A device and method for measuring the deviation of the center of a sphere based on image recognition

Abstract

The application is a kind of device and method for measuring the deviation of the center of a sphere based on image recognition, which is used to overcome the low measuring accuracy of the deviation of the center of a sphere in the gas suspension method. The device includes a gas suspension unit, a motion limiting unit, an image acquisition unit and a data processing unit. The gas suspension unit outputs high-pressure gas to make the sphere to be measured suspended above the gas suspension unit. The motion limiting unit is set on one side of the gas suspension unit, and it is in contact with the side of the sphere to be measured. The contact point of the motion limiting unit and the sphere to be measured is at the same level as the center of the sphere to be measured. The image acquisition unit is set above the gas suspension unit, and it records the swing of the sphere to be measured. The input end of the data processing unit is connected with the output end of the image acquisition unit. The data processing unit analyzes the image data of the swing of the sphere to be measured, and obtains the period of the swing. Then, according to the relationship between the deviation of the center of the sphere and the period of the swing, the size of the deviation of the center of the sphere to be measured is obtained.

Description

Technical Field

[0001] This invention relates to the field of measurement technology, and more specifically, to a device and method for measuring the centroid deviation of a sphere based on image recognition. Background Technology

[0002] The suspension method is a commonly used method for measuring the deviation between the center of mass and the centroid of a sphere. It typically includes electrostatic suspension and gas suspension methods. The principle is to suspend the sphere using electrostatic or air flotation, allowing it to rotate freely. If the center of mass of the sphere is O... m With the centroid O O If they do not coincide, then the sphere will undergo a simple pendulum motion around its centroid. By measuring the period of this pendulum motion, the deviation between the sphere's center of mass and its centroid can be obtained. For example... Figure 1 The diagram shown illustrates the principle of measuring the eccentricity of a sphere using the air flotation method.

[0003] The existing air flotation method for measuring the eccentricity of a sphere has two drawbacks: firstly, the sphere can rotate freely in any direction, resulting in complex and variable motion; secondly, there is a lack of high-precision monitoring methods for the sphere's motion, leading to low accuracy in measuring the oscillation period. Summary of the Invention

[0004] To overcome the shortcomings of the gas suspension method for measuring sphere eccentricity, which results in low measurement accuracy due to the sphere's ability to rotate freely in any direction, this invention provides a sphere eccentricity deviation measurement device and method based on image recognition.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] A sphere centroid deviation measurement device based on image recognition includes an air flotation unit, a motion limiting unit, an image acquisition unit, and a data processing unit. The air flotation unit outputs high-pressure gas to suspend the sphere under test directly above it. The motion limiting unit is located on one side of the air flotation unit and is used to make contact with the side of the sphere under test, with the contact point between the motion limiting unit and the sphere under test at the same horizontal level as the centroid of the sphere. The image acquisition unit is located above the air flotation unit and is used to capture and record the oscillation of the sphere under test. The input end of the data processing unit is connected to the output end of the image acquisition unit, and it performs image recognition analysis on the acquired image data of the sphere's oscillation to obtain the oscillation period. Then, based on the relationship between the sphere's eccentricity and the oscillation period, the magnitude of the eccentricity of the sphere under test is obtained.

[0007] In this technical solution, an air flotation unit is used to suspend the sphere under high pressure gas. A motion limiting unit is used to restrict the multi-degree-of-freedom motion of the sphere by contacting it. An image acquisition unit set above the air flotation unit records the motion of the marked points on the sphere in real time. The data processing unit then obtains the period of the sphere's oscillation from the recorded motion. Finally, the magnitude of the sphere's center of mass deviation is calculated based on the period.

[0008] As a preferred embodiment, the motion limiting unit includes a fixed bracket and a measuring instrument. The measuring instrument is disposed on the top of the fixed bracket, and the measuring end of the measuring instrument is in close contact with the side of the ball to be measured, for measuring the force generated by contact with the ball to be measured.

[0009] As a preferred embodiment, the measuring instrument includes a dial indicator.

[0010] As a preferred option, before performing precise measurement of the centroid deviation of the sphere to be measured, the measuring instrument is adjusted to measure the reading position with minimal change.

[0011] As a preferred embodiment, the air flotation unit includes an air compressor, a pressure reducing valve, an air pipe, and an air flotation platform. The air outlet of the air pipe is located on the upper surface of the air flotation platform, the air inlet of the air pipe is connected to the output end of the pressure reducing valve, and the input end of the pressure reducing valve is connected to the output end of the air compressor.

[0012] As a preferred embodiment, the upper surface of the air-floating platform is provided with a hemispherical groove, and the air outlet end of the air pipe is located at the bottom of the hemispherical groove.

[0013] As a preferred embodiment, the image acquisition unit includes a CCD camera.

[0014] A method for measuring the centroid deviation of a sphere based on image recognition, applied to the image recognition-based sphere centroid deviation measurement device proposed in any of the above technical solutions, includes the following steps:

[0015] S1: Set a marker point on the sphere to be tested;

[0016] S2: The air flotation unit outputs high-pressure gas to suspend the sphere under test above the air flotation unit. The motion limiting unit is in close contact with the sphere under test, and the contact point between the motion limiting unit and the sphere under test is at the same horizontal height as the centroid of the sphere under test.

[0017] S3: The image acquisition unit acquires the swing image of the sphere under test and transmits it to the data processing unit for data processing;

[0018] S4: The data processing unit extracts the oscillation period of the sphere under test based on the collected oscillation image of the sphere under test, and then calculates the eccentricity of the sphere under test based on the relationship between the eccentricity of the sphere and the oscillation period of the sphere.

[0019] As a preferred embodiment, the formula for calculating the eccentricity of the sphere to be measured in step S4 is as follows:

[0020]

[0021] In the formula, e is the eccentricity of the sphere, I is the moment of inertia of the sphere, m is the mass of the sphere, g is the gravitational acceleration; θ0 is the swing angle amplitude of the sphere, K(θ0) represents the swing angle correction coefficient; and T is the period of the sphere's swing.

[0022] As a preferred embodiment, the method further includes the following steps: making uniform reading marks on the outer periphery of the air flotation unit to obtain the swing angle amplitude θ0 of the sphere.

[0023] Compared with the prior art, the beneficial effects of the technical solution of the present invention are: the present invention restricts the multi-degree-of-freedom motion of the sphere under test by using a motion restriction unit, thereby reducing the error caused by the multi-degree-of-freedom motion coupling on the measurement of the deviation between the centroid and centroid of the sphere. Furthermore, the image acquisition unit improves the extraction accuracy of the sphere's motion period, further improving the measurement accuracy of the sphere's eccentricity. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating the principle of measuring the eccentricity of a sphere using the air flotation method.

[0025] Figure 2 This is a schematic diagram of the structure of the image recognition-based sphere centroid deviation measurement device in Example 1.

[0026] Figure 3 This is a cross-sectional view of the air-floating platform in Example 1.

[0027] Figure 4 This is a flowchart of the image recognition-based method for measuring the centroid deviation of a sphere, as described in Example 2.

[0028] Among them, 1-air flotation unit, 101-air compressor, 102-pressure reducing valve, 103-air pipe, 104-air flotation platform, 2-motion limiting unit, 201-fixed bracket, 202-measuring tool, 3-image acquisition unit, and 4-data processing unit. Detailed Implementation

[0029] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this patent.

[0030] To better illustrate this embodiment, some parts in the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions.

[0031] It will be understood by those skilled in the art that certain well-known structures and their descriptions may be omitted in the accompanying drawings.

[0032] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] Example 1

[0034] This embodiment proposes a device for measuring the centroid deviation of a sphere based on image recognition, such as... Figure 2 The diagram shown is a structural schematic of the image recognition-based sphere centroid deviation measurement device of this embodiment.

[0035] The image recognition-based sphere centroid deviation measurement device proposed in this embodiment includes an air flotation unit 1, a motion limiting unit 2, an image acquisition unit 3, and a data processing unit 4, wherein:

[0036] The air flotation unit 1 is used to output high-pressure gas to suspend the sphere under test directly above the air flotation unit 1;

[0037] The motion limiting unit 2 is disposed on one side of the air flotation unit 1 and is used to make contact with the side of the ball to be tested. The contact point between the motion limiting unit 2 and the ball to be tested is at the same horizontal height as the centroid of the ball to be tested.

[0038] The image acquisition unit 3 is located above the air flotation unit 1 and is used to capture and record the swing of the sphere under test.

[0039] The input end of the data processing unit 4 is connected to the output end of the image acquisition unit 3, and is used to perform image recognition analysis on the acquired image data of the oscillation of the ball under test, obtain the period of the oscillation of the ball under test, and then obtain the size of the eccentricity of the ball under test according to the relationship between the eccentricity of the ball and the period of the oscillation.

[0040] In this embodiment, the motion limiting unit 2 includes a fixed bracket 201 and a measuring instrument 202. The measuring instrument 202 in this embodiment is a dial indicator, which is mounted on the top of the fixed bracket 201, and the measuring end of the measuring instrument 202 is in close contact with the side of the ball to be measured, for measuring the force generated by the contact between the measuring instrument 202 and the ball to be measured.

[0041] Furthermore, by adjusting the measuring instrument 202 to a position where the minimum change in reading can be measured, the measuring instrument 202 is ensured to contact the ball to be measured with the smallest possible force. Specifically, the reading of the dial indicator is adjusted so that the reading of the dial indicator is slightly greater than 0.

[0042] In this embodiment, the air flotation unit 1 includes an air compressor 101, a pressure reducing valve 102, an air pipe 103, and an air flotation platform 104. The outlet end of the air pipe 103 is located on the upper surface of the air flotation platform 104, the inlet end of the air pipe 103 is connected to the output end of the pressure reducing valve 102, and the input end of the pressure reducing valve 102 is connected to the output end of the air compressor 101. A hemispherical groove is formed on the upper surface of the air flotation platform 104, and the outlet end of the air pipe 103 is located at the bottom of the hemispherical groove. Figure 3 The figure shown is a cross-sectional view of the air-floating platform 104 in this embodiment.

[0043] In this embodiment, the image acquisition unit 3 uses a CCD camera, and the data processing unit 4 uses a computer.

[0044] In the specific implementation process, marking points are first set on the sphere to be tested. The sphere is then placed in the hemispherical slot of the air-float platform 104. The high-pressure gas output from the air compressor 101 is stabilized by the pressure reducing valve 102 and then transmitted to the bottom of the slot of the air-float platform 104 through the air pipe 103, so that the sphere to be tested is in a suspended state. Under the action of the high-pressure gas and the motion limiting unit 2, the sphere to be tested only performs a simple pendulum motion around one axis, where the motion limiting unit 2 restricts the multi-degree-of-freedom motion of the sphere to be tested. The image acquisition unit 3 acquires the motion of the marking points on the sphere to be tested, records the oscillation of the sphere to be tested, and then sends it to the data processing unit 4. The data processing unit 4 performs image recognition analysis on the acquired image data of the oscillation of the sphere to be tested, obtains the period of the oscillation of the sphere to be tested, and then obtains the magnitude of the eccentricity of the sphere to be tested, which is the magnitude of the deviation of the sphere's center of mass, based on the relationship between the sphere's eccentricity and the period of the oscillation.

[0045] This embodiment uses motion restriction unit 2 to restrict the multi-degree-of-freedom motion of the sphere under test, thereby reducing the error caused by the coupling of multi-degree-of-freedom motion to the measurement of the deviation between the sphere's center of mass and centroid. Furthermore, the image acquisition unit 3 improves the extraction accuracy of the sphere's motion period, further improving the measurement accuracy of the sphere's eccentricity.

[0046] Example 2

[0047] This embodiment proposes an image recognition-based method for measuring the centroid deviation of a sphere, applied to the image recognition-based sphere centroid deviation measurement device proposed in Embodiment 1. For example... Figure 4 The diagram shown is a flowchart of the image recognition-based method for measuring the centroid deviation of a sphere in this embodiment.

[0048] The image recognition-based method for measuring the centroid deviation of a sphere proposed in this embodiment includes the following steps:

[0049] S1: Set a marker point on the sphere to be tested;

[0050] S2: High-pressure gas is output by the air flotation unit 1 to suspend the sphere to be tested above the air flotation unit 1. The motion restriction unit 2 is in close contact with the sphere to be tested, and the contact point between the motion restriction unit 2 and the sphere to be tested is at the same horizontal height as the centroid of the sphere to be tested.

[0051] S3: The image acquisition unit 3 acquires the swing image of the sphere under test and transmits it to the data processing unit 4 for data processing;

[0052] S4: The data processing unit 4 extracts the period of the oscillation of the sphere under test based on the collected oscillation image of the sphere under test, and then calculates the size of the eccentricity of the sphere under test based on the relationship between the eccentricity of the sphere and the oscillation period of the sphere.

[0053] In this embodiment, the formula for calculating the eccentricity of the sphere to be measured is as follows:

[0054]

[0055] In the formula, e is the eccentricity of the sphere, I is the moment of inertia of the sphere, m is the mass of the sphere, g is the gravitational acceleration; θ0 is the swing angle amplitude of the sphere, K(θ0) represents the swing angle correction coefficient; and T is the period of the sphere's swing.

[0056] The moment of inertia I of the sphere is calculated using the mass and diameter of the sphere, which is measured using a coordinate measuring machine; the gravitational acceleration g is taken as a constant of 9.8 m / s². 2 The swing angle amplitude θ0 of the ball is obtained by making uniform reading marks on the outer periphery of the air-bearing platform 104. θ0 is generally very small, so the swing angle correction coefficient K(θ0) in this embodiment is taken as 1.

[0057] The same or similar labels correspond to the same or similar parts;

[0058] The terms used to describe positional relationships in the accompanying drawings are for illustrative purposes only and should not be construed as limiting this patent.

[0059] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A device for measuring the deviation of the centroid of a sphere from its center of mass based on image recognition, characterized in that, It includes an air flotation unit (1), a motion limiting unit (2), an image acquisition unit (3), and a data processing unit (4), wherein: The air flotation unit (1) is used to output high-pressure gas to suspend the sphere under test directly above the air flotation unit (1); The motion limiting unit (2) is disposed on one side of the air flotation unit (1) for contacting the side of the ball to be tested, and the contact point between the motion limiting unit (2) and the ball to be tested is at the same horizontal height as the centroid of the ball to be tested; The image acquisition unit (3) is located above the air flotation unit (1) and is used to capture and record the swing of the sphere under test. The input end of the data processing unit (4) is connected to the output end of the image acquisition unit (3) for image recognition analysis of the acquired image data of the oscillation of the ball under test, to obtain the period of the oscillation of the ball under test, and then to obtain the size of the eccentricity of the ball under test according to the relationship between the eccentricity of the ball and the period of the oscillation of the ball. The motion limiting unit (2) includes a fixed bracket (201) and a measuring instrument (202). The measuring instrument (202) is disposed on the top of the fixed bracket (201), and the measuring end of the measuring instrument (202) is in close contact with the side of the ball to be measured, for measuring the force generated by contact with the ball to be measured. The measuring instrument (202) includes a dial indicator; Before performing a precise measurement of the centroid deviation of the sphere to be measured, adjust the measuring instrument (202) to measure the reading position with minimal change.

2. The sphere centroid deviation measuring device according to claim 1, characterized in that, The air flotation unit (1) includes an air compressor (101), a pressure reducing valve (102), an air pipe (103), and an air flotation platform (104). The air outlet of the air pipe (103) is located on the upper surface of the air flotation platform (104). The air inlet of the air pipe (103) is connected to the output end of the pressure reducing valve (102), and the input end of the pressure reducing valve (102) is connected to the output end of the air compressor (101).

3. The sphere centroid deviation measuring device according to claim 2, characterized in that, The upper surface of the air-floating platform (104) is provided with a hemispherical groove, and the air outlet of the air pipe (103) is located at the bottom of the hemispherical groove.

4. The sphere centroid deviation measuring device according to claim 1, characterized in that, The image acquisition unit (3) includes a CCD camera.

5. A method for measuring the centroid deviation of a sphere based on image recognition, applied to the image recognition-based sphere centroid deviation measuring device according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1: Set a marker point on the sphere to be tested; S2: The air flotation unit (1) outputs high-pressure gas to suspend the ball under test above the air flotation unit (1), and the motion restriction unit (2) is in close contact with the ball under test, and the contact point between the motion restriction unit (2) and the ball under test is at the same horizontal height as the centroid of the ball under test; S3: The image acquisition unit (3) acquires the swing image of the sphere to be tested and transmits it to the data processing unit (4) for data processing; S4: The data processing unit (4) extracts the period of the swing of the ball under test based on the swing image of the ball under test collected, and then calculates the size of the eccentricity of the ball under test based on the relationship between the eccentricity of the ball and the swing period of the ball.

6. The method for measuring the deviation of the centroid of a sphere according to claim 5, characterized in that, In step S4, the formula for calculating the eccentricity of the sphere to be measured is as follows: In the formula, e The eccentricity of the sphere, I Let be the moment of inertia of the sphere. m For the mass of a sphere, g It is the acceleration due to gravity; The amplitude of the spherical swing angle. Indicates the swing angle correction factor; T The period of the sphere's oscillation.

7. The method for measuring the deviation of the centroid of a sphere according to claim 6, characterized in that, It also includes the following steps: Uniform reading marks are made on the outer periphery of the air flotation unit (1) to obtain the swing angle amplitude of the sphere. .

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