A multi-dimensional error measurement device and method based on porous diffraction interference

Abstract

The present application discloses a multi-dimensional error measurement device and method based on porous diffraction interference, which relates to the field of equipment measurement. The measurement component in the multi-dimensional error measurement device based on porous diffraction interference includes a diffraction aperture plate; the measurement component is fixed on the target equipment and is parallel to the axis direction of the target equipment; when the target equipment moves with multiple degrees of freedom in space, the measurement component is driven to move; the laser source and the measurement component are in the same axis direction; a plurality of diffraction pores are arranged on the diffraction aperture plate in the horizontal and vertical directions of a plane orthogonal to the optical axis; the laser emitted by the laser source forms a porous diffraction interference image after passing through the plurality of diffraction pores on the diffraction aperture plate; the calculation module obtains the multi-degree-of-freedom pose change based on the pose recognition model and the collected porous diffraction interference images during the multi-degree-of-freedom movement, and compensates it to obtain the multi-dimensional error of the target equipment. The present application can achieve the measurement of the multi-dimensional error of the equipment with high precision and low cost.

Description

Technical Field

[0001] The present application relates to the field of equipment measurement, and particularly to a multi-dimensional error measurement device and method based on porous diffraction interference. Background Art

[0002] With the development of modern manufacturing industry, precision equipment such as high-end CNC machine tools and high-precision coordinate measuring machines with multi-axis motion mechanisms has become increasingly important in the precision manufacturing industry. Spatial geometric position accuracy is one of the key indicators for evaluating such precision equipment.

[0003] Currently, for precision equipment such as high-end CNC machine tools and high-precision coordinate measuring machines, during the working process, due to factors such as machining errors and friction effects of the motion axis structure, the axis will jump up and down, left and right, etc. when moving, resulting in multi-dimensional deviations between the target pose and the actual pose of key components. These spatial geometric position errors will lead to serious characteristic pose errors or motion profile deviations, and further cause multi-dimensional errors in the size and shape of the workpieces processed by the machine tool or the measurement results of the measuring machine. Therefore, high-precision measurement and compensation of multi-dimensional errors of the motion unit have very important scientific significance and have a very wide application prospect in the field of precision instrument equipment.

[0004] Among the current methods for measuring errors of precision equipment, laser trackers have the advantages of simple operation, fast measurement speed, large measurement range, etc. However, most of the existing trackers can only perform single target ball measurement, and inevitably amplify the influence of human errors and repeatability errors when measuring spatial errors. Although laser interferometers can perform high-precision measurement of errors in each degree of freedom, a laser interferometer can only measure the error in one direction at a time and cannot measure the roll and pitch (rotation angle around the axial direction of the linear platform) errors. Renishaw's multi-beam interferometer has significant advantages in six-degree-of-freedom error measurement and can measure errors in multiple degrees of freedom at one time, but it is expensive, sensitive to the stability of the light source and environmental interference, the software system is not open, and it is only compatible with some control systems.

[0005] Therefore, how to achieve multi-dimensional error measurement of equipment with high precision and low cost has become an urgent problem to be solved at present. Summary of the Invention

[0006] The purpose of the present application is to provide a multi-dimensional error measurement device and method based on porous diffraction interference, which can achieve the measurement of multi-dimensional errors (i.e., multi-degree-of-freedom pose changes) of equipment with high precision and low cost.

[0007] To achieve the above purpose, the present application provides the following solutions:

[0008] In a first aspect, the present application provides a multi-dimensional error measurement device based on porous diffraction interference, including: a laser source, a measurement component, and a calculation module; the measurement component includes: a diffraction aperture plate;

[0009] The measurement component is fixed on the target equipment; the axis direction of the measurement component is parallel to the axis direction of the target equipment; when the target equipment is used to move in multiple degrees of freedom in space, it drives the measurement component to move in multiple degrees of freedom; the laser source and the measurement component are in the same axis direction; multiple diffraction pores are provided on the diffraction aperture plate; the multiple diffraction pores are distributed in the horizontal and vertical directions of a plane orthogonal to the optical axis;

[0010] The laser source is used to emit laser light; the laser light is used to form a porous diffraction interference image after passing through the multiple diffraction pores on the diffraction aperture plate;

[0011] The calculation module is used to obtain the porous diffraction interference image during the process of the target equipment moving in multiple degrees of freedom in space, obtain the multi-degree-of-freedom pose change of the target equipment according to the pose recognition model and the collected porous diffraction interference image, compensate for the multi-degree-of-freedom pose change, and determine the compensated multi-degree-of-freedom pose change as the multi-dimensional error of the target equipment; the pose recognition model is constructed based on a machine learning model.

[0012] Optionally, in terms of obtaining the multi-degree-of-freedom pose change of the target equipment according to the pose recognition model and the collected porous diffraction interference image, the calculation module specifically is used to:

[0013] Train the machine learning model with a training data set, and determine the trained machine learning model as the pose recognition model; the training data set includes: porous diffraction interference images at different times when the equipment for training moves in multiple degrees of freedom in space and the corresponding real multi-degree-of-freedom pose changes;

[0014] Input the porous diffraction interference image of the target equipment at the current moment collected into the pose recognition model to obtain the multi-degree-of-freedom pose change of the target equipment at the current moment.

[0015] Optionally, the diffraction pores on the diffraction aperture plate are diffraction holes or diffraction slits with different shapes and different sizes.

[0016] Optionally, in terms of inputting the porous diffraction interference image of the target equipment at the current moment collected into the pose recognition model to obtain the multi-degree-of-freedom pose change of the target equipment at the current moment, the calculation module specifically is used to:

[0017] Input the porous diffraction interference image of the target equipment at the current moment collected into the pose recognition model. The pose recognition model extracts the key features of the porous diffraction interference image at the current moment and identifies the multi-degree-of-freedom pose change at the current moment according to the key features at the current moment. The key features include one or several of the following: stripe distribution state, number of stripes, stripe form, stripe spacing, phase included in the stripes, various stripe change gradients, and various stripe change gradient distribution information.

[0018] Optionally, the multi-dimensional error measurement device based on porous diffraction interference further includes: an adjustment device; the measurement component is fixed to the end of the target equipment through the adjustment device; the adjustment device is used to adjust the relative multi-dimensional position of the axis of the laser source and the axis of the measurement component.

[0019] Optionally, the measurement component further includes: an image acquisition device; the image acquisition device is connected to the calculation module; the image acquisition device is used to acquire the porous diffraction interference image and send the acquired porous diffraction interference image to the calculation module.

[0020] Optionally, the measurement component further includes: an optical mirror group; the laser irradiates the diffraction hole plate after passing through the optical mirror group; the axial distances among the optical mirror group, the diffraction hole plate, and the image acquisition device are in the optimal imaging position; the optimal imaging position is determined according to the clarity of the porous diffraction interference image and the sensitivity of the fringe edge of the porous diffraction interference image to the position change of the diffraction hole plate.

[0021] Optionally, the target equipment moves with six degrees of freedom in space; the six degrees of freedom include: linearity, horizontal straightness, vertical straightness, pitch, yaw, and roll.

[0022] Optionally, the image acquisition device is an image sensor.

[0023] In a second aspect, the present application provides a multi-dimensional error measurement method based on porous diffraction interference. The multi-dimensional error measurement method based on porous diffraction interference is used for the above-mentioned multi-dimensional error measurement device based on porous diffraction interference. The multi-dimensional error measurement method based on porous diffraction interference includes:

[0024] Obtain the porous diffraction interference image during the multi-degree-of-freedom movement of the target equipment in space;

[0025] Obtain the multi-degree-of-freedom pose change of the target equipment according to the pose recognition model and the acquired porous diffraction interference image;

[0026] Compensate for the multi-degree-of-freedom pose change, and determine the compensated multi-degree-of-freedom pose change as the multi-dimensional error of the target equipment; the pose recognition model is constructed based on a machine learning model.

[0027] According to the specific embodiments provided in this application, the following technical effects are achieved in this application:

[0028] This application provides a multi-dimensional error measurement device and method based on porous diffraction interference. A measurement component including a diffraction orifice plate is provided. By arranging a plurality of diffraction pores on the diffraction orifice plate in the horizontal and vertical directions of a plane orthogonal to the optical axis, the complex diffraction interference image formed by the diffraction pores includes the poses of the diffraction orifice plate in multiple degrees of freedom in space. When the target equipment drives the diffraction orifice plate to move, the multi-degree-of-freedom pose change, that is, the multi-dimensional error, is obtained by recognizing the porous diffraction interference image. In this way, the multi-dimensional error is measured through the diffraction interference principle, which can reduce costs; the calculation module recognizes the multi-degree-of-freedom pose change according to the pose recognition model constructed based on the machine learning model, which can improve the measurement accuracy. Therefore, this application realizes the measurement of the multi-dimensional error of the equipment with high precision and low cost. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0030] Figure 1 It is a schematic structural diagram of a multi-dimensional error measurement device based on porous diffraction interference provided by an embodiment of this application;

[0031] Figure 2 It is a schematic structural diagram of the measurement component provided by an embodiment of this application;

[0032] Figure 3 It is a flowchart of a multi-dimensional error measurement method based on porous diffraction interference provided by an embodiment of this application.

[0033] Reference numerals: laser source - 1, measurement component - 2, adjustment device - 3, calculation module - 4, optical mirror group - 201, diffraction orifice plate - 202, image acquisition device - 203, measurement tooling - 204. Detailed Embodiments

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0035] To make the above objects, features, and advantages of the present application more obvious and understandable, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] The present application provides a low-cost measurement solution with a novel principle. It utilizes the sensitivity of the diffraction result of a light beam passing through a small hole to the position of the small hole, and further enhances the sensitivity and correlation through the diffraction interference information of multiple holes after increasing the multi-hole distribution. A mapping model between the diffraction interference image and the multi-degree-of-freedom pose is established, and the change of the multi-degree-of-freedom pose is solved by obtaining the diffraction interference image. The principle of the present application is novel, with low cost, low requirements for the stability of the light source and environmental conditions, and high measurement accuracy at the same time.

[0037] In an exemplary embodiment, as Figure 1 shown, a multi-dimensional error measurement device based on multi-hole diffraction interference is provided, including: a laser source 1, a measurement component 2, and a calculation module 4. Refer to Figure 2 , the measurement component 2 includes: a diffraction aperture plate 202. Figure 1 In, Δx, Δy, and Δz are translations in three directions; Δα, Δβ, and Δγ are rotational yaws in three directions.

[0038] The measurement component 2 is fixed on the target equipment; the axis direction of the measurement component 2 is parallel to the axis direction of the target equipment; when the target equipment moves in multiple degrees of freedom in space, it drives the measurement component 2 to move in multiple degrees of freedom; the laser source 1 and the measurement component 2 are in the same axis direction; multiple diffraction pores are provided on the diffraction aperture plate 202; the multiple diffraction pores are distributed in the horizontal and vertical directions of a plane orthogonal to the optical axis. The target equipment can be a linear platform to be measured.

[0039] The laser source 1 is used to emit laser light; the laser light is used to form a multi-hole diffraction interference image after passing through the multiple diffraction pores on the diffraction aperture plate 202.

[0040] The calculation module 4 is configured to obtain the multi - hole diffraction interference image during the multi - degree - of - freedom movement of the target equipment in space, obtain the multi - degree - of - freedom pose change of the target equipment according to the pose recognition model and the acquired multi - hole diffraction interference image, compensate for the multi - degree - of - freedom pose change, and determine the compensated multi - degree - of - freedom pose change as the multi - dimensional error of the target equipment; the pose recognition model is constructed based on a machine learning model.

[0041] In another exemplary embodiment of the present application, in terms of obtaining the multi - degree - of - freedom pose change of the target equipment according to the pose recognition model and the acquired multi - hole diffraction interference image, the calculation module 4 is specifically configured to:

[0042] Train the machine learning model using a training data set, and determine the trained machine learning model as the pose recognition model; the training data set includes: multi - hole diffraction interference images at different times during the multi - degree - of - freedom movement of the equipment for training and the corresponding real multi - degree - of - freedom pose changes. Among them, the real multi - degree - of - freedom pose changes can be obtained in the following two ways: one is to measure the multi - dimensional error of some linear platforms using a high - precision multi - dimensional error measurement device that currently has a leading advantage, and then use the proposed method to measure and collect the corresponding multi - hole diffraction interference images, so that the multi - hole diffraction interference images correspond to the measured multi - degree - of - freedom pose changes; the other is to install a high - precision five - axis electric displacement stage on a high - precision linear displacement stage, install the measurement component 2 on this five - axis displacement stage, record the diffraction interference images while the five - axis displacement stage and the linear platform move, and use the movement amounts of the five - axis displacement stage and the linear platform as a reference, repeat multiple groups to obtain the real multi - degree - of - freedom pose changes.

[0043] Input the multi - hole diffraction interference image of the target equipment at the current moment into the pose recognition model to obtain the multi - degree - of - freedom pose change of the target equipment at the current moment.

[0044] In another exemplary embodiment of the present application, the diffraction pores on the diffraction orifice plate 202 are diffraction holes or diffraction slits with different shapes and different sizes. The shape and size of the diffraction hole or the diffraction slit are determined according to actual needs and are not limited herein. For example, the shape of the diffraction hole can be a round hole, a square hole, a triangular hole, or an oblong hole, etc.

[0045] In another exemplary embodiment of the present application, in terms of compensating for the multi - degree - of - freedom pose change and determining the compensated multi - degree - of - freedom pose change as the multi - dimensional error of the target equipment, the calculation module 4 is specifically configured to:

[0046] Use the formula Y=(1 - k)y pre-b compensates for the multi-degree-of-freedom pose change, and determines the compensated multi-degree-of-freedom pose change as the multi-dimensional error of the target equipment; where y pre represents the multi-degree-of-freedom pose change of the target equipment; Y represents the compensated multi-degree-of-freedom pose change; k and b represent fitting parameters; k and b are obtained by fitting the predicted multi-degree-of-freedom pose change and the true multi-degree-of-freedom pose change using a fitting method (for example, the least squares method); the predicted multi-degree-of-freedom pose change is determined according to the multi-degree-of-freedom pose output by the pose recognition model.

[0047] In another exemplary embodiment of the present application, in terms of inputting the multi-hole diffraction interference image of the target equipment at the current moment collected into the pose recognition model to obtain the multi-degree-of-freedom pose change of the target equipment at the current moment, the calculation module 4 is specifically configured to:

[0048] Input the multi-hole diffraction interference image of the target equipment at the current moment collected into the pose recognition model, and the pose recognition model extracts the key features of the multi-hole diffraction interference image at the current moment, and recognizes the multi-degree-of-freedom pose change at the current moment according to the key features at the current moment; the key features include, but are not limited to, one or several of the stripe distribution state, the number of stripes, the stripe form, the stripe spacing, the phase included in the stripes, various stripe change gradients, and various stripe change gradient distribution information.

[0049] In another exemplary embodiment of the present application, still referring to Figure 1 , the multi-dimensional error measurement device based on multi-hole diffraction interference further includes: an adjustment device 3; the measurement component 2 is fixed to the end of the target equipment through the adjustment device 3; the adjustment device 3 is used to adjust the relative multi-dimensional position of the axis of the laser source 1 and the axis of the measurement component 2.

[0050] Among them, the adjustment device 3 can be a five-axis adjustment mechanism with two translations and three rotations.

[0051] In another exemplary embodiment of the present application, the calculation module 4 is mainly used for data processing and the deployment of a pre-trained machine learning model.

[0052] In another exemplary embodiment of the present application, still referring to Figure 2 , the measurement component 2 further includes: an image acquisition device 203; the image acquisition device 203 is connected to the calculation module 4; the image acquisition device 203 is used to acquire the multi-hole diffraction interference image and send the acquired multi-hole diffraction interference image to the calculation module 4.

[0053] The image acquisition device 203 can be an image sensor.

[0054] In another exemplary embodiment of the present application, the computing module 4 may be a general-purpose computer or a dedicated data analysis device.

[0055] In another exemplary embodiment of the present application, still referring to Figure 2 , the measurement component 2 further includes: an optical lens group 201; the laser is irradiated onto the diffraction orifice plate 202 after passing through the optical lens group 201. The axial distances among the optical lens group 201, the diffraction orifice plate 202, and the image acquisition device 203 are at the optimal imaging position; the optimal imaging position is determined according to the clarity of the multi-hole diffraction interference image and the sensitivity of the fringe edges of the multi-hole diffraction interference image to the position change of the diffraction orifice plate 202.

[0056] In practical applications, the laser is irradiated onto the diffraction orifice plate 202 after being transformed by the optical lens group 201 (for example, adjusting the optical path).

[0057] In another exemplary embodiment of the present application, still referring to Figure 2 , the measurement component 2 further includes: a measurement tooling 204; the measurement tooling 204 is used to install the optical lens group 201, the diffraction orifice plate 202, and the image acquisition device 203. The relative positions of the optical lens group 201, the diffraction orifice plate 202, and the image acquisition device 203 can be adjusted according to measurement requirements.

[0058] In another exemplary embodiment of the present application, the shape, quantity, size, thickness, and distribution of the diffraction pores are used to determine different types of diffraction orifice plates 202 to be replaced according to measurement requirements; the pose information of the diffraction orifice plate 202 in multiple degrees of freedom in space is obtained by identifying the complex multi-hole diffraction interference image formed by the diffraction pores.

[0059] In another exemplary embodiment of the present application, the target equipment moves in six degrees of freedom in space; the six degrees of freedom include: linearity, horizontal straightness, vertical straightness, pitch, yaw, and roll.

[0060] The overall pose relationship of the multi-dimensional error measurement device based on multi-hole diffraction interference in this embodiment can be described as follows: The measurement component 2 is installed on the adjustment device 3, and the spatial pose of the measurement component 2 is adjusted through the adjustment device 3 to achieve calibration; the computing module 4 is connected to the measurement end component through a cable; the optical lens group 201, the diffraction orifice plate 202, and the image acquisition device 203 are sequentially installed on the measurement tooling 204 to ensure that the light emitted by the laser source 1 passes through in sequence and finally forms an image on the image acquisition device 203; after the optical lens group 201, the diffraction orifice plate 202, and the image acquisition device 203 are installed on the measurement tooling 204, their relative poses are determined, and after calibration before use, the pose is no longer adjusted and the measurement component 2 is integrally encapsulated.

[0061] Taking six degrees of freedom as an example, the implementation process of the multi-dimensional error measurement device based on porous diffraction interference in practical applications will be further described in detail below.

[0062] Six-dimensional error means that during the movement of the linear module, the slider does not simply translate along the track direction. Instead, it will have pose jumps in six degrees of freedom (linearity, straightness in the horizontal direction, straightness in the vertical direction, pitch, yaw, roll) in space, that is, pose changes in six degrees of freedom.

[0063] First, install the multi-dimensional error measurement device based on porous diffraction interference. The measurement component 2 is composed of an optical lens group 201, a diffraction aperture plate 202, an image acquisition device 203, and a measurement end tooling 204. The measurement component 2 is installed on the adjustment device 3, and the spatial pose of the measurement component 2 is adjusted through the adjustment device 3 for calibration. The calculation module 4 is connected to the measurement component 2 through a cable. The optical lens group 201, the diffraction aperture plate 202, and the image acquisition device 203 are sequentially installed on the measurement end tooling 204 to ensure that the light emitted by the laser source 1 passes through in sequence and finally forms an image on the image acquisition device 203. After installation, the mutual pose is determined, and after calibration before use, no further adjustment is made and the measurement component 2 is integrally encapsulated.

[0064] Among them, the optical lens group 201 is a combination of optical elements adjusted for changes in the axial range (i.e., the range along the axial movement direction of the linear platform) and the radial range (i.e., the range along the radial movement direction of the linear platform). Corresponding adjustments can be made for measurements in different axial and radial range (i.e., replacing or combining the elements in the optical lens group 201). Since the axial range along the linear platform movement is large, the laser emitted by the laser source 1 passes through the front optical lens group 201 to adjust the optical path, and the axial and radial resolutions and sensitivities of the image can also be improved through the adjustment of some optical elements.

[0065] On the diffraction aperture plate 202, a plurality of diffraction pores are provided in the horizontal and vertical directions of the plane orthogonal to the optical axis. The shape, number, size, thickness, and distribution of the diffraction pores are determined according to the measurement requirements, and different types of diffraction aperture plates 202 are replaced. The pose information of the diffraction aperture plate 202 in six degrees of freedom in space is obtained by identifying the complex diffraction interference image formed by the diffraction pores.

[0066] The image acquisition device 203 uses an image sensor to receive the porous diffraction interference image, and other types of image sensors can also be used for replacement.

[0067] The relative positions of the optical lens group 201, the diffraction aperture plate 202, and the image acquisition device 203 can be adjusted according to the measurement requirements.

[0068] Based on the above-mentioned multi-dimensional error measurement device based on porous diffraction interference, the process of realizing six-dimensional error measurement is as follows:

[0069] Step 1: Construct the measurement system device.

[0070] Fix the measurement component 2 to the adjustment device 3, fix the adjustment component 3 to the end of the linear platform to be measured, and adjust the spatial pose of the measurement component 2 through the adjustment device 3 so that the optical axis direction of the measurement component 2 is parallel to the axial direction of the linear platform.

[0071] Step 2: Calibrate the measurement device.

[0072] Arrange the laser source 1, arrange the laser source 1 in the same axial direction as the measurement component 2 so that the axis of the laser source 1 is parallel to the optical path direction of the measurement system; then adjust the relative position of the axis of the laser source 1 and the axis of the measurement component 2 through the adjustment device 3 to complete the calibration of the measurement system.

[0073] Step 3: Six-dimensional error measurement.

[0074] When the linear platform moves, the image acquisition device 203 acquires the porous diffraction interference image and transmits it to the calculation module 4. After normalization and preprocessing, it is input into the pre-trained machine learning model (pose recognition model) for recognition, and the six-dimensional error generated when the adjustment device 3 and the measurement component 2 are driven by the end of the linear axis is obtained by recognizing the key features of the porous diffraction interference image.

[0075] In this step, to improve the generalization and robustness of the machine learning model and reduce the instability caused by the difference in order of magnitude. The sample value of each feature is normalized to [0, 1] by the Min-Max method. The normalization equation is as follows:

[0076]

[0077] where, x n is the normalized eigenvalue, x is the original sample eigenvalue, x min is the minimum eigenvalue of the sample data, x max is the maximum eigenvalue of the sample data.

[0078] The corresponding relationship between the image and the pose in this step can be explained by the Fresnel-Kirchhoff diffraction formula:

[0079]

[0080] The spherical wave emitted by the monochromatic point source irradiates the aperture ∑, and the complex amplitude of the optical vibration generated at any point P behind ∑. In the formula, l is the distance from the point source S to any point Q on ∑, r is the distance from the Q point to the P point, and (n, l) and (n, r) are the included angles between the normal n of the aperture surface ∑ and the directions of l and r respectively. is the diffraction result, i is the imaginary unit, k is the wave number, A is the amplitude at a unit distance from the light source, λ is the wavelength, and dσ is the integral element of the surface integral. Therefore, changes in the position and posture of the diffraction pinhole will affect the distribution of the complex amplitude of the light source on the diffraction pinhole, the angle between the normal of the aperture surface ∑ and the l and r directions, and ultimately cause the diffraction image to change. There is obviously a mapping relationship between the diffraction result and the pinhole position and posture, but it is obviously very difficult to reversely calculate the change in the pinhole position and posture through the diffraction result. In addition, it is difficult to obtain accurate diffraction results in actual experiments, which further increases the difficulty of analytical calculations.

[0081] Furthermore, this embodiment increases the distribution of holes, adds interference information based on the diffraction image, enhances the mapping relationship between the diffraction interference image and the six-dimensional error, and improves the measurement performance.

[0082] The machine learning model uses a large amount of data collected previously as a training data set to train the model and obtain model parameters that can accurately derive the six-dimensional posture according to the diffraction interference image. The training data set includes: the porous diffraction interference images and the corresponding real six-degree-of-freedom posture changes at different times when the equipment used for training moves in space with six degrees of freedom. Among them, the acquisition method of the real six-degree-of-freedom posture change can be adopted in the following two ways: one is to use the high-precision multi-dimensional error measurement device that currently occupies a leading advantage to measure the six-dimensional error of some linear platforms, and then use the proposed method to measure and collect the corresponding porous diffraction interference images, so that the porous diffraction interference images correspond to the measured six-degree-of-freedom posture changes; the second is to install a high-precision five-axis electric displacement stage on the high-precision linear displacement stage, install the measurement component 2 on this five-axis displacement stage, and record the diffraction interference images while the five-axis displacement stage and the linear platform move, and repeat multiple groups based on the movement amount of the five-axis displacement stage and the linear platform. The five-axis precision displacement stage here is different from the aforementioned adjustment device 3.

[0083] During training, the training data set can be composed of a large number of spatial six-degree-of-freedom posture changes and multi-aperture diffraction interference images under corresponding postures. The multi-aperture diffraction interference images are model inputs and the six-degree-of-freedom posture changes are outputs. The multi-aperture diffraction interference images are input into the machine learning model (such as a neural network) in the form of a digital matrix. During the entire model training process, the machine learning model adjusts the parameters in each layer through optimization methods such as backpropagation algorithms and gradient descent to minimize the prediction error. As the training progresses, the model gradually learns to extract key features that are useful for the task from the original image data and make accurate predictions based on these features. The machine learning model obtains six-dimensional posture changes by extracting key features.

[0084] Step 4: Compensation of measurement results.

[0085] Compensate the six - dimensional pose change obtained in step 3 for systematic errors to obtain the final six - dimensional pose change (six - dimensional error).

[0086] After the model training is completed, test the model with a sufficient number of test data, and use the least - squares method to perform linear fitting on the actual values and model prediction errors of six degrees of freedom respectively. The calculation formula is y = kx + b; where, x i is the model prediction value of the i - th test data, y i is the model prediction error of the i - th test data (the difference between the actual value and the model prediction value), and x and y are the means of the corresponding samples respectively. The measurement result in the final use process is Y = y pre -y = y pre -(ky pre +b)=(1 - k)y pre -b.

[0087] In the above - mentioned embodiment, a plurality of diffraction pores are arranged on the diffraction orifice plate 202 along a plane orthogonal to the optical axis; the complex optical diffraction interference image formed after the light emitted by the laser source 1 passes through the plurality of diffraction pores on the diffraction orifice plate 202 contains the pose information of the diffraction orifice plate 202 in six degrees of freedom in space; when the diffraction orifice plate 202 moves, the non - linear mapping model established based on the relationship between the pose information of the diffraction orifice plate 202 and the change of the diffraction interference image can be used as a high - precision recognition model for the six - degree - of - freedom pose of the diffraction orifice plate 202, that is, the measurement of the six - degree - of - freedom pose change (i.e., six - dimensional error) of the diffraction orifice plate 202 is realized by recognizing the porous diffraction interference image.

[0088] The advantages of this embodiment will be described below based on the existing problems.

[0089] High - precision coordinate measuring machines and high - end numerically controlled machine tools are key equipment in the fields of national defense, military industry, and civilian precision manufacturing. The spatial geometric position accuracy level during their movement directly affects the development of products towards high stability and high precision. There are many reasons for the relatively low manufacturing technology of high - precision coordinate measuring machines and high - end numerically controlled machine tools, but the lack of high - precision measurement technology and its equipment is one of the main reasons.

[0090] For high - end numerically controlled machine tools and coordinate measuring machines, for the linear motion units such as modules and guide - rail sliders among them, the six - dimensional error generated by their sliders will cause spatial geometric position errors at the end of the machine tool and the coordinate measuring head, etc., and finally errors will occur in the size, shape of the workpiece processed by the machine tool or the measurement result of the measuring machine.

[0091] The multi-dimensional error measurement device based on porous diffraction interference in this embodiment can measure six-dimensional errors, analyze the true error sources of the current moving platform, then make targeted adjustments, and compensate for its six-dimensional spatial errors to improve the spatial geometric position accuracy of the device.

[0092] The multi-dimensional error measurement device based on porous diffraction interference in this embodiment measures multi-dimensional errors through the principle of diffraction interference, and is insensitive to the original errors in the optical path system, which is conducive to reducing manufacturing costs; by setting a plurality of diffraction pores in the horizontal and vertical directions of the plane orthogonal to the optical axis along the diffraction aperture plate 202, the complex diffraction interference images formed by these diffraction pores contain the pose information of the diffraction aperture plate 202 in multiple degrees of freedom in space. When the diffraction aperture plate 202 moves, the pose change information of the diffraction aperture plate 202 in multiple degrees of freedom in space, that is, multi-dimensional errors, is obtained by identifying the complex diffraction interference images formed by the diffraction pores; the complex porous diffraction interference images are subjected to feature recognition by a pre-trained machine learning model, and effective information is extracted from the massive features contained in the diffraction interference images to improve performance indicators such as measurement resolution and measurement accuracy.

[0093] Based on the same inventive concept, an embodiment of the present application also provides a multi-dimensional error measurement method based on porous diffraction interference implemented by using the above-mentioned multi-dimensional error measurement device based on porous diffraction interference. The implementation solutions provided by this method to solve problems are similar to the implementation solutions described in the above device. Therefore, the specific limitations in one or more embodiments of the multi-dimensional error measurement method based on porous diffraction interference provided below can refer to the limitations on the multi-dimensional error measurement device based on porous diffraction interference in the above text, and will not be repeated here.

[0094] In an exemplary embodiment, as Figure 3 shown, a multi-dimensional error measurement method based on porous diffraction interference is provided, including:

[0095] Step 301, obtain a porous diffraction interference image during the multi-degree-of-freedom movement of the target equipment in space.

[0096] Step 302, obtain the multi-degree-of-freedom pose change of the target equipment according to the pose recognition model and the collected porous diffraction interference image.

[0097] Step 303, compensate for the multi-degree-of-freedom pose change, and determine the compensated multi-degree-of-freedom pose change as the multi-dimensional error of the target equipment; the pose recognition model is constructed based on a machine learning model.

[0098] This application only needs to be set once to accurately measure the pose changes of multiple degrees of freedom along a linear platform simultaneously, which is beneficial to measuring and compensating the multi-dimensional geometric pose changes at the end of precision equipment. The measurement method has a novel principle, low cost, and high measurement accuracy.

[0099] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0100] Specific examples are used in this article to elaborate on the principle and implementation manner of this application. The description of the above embodiments is only used to help understand the method and its core idea of this application; at the same time, for those of ordinary skill in the art, according to the idea of this application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to this application.

Claims

1. A multi-dimensional error measurement device based on porous diffraction interference, characterized in that The multi-dimensional error measurement device based on porous diffraction interference includes: a laser source, a measurement component, and a calculation module; the measurement component includes: a diffraction aperture plate; The measurement component is fixed on the target equipment; the axis direction of the measurement component is parallel to the axis direction of the target equipment; when the target equipment moves with multiple degrees of freedom in space, it drives the measurement component to move with multiple degrees of freedom; the laser source and the measurement component are in the same axis direction; multiple diffraction pores are arranged on the diffraction aperture plate; the multiple diffraction pores are distributed in the horizontal direction and the vertical direction of a plane orthogonal to the optical axis; The laser source is used to emit laser light; the laser light is used to form a porous diffraction interference image after passing through the multiple diffraction pores on the diffraction aperture plate; The calculation module is used to obtain the porous diffraction interference image during the process of the target equipment moving with multiple degrees of freedom in space, obtain the multi-degree-of-freedom pose change of the target equipment according to the pose recognition model and the collected porous diffraction interference image, compensate the multi-degree-of-freedom pose change, and determine the compensated multi-degree-of-freedom pose change as the multi-dimensional error of the target equipment; the pose recognition model is constructed based on a machine learning model.

2. The multi-dimensional error measurement device based on porous diffraction interference according to claim 1, characterized in that, In terms of obtaining the multi-degree-of-freedom pose change of the target equipment according to the pose recognition model and the collected porous diffraction interference image, the calculation module specifically is used for: Training the machine learning model with a training data set, and determining the trained machine learning model as the pose recognition model; the training data set includes: porous diffraction interference images at different times and corresponding real multi-degree-of-freedom pose changes when the equipment for training moves with multiple degrees of freedom in space; Inputting the porous diffraction interference image of the target equipment at the current moment collected into the pose recognition model to obtain the multi-degree-of-freedom pose change of the target equipment at the current moment.

3. The multi-dimensional error measurement device based on porous diffraction interference according to claim 1, characterized in that, The diffraction pores on the diffraction aperture plate are diffraction holes or diffraction slits with different shapes and different sizes.

4. The multi-dimensional error measurement device based on porous diffraction interference according to claim 2, characterized in that, In terms of inputting the porous diffraction interference image of the target equipment at the current moment collected into the pose recognition model to obtain the multi-degree-of-freedom pose change of the target equipment at the current moment, the calculation module specifically is used for: Inputting the porous diffraction interference image of the target equipment at the current moment collected into the pose recognition model, the pose recognition model extracts the key features of the porous diffraction interference image at the current moment, and recognizes the multi-degree-of-freedom pose change at the current moment according to the key features at the current moment; the key features include: one or several of the stripe distribution state, the number of stripes, the stripe form, the stripe spacing, the phase included in the stripes, the gradient of various stripe changes, and the distribution information of the gradient of various stripe changes.

5. The multi-dimensional error measurement device based on porous diffraction interference according to claim 1, characterized in that, The multi-dimensional error measurement device based on porous diffraction interference further includes: an adjustment device; the measurement component is fixed at the end of the target equipment through the adjustment device; the adjustment device is used to adjust the relative multi-dimensional position of the axis of the laser source and the axis of the measurement component.

6. The multi-dimensional error measurement device based on porous diffraction interference according to claim 1, characterized in that The measurement component further includes: an image acquisition device; the image acquisition device is connected to the calculation module; the image acquisition device is configured to acquire the porous diffraction interference image and send the acquired porous diffraction interference image to the calculation module.

7. The multi-dimensional error measurement device based on porous diffraction interference according to claim 6, characterized in that, The measurement component further includes: an optical lens group; the laser passes through the optical lens group and then irradiates onto the diffraction aperture plate; the axial distances among the optical lens group, the diffraction aperture plate, and the image acquisition device are at the optimal imaging position; the optimal imaging position is determined according to the clarity of the porous diffraction interference image and the sensitivity of the fringe edge of the porous diffraction interference image to the position change of the diffraction aperture plate.

8. The multi-dimensional error measurement device based on porous diffraction interference according to claim 1, characterized in that, The target equipment moves with six degrees of freedom in space; the six degrees of freedom include: linearity, horizontal straightness, vertical straightness, pitch, yaw, and roll.

9. The multi-dimensional error measurement device based on porous diffraction interference according to claim 6, characterized in that, The image acquisition device is an image sensor.

10. A multi-dimensional error measurement method based on porous diffraction interference, characterized in that, The multi-dimensional error measurement method based on porous diffraction interference is used for the multi-dimensional error measurement device based on porous diffraction interference according to any one of claims 1-9; The multi-dimensional error measurement method based on porous diffraction interference includes: Obtaining a porous diffraction interference image during the multi-degree-of-freedom movement of the target equipment in space; Obtaining the multi-degree-of-freedom pose change of the target equipment according to the pose recognition model and the acquired porous diffraction interference image; Compensating the multi-degree-of-freedom pose change, and determining the compensated multi-degree-of-freedom pose change as the multi-dimensional error of the target equipment; the pose recognition model is constructed based on a machine learning model.

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