CN114453977B - Wide-range displacement measuring device and method of visual scanning linear variable density stripe ruler - Google Patents

Abstract

The invention relates to a wide-range displacement measuring device and method of a visual scanning linear variable density stripe ruler, wherein the device comprises: the linear variable density stripe ruler is used for measuring the displacement information of the slide rail; the imaging module is arranged and fixed on the sliding rail and used for carrying out continuous imaging and data acquisition on the linear variable density stripes on the stripe ruler and transmitting the acquired information to the processing module; the displacement sliding platform is used for driving the sliding rail to drive the imaging module to do linear motion so as to enable the imaging module to perform linear imaging on the linear variable density stripes; and the processing module is used for controlling the imaging module, processing the imaging stripe information in real time, obtaining a stripe density signal frequency change curve according to the density change rule of the imaging stripe, establishing a mapping relation and a mathematical model between the frequency change information and the actual displacement of the sliding rail, and further calculating the actual displacement information of the sliding rail. The device and the method are beneficial to improving the measurement efficiency and the measurement precision, and the device is simple and low in implementation cost.

Description

Device and method for large-range displacement measurement of visual scanning linear variable-density strip ruler

technical field

The invention belongs to the field of machine vision measurement, and in particular relates to a large-range displacement measurement device and method for visually scanning a linear variable-density stripe ruler.

Background technique

During the processing of the machine tool, due to friction, tool wear and other reasons, there will be errors in the tool movement of the machine tool, which will affect the processing quality of the workpiece. Therefore, it is necessary to compensate the error of the machine tool to improve the machining quality of the workpiece.

At present, in order to improve machining accuracy, grating scales, magnetic scales, and ball scales are often used in machine tools. The grating ruler is based on the optical glass scribe line, and the optical glass is installed in the aluminum alloy ruler body and the reading head and other accessories to form the grating ruler. The aluminum alloy semi-sealed design. Grating rulers are widely used, but due to their semi-sealed design, if water, oil, or iron filings enter during use, the grating may be damaged, and the grating is not easy to process, and the replacement cost is relatively high. Because the magnetic scale adopts the magnetic tape principle, the price is low and the installation is simple, but the measurement accuracy will be affected due to the wide reference signal and the existence of degaussing problems. The ball scale uses the change of the amount of magnetic medium to realize the electromagnetic/magnetoelectric conversion, which has high precision, and because it is a fully sealed design, it is not easy to be damaged by the working environment, but its cost is high.

Contents of the invention

The object of the present invention is to provide a large-range displacement measurement device and method for visually scanning linear variable-density strip ruler. The device and method are conducive to improving measurement efficiency and measurement accuracy, and the device is simple and the implementation cost is low.

In order to achieve the above object, the technical solution adopted in the present invention is: a large-range displacement measuring device for visually scanning linear variable-density stripe ruler, comprising:

Linear variable density stripe ruler, used to measure the actual displacement information of the slide rail;

The imaging module is installed and fixed on the slide rail, and is used for continuous imaging and data collection of the linear variable density stripes on the surface of the linear variable density stripe ruler, and transmits the collected imaging stripe information to the processing module;

The displacement sliding platform is used to drive the slide rail to drive the imaging module to perform linear motion, so that the imaging module can linearly image the linear variable density stripes; and

The processing module is used to control the imaging module and process the imaging fringe information in real time, obtain the fringe density signal frequency variation curve according to the density variation rule of the imaging fringe, and establish the mapping relationship between the frequency variation information and the actual displacement of the slide rail And the mathematical model, and then calculate the actual displacement information of the slide rail; the mathematical relationship between the fringe frequency and the actual displacement of the slide rail is:

Among them, Δ x ( i ) is the actual displacement of the sliding rail when the i-th frame collects the linear variable-density stripe ruler, L is the actual length of the linear variable-density stripe ruler, f _i is the frequency of imaging the linear variable-density stripe in the i -th frame, f _e is the maximum frequency of the linear variable density fringe, f _s is the initial frequency of the linear variable density fringe.

Further, the linear variable density stripe ruler is a steel ruler with linear variable density stripes sprayed on the surface, and the linear variable density stripe ruler is fixedly arranged on the front side of the imaging module along the moving direction of the slide rail, so that the imaging module can follow the slide rail Imaging fringe information is collected during motion.

Further, the fringe image density of the linear variable density stripe ruler changes linearly along the direction of the change of the light and shade of the stripes.

Further, the linear variable density stripe ruler is installed on the displacement sliding platform, and the actual displacement information of the slide rail is calculated according to the stripe density variation law.

Further, the imaging module is mainly composed of an imaging lens, a line sensor and a control circuit.

Further, the sampling frame rate and imaging resolution of the imaging module can be adjusted according to the measurement accuracy requirements of the displacement sliding platform.

Further, when the imaging module images the linear variable density fringes, its imaging optical axis is perpendicular to the fringe plane, and the imaging range of the imaging module corresponds to the fringe plane.

The present invention also provides a large-scale displacement measurement method of a visual scanning linear variable density strip ruler, comprising the following steps:

Step S1: Install the linear variable-density strip ruler on the displacement sliding platform, install and fix the imaging module on the slide rail of the displacement sliding platform, and adjust the imaging position of the imaging module so that it is aligned with the linear variable-density strip ruler, so that The fringe center is within the imaging range of the imaging module;

Step S2: When the displacement sliding platform drives the slide rail to move, the slide rail drives the imaging module to move, and the imaging module continuously images the linear variable density stripes on the surface of the linear variable density stripe ruler;

Step S3: The imaging module transmits the collected imaging fringe information to the processing module. Since the linear variable density fringe is continuously imaged, the density of the imaging fringe will change with the imaging process, and the processing module obtains the density of the imaging fringe According to the change law, the frequency change curve of the fringe density signal is obtained, and the mapping relationship and mathematical model between the frequency change information and the actual displacement of the slide rail are established, and then the actual displacement information of the slide rail is calculated.

Compared with the prior art, the present invention has the following beneficial effects: by setting the imaging module to move with the slide rail, it can continuously image the linear variable-density stripes on the linear variable-density stripe scale, and obtain the imaged stripe information by real-time processing Imaging the change rule of fringe density information, and then establishing the mapping relationship and mathematical model between the fringe frequency change information and the actual displacement of the slide rail, and realizing the measurement of the actual displacement of the slide rail. This kind of measurement not only makes the signal extraction faster and more efficient, but also improves the efficiency of the measurement. By increasing the sampling frame rate of the imaging module, the measurement accuracy can be further improved. In addition, the structure and stripes of the device are simpler, and the manufacturing and maintenance costs are low. Therefore, the present invention has strong practicability and wide application prospect.

Description of drawings

Fig. 1 is a schematic diagram of the device structure of the embodiment of the present invention.

In the figure: 1-linear variable density stripe ruler, 2-displacement sliding platform, 3-imaging module, 4-processing module, 5-linear variable density stripe, 6-sliding rail.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

It should be pointed out that the following detailed description is exemplary and is intended to provide further explanation to the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terminology used here is only for describing specific implementations, and is not intended to limit the exemplary implementations according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural, and it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, they mean There are features, steps, operations, means, components and/or combinations thereof.

As shown in FIG. 1 , this embodiment provides a large-range displacement measurement device for visually scanning a linear variable-density strip ruler, including a linear variable-density strip ruler 1 , a displacement sliding platform 2 , an imaging module 3 and a processing module 4 . The linear variable density stripe ruler 1 has linear variable density stripes 5 for measuring the actual displacement information of the slide rail. A movable sliding rail 6 is provided on the displacement sliding platform 2 , and the displacement sliding platform 2 is used to drive the sliding rail 6 to drive the imaging module 3 to move linearly, so that the imaging module 3 performs linear imaging on the linear variable density stripes 5 . The imaging module 3 is installed and fixed on the slide rail 6 for continuous imaging and data collection of the linear variable density stripes 5 on the surface of the linear variable density strip ruler 1 , and transmits the collected imaged stripe information to the processing module 4 . The processing module 4 is used to control the imaging module 3, including controlling its start and stop and parameter setting; it is also used to store and process the imaging fringe information in real time, and obtain the frequency variation curve of the fringe density signal according to the density variation rule of the imaging fringe, The mapping relationship and mathematical model between the frequency change information and the actual displacement of the slide rail are established, and each imaging position corresponds to a frequency of the fringe, and then the actual displacement information of the slide rail is calculated. ; The mathematical relationship between the fringe frequency and the actual displacement of the slide rail is:

Among them, Δ x ( i ) is the actual displacement of the sliding rail when the i-th frame collects the linear variable-density stripe ruler, L is the actual length of the linear variable-density stripe ruler, f _i is the frequency of imaging the linear variable-density stripe in the i -th frame, f _e is the maximum frequency of the linear variable density fringe, f _s is the initial frequency of the linear variable density fringe.

In this embodiment, the linear variable density stripe ruler 1 is a steel ruler with linear variable density stripes sprayed on the surface, and the linear variable density stripe ruler 1 is fixedly arranged on the front side of the imaging module 3 along the moving direction of the slide rail, so that The imaging module 3 collects imaging fringe information during its movement with the slide rail 6 . The fringe image density of the linear variable density stripe ruler 1 changes linearly along the direction in which the light and shade of the stripes change. The linear variable density stripe ruler 1 is installed on the displacement sliding platform 2, and the actual displacement information of the slide rail is calculated according to the variation rule of the stripe density.

In this embodiment, the imaging module 3 is mainly composed of an imaging lens, a line sensor and a control circuit. The sampling frame rate and imaging resolution of the imaging module 3 can be adjusted according to the measurement accuracy requirements of the displacement sliding platform. When the imaging module 3 images the linear variable density fringes, its imaging optical axis is perpendicular to the fringe plane, and the imaging range of the imaging module corresponds to the fringe plane.

The present embodiment also provides a large-range displacement measurement method based on the above device, comprising the following steps:

Step S1: install the linear variable density strip ruler 1 on the displacement sliding platform 2, install and fix the imaging module 3 on the slide rail 6 of the displacement sliding platform 2, and adjust the imaging position of the imaging module 3 so that it is aligned with the linear variable density Density stripe ruler, so that the stripe center is in the imaging range of imaging module 3.

Step S2: When the displacement slide platform 2 drives the slide rail 6 to move, the slide rail 6 drives the imaging module 3 to move, and the imaging module 3 continuously images the linear variable density stripes 5 on the surface of the linear variable density strip ruler 1 .

Step S3: The imaging module 3 transmits the collected imaging fringe information to the processing module 4. Since the linear variable density fringe 5 is continuously imaged, the density of the imaging fringe will change with the imaging process, and the processing module 4 processes and obtains The density change rule of the imaging fringe is obtained to obtain the frequency change curve of the fringe density signal, and the mapping relationship and mathematical model between the frequency change information and the actual displacement of the slide rail are established, and finally the actual displacement information of the slide rail 6 is calculated by correlation calculation. In this way, the actual displacement information of the mechanism that is fixedly connected with the slide rail 6 can be measured.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention to other forms. Any skilled person who is familiar with this profession may use the technical content disclosed above to change or modify the equivalent of equivalent changes. Example. However, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims (7)

1. A wide-range displacement measuring method of a visual scanning linear variable density stripe ruler is characterized in that a wide-range displacement measuring device is provided, and the method comprises the following steps:

the linear variable density stripe ruler is used for measuring the actual displacement information of the slide rail;

the imaging module is arranged and fixed on the sliding rail and used for carrying out continuous imaging and data acquisition on the linear variable density stripes on the surface of the linear variable density stripe ruler and transmitting the acquired imaging stripe information to the processing module;

the displacement sliding platform is used for driving the sliding rail to drive the imaging module to do linear motion so as to enable the imaging module to perform linear imaging on the linear variable density stripes; and

the processing module is used for controlling the imaging module, processing the imaging stripe information in real time, obtaining a stripe density signal frequency change curve according to the density change rule of the imaging stripe, establishing a mapping relation and a mathematical model between the frequency change information and the actual displacement of the slide rail, and further calculating the actual displacement information of the slide rail; the mathematical relationship between the fringe frequency and the actual displacement of the slide rail is as follows:

wherein, deltax(i) Is a firstiThe actual displacement of the slide rail when the linear variable density stripe ruler is collected by frames,Lis the actual length of the linear variable density stripe ruler,f _i is a firstiThe frequency at which the frame images the linear variable density fringes,f _e is the maximum frequency of the linear variable density fringes,f _s the initial frequency of the linear variable density stripe;

the wide-range displacement measuring method based on the wide-range displacement measuring device comprises the following steps of:

step S1: installing a linear variable density stripe ruler on a displacement sliding platform, installing and fixing an imaging module on a sliding rail of the displacement sliding platform, and adjusting the imaging position of the imaging module to align the imaging position with the linear variable density stripe ruler so as to enable the center of a stripe to be in the imaging range of the imaging module;

step S2: when the displacement sliding platform drives the sliding rail to move, the sliding rail drives the imaging module to move, and the imaging module continuously images linear variable density stripes on the surface of the linear variable density stripe ruler;

and step S3: the imaging module transmits the acquired imaging stripe information to the processing module, and the linear variable density stripe is continuously imaged, so that the density of the imaging stripe can change along with the imaging process, the processing module processes the density change rule of the imaging stripe to obtain a stripe density signal frequency change curve, a mapping relation and a mathematical model between the frequency change information and the actual displacement of the sliding rail are established, and the actual displacement information of the sliding rail is calculated.

2. The method according to claim 1, wherein the linear variable density strip ruler is a steel ruler coated with linear variable density strips on the surface, and the linear variable density strip ruler is fixedly arranged on the front side of the imaging module along the moving direction of the slide rail so that the imaging module collects the information of the imaging strips during the movement of the imaging module along the slide rail.

3. The method as claimed in claim 2, wherein the fringe image density of the linear variable density fringe ruler is linearly changed along the direction of fringe brightness change.

4. The method as claimed in claim 2, wherein the linear variable density stripe ruler is mounted on a displacement sliding platform, and the actual displacement information of the slide rail is calculated according to the stripe density variation rule.

5. The method as claimed in claim 1, wherein the imaging module is mainly composed of an imaging lens, a linear array sensor and a control circuit.

6. The method of claim 1, wherein the sampling frame rate and the imaging resolution of the imaging module are adjustable according to the measurement accuracy requirement of the displacement sliding platform.

7. The method as claimed in claim 1, wherein the imaging module images the linear variable density stripe with an imaging optical axis perpendicular to the stripe plane, and an imaging range of the imaging module corresponds to the stripe plane.

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