Laser displacement sensor calibration device, calibration method and calibration result verification method

Abstract

The invention discloses a laser displacement sensor calibration device, a calibration method and a calibration result verification method, and belongs to the technical field of precision measurement and sensing. According to the scheme, the mobile platform is controlled to continuously move in the whole measurement range of the laser displacement sensor, the calibration data are collected in real time, function fitting is carried out based on a small amount of collected calibration data to obtain the correction function, and then the correction function is burnt to the laser displacement sensor. According to the laser displacement sensor calibration scheme, the automation degree is high, a large number of expensive measuring instruments such as standard gauge blocks and interferometers are not needed, and individual correction functions for all the laser displacement sensors can be rapidly generated through function fitting only by collecting calibration data of a small number of calibration points in real time; consistency and comparability of measurement results of the laser displacement sensor are achieved, and cost and resource consumption are reduced at the same time.

Description

Technical Field

[0001] The present invention relates to the field of precision measurement and sensing technology, and in particular to a laser displacement sensor calibration device, a calibration method and a calibration result verification method. Background Art

[0002] Laser displacement sensors are sensors that use laser technology to measure displacement. There are three common principles: Triangulation method: A laser transmitter emits a laser beam to the surface of the object to be measured. After being reflected by the surface of the object, the reflected light is received by the receiver. Based on the geometric relationship between the transmitter, receiver and the object to be measured, as well as the imaging position of the reflected light on the receiver, the distance between the object to be measured and the sensor is calculated through trigonometric functions. Triangulation method is often used in short and medium distance measurement scenarios with high accuracy requirements, such as dimensional measurement in precision machining.

[0003] Time of flight method: The sensor emits a laser pulse, which is reflected back after reaching the surface of the object being measured and received by the sensor. By measuring the time interval from the emission to the reception of the laser pulse and combining it with the speed of light, the distance between the sensor and the object being measured is calculated. The time of flight method is suitable for long-distance measurement, such as distance measurement in construction and inventory counting in logistics warehousing.

[0004] Interference measurement method: Using the principle of laser interference, when a laser beam is divided into two beams, one beam is irradiated to the surface of the object to be measured, and the other beam is used as a reference beam, the two beams will produce interference fringes when they meet. According to the change of the interference fringes, the displacement change of the object to be measured is calculated. Interference measurement method is mainly used for ultra-precision measurement, such as wafer flatness measurement in semiconductor manufacturing and surface profile measurement of optical components.

[0005] During the manufacturing process of laser displacement sensors, due to the influence of various factors, such as processing errors of optical components, performance differences of electronic components, etc., there will be a deviation between the actual measured value of the sensor and the true value. In addition, under different environmental conditions, such as temperature, humidity, air pressure, etc., its performance will change.

[0006] The purpose of calibrating the laser displacement sensor is to determine the measurement error of the sensor and correct the measurement results to ensure that in actual use, the sensor can provide accurate and reliable measurement results regardless of how the environment changes; at the same time, different sensor individuals have the same measurement reference and accuracy under the same measurement conditions, thereby achieving consistency and comparability of measurement results.

[0007] Calibration refers to the process of calibrating and calibrating sensors, measuring instruments or other equipment using standard measuring instruments to determine the relationship between their measured values ​​and true values ​​to ensure the accuracy and reliability of the equipment's measurement results.

[0008] Calibration is an important step in the assembly process, which affects the final accuracy of the product. Existing calibration methods are usually time-consuming and labor-intensive. An experienced technician usually needs about an hour to complete the calibration of a laser displacement sensor, so the production capacity is very limited.

[0009] At present, there are mainly the following calibration schemes for laser displacement sensors: (1) Calibration based on standard gauge blocks Principle: The standard gauge block has a known and precise size. By using the laser displacement sensor to measure gauge blocks of different lengths in turn, the corresponding relationship between the sensor's measurement value and the actual length of the gauge block is obtained, thereby determining the sensor's measurement error and accuracy.

[0010] Steps: Preparation: Select a set of standard gauge blocks with appropriate accuracy level. The length of the gauge blocks should cover the measurement range of the laser displacement sensor. Place the sensor and gauge blocks on a stable workbench to ensure that the measurement environment temperature, humidity and other conditions are relatively stable.

[0011] Measuring process: Starting from the gauge block with the smallest length, aim the laser displacement sensor at the surface of the gauge block, perform multiple measurements and record the measured values. Then replace gauge blocks of different lengths in turn and repeat the measurement operation.

[0012] Data processing: Compare the measured value of the sensor with the actual length of the gauge block and calculate the error of each measuring point. Evaluate the measurement accuracy and linearity of the sensor by drawing the error curve and calculating the average error, standard deviation and other indicators. Correct the measurement results of the sensor according to the error.

[0013] Problems with solution (1): Although standard gauge blocks have high accuracy, there are still certain errors between gauge blocks of different grades. For high-precision laser displacement sensors, the accuracy of the gauge blocks may not meet their calibration requirements. The length of standard gauge blocks is fixed and usually can only cover a limited measurement range. If the measurement range of the laser displacement sensor is large, a large number of gauge blocks of different lengths are required, which is cumbersome and increases costs. Only one gauge block length can be measured at a time, and it is impossible to calibrate the entire measurement range of the sensor continuously, which takes a long time to calibrate.

[0014] (2) Calibration based on interferometer Principle: Interferometer is an instrument that uses the principle of light interference for high-precision measurement. The laser displacement sensor is combined with the interferometer, and the high-precision displacement measured by the interferometer is used as the standard value to compare with the measurement result of the laser displacement sensor, thereby realizing the calibration of the sensor.

[0015] Steps: Build the measurement system: Arrange the optical paths of the laser displacement sensor and interferometer reasonably so that they can measure the same object at the same time. Ensure the stability and accuracy of the optical path system and avoid the influence of external interference on the measurement results.

[0016] Perform synchronous measurement: During the measurement process, the object to be measured is subjected to a certain displacement, and the displacement is measured using the laser displacement sensor and the interferometer. The precise displacement value measured by the interferometer and the measurement value of the laser displacement sensor at different displacement moments are recorded.

[0017] Data comparison and calibration: The measured values ​​of the laser displacement sensor are compared point by point with those of the interferometer, and the difference between the two is calculated. Based on the comparison results, the laser displacement sensor is calibrated and corrected to improve its measurement accuracy.

[0018] Problems with solution (2): The interferometer itself is a high-precision, complex optical instrument that is very expensive. Its operation and debugging require professional optical knowledge and skills, and the requirements for operators are very high. The construction and adjustment of the optical path need to be very precise, and any slight deviation may affect the measurement results. Since interferometric measurement requires the analysis and processing of light interference fringes, the measurement speed is relatively slow and is not suitable for rapid calibration.

[0019] Therefore, there is an urgent need for an automatic, real-time, fast and economical laser displacement sensor calibration solution. Summary of the invention

[0020] The technical problem to be solved by the present invention is: in view of the above-mentioned defects of the prior art, a laser displacement sensor calibration device is provided, the device comprising an optical reference platform, on which a laser displacement sensor bracket and a movable base are sequentially arranged along the length direction thereof; The laser displacement sensor bracket is provided with a laser displacement sensor and a burning device, the laser displacement sensor is installed at a vertical position directly above the movable base close to one end thereof, and the burning device is used to burn the correction function into the laser displacement sensor; The length direction of the mobile base is parallel to the length direction of the optical reference table; a mobile platform is movably connected to the mobile base, and the mobile platform moves along the length direction of the mobile base; a calibration sample fixing plate is fixedly arranged on the mobile platform, and a calibration sample is fixedly arranged on a side of the calibration sample fixing plate facing the laser displacement sensor; a ruler is arranged on the outer side of the mobile base along its length direction, and a ruler scale reader is arranged on the same side of the mobile platform as the ruler, and the ruler scale reader is used to read the scale information of the ruler; The optical axis of the laser displacement sensor is parallel to the moving direction of the moving platform, and the measuring beam of the laser displacement sensor is facing the center of the calibration sample; The laser displacement sensor calibration device further comprises a control device, which is connected to the laser displacement sensor, the mobile platform, and the scale reader for motion control and data interaction; The control device calculates a correction function based on the acquired data; The control device also determines whether it is necessary to recalculate or re-burn the correction function according to the error information obtained when verifying the calibration result; The control device determines whether the laser displacement sensor is qualified based on the error information.

[0021] In the laser displacement sensor calibration device of the present invention, the zero line of the ruler is collinear with the laser emission point of the laser displacement sensor, and the line connecting the ruler scale reader and the calibration sample is perpendicular to the moving direction of the moving platform.

[0022] In the laser displacement sensor calibration device of the present invention, the scale is a grating scale, and the scale scale reader is a reading head matched with the grating scale.

[0023] In the laser displacement sensor calibration device of the present invention, the burning device is connected to the control device, and burns the correction function into the laser displacement sensor under the control of the control device.

[0024] The present invention also provides a laser displacement sensor calibration method, which is applied to the laser displacement sensor calibration device as described above, and the method comprises the following steps: Step S1, determining the number of calibration points and calibration positions according to the measurement range of the laser displacement sensor; Step S2, controlling the mobile platform to move to each calibration position in sequence, and reading in real time the reading y of the scale reader and the reflection information x received by the laser displacement sensor from the calibration sample when the mobile platform is at each calibration position; repeating step S2 until the calibration data of all calibration positions are obtained; Step S3, fitting a correction function y=F(x) according to the readings y of the scale reader at all calibration positions and the reflection information x received by the laser displacement sensor from the calibration sample; Step S4, burning the correction function y=F(x) into the laser displacement sensor.

[0025] In the laser displacement sensor calibration method of the present invention, before step S1, the method further includes: Install the laser displacement sensor on the laser displacement sensor bracket, ensure that the optical axis of the laser displacement sensor remains parallel to the mobile platform and the ruler, and ensure that the laser emission point of the laser displacement sensor is collinear with the zero line of the ruler; control the movement of the mobile platform so that the reading of the ruler scale reader is zero.

[0026] In the laser displacement sensor calibration method of the present invention, the specific method of step S1 is: determine the number of calibration points N according to the measurement range of the laser displacement sensor, and evenly set N calibration positions within the measurement range, and the calibration positions include the two end points of the measurement range.

[0027] The present invention also provides a method for verifying the calibration result of a laser displacement sensor, which is used to verify the calibration result of the laser displacement sensor calibrated by the above calibration method. The method comprises the following steps: A1, determining the number of verification points and verification positions according to the measurement range of the laser displacement sensor; the verification positions are randomly distributed within the measurement range; A2, control the mobile platform to move to each verification position in turn, and read in real time the reading y of the scale reader, the reflection information x received by the laser displacement sensor from the calibration sample, and the reading z of the laser displacement sensor when the mobile platform is at each verification position; repeat this step until the verification data of all verification positions are obtained; A3, calculate the first error e1 and the second error e2 at each verification position. If the first error e1 exceeds the first preset threshold, recalibration is required. If the second error e2 exceeds the second preset threshold, a different algorithm needs to be selected to refit the correction function F(x); the first error e1 is the error between the reading y of the scale reader and the reading z of the laser displacement sensor; the second error e2 is the correction result The error between the reading z of the laser displacement sensor and the correction result Calculated by the correction function F(x).

[0028] In the laser displacement sensor calibration result verification method of the present invention, the method further includes: if the first error e1 and the second error e2 simultaneously exceed the preset threshold value more than the preset number of times, then determining that the laser displacement sensor is a defective product.

[0029] The present invention has the following beneficial effects: the scheme of the present invention controls the mobile platform to move continuously within the entire measurement range of the laser displacement sensor, collects calibration data in real time, performs function fitting based on the collected small amount of calibration data to obtain a correction function, and then burns the correction function into the laser displacement sensor. The laser sensor calibration scheme of the present invention has a high degree of automation, does not require a large number of expensive measuring instruments such as standard gauge blocks and interferometers, and only needs to collect calibration data of a small number of calibration points in real time to quickly generate a personalized correction function for each laser displacement sensor through function fitting, thereby achieving consistency and comparability of the measurement results of the laser displacement sensor, while reducing costs and resource consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 A schematic diagram of the principle of a laser sensor calibration device provided in an embodiment of the present invention.

[0031] Figure 2 A schematic diagram of the structure of a laser sensor calibration device provided in an embodiment of the present invention.

[0032] Figure 3 A schematic diagram of the steps of a laser sensor calibration method provided in an embodiment of the present invention.

[0033] Figure 4 A schematic diagram of the steps of a method for verifying laser sensor calibration results provided in an embodiment of the present invention.

[0034] In the attached picture: 1. Optical reference table; 2. Laser displacement sensor bracket; 3. Laser displacement sensor; 4. Mobile base; 5. Ruler; 6. Mobile platform; 7. Calibration sample fixing plate; 8. Calibration sample; 9. Ruler scale reader; 10. Control device. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings of the specification. It should be understood that the embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0037] The present invention is suitable for automatically calibrating a laser displacement sensor and verifying the calibration result.

[0038] like Figure 1 , Figure 2 As shown, an embodiment of the present invention provides a laser displacement sensor calibration device, which includes an optical reference platform 1, on which a laser displacement sensor bracket 2 and a moving base 4 are sequentially arranged along the length direction thereof.

[0039] In the embodiment of the present invention, the optical reference platform 1 has a horizontal surface for supporting other mechanisms and maintaining their stability. The horizontal surface is usually made of marble.

[0040] The laser displacement sensor bracket 2 is provided with a laser displacement sensor 3 and a burning device (not shown in the figure). The laser displacement sensor 3 is installed at a vertical position directly above the movable base 4 near one end thereof. The burning device is used to burn the correction function into the laser displacement sensor 3.

[0041] like Figure 2 As shown, the laser displacement sensor bracket 2 includes an L-shaped bracket and a laser displacement sensor carrier plate fixed on the top of the L-shaped bracket, one end of the L-shaped bracket is fixed on the optical reference platform 1, and the laser displacement sensor 3 is fixed on the laser displacement sensor carrier plate.

[0042] The length direction of the mobile base 4 is parallel to the length direction of the optical reference table 1; a mobile platform 6 is movably connected to the mobile base 4, and the mobile platform 6 moves along the length direction of the mobile base 4; a calibration sample fixing plate 7 is fixedly arranged on the mobile platform 6, and a calibration sample 8 is fixedly arranged on the side of the calibration sample fixing plate 7 facing the laser displacement sensor 3; a ruler 5 is arranged on the outer side of the mobile base 4 along its length direction, and a ruler scale reader 9 is arranged on the same side of the mobile platform 6 as the ruler 5, and the ruler scale reader 9 is used to read the scale information of the ruler 5.

[0043] The optical axis of the laser displacement sensor 3 is parallel to the moving direction of the mobile platform 6, and the measuring beam of the laser displacement sensor 3 is facing the center of the calibration sample 8. Figure 2 The laser displacement sensor 3 is fixed by auxiliary fixing devices such as the fixing clamp shown, so as to ensure that the optical axis of the laser displacement sensor 3 remains parallel to the moving direction of the mobile platform 6. The type of the calibration sample 8 can be changed according to the test needs. Preferably, the calibration sample 8 is made of the same material as the object actually measured by the laser displacement sensor 3 to improve the calibration accuracy, such as ceramics, metals, graphite, plastics, etc.

[0044] The laser displacement sensor calibration device also includes a control device 10, which is connected to the laser displacement sensor 3, the mobile platform 6, and the scale reader 9 for motion control and data interaction; the control device 10 drives the mobile platform 6 to a preset position through a driving device such as a motor or a cylinder, and reads the signal inside the laser displacement sensor 3 and the reading of the scale reader 9.

[0045] The control device 10 calculates the correction function according to the acquired data; the control device 10 also determines whether the correction function needs to be recalculated or re-burned according to the error information obtained during the calibration result verification; the control device 10 determines whether the laser displacement sensor 3 is qualified based on the error information.

[0046] The laser displacement sensor calibration device provided in the embodiment of the present invention can control the mobile platform 6 to move continuously within the entire measurement range of the laser displacement sensor 3 through the control device 10, and obtain calibration data such as scale readings and internal signals of the laser displacement sensor 3 in real time, so as to quickly and automatically realize the calibration of multiple calibration points within the measurement range.

[0047] In the embodiment of the present invention, the zero line of the scale 5 is collinear with the laser emission point of the laser displacement sensor 3, and the line connecting the scale scale reader 9 and the calibration sample 8 is perpendicular to the moving direction of the mobile platform 6. In this way, the reading read by the scale scale reader 9 is the displacement value measured by the laser displacement sensor 3. In practical applications, if the zero line of the scale 5 and the laser emission point of the laser displacement sensor 3 cannot be precisely collinear or the line connecting the scale scale reader 9 and the calibration sample 8 is not perpendicular to the moving direction of the mobile platform 6, the calibration data should be compensated accordingly according to the relative position relationship among the scale 5, the scale scale reader 9, the laser emission point, and the calibration sample 8.

[0048] In some embodiments of the present invention, the scale is a grating scale, and the scale scale reader 9 is a reader that matches the grating scale. There are a series of equally spaced lines on the grating scale, which can be transparent and opaque lines or lines with different reflectivity. The reader is responsible for reading the information of these lines and converting them into electrical signals for processing. The reader usually contains a light source, a photodetector, and a signal processing circuit. When the reader moves along the grating scale with the moving platform 6, the reader detects the change in light intensity caused by the lines, thereby generating a periodic electrical signal. By analyzing these signals, the position of the reader relative to the grating scale can be accurately determined.

[0049] In other embodiments of the present invention, other high-precision mechanical scales and matching scale readers are used. The present invention has no special restrictions on the types of the scale 5 and the scale reader 9, as long as the scale 5 can meet the measurement accuracy and the scale reader 9 can read the scale value on the scale 5 in real time and feed it back to the control device 10.

[0050] In the embodiment of the present invention, the burning device is connected to the control device 10, and under the control of the control device 10, the correction function is burned into the laser displacement sensor 3. In practical applications, a matching burning device can be selected according to the hardware architecture and interface type of the laser displacement sensor 3.

[0051] like Figure 3 As shown, an embodiment of the present invention further provides a laser displacement sensor calibration method, which is applied to the laser displacement sensor calibration device as described above, and the method comprises the following steps: Step S1, determining the number of calibration points and calibration positions according to the measurement range of the laser displacement sensor.

[0052] In some embodiments of the present invention, the specific method of step S1 is: determine the number of calibration points N according to the measurement range of the laser displacement sensor, and evenly set N calibration positions within the measurement range, wherein the calibration positions include two end points of the measurement range.

[0053] The measurement range of the laser displacement sensor refers to the upward and downward floating range starting from the nominal working distance, and the upper and lower floating extremes are usually the same. For example, for a 30mm±5mm laser displacement sensor, its nominal working distance is 30mm, and the upper and lower floating extremes are both 5mm, then its measurement range is 25mm~35mm. A represents the nominal working distance, and B represents the upper and lower floating extremes of the measurement range, then the measurement range of the laser displacement sensor is AB~A+B. Assuming that N calibration points are selected, the calibration position includes the two end points AB and A+B of the measurement range, then the distance between adjacent calibration positions is 2B / (N-1). Evenly setting the calibration positions within the measurement range can make the distances between adjacent calibration positions equal, which is convenient for controlling the step length of the mobile platform.

[0054] In the embodiment of the present invention, in order to fit the correction function according to the calibration position, the number of calibration points N is usually greater than 20. Generally, the larger the measurement range, the larger the number of calibration points N.

[0055] In the embodiment of the present invention, before step S1, the following steps are further included: The laser displacement sensor is mounted on the laser displacement sensor bracket, ensuring that the optical axis of the laser displacement sensor is parallel to the mobile platform and the ruler, and ensuring that the laser emission point of the laser displacement sensor is collinear with the zero line of the ruler; the mobile platform is controlled to move so that the reading of the ruler scale reader is zero. The above setting is equivalent to resetting the laser displacement sensor device to ensure accurate calibration data.

[0056] Step S2, controlling the mobile platform to move to each calibration position in turn, and reading in real time the reading y of the scale reader and the reflection information x received by the laser displacement sensor from the calibration sample when the mobile platform is at each calibration position; repeating step S2 until the calibration data of all calibration positions are obtained.

[0057] In the embodiment of the present invention, the measurement range and the number of calibration points N of the laser displacement sensor 3 are set in the input interface of the control device 10, and the control device 10 can automatically calculate the calibration position according to the preset algorithm, and then control the mobile platform 6 to move to each calibration position in turn, read the information of the scale reader and the laser displacement sensor at each calibration position in real time, and store it for subsequent correction function fitting.

[0058] In some embodiments of the present invention, the mobile platform 6 moves from the starting position of the range of the laser displacement sensor 3 to the end position of the range. In other embodiments of the present invention, the mobile platform 6 moves from the end position of the range of the laser displacement sensor 3 to the starting position of the range. The present invention has no special restrictions on the moving direction of the mobile platform.

[0059] In the embodiment of the present invention, because the zero line of the ruler is collinear with the laser emission point of the laser displacement sensor, and the line connecting the ruler scale reader and the calibration sample is perpendicular to the moving direction of the mobile platform, the reading y of the ruler scale reader corresponds to the distance from the laser emission point of the laser displacement sensor to the calibration sample.

[0060] The embodiment of the present invention has no special restrictions on the type of laser displacement sensor. For a laser displacement sensor using the triangulation method, the reflection information x is the pixel position information at the center of the light spot; for a laser displacement sensor using the time of flight method, the reflection information x is the time difference between the moment of emission and the moment of receiving the reflected light, or the phase difference between the emitted light and the reflected light; for a laser displacement sensor using the interferometry method, the reflection information x is the amount of change in the interference fringes. By providing an auxiliary fixing device on the laser displacement sensor bracket 2, compatibility with laser displacement sensors of different models can be achieved.

[0061] Step S3, fitting a correction function y=F(x) according to the readings y of the scale reader at all calibration positions and the reflection information x received by the laser displacement sensor from the calibration sample.

[0062] In the embodiment of the present invention, the control device 10 obtains the correction function by fitting according to the information of each calibration position stored, and the specific fitting method includes least square method, weighted least square method, B-spline, genetic algorithm and the like.

[0063] Step S4, burning the correction function y=F(x) into the laser displacement sensor.

[0064] In the embodiment of the present invention, after the control device 10 obtains the correction function, the correction function is burned into the laser displacement sensor through the burning device. Using the calibration method of the embodiment of the present invention, each laser displacement sensor is calibrated individually to obtain personalized calibration data, and then the correction function is obtained according to the calibration data. Therefore, the correction functions of different laser displacement sensors may also be different, and adaptive correction for different laser displacement sensors is realized, so that different laser displacement sensors have the same measurement reference and accuracy under the same measurement conditions, thereby achieving consistency and comparability of the measurement results. After the laser displacement sensor has a built-in correction function, in the subsequent measurement process, the reflection information x received from the calibration sample is subjected to preliminary processing such as anti-shake, and then the correction function is used to calculate the final measurement result.

[0065] The laser displacement sensor calibration method provided by the embodiment of the present invention has the following significant advantages: (1) This method can automatically and continuously calibrate each calibration position within the measurement range and collect calibration data in real time during the calibration process without manual intervention, which greatly improves work efficiency and operation convenience.

[0066] (2) It avoids the use of a large number of expensive measuring instruments such as standard gauge blocks and interferometers. Only a small amount of calibration data is needed to quickly generate a personalized correction function for each laser displacement sensor through function fitting. This method not only reduces the demand for calibration samples and improves calibration efficiency, but also ensures the accuracy of each different laser displacement sensor, achieves consistency and comparability of measurement results, and reduces costs and resource consumption, which is obviously economical.

[0067] (3) The generated correction function is directly burned into the laser displacement sensor, so that the subsequent measurement process can be automatically corrected, further improving the measurement accuracy and efficiency.

[0068] In summary, the laser displacement sensor calibration method provided by the embodiment of the present invention, with its characteristics of automation, real-time, rapid response and economy, significantly reduces time, manpower and equipment costs while improving calibration efficiency, and is suitable for a wide range of industrial applications. In practical applications, using the laser displacement sensor calibration method of the present invention, it only takes about 1 second to calibrate a point, and the entire calibration process can be shortened from the original 1 hour to within 2 to 5 minutes, which greatly improves production efficiency, and the overall yield of laser displacement sensor products is increased by 5%.

[0069] The embodiment of the present invention further provides a method for verifying the calibration result of a laser displacement sensor, which is used to verify the calibration result of a laser displacement sensor calibrated by the calibration method as described above. The method comprises the following steps: A1, determining the number of verification points and verification positions according to the measurement range of the laser displacement sensor; the verification positions are randomly distributed within the measurement range.

[0070] In the embodiment of the present invention, during calibration, calibration positions are uniformly selected within the measurement range. In order to obtain a more accurate verification effect, during verification, verification positions are randomly selected within the measurement range. The number of verification points can be selected according to the measurement range and the number of calibration points.

[0071] In the embodiment of the present invention, before step A1, the following steps are further included: Ensure that the optical axis of the laser displacement sensor is parallel to the mobile platform and the ruler; ensure that the laser emission point of the laser displacement sensor is in line with the zero line of the ruler; control the movement of the mobile platform so that the reading of the ruler scale reader is zero.

[0072] A2, control the mobile platform to move to each verification position in turn, and read in real time the reading y of the ruler scale reader, the reflection information x received by the laser displacement sensor from the calibration sample, and the reading z of the laser displacement sensor when the mobile platform is at each verification position; repeat this step until the verification data of all verification positions are obtained.

[0073] The reading y of the scale reader is the scale reading of the scale when the mobile platform moves to each verification position, and the reading z of the laser displacement sensor is the final measurement result obtained by the laser displacement sensor based on the correction function and the reflection information x received from the calibration sample.

[0074] A3, calculate the first error e1 and the second error e2 at each verification position. If the first error e1 exceeds the first preset threshold, recalibration is required. If the second error e2 exceeds the second preset threshold, a different algorithm needs to be selected to refit the correction function F(x); the first error e1 is the error between the reading y of the scale reader and the reading z of the laser displacement sensor; the second error e2 is the correction result The error between the reading z of the laser displacement sensor and the correction result Calculated by the correction function F(x).

[0075] In actual engineering applications, in order to simplify the processing, binomial fitting is generally used to obtain the correction function, but its effect is not good at the beginning and end of the range. If it is found in the verification stage that the accuracy of the laser displacement sensor after correction does not meet the requirements, the fitting formula needs to be upgraded.

[0076] In practical applications, the first preset threshold and the second preset threshold are set as needed.

[0077] In some embodiments of the present invention, the method further comprises: if the number of times that the first error e1 and the second error e2 simultaneously exceed a preset threshold exceeds a preset number of times, determining that the laser displacement sensor is a defective product. The first error e1 and the second error e2 simultaneously exceed the preset threshold, which means that the first error e1 exceeds the first preset threshold, and the second error e2 exceeds the second preset threshold.

[0078] In the embodiment of the present invention, the calibration result verification method can realize the rapid and effective verification of the calibration result. In practical applications, it is necessary to analyze the reasons that may cause the deviation between the calibration result and the actual displacement according to the verification result, and accordingly improve the accuracy of the corrected measurement result by adjusting the position of each component in the laser displacement sensor device, increasing the number of calibration points, adjusting the fitting algorithm, etc.

[0079] The above are only specific implementations of the present invention, which cannot be used to limit the scope of the present invention. Equivalent changes made by ordinary technicians in this technical field based on this creation, as well as changes known to technicians in this field, should still fall within the scope of the present invention.

Claims

1. A laser displacement sensor calibration device, characterized in that: The device comprises an optical reference platform (1), on which a laser displacement sensor bracket (2) and a movable base (4) are sequentially arranged along the length direction of the optical reference platform (1); The laser displacement sensor bracket (2) is provided with a laser displacement sensor (3) and a burning device, the laser displacement sensor (3) being mounted on the movable base (4) at a position vertically directly above one end thereof, and the burning device being used to burn a correction function into the laser displacement sensor (3); The length direction of the movable base (4) is parallel to the length direction of the optical reference table (1); a movable platform (6) is movably connected to the movable base (4), and the movable platform (6) moves along the length direction of the movable base (4); a calibration sample fixing plate (7) is fixedly arranged on the movable platform (6), and a calibration sample (8) is fixedly arranged on a side of the calibration sample fixing plate (7) facing the laser displacement sensor (3); a ruler (5) is arranged on the outer side of the movable base (4) along its length direction, and a ruler scale reader (9) is arranged on the same side of the movable platform (6) as the ruler (5), and the ruler scale reader (9) is used to read the scale information of the ruler (5); The optical axis of the laser displacement sensor (3) is parallel to the moving direction of the moving platform (6), and the measuring light beam of the laser displacement sensor (3) faces the center of the calibration sample (8); The laser displacement sensor calibration device further comprises a control device (10), wherein the control device (10) is connected to the laser displacement sensor (3), the mobile platform (6), and the scale reader (9) for motion control and data interaction; The control device (10) calculates a correction function based on the acquired data; The control device (10) further determines whether the correction function needs to be recalculated or re-burned according to error information obtained during calibration result verification; The control device (10) determines whether the laser displacement sensor (3) is qualified based on the error information.

2. The laser displacement sensor calibration device according to claim 1, characterized in that: The zero line of the ruler (5) is collinear with the laser emission point of the laser displacement sensor (3), and the line connecting the ruler scale reader (9) and the calibration sample (8) is perpendicular to the moving direction of the moving platform (6).

3. The laser displacement sensor calibration device according to claim 1, characterized in that: The scale ruler (5) is a grating ruler, and the scale ruler scale reader (9) is a reading head matching the grating ruler.

4. The laser displacement sensor calibration device according to claim 1, characterized in that: The burning device is connected to the control device (10), and burns the correction function into the laser displacement sensor (3) under the control of the control device (10).

5. A laser displacement sensor calibration method, characterized in that: Applied to the laser displacement sensor calibration device according to any one of claims 1 to 4, the method comprises the following steps: Step S1, determining the number of calibration points and calibration positions according to the measurement range of the laser displacement sensor; Step S2, controlling the mobile platform to move to each calibration position in sequence, and reading in real time the reading y of the scale reader and the reflection information x received by the laser displacement sensor from the calibration sample when the mobile platform is at each calibration position; repeating step S2 until the calibration data of all calibration positions are obtained; Step S3, fitting a correction function y=F(x) according to the readings y of the scale reader at all calibration positions and the reflection information x received by the laser displacement sensor from the calibration sample; Step S4, burning the correction function y=F(x) into the laser displacement sensor.

6. The laser displacement sensor calibration method according to claim 5, characterized in that: Before step S1, the method further includes: Install the laser displacement sensor on the laser displacement sensor bracket, ensure that the optical axis of the laser displacement sensor remains parallel to the mobile platform and the ruler, and ensure that the laser emission point of the laser displacement sensor is collinear with the zero line of the ruler; control the movement of the mobile platform so that the reading of the ruler scale reader is zero.

7. The laser displacement sensor calibration method according to claim 5, characterized in that: The specific method of step S1 is: determine the number of calibration points N according to the measuring range of the laser displacement sensor, and evenly set N calibration positions within the measuring range, wherein the calibration positions include two end points of the measuring range.

8. A method for verifying calibration results of a laser displacement sensor, used to verify the calibration results of a laser displacement sensor calibrated by the calibration method according to any one of claims 5 to 7, characterized in that: The method The following steps are involved: A1, determining the number of verification points and verification positions according to the measurement range of the laser displacement sensor; the verification positions are randomly distributed within the measurement range; A2, control the mobile platform to move to each verification position in turn, and read in real time the reading y of the scale reader, the reflection information x received by the laser displacement sensor from the calibration sample, and the reading z of the laser displacement sensor when the mobile platform is at each verification position; repeat this step until the verification data of all verification positions are obtained; A3, calculate the first error e1 and the second error e2 at each verification position. If the first error e1 exceeds the first preset threshold, recalibration is required. If the second error e2 exceeds the second preset threshold, a different algorithm needs to be selected to refit the correction function F(x); the first error e1 is the error between the reading y of the scale reader and the reading z of the laser displacement sensor; the second error e2 is the correction result The error between the reading z of the laser displacement sensor and the correction result Calculated by the correction function F(x).

9. The method for verifying the calibration result of a laser displacement sensor according to claim 8, characterized in that: The method further includes: if the number of times that the first error e1 and the second error e2 simultaneously exceed a preset threshold exceeds a preset number, determining that the laser displacement sensor is a defective product.

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