A planar two-dimensional displacement measurement method based on surface topography

Abstract

The invention belongs to the technical field of linear displacement measurement, and particularly relates to a planar two-dimensional displacement measurement method based on surface morphology features, comprising a base scale and a measuring scale, wherein the base scale has a surface morphology feature specific to a two-dimensional region, and the measuring scale comprises a substrate and a sensor array, wherein the sensor array is fixed by the substrate and keeps the relative positions between the sensors unchanged; the measuring scale and the base scale are arranged parallel and opposite to each other with a gap, and the surface morphology features of the base scale are detected by using the sensor array; when a relative two-dimensional movement occurs between the measuring scale and the base scale, an output signal of the sensor array changes accordingly, a neural network model is established through learning and training for the output signal of the sensor array, and the relative two-dimensional displacement between the measuring scale and the base scale is determined by using the neural network model, so as to realize planar two-dimensional displacement measurement; the invention reduces the processing technology requirements to a large extent, reduces the influence of the processing technology on the measurement accuracy, and has the measurement advantages of high accuracy, high robustness, and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of linear displacement measurement, and in particular relates to a planar two-dimensional displacement measurement method based on surface morphology characteristics. Background Art

[0002] Existing two-dimensional displacement measurement methods can be divided into three categories according to different principles: the first category is optical two-dimensional displacement measurement, such as the two-dimensional grating of German HEIDENHAIN, British RENISHAW, and Japanese MITUTOYO; the second category is capacitive two-dimensional displacement measurement, such as Hartwell in the United States and Wang Bibo's two-dimensional capacitive micro displacement sensor of Huazhong University of Science and Technology; the third category is inductive two-dimensional displacement measurement. Optical two-dimensional displacement measurement is highly dependent on precision characterization technology, and has poor resistance to oil and dust; the measurement range of capacitive two-dimensional displacement measurement is generally small.

[0003] Prior art, such as the Chinese patent with publication number "CN 112857194 A", discloses a planar two-dimensional displacement sensor based on the eddy current effect. The concept is to evenly arrange square metal blocks of equal area on a non-magnetic and non-conductive fixed-size substrate to form a fixed scale, and to arrange four planar spiral coils distributed in a rectangular shape on a non-magnetic and non-conductive moving scale substrate to form a moving scale. An AC excitation signal is passed through the spiral coil to generate a magnetic field that changes with both time and the displacement of the moving scale, and two-dimensional displacement measurement can be achieved through signal processing. However, the planar two-dimensional displacement sensor only has the function of relative displacement measurement, but not the absolute displacement measurement capability, and the structural parameter deviation caused by processing, manufacturing, and assembly has a great influence on the measurement accuracy, resulting in low resolution of two-dimensional displacement measurement, large measurement error, and insufficient robustness. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a planar two-dimensional displacement measurement method based on surface morphology features, which has the advantages of high precision and high robustness.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A planar two-dimensional displacement measurement method based on surface morphology, comprising a base ruler and a measuring ruler, wherein the base ruler has a two-dimensional region-specific surface morphology, and the measuring ruler comprises a substrate and a sensor array, wherein the sensor array is fixed by the substrate and the relative positions between sensors are kept unchanged;

[0007] The measuring ruler is arranged parallel to the base ruler with a gap therebetween, and the sensor array is used to detect the surface topography of the base ruler;

[0008] When a relative two-dimensional movement occurs between the measuring ruler and the base ruler, the output signal of the sensor array changes accordingly. A neural network model is established through learning and training for the output signal of the sensor array. The neural network model is used to determine the relative two-dimensional displacement between the measuring ruler and the base ruler, thereby realizing planar two-dimensional displacement measurement.

[0009] In a further technical solution, the material of the base ruler is a conductive metal, and its surface morphology is a surface profile processed according to a preset rule;

[0010] The sensor array is an eddy current displacement sensor.

[0011] In a further technical solution, the surface morphology feature of the base ruler is a coding pattern set on its surface, which is characterized by horizontal and vertical rectangular grooves of different sizes and spacings on the surface of the base ruler. The depth and width values ​​of each groove are uniquely set according to a pseudo-random sequence, and each element of the sequence is randomly distributed within a fixed threshold, so that the base ruler forms a two-dimensional region-specific surface morphology feature.

[0012] In a further technical solution, the material of the base ruler is metal or non-metal, and its surface morphology is the surface roughness and waviness characteristics after mechanical processing;

[0013] The sensor array is an eddy current roughness sensor or an optical fiber roughness sensor.

[0014] In a further technical solution, the number of sensors in the sensor array is equal to or greater than three.

[0015] In a further technical solution, the gap between the measuring ruler and the base ruler is large enough to ensure that the output signal of the sensor array is within the measuring range during the entire measuring process.

[0016] Compared with the prior art, the present invention has the following technical effects:

[0017] 1. The planar two-dimensional displacement measurement method based on surface morphology provided by the present invention can realize linear displacement measurement by using the designed and processed macroscopic surface morphology features, or can realize planar two-dimensional linear displacement measurement by using the inherent microscopic surface morphology features of surface roughness without changing the original surface profile of the parts, and the measurement scheme is flexible;

[0018] 2. The planar two-dimensional displacement measurement method provided by the present invention has the advantages of easy installation, flexible measurement scheme, and fast measurement speed. It can perform one-dimensional or two-dimensional linear displacement measurement and can be used as an alternative measurement scheme when it is inconvenient to install a grating, and has good applicability;

[0019] 3. The planar two-dimensional displacement measurement method provided by the present invention, by adopting a neural network measurement model and multi-sensor fusion, reduces the processing technology requirements to a large extent, reduces the impact of the processing technology on the measurement accuracy, and has measurement advantages such as high precision and high robustness. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of a macroscopic surface topography feature measurement principle provided according to a specific embodiment of the present invention is shown;

[0021] Figure 2 A macroscopic surface morphology feature base scale diagram provided according to a specific embodiment of the present invention is shown;

[0022] Figure 3 A microscopic surface morphology feature base scale diagram provided according to a specific embodiment of the present invention is shown;

[0023] Figure 4 It is a diagram of a calibration device according to Embodiment 1 of the present invention;

[0024] Figure 5 It is shown as a measurement diagram of Example 1 of the present invention;

[0025] Figure 6 A one-dimensional mobile platform diagram provided according to a specific embodiment of the present invention is shown;

[0026] Figure 7 A partial diagram showing a base ruler and a motion platform provided according to a specific embodiment of the present invention;

[0027] Explanation of the numbers in the figure: 1. Base scale; 2. Measuring scale; 3. Matrix; 4. Sensor array; 5. Base; 6. Lower one-dimensional mobile platform; 7. Upper one-dimensional mobile platform; 8. Motion platform; 9. Target mirror; 10. Laser tracker host. DETAILED DESCRIPTION

[0028] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific drawings.

[0029] It should be noted that, in the present invention, when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0031] Example 1

[0032] like Figure 1 , 4 As shown in , 7, this embodiment provides a planar two-dimensional displacement measurement method based on surface topography, including a base ruler 1 and a measuring ruler 2. The measuring ruler 2 includes a substrate 3 and a sensor array 4, and the sensor array 4 is fixed by the substrate 3 to keep the relative positions between sensors unchanged.

[0033] The base ruler 1 is made of conductive metal and is fixed on a horizontal surface of a base 5 made of marble.

[0034] The base ruler 1 has a two-dimensional region-specific surface morphology feature, and the surface morphology feature of the base ruler 1 is a macroscopic surface morphology feature, and the macroscopic surface morphology feature refers to a surface contour processed according to a preset rule;

[0035] Specific, combined Figure 2 As shown, the macroscopic surface morphology feature of the base ruler 1 is a surface profile processed according to a preset rule, which means that a coding pattern is set on the surface of the base ruler 1, which is characterized by horizontal and vertical rectangular grooves of different sizes and spacings on the surface of the base ruler 1. The depth and width values ​​of each groove are uniquely set according to a pseudo-random sequence, and each element of the sequence is randomly distributed within a fixed threshold, so that the base ruler 1 forms a two-dimensional region-specific surface morphology feature;

[0036] The base 3 of the measuring ruler 2 is integrated with the motion platform 8, and the motion platform 8 and the sensor array 4 constitute the measuring ruler 2; that is, the sensor array 4 is fixed by the motion platform 8 and the relative positions between the sensors are kept unchanged; the measuring ruler 2 is arranged parallel to the base ruler 1 with a gap, and the sensor array 4 is used to detect the surface morphology of the base ruler 1;

[0037] Specifically, the sensor array 4 is an eddy current displacement sensor;

[0038] Specifically, the number of sensors in the sensor array 4 is equal to four, and they are evenly distributed on the four corners of the cuboid motion platform 8;

[0039] Specifically, the measuring ruler 2 is arranged parallel to the base ruler 1 and there is a gap therebetween, and the size of the gap is required to ensure that the output signal of the sensor array 4 is within the measuring range during the entire measurement process;

[0040] The sensor array 4 is fixed and driven by the motion platform 8, and the motion platform 8 is driven by the two-dimensional moving platform. When the measuring ruler 2 and the base ruler 1 move relative to each other in two dimensions, the output signal of the sensor array 4 changes accordingly.

[0041] Specifically, the two-dimensional mobile platform is composed of a lower one-dimensional mobile platform 6 and an upper one-dimensional mobile platform 7, and the upper and lower one-dimensional mobile platforms are arranged orthogonally, such as Figure 6 As shown, the one-dimensional mobile platform consists of a base, two precision guide rails, a ball screw, a motor drive component, four sliders and a mobile platform. The two precision guide rails are fixedly arranged in parallel on both sides above the base, the ball screw is arranged in the middle above the base, the motor drive component is installed at both ends of the ball screw, two sliders are arranged on each guide rail, a total of four sliders, the mobile platform is fixed on the four sliders and connected to the ball screw, and the mobile platform is driven to move by the form of a motor + ball screw pair;

[0042] Building a calibration device to perform calibration sampling on the output signals of the sensor array 4 and create a training set and a test set for the neural network model;

[0043] Specifically, the output signals of the sensor array 4 and the displacement values ​​of the two-dimensional movement of the plane are corresponded one by one to form an array and used as training set and test set data, and the neural network measurement model is established using the training set and the test set;

[0044] Specifically, the structure of the calibration device is:

[0045] like Figure 4 As shown, the calibration device is a laser tracker, which includes a target mirror 9 and a laser tracker host 10. The target mirror 9 is fixed on the motion platform 8 and can move synchronously with the motion platform 8. The laser tracker host 10 is placed on the horizontal ground. The laser signal source emitted by the laser tracker host 10 is reflected by the target mirror 9 and then received and processed by the laser tracker host 10, so that the position of the target mirror 9 can be known, and thus the position of the motion platform 8 and the sensor array 4 can be known.

[0046] Specifically, an array of displacement values ​​of the two-dimensional plane movement and output signals of the sensor array 4 corresponding to each other is obtained as follows:

[0047] Establish a plane coordinate system XOY, where the X axis is parallel to the lower one-dimensional mobile platform 6 of the two-dimensional mobile platform, and the Y axis is parallel to the upper one-dimensional mobile platform 7 of the two-dimensional mobile platform;

[0048] Step 1: Keep the lower one-dimensional moving platform 6 fixed at the set position of the X-axis, control the upper one-dimensional moving platform 7 to move along the Y-axis according to the set step distance, and the motion platform 8 and the sensor array 4 move in the Y direction accordingly, so that the displacement of the sensor array 4 is Y1, Y2, ..., Yn in sequence, and obtain the corresponding array of the output signal of the displacement sensor array 4 and the Y-direction displacement, and Y1-Yn is the Y-direction movable range of the sensor array 4;

[0049] Step 2: Set the lower one-dimensional mobile platform 6 at position X1 and execute step 1; control the lower one-dimensional mobile platform 6 to move along the X-axis according to the set step size, move the lower one-dimensional mobile platform 6 to position X2, and then execute step 1; similarly, make the displacement of the lower one-dimensional mobile platform 6 along the X-axis X1, X2, ..., Xn in sequence, and then execute step 1 in sequence until completion.

[0050] Finally, the corresponding arrays of the output signals of the sensor array 4 and the X-direction displacements X1-Xn and the Y-direction displacements Y1-Yn are obtained.

[0051] like Figure 5 As shown, by using the established neural network model, according to the real-time output signal of the sensor array 4, the relative two-dimensional displacement between the sensor array 4, the motion platform 8 and the base scale 1 can be determined, thereby realizing the planar two-dimensional displacement measurement.

[0052] Example 2

[0053] This embodiment is basically the same as the planar two-dimensional displacement measurement method based on surface topography provided in Embodiment 1, except that Figure 3 As shown, the material of the base ruler 1 is metal, and its surface morphology is the surface roughness and waviness characteristics after mechanical processing; the sensor array 4 is an eddy current roughness sensor;

[0054] The rest remain unchanged, and the planar two-dimensional displacement measurement is implemented according to the method of Example 1.

[0055] The above shows and describes the basic principles, main features and characteristics of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of the present invention to be protected is defined by the attached claims and their equivalents.

Claims

1. A method for measuring two-dimensional displacement of a plane based on surface topography, comprising a base ruler and a measuring ruler, characterized in that: The base ruler has a two-dimensional region-specific surface morphology, and the measuring ruler includes a base and a sensor array, wherein the sensor array is fixed by the base and the relative positions between the sensors are kept unchanged; The measuring ruler is arranged parallel to the base ruler with a gap therebetween, and the sensor array is used to detect the surface topography of the base ruler; When the measuring ruler and the base ruler move relative to each other in two dimensions, the output signal of the sensor array changes accordingly. A neural network model is established through learning and training for the output signal of the sensor array. The relative two-dimensional displacement between the measuring ruler and the base ruler is determined by using the neural network model to realize planar two-dimensional displacement measurement. The material of the base ruler is metal or non-metal, and its surface morphology is the surface roughness and waviness characteristics after mechanical processing; The sensor array is an eddy current roughness sensor or an optical fiber roughness sensor.

2. The method for measuring two-dimensional displacement of a plane based on surface topography according to claim 1, characterized in that: The material of the base ruler is a conductive metal, and its surface morphology is a surface profile processed according to a preset rule; The sensor array is an eddy current displacement sensor.

3. The planar two-dimensional displacement measurement method based on surface morphology characteristics according to claim 2 is characterized in that: The surface morphology feature of the base ruler is a coding pattern set on its surface, which is characterized by horizontal and vertical rectangular grooves of different sizes and spacings on the surface of the base ruler. The depth and width values ​​of each groove are uniquely set according to a pseudo-random sequence, and each element of the sequence is randomly distributed within a fixed threshold, so that the base ruler forms a two-dimensional region-specific surface morphology feature.

4. The method for measuring two-dimensional displacement of a plane based on surface topography according to any one of claims 1 to 3, characterized in that: The number of sensors in the sensor array is equal to or greater than three.

5. The planar two-dimensional displacement measurement method based on surface topography according to claim 4 is characterized in that: The gap between the measuring ruler and the base ruler is large enough to ensure that the output signal of the sensor array is within the measuring range during the entire measuring process.

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