Image measurement device and measurement method based on real-time compensation of laser interferometer

Abstract

The application discloses an image measurement device and a measurement method based on real-time compensation of a laser interferometer, comprising an X-axis guide rail, an X-axis air floating moving platform arranged on the X-axis guide rail, a Y-axis guide rail arranged on the X-axis air floating moving platform, a Y-axis moving platform arranged on the Y-axis guide rail, an image acquisition module arranged on the Y-axis moving platform, an X-axis laser interference measurement module, a Y-axis laser interference measurement module, an X-axis position detection module and a Y-axis position detection module. The X-axis laser interference measurement module and the Y-axis laser interference measurement module are used for respectively accurately measuring straightness error of the X-axis guide rail and the Y-axis guide rail in the horizontal and vertical directions, the straightness deviation of the double guide rails is quantified and fused into positioning comprehensive error, real-time compensation of the double shafts is realized, positioning precision is improved, and the deep linkage of the positioning system and the image measurement system is combined, so that the actual demand of the precise image measurement field is met.

Description

Technical Field

[0001] This invention relates to the field of precision image measurement technology, and in particular to an image measurement device and method based on real-time compensation using a laser interferometer. Background Technology

[0002] Image measurement technology, with its significant advantages of being non-contact, highly efficient, and high-resolution, has become one of the core technologies in the field of precision component dimensional inspection, and is widely used in high-end manufacturing fields such as semiconductors, medical devices, and precision optics. This technology captures a clear image of the workpiece being measured through an optical imaging system, and combines this with high-precision image processing algorithms to extract features and identify edges, thereby calculating the geometric parameters of the workpiece. This effectively meets the stringent precision measurement requirements of modern manufacturing. However, in actual industrial measurement scenarios, due to the combined interference of various complex factors, the measurement accuracy of traditional image measurement devices struggles to consistently break through the sub-micron level, exhibiting significant error defects. This defect has become a core bottleneck restricting the improvement of product yield in high-end manufacturing and hindering the industry's development towards higher precision. Specific problems are as follows:

[0003] Firstly, the measurement range is significantly limited: the measurement capability of traditional image measuring instruments is constrained by both the stage range and positioning accuracy, with the measurement range in the X-axis direction being difficult to extend effectively. Forcibly increasing the stage travel leads to a sharp decrease in positioning accuracy, making it unsuitable for the precision measurement needs of large workpieces. Simultaneously, factors such as mechanical structure deviations, ambient temperature fluctuations, and lens optical distortion further exacerbate the decline in measurement accuracy, severely impacting the reliability and consistency of the inspection results and failing to meet the precision measurement requirements of high-end manufacturing scenarios.

[0004] Secondly, existing error compensation methods have significant shortcomings and cannot fundamentally solve the accuracy bottleneck. Current technologies mostly employ standard component compensation (offline compensation) or a single error compensation mode, but their application effectiveness has significant limitations. For example, some solutions pre-calibrate measurement errors using standard components and establish a compensation database, then call the database for static compensation during measurement. This method cannot handle dynamically changing errors during measurement (such as real-time temperature fluctuations in the environment, instantaneous shifts in the measurement platform, etc.), resulting in poor compensation timeliness and difficulty adapting to dynamic measurement scenarios. Furthermore, some devices only compensate for optical errors separately, failing to fully consider the coupling errors of mechanical structure and environmental factors, leading to a significant reduction in compensation effectiveness and an inability to achieve stable control of sub-micron level measurement accuracy. In addition, traditional compensation methods often employ serial compensation logic, resulting in low compensation efficiency and difficulty in achieving simultaneous measurement and compensation, thus failing to meet the actual needs of high-precision measurement in modern manufacturing. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the prior art by providing an image measurement device and method based on real-time compensation using a laser interferometer.

[0006] The objective of this invention is achieved through the following technical solution: an image measurement device based on real-time compensation using a laser interferometer, comprising an X-axis guide rail, an X-axis air-floating moving platform mounted on the X-axis guide rail, a Y-axis guide rail mounted on the X-axis air-floating moving platform, a Y-axis moving platform mounted on the Y-axis guide rail, an image acquisition module mounted on the Y-axis moving platform, an X-axis laser interferometry module, a Y-axis laser interferometry module, an X-axis position detection module, and a Y-axis position detection module; the X-axis laser interferometry module is used to acquire the horizontal and vertical straightness errors of the X-axis air-floating moving platform in real time throughout its movement, and the Y-axis laser interferometry module is used to acquire the horizontal and vertical straightness errors of the Y-axis moving platform in real time throughout its movement; the position of the image acquisition module is compensated and corrected using the data acquired by the X-axis and Y-axis laser interferometry modules.

[0007] Preferably, the X-axis guide rail is a marble guide rail with a rectangular cross-section.

[0008] Preferably, the X-axis laser interferometry module includes a laser interferometer B, a laser interferometer mirror B located in front of the laser interferometer B, and a straightness mirror group B set on the X-axis air-floating moving platform and corresponding to the laser interferometer B; the Y-axis laser interferometry module includes a laser interferometer A, a laser interferometer mirror A located in front of the laser interferometer A, and a straightness mirror group A set on the Y-axis moving platform and corresponding to the laser interferometer A.

[0009] Preferably, the X-axis position detection module is a grating ruler set on the X-axis guide rail and arranged along its axial direction, used to detect the actual displacement data of the X-axis air-bearing moving platform in real time; the Y-axis position detection module is a grating ruler set on the X-axis air-bearing moving platform and arranged along the Y-axis direction, used to detect the actual displacement data of the Y-axis moving platform in real time.

[0010] Preferably, a Z-axis moving module is provided on the Y-axis moving platform, and the image acquisition module is set on the Z-axis moving module. The Z-axis moving module drives the image acquisition module to move along the Z-axis direction to achieve focusing.

[0011] An image measurement method based on real-time compensation using a laser interferometer includes the following specific steps: Step 1: The Y-axis moving platform moves from its initial position along the Y-axis direction to the target position along the Y-axis. During this movement, the actual displacement data along the Y-axis is acquired. The horizontal straightness error data in the Y-axis direction is measured in real time using a Y-axis laser interferometry module. and vertical straightness error data The X-axis air-float moving platform moves from its initial position along the X-axis direction to its target position. During this movement, the actual displacement data along the X-axis is acquired. The horizontal straightness error data in the X-axis direction is measured in real time using the X-axis laser interferometry module. and vertical straightness error data ; Step 2: Compare the obtained straightness error data, actual displacement data, and X-axis target position. Y-axis target position Perform fusion processing, calculate the dual-axis integrated positioning error, and solve the X-axis integrated error compensation value and Y-axis integrated error compensation value; Step 3: Set the termination compensation conditions based on the dual-axis integrated positioning error; Step 4: Transmit the X-axis comprehensive error compensation value and Y-axis comprehensive error compensation value obtained in Step 3 to the servo drive unit. The servo drive unit controls the X-axis air-float moving platform and the Y-axis moving platform to perform X-axis displacement compensation and Y-axis displacement compensation respectively. Calculate the dual-axis comprehensive positioning error in real time and determine whether the termination compensation condition is met. If it is met, proceed to the next step; if it is not met, repeat Steps 2 to 4. Step 5: Acquire images of the target object using the image acquisition module.

[0012] As a preferred option, the specific method for step two is as follows: S1. Preprocess the collected data; S2. Based on the difference in the impact of horizontal and vertical straightness on positioning accuracy, set differentiated weighting coefficients, convert the collected horizontal and vertical straightness error data in the Y-axis direction into equivalent error values ​​in the Y-axis direction, and convert the collected horizontal and vertical straightness error data in the X-axis direction into equivalent error values ​​in the X-axis direction. S3. Combining the target position on the X-axis, the actual displacement data on the X-axis, the target position on the Y-axis, the actual displacement data on the Y-axis, the equivalent error value in the X-axis direction, and the equivalent error value in the Y-axis, calculate the comprehensive positioning error on the X-axis and the comprehensive positioning error on the Y-axis respectively, and calculate the comprehensive positioning error of the two axes based on the comprehensive positioning error on the X-axis and the comprehensive positioning error on the Y-axis. S4. Fit the X-axis comprehensive positioning error and the Y-axis comprehensive positioning error respectively to generate continuous X-axis comprehensive error curves and Y-axis comprehensive error curves, so as to restore the error change trend jointly affected by the straightness of the guide rail and the position of the moving parts. S5. Based on the fitted Y-axis comprehensive error curve and X-axis comprehensive error curve, and by introducing a PID algorithm with integral separation and derivative-first steps, the X-axis comprehensive error compensation value and the Y-axis comprehensive error compensation value are calculated.

[0013] Preferably, in step S2: Y-axis equivalent error value and the equivalent error value of the X-axis The calculation formula is as follows: ; ; in, , These are the weighting coefficients for the straightness error in the horizontal and vertical directions of the X-axis guide rail, respectively. , This contains the pre-processed straightness error data for the X-axis guide rail in the horizontal and vertical directions. , The weighting coefficients for the straightness errors in the horizontal and vertical directions of the Y-axis motion guide rail are given. , These are the preprocessed horizontal straightness error data and vertical straightness error data along the Y-axis; In step S3, the X-axis comprehensive positioning error and Y-axis comprehensive positioning error The calculation method is as follows: ; ; in, , These are the target positions on the X-axis and Y-axis, respectively. , These are the preprocessed actual X-axis displacement data and the preprocessed actual Y-axis displacement data, respectively. Dual-axis integrated positioning error The calculation formula is as follows: ; In step S4, the X-axis composite error curve and the Y-axis comprehensive error curve The fitting formula is as follows: ; ; in, , , , All are X-axis interpolation coefficients. , , , All are Y-axis interpolation coefficients.

[0014] Preferably, in step S5, the X-axis comprehensive error compensation value The formula for calculating the Y-axis comprehensive error compensation value is as follows: ; ; in, , These are the scaling factors for the X-axis and Y-axis, respectively. , These are the integration time constants for the X and Y axes, respectively. , These are the differential time constants for the X and Y axes, respectively; and an error threshold is set to control the integral element. ; when At that time, points will be turned off; At that time, the points system will be activated.

[0015] Preferably, in step five, if the image of the target object is blurry, the focus is adjusted using the Z-axis movement module to ensure the image is clear.

[0016] The beneficial effects of this invention are: 1. This invention uses X-axis laser interferometry and Y-axis laser interferometry modules to accurately measure the straightness errors of the X-axis and Y-axis guide rails in the horizontal and vertical directions, respectively. The straightness deviation of the two guide rails is quantified and integrated into the overall positioning error to achieve real-time compensation of the two axes. This simplifies the data preprocessing process and clarifies the dedicated function of focal length adjustment of the Z-axis movement module. Combined with the deep linkage between the positioning system and the image measurement system, it meets the actual needs of the precision image measurement field.

[0017] 2. The measurement mode adopts a position detection module (grating ruler) as the basic positioning + laser interferometer for high-precision measurement of the straightness of the dual guide rails. Through "error preprocessing - PID compensation algorithm" for dual-axis comprehensive error compensation, the straightness deviation across directions is converted into calculable X / Y axis equivalent errors. This effectively suppresses positioning deviations caused by factors such as air buoyancy disturbance, temperature drift, dual-axis guide rail straightness deviation, and moving part position offset. It dynamically corrects the attitude of moving parts, so that the dual-axis comprehensive positioning error is controlled within 0.001mm, and the positioning accuracy is significantly better than existing technologies.

[0018] 3. Leveraging the advantages of high precision and long stroke measurement of guide rail straightness and worktable position by laser interferometer, combined with real-time comprehensive compensation system, it breaks through the bottleneck of traditional image measuring instruments constrained by the grating ruler range, effectively suppresses the cumulative effect of guide rail straightness deviation under long stroke, and expands the X-axis measurement range to more than 3000mm while ensuring consistent positioning accuracy across the entire range. It can stably adapt to the precision measurement needs of X-axis direction for large-size workpieces.

[0019] 4. The overall structure of the device of this invention has a clear division of labor, and the functions of each module work together. The device is easy to integrate and maintain, and can be directly applied to the upgrade and transformation of existing image measurement devices without large-scale equipment replacement. The straightness error weight coefficient, PID parameters and other parameters in the algorithm can be flexibly adjusted according to workpieces of different sizes and with different precision requirements and actual guide rail conditions. The simple preprocessing method does not require complex parameter calibration, can adapt to the comprehensive compensation needs in different scenarios, and is applicable to a variety of precision image measurement scenarios. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the image measuring device of the present invention.

[0021] In the diagram: 1. X-axis guide rail, 2. Y-axis guide rail, 3. Y-axis moving platform, 4. Straightness mirror group B, 5. Laser interferometer B, 6. Laser interferometer B, 7. Straightness mirror group A, 8. Z-axis moving module, 9. Image acquisition module, 10. Laser interferometer A, 11. Laser interferometer A, 12. X-axis air-bearing moving platform. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0023] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention.

[0024] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0025] like Figure 1 As shown, an image measurement device based on real-time compensation using a laser interferometer includes an X-axis guide rail 2, an X-axis air-floating moving platform 12 mounted on the X-axis guide rail 2, a Y-axis guide rail 2 mounted on the X-axis air-floating moving platform 12, a Y-axis moving platform 3 mounted on the Y-axis guide rail 2, an image acquisition module 9 mounted on the Y-axis moving platform 3, an X-axis laser interferometry module, a Y-axis laser interferometry module, an X-axis position detection module, and a Y-axis position detection module. The X-axis laser interferometry module is used to acquire the horizontal and vertical straightness errors of the X-axis air-floating moving platform 12 in real time throughout its movement. The Y-axis laser interferometry module is used to acquire the horizontal and vertical straightness errors of the Y-axis moving platform 3 in real time throughout its movement. The position of the image acquisition module 9 is compensated and corrected using the data acquired by the X-axis and Y-axis laser interferometry modules.

[0026] This device uses X-axis guide rail 2 and Y-axis guide rail 2 to construct a two-dimensional motion architecture. With X-axis guide rail 2 as the basic bearing reference, X-axis air-bearing moving platform 12 can move linearly along X-axis guide rail 2. Y-axis guide rail 2 is fixedly mounted on X-axis air-bearing moving platform 12 and completes X-axis position adjustment with X-axis air-bearing moving platform 12. Y-axis moving platform 3 can move linearly in the Y-axis along Y-axis guide rail 2. Image acquisition module 9 is fixed on Y-axis moving platform 3 and completes Y-axis position adjustment with Y-axis moving platform 3. Finally, it realizes the movement of image acquisition module 9 at any target position in the two-dimensional measurement plane, providing a motion basis for full-range image measurement.

[0027] The X-axis movement adopts a non-contact motion method with air bearing support, which can eliminate the inherent defects of traditional contact guide rails such as mechanical friction, crawling gap, and reverse dead zone. It significantly reduces the basic error of the X-axis full-stroke motion from the mechanical structure source, improves motion stability and repeatability, and lays a mechanical benchmark for high-precision measurement under long stroke.

[0028] This device uses X-axis and Y-axis position detection modules to collect real-time axial displacement data of the X-axis air-bearing moving platform 12 and the Y-axis moving platform 3, respectively. Combined with the two-dimensional straightness error data collected synchronously by the X and Y-axis laser interferometry modules, an error mapping model is established between the theoretical target position and the actual spatial position of the image acquisition module 9. The straightness error data obtained by the laser interferometry module is converted into a two-dimensional position correction value for the image acquisition module 9, which compensates and corrects the actual spatial position of the image acquisition module 9, eliminates the position offset caused by multi-source errors, and ensures that the image acquisition module 9 is always accurately positioned at the preset theoretical measurement position throughout its entire stroke range.

[0029] Among them, the X-axis guide rail 2 is a marble guide rail with a rectangular cross-section.

[0030] Specifically, the X-axis laser interferometry module includes a laser interferometer B6, a laser interferometer B5 located in front of the laser interferometer B6, and a straightness mirror group B4 set on the X-axis air-floating moving platform 12 and corresponding to the laser interferometer B6; the Y-axis laser interferometry module includes a laser interferometer A11, a laser interferometer A10 located in front of the laser interferometer A11, and a straightness mirror group A7 set on the Y-axis moving platform 3 and corresponding to the laser interferometer A11.

[0031] The X-axis position detection module is a grating ruler set on the X-axis guide rail 2 and arranged along its axial direction, used to detect the actual displacement data of the X-axis air-bearing moving platform 12 in real time; the Y-axis position detection module is a grating ruler set on the X-axis air-bearing moving platform 12 and arranged along the Y-axis direction, used to detect the actual displacement data of the Y-axis moving platform 3 in real time.

[0032] The Y-axis moving platform 3 is also equipped with a Z-axis moving module 8, and the image acquisition module 9 is mounted on the Z-axis moving module 8. The Z-axis moving module 8 drives the image acquisition module 9 to move along the Z-axis direction to achieve focusing. An image measurement method based on real-time compensation using a laser interferometer includes the following specific steps: Step 1: The Y-axis moving platform moves from its initial position along the Y-axis direction to the target position along the Y-axis. During this movement, the actual displacement data along the Y-axis is acquired. The horizontal straightness error data in the Y-axis direction is measured in real time using a Y-axis laser interferometry module. and vertical straightness error data The X-axis air-float moving platform moves from its initial position along the X-axis direction to its target position. During this movement, the actual displacement data along the X-axis is acquired. The horizontal straightness error data in the X-axis direction is measured in real time using the X-axis laser interferometry module. and vertical straightness error data .

[0033] It is worth mentioning that horizontal straightness error, or straightness error in the horizontal direction, refers to the deviation of the platform's actual trajectory from the ideal straight line in the horizontal plane along its own direction of movement. It reflects whether the platform deviates horizontally (left-right) during movement. Vertical straightness error, or straightness error in the vertical direction, refers to the deviation of the platform's actual trajectory from the ideal straight line in the vertical plane along its own direction of movement. It reflects whether the platform deviates vertically (up-down) during movement.

[0034] Step 2: Compare the obtained straightness error data, actual displacement data, and X-axis target position. Y-axis target position Perform fusion processing, calculate the dual-axis integrated positioning error, and solve the X-axis integrated error compensation value and Y-axis integrated error compensation value.

[0035] The specific method for this step is as follows: S1. Preprocess the collected data as follows: A simple filtering method using a three-point moving average was employed to eliminate random noise caused by environmental vibrations and air buoyancy disturbances. A sliding window was defined as three consecutive sampling times. Starting from the first sampling time, the window moved backward one time along the sampling time axis after each calculated filtered value, until all original data were covered.

[0036] For each type of raw data, a continuous raw data sequence is defined according to the chronological order of sampling time: , , ..., ,(in This is the raw data from the first sampling time. The raw data at the second sampling time, ... Given the original data at the nth sampling time (where n is the total number of samples), then... for: ; Where k is the sampling time number of the last data in the current sliding window, k≥3, , , This refers to the original data of the same type at sampling times k-2, k-1, and k in the current window; This represents the filtered data value at the k-th sampling time.

[0037] S2. Based on the difference in the impact of horizontal and vertical straightness on positioning accuracy, set differentiated weighting coefficients, convert the collected horizontal and vertical straightness error data in the Y-axis direction into equivalent error values ​​in the Y-axis direction, and convert the collected horizontal and vertical straightness error data in the X-axis direction into equivalent error values ​​in the X-axis direction, thereby realizing the conversion of cross-directional errors into corresponding axis positioning errors.

[0038] Specifically, the equivalent error value of the Y-axis and the equivalent error value of the X-axis The calculation formula is as follows: ; ; in, , These are the weighting coefficients for the straightness error in the horizontal and vertical directions of the X-axis guide rail, respectively. , This contains the pre-processed straightness error data for the X-axis guide rail in the horizontal and vertical directions. , The weighting coefficients for the straightness errors in the horizontal and vertical directions of the Y-axis motion guide rail are given. , These are the preprocessed horizontal straightness error data and vertical straightness error data along the Y-axis.

[0039] Since horizontal straightness errors in the X and Y axes directly affect the horizontal positioning of the guide rail's motion trajectory, they have a greater impact on the positioning accuracy of the axis system and therefore carry higher weight; while vertical straightness errors indirectly affect positioning through slight changes in the attitude of the worktable and modules, and thus have a relatively lower weight. Based on this, , Select within the range of (0.85-0.95). , Select within the range of (0.10-0.20); the weighting coefficient can be flexibly adjusted according to the actual guide rail accuracy and the structure of the air-bearing worktable.

[0040] S3. Combining the target position on the X-axis, the actual displacement data on the X-axis, the target position on the Y-axis, the actual displacement data on the Y-axis, the equivalent error value in the X-axis direction, and the equivalent error value in the Y-axis, calculate the comprehensive positioning error on the X-axis and the comprehensive positioning error on the Y-axis respectively, and calculate the comprehensive positioning error of the two axes based on the comprehensive positioning error on the X-axis and the comprehensive positioning error on the Y-axis.

[0041] Among them, the X-axis comprehensive positioning error and Y-axis comprehensive positioning error The calculation method is as follows: ; ; in, , These are the target positions on the X-axis and Y-axis, respectively. , These are the preprocessed actual X-axis displacement data and the preprocessed actual Y-axis displacement data, respectively. Dual-axis integrated positioning error The calculation formula is as follows: .

[0042] S4. Fit the X-axis comprehensive positioning error and the Y-axis comprehensive positioning error respectively to generate continuous X-axis comprehensive error curves and Y-axis comprehensive error curves, so as to restore the error change trend jointly affected by the straightness of the guide rail and the position of the moving parts.

[0043] When performing curve fitting, a cubic spline interpolation algorithm is used to comprehensively measure the X-axis positioning error at consecutive sampling times. Y-axis positioning comprehensive error A continuous X-axis composite error curve is formed through fitting. Y-axis composite error curve The error variation trend, influenced by the straightness of the dual-axis guide rail and the position of the corresponding moving parts during movement in the X and Y axes, is fitted by the following formula: ; ; in, , , , All are X-axis interpolation coefficients. , , , These are all Y-axis interpolation coefficients. The difference coefficients are all calculated using the combined error data of the corresponding axes at three adjacent sampling times.

[0044] S5. Based on the fitted Y-axis comprehensive error curve and X-axis comprehensive error curve, and by introducing a PID algorithm with integral separation and derivative-first steps, the X-axis comprehensive error compensation value and the Y-axis comprehensive error compensation value are calculated.

[0045] Among them, the X-axis comprehensive error compensation value and Y-axis comprehensive error compensation value The calculation formula is as follows: ; ; in, , These are the scaling factors for the X and Y axes, respectively, with values ​​ranging from 4.5 to 6.0. , These are the integration time constants for the X and Y axes, respectively, with values ​​ranging from 0.6 to 1.0 s; , The time constants for the X and Y axes are the differential time constants, with values ​​ranging from 0.1 to 0.15 s.

[0046] Set an error threshold to control the integral phase. ; when At that time, points will be turned off; At that time, the points system will be activated.

[0047] In this embodiment, the error threshold The value is 0.005mm.

[0048] Step 3: Set the termination compensation condition based on the dual-axis integrated positioning error. The termination compensation condition is: when the absolute value of the integrated positioning error reaches a certain threshold... If the value is ≤0.001mm and remains stable for three consecutive sampling times, then compensation should be stopped.

[0049] Step 4: Transmit the X-axis comprehensive error compensation value and Y-axis comprehensive error compensation value obtained in Step 3 to the servo drive unit. The transmission method can be USB interface or Ethernet interface. Control the X-axis air-float moving platform and the Y-axis moving platform to perform X-axis displacement compensation and Y-axis displacement compensation respectively through the servo drive unit. Calculate the dual-axis comprehensive positioning error in real time and determine whether the termination compensation condition is met. If it is met, proceed to the next step. If it is not met, repeat Steps 2 to 4.

[0050] Step 5: Acquire an image of the target object using the image acquisition module 9. If the image of the target object is blurry, adjust the focus using the Z-axis movement module 8 to ensure a clear image. The image acquisition module 9 performs image acquisition, feature extraction, and size measurement of the target object.

[0051] After the measurement is completed, the image acquisition module 9 summarizes the measurement data and transmits it to the motion control system, and generates a measurement report; finally, the X-axis air-bearing worktable moves and resets along the X-axis direction, the Y-axis moving platform 3 moves and resets along the Y-axis direction, and the Z-axis moving module 8 drives the image acquisition module 9 back to the initial height, and the measurement process ends.

[0052] The beneficial effects of this invention are as follows: 1. This invention uses X-axis laser interferometry and Y-axis laser interferometry modules to accurately measure the straightness errors of the X-axis and Y-axis guide rails in the horizontal and vertical directions, respectively. The straightness deviation of the two guide rails is quantified and integrated into the overall positioning error to achieve real-time compensation of the two axes. This simplifies the data preprocessing process and clarifies the dedicated function of focal length adjustment of the Z-axis movement module. Combined with the deep linkage between the positioning system and the image measurement system, it meets the actual needs of the precision image measurement field.

[0053] 2. The measurement mode adopts a position detection module (grating ruler) as the basic positioning + laser interferometer for high-precision measurement of the straightness of the dual guide rails. Through "error preprocessing - PID compensation algorithm" for dual-axis comprehensive error compensation, the straightness deviation across directions is converted into calculable X / Y axis equivalent errors. This effectively suppresses positioning deviations caused by factors such as air buoyancy disturbance, temperature drift, dual-axis guide rail straightness deviation, and moving part position offset. It dynamically corrects the attitude of moving parts, so that the dual-axis comprehensive positioning error is controlled within 0.001mm, and the positioning accuracy is significantly better than existing technologies.

[0054] 3. Leveraging the advantages of high precision and long stroke measurement of guide rail straightness and worktable position by laser interferometer, combined with real-time comprehensive compensation system, it breaks through the bottleneck of traditional image measuring instruments constrained by the grating ruler range, effectively suppresses the cumulative effect of guide rail straightness deviation under long stroke, and expands the X-axis measurement range to more than 3000mm while ensuring consistent positioning accuracy across the entire range. It can stably adapt to the precision measurement needs of X-axis direction for large-size workpieces.

[0055] 4. The overall device structure has a clear division of labor, and the functions of each module work together. The device is easy to integrate and maintain, and can be directly applied to the upgrade and transformation of existing image measurement devices without large-scale equipment replacement. The straightness error weight coefficient and PID parameters in the algorithm can be flexibly adjusted according to workpieces of different sizes and with different precision requirements and actual guide rail conditions. The simple preprocessing method does not require complex parameter calibration, can adapt to the comprehensive compensation needs in different scenarios, and is suitable for a variety of precision image measurement scenarios.

[0056] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes in shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. An image measurement device based on real-time compensation using a laser interferometer, characterized in that, The system includes an X-axis guide rail, an X-axis air-bearing moving platform mounted on the X-axis guide rail, a Y-axis guide rail mounted on the X-axis air-bearing moving platform, a Y-axis moving platform mounted on the Y-axis guide rail, an image acquisition module mounted on the Y-axis moving platform, an X-axis laser interferometry module, a Y-axis laser interferometry module, an X-axis position detection module, and a Y-axis position detection module. The X-axis laser interferometry module is used to acquire the horizontal and vertical straightness errors of the X-axis air-bearing moving platform in real time throughout its movement. The Y-axis laser interferometry module is used to acquire the horizontal and vertical straightness errors of the Y-axis moving platform in real time throughout its movement. The data acquired by the X-axis and Y-axis laser interferometry modules are used to compensate and correct the position of the image acquisition module. A Z-axis moving module is mounted on the Y-axis moving platform, and the image acquisition module is mounted on the Z-axis moving module. The Z-axis moving module drives the image acquisition module to move along the Z-axis direction to achieve focusing. The image measurement method based on the laser interferometer real-time compensation image measurement device includes the following specific steps: Step 1: The Y-axis moving platform moves from its initial position along the Y-axis direction to the target position along the Y-axis. During this movement, the actual displacement data along the Y-axis is acquired. The horizontal straightness error data in the Y-axis direction is measured in real time using a Y-axis laser interferometry module. and vertical straightness error data The X-axis air-float moving platform moves from its initial position along the X-axis direction to its target position. During this movement, the actual displacement data along the X-axis is acquired. The horizontal straightness error data in the X-axis direction is measured in real time using the X-axis laser interferometry module. and vertical straightness error data ; Step 2: Compare the obtained straightness error data, actual displacement data, and X-axis target position. Y-axis target position The process involves fusion processing to calculate the dual-axis integrated positioning error, and then determining the X-axis and Y-axis integrated error compensation values. The specific method is as follows: S1. Preprocess the collected data; S2. Based on the difference in the impact of horizontal and vertical straightness on positioning accuracy, set differentiated weighting coefficients, convert the collected horizontal and vertical straightness error data in the Y-axis direction into equivalent error values ​​in the Y-axis direction, and convert the collected horizontal and vertical straightness error data in the X-axis direction into equivalent error values ​​in the X-axis direction. S3. Combining the target position on the X-axis, the actual displacement data on the X-axis, the target position on the Y-axis, the actual displacement data on the Y-axis, the equivalent error value in the X-axis direction, and the equivalent error value in the Y-axis, calculate the comprehensive positioning error on the X-axis and the comprehensive positioning error on the Y-axis respectively, and calculate the comprehensive positioning error of the two axes based on the comprehensive positioning error on the X-axis and the comprehensive positioning error on the Y-axis. S4. Fit the X-axis comprehensive positioning error and the Y-axis comprehensive positioning error respectively to generate continuous X-axis comprehensive error curves and Y-axis comprehensive error curves, so as to restore the error change trend jointly affected by the straightness of the guide rail and the position of the moving parts. S5. Based on the fitted Y-axis comprehensive error curve and X-axis comprehensive error curve, and by introducing a PID algorithm with integral separation and derivative-first steps, the X-axis comprehensive error compensation value and the Y-axis comprehensive error compensation value are calculated. Step 3: Set the termination compensation conditions based on the dual-axis integrated positioning error; Step 4: Transmit the X-axis comprehensive error compensation value and Y-axis comprehensive error compensation value obtained in Step 3 to the servo drive unit. The servo drive unit controls the X-axis air-float moving platform and the Y-axis moving platform to perform X-axis displacement compensation and Y-axis displacement compensation respectively. Calculate the dual-axis comprehensive positioning error in real time and determine whether the termination compensation condition is met. If it is met, proceed to the next step; if it is not met, repeat Steps 2 to 4. Step 5: Acquire images of the target object using the image acquisition module.

2. The image measurement device based on real-time compensation using a laser interferometer according to claim 1, characterized in that, The X-axis guide rail is a marble guide rail with a rectangular cross-section.

3. The image measurement device based on real-time compensation using a laser interferometer according to claim 1, characterized in that, The X-axis laser interferometry module includes a laser interferometer B, a laser interferometer mirror B located in front of the laser interferometer B, and a straightness mirror group B set on the X-axis air-floating moving platform and corresponding to the laser interferometer B; the Y-axis laser interferometry module includes a laser interferometer A, a laser interferometer mirror A located in front of the laser interferometer A, and a straightness mirror group A set on the Y-axis moving platform and corresponding to the laser interferometer A.

4. The image measurement device based on real-time compensation using a laser interferometer according to claim 1, characterized in that, The X-axis position detection module is a grating ruler set on the X-axis guide rail and arranged along its axial direction, used to detect the actual displacement data of the X-axis air-float moving platform in real time; the Y-axis position detection module is a grating ruler set on the X-axis air-float moving platform and arranged along the Y-axis direction, used to detect the actual displacement data of the Y-axis moving platform in real time.

5. The image measurement device based on real-time compensation using a laser interferometer according to claim 1, characterized in that, In step S2: Y-axis equivalent error value and the equivalent error value of the X-axis The calculation formula is as follows: ； ； in, , These are the weighting coefficients for the straightness error in the horizontal and vertical directions of the X-guide rail, respectively. , This contains the pre-processed straightness error data for the X-axis guide rail in the horizontal and vertical directions. , The weighting coefficients for the straightness errors in the horizontal and vertical directions of the Y-axis motion guide rail are given. , These are the preprocessed horizontal straightness error data and vertical straightness error data along the Y-axis; In step S3, the X-axis comprehensive positioning error and Y-axis comprehensive positioning error The calculation method is as follows: ； ； in, , These are the target positions on the X-axis and Y-axis, respectively. , These are the preprocessed actual X-axis displacement data and the preprocessed actual Y-axis displacement data, respectively. Dual-axis integrated positioning error The calculation formula is as follows: ； In step S4, the X-axis composite error curve and the Y-axis comprehensive error curve The fitting formula is as follows: ； ； in, , , , All are X-axis interpolation coefficients. , , , All are Y-axis interpolation coefficients.

6. The image measurement device based on real-time compensation using a laser interferometer according to claim 5, characterized in that, In step S5, the X-axis comprehensive error compensation value The formula for calculating the Y-axis comprehensive error compensation value is as follows: ； ； in, , These are the scaling factors for the X-axis and Y-axis, respectively. , These are the integration time constants for the X and Y axes, respectively. , These are the differential time constants for the X and Y axes, respectively; and an error threshold is set to control the integral element. ; when At that time, points will be turned off; At that time, the points system will be activated.

7. The image measurement device based on real-time compensation using a laser interferometer according to claim 1, characterized in that, In step five, if the image of the target object is blurry, the focus is adjusted using the Z-axis movement module to ensure the image is clear.

Images