t , y t , z t ), the receiving antenna R x (x r , y r , z r ), combined with the geometric position, the radial distance R t of the radar is calculated, and the pitch angle θ t is calculated by the trigonometric function, and the lateral distance, axial distance, vertical distance and installation angle are pre-stored to the processing system; Step three, setting radar parameters, including center frequency, wavelength λ and bandwidth; Step four, isolate Doppler shift in echo, identify main spectral peak frequency f d , extract radial velocity v radial ; Step five, the initial position of the cable (3) center as the coordinate origin, located at the radar position of the pitch angle θ t establishes a rectangular coordinate system, and calculates the cable (3) axial linear speed v x combined with the trigonometric function relationship.

2. The device and method of claim 1, wherein the device and method are based on the micro-Doppler effect. The initial geometric position parameters in step two, the relationship is: x t = x r y t = -y r z t = z r where: y t is the lateral distance; x t is the axial distance; z t is the vertical distance; y r is the lateral distance; x r is the axial distance; z r is the vertical distance.

3. The device and method of claim 2, wherein the device and method are based on the micro-Doppler effect. The step two combines the geometric position to calculate the radial distance R of the radar t And combines the trigonometric function to calculate the installation pitch angle θ t The mathematical expression is: where: y r is the lateral distance; x r is the axial distance; z r is the vertical distance.

4. The micro-Doppler-based cable pull speed non-contact high-precision measurement device and method of claim 3, wherein: The step four extracts the radial velocity v radial whose computational expression is: where: f d is the main spectral peak frequency; λ is the wavelength.

5. The micro-Doppler-based non-contact high-precision measurement device and method for cable pulling line speed according to claim 4, characterized in that: The step five trigonometric function relation calculates the linear speed v of the cable (3) in the axial direction x The calculation expression is as follows: υ radial = υ x cos θ where: y t is the lateral distance; x t is the axial distance; z t is the vertical distance.

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