Groove cylinder radius high-precision measurement system and method

Abstract

The invention discloses a groove cylinder radius high-precision measuring system and method, and belongs to a laser radar measuring method.The system comprises a hardware part and a software part, the hardware part comprises a laser radar, a laser tracker, an axial movement module and a target ball assembly, the laser radar is installed on a support, the support is installed on a sliding rail, and the laser tracker is installed on the sliding rail; the sliding rail is used for penetrating through the groove barrel in the axial direction of the groove barrel. A target ball assembly is further installed on the support. The target ball assembly is used for performing reciprocating rectilinear motion on the sliding rail synchronously with the laser radar; and the laser tracker is arranged at one end of the sliding rail. The laser radar and the target ball assembly synchronously move on the sliding rail in the radial direction of the groove cylinder, so that the laser radar can continuously measure and scan in the radial direction and obtain three-dimensional point cloud data of the groove cylinder, and the laser tracker obtains the 6D pose of the laser radar through the target ball assembly synchronously moving with the laser radar for compensation measurement. And the precision and the efficiency of measuring the radius of the groove cylinder can be obviously improved.

Description

Technical Field

[0001] The present invention relates to a method for lidar measurement. More specifically, the present invention mainly relates to a high-precision measurement system and method for the radius of a grooved cylinder body. Background Art

[0002] The detection of traditional cylinder-shaped workpieces is based on the geometric assembly relationship of the rotor or central shaft and the surface topography measurement. It mainly relies on manual detection using traditional methods. It is necessary to repeatedly hoist the rotor or central shaft to complete the assembly relationship detection, and there are the following problems: First, the efficiency is low. Contact measurement requires point-by-point acquisition, which takes a long time and is difficult to cover large-area complex curved surfaces. Second, the accuracy is limited. Manual detection is easily affected by subjective factors, and it is difficult to accurately locate hidden parts such as deep grooves and tooth tips. Third, the dynamic adaptability is poor. The existing system is difficult to track the relative pose changes between the workpiece and the measuring device in real time, resulting in large errors in the fusion of multi-position measurement data. Fourth, the safety hazard is very large. Repeated hoisting of large workpieces such as rotors has a very large safety hazard. There are safety hazards such as stepping into the air when personnel work inside. Fifth, the probability of foreign objects falling is high. It is extremely easy for measuring instruments on the cylinder surface and inside to fall for the inspectors. Therefore, it is necessary to further research and improve the measurement system and method for grooved cylinders such as rotors or central shafts. Summary of the Invention

[0003] One of the purposes of the present invention is to solve the deficiencies, and provide a high-precision measurement system and method for the radius of a grooved cylinder body, in order to solve the technical problems such as low measurement efficiency, limited accuracy, and poor dynamic adaptability in the existing technology.

[0004] To solve the above technical problems, the present invention adopts the following technical solutions: On the one hand, the present invention provides a high-precision measurement system for the radius of a grooved cylinder body. The measurement system includes a lidar and a laser tracker. The lidar is installed on a support, and the support is installed on a slide rail. The slide rail is used to axially penetrate the grooved cylinder body along the axial direction of the grooved cylinder body; a target ball assembly is also installed on the support; the target ball assembly is used to reciprocate linearly on the slide rail synchronously with the lidar; the laser tracker is placed at one end of the slide rail, and the tracking direction of the laser tracker is used to correspond to the target ball assembly; wherein: the lidar is used to move along the slide rail and perform non-contact scanning measurement along the radial direction of the grooved cylinder body to obtain the three-dimensional point cloud data of the grooved cylinder body; the laser tracker is used to measure the positions of each target ball in the target ball assembly, and then obtain the 6D pose of the lidar, and make the three-dimensional coordinates of the laser tracker and the lidar unified through target ball calibration; the support is used to cooperate with the laser tracker to drive the lidar and the target ball assembly to move synchronously to a preset measurement position.

[0005] Preferably, a further technical solution is that the target ball assembly has three target balls, and the three target balls are based on the rotation central axis of the lidar, and the angle between each other is 120 degrees; the rotation central axis of the lidar is near or coincides with the central axis of the groove cylinder.

[0006] A further technical solution is that the measurement system further includes a measurement data unit, and the measurement data unit includes: a measurement network adjustment module for eliminating the cumulative error between the coordinates of the lidar and the coordinates of the laser tracker according to the calibration of the target ball position by the laser tracker; a coordinate fusion module for dynamically aligning the three-dimensional point cloud data obtained by the lidar with the workpiece coordinate system obtained by the laser tracker through the target ball position; a motion control module for driving the support to drive the lidar and the target ball assembly to move to a preset measurement position; a point cloud processing module for calculating the geometric relationship between the measured part of the groove cylinder and the central axis in the three-dimensional point cloud data.

[0007] A further technical solution is that the way the point cloud processing module calculates the geometric relationship between the measured part of the groove cylinder and the central axis is as follows: based on a preset scanning path, the annular tooth surface of the inner wall of the groove cylinder is divided into multiple small arc segments of equal length, and each small arc segment contains a complete tooth profile feature; three axial scanning lines are intercepted at the starting end, the middle position, and the ending end of each small arc segment respectively; the least squares method is used to fit the scanning line through the point cloud into a point; the coordinate system of the groove cylinder is defined as a cylindrical coordinate system, and then the radius values ρ_i of the starting point, the midpoint, and the ending point of each small arc segment are recorded respectively, and a radius change function of the following formula is generated; ρ(θ)=aθ²+bθ+c In the formula, ρ is the radius value, θ is the azimuth angle, a is the quadratic term coefficient of θ, b is the linear term coefficient of θ, and c is the constant term; then a statistical chart including the radius range Δρ_max and the roundness deviation δ is output; the radius range Δρ_max is calculated by the following formula: Δρ_max=max(ρ_i)-min(ρ_i) The roundness deviation δ is calculated by the following formula: δ=|ρ_avg-ρ_design| In the formula, ρ_avg is the average radius of each small arc segment, and ρ_design is the designed radius of each small arc segment.

[0008] A further technical solution is that the measurement data unit further includes a damage analysis module for calibrating the damaged position of the inner wall of the groove cylinder through the statistical chart of the radius range Δρ_max and the roundness deviation δ, and generating a digital report on the damage of the groove cylinder in combination with the corresponding camera photos.

[0009] On the other hand, the present invention provides a method for accurately measuring the radius of a grooved cylinder, characterized in that the method comprises the following steps: Step A: The support drives the lidar and the target ball assembly to move linearly on the slide rail synchronously, and the slide rail penetrates the grooved cylinder along the axial direction of the grooved cylinder; the motion control module drives the support to drive the lidar and the target ball assembly to move to a preset measurement position.

[0010] Step B: The lidar and the target ball assembly move along the slide rail, and the lidar performs non-contact scanning measurement along the radial direction of the grooved cylinder to obtain the three-dimensional point cloud data of the grooved cylinder; the coordinate fusion module dynamically aligns the three-dimensional point cloud data obtained by the lidar with the workpiece coordinate system obtained by the laser tracker through the target ball position.

[0011] Step C: The laser tracker measures the positions of the target balls in the target ball assembly, and then obtains the 6D pose of the lidar, and makes the three-dimensional coordinates of the laser tracker and the lidar unified through target ball calibration; the measurement network adjustment module eliminates the cumulative error between the coordinates of the lidar and the laser tracker according to the calibration of the target ball position by the laser tracker.

[0012] Step D: The point cloud processing module calculates the geometric relationship between the measured part of the grooved cylinder and the central axis in the three-dimensional point cloud data.

[0013] Preferably, a further technical solution is that the way for the point cloud processing module to calculate the geometric relationship between the measured part of the grooved cylinder and the central axis is: Based on a preset scanning path, the annular tooth surface of the inner wall of the grooved cylinder is divided into multiple equal-length small arc segments, and each small arc segment contains complete tooth shape features.

[0014] At the starting end, the middle position and the ending end of each small arc segment, three axial scanning lines are respectively intercepted.

[0015] The least squares method is used to fit the scanning line through the point cloud into points.

[0016] The coordinate system of the grooved cylinder is defined as a cylindrical coordinate system, and then the radius values ρ_i of the starting point, the midpoint and the ending point of each small arc segment are respectively recorded, and a radius change function of the following formula is generated: ρ(θ)=aθ²+bθ+c In the formula, ρ is the radius value, θ is the azimuth angle, a is the quadratic term coefficient of θ, b is the linear term coefficient of θ, and c is the constant term.

[0017] Then a statistical chart including the radius range Δρ_max and the roundness deviation δ is output.

[0018] The radius range Δρ_max is calculated by the following formula: Δρ_max = max(ρ_i) - min(ρ_i) The roundness deviation δ is calculated by the following formula: δ = |ρ_avg - ρ_design| Where ρ_avg is the average radius of each small arc segment, and ρ_design is the designed radius of each small arc segment.

[0019] A further technical solution is that the damage analysis module calibrates the damaged position on the inner wall of the groove cylinder through the statistical chart of the radius range Δρ_max and the roundness deviation δ, and combines the corresponding camera photos to generate a digital report on the damage of the groove cylinder.

[0020] Compared with the prior art, one of the beneficial effects of the present invention is that through the synchronous movement of the lidar and the target ball assembly along the radial direction of the groove cylinder on the slide rail, the lidar can continuously measure and scan from the radial direction to obtain the three-dimensional point cloud data of the groove cylinder, and the laser tracker obtains the 6D pose of the lidar through the target ball assembly that moves synchronously with the lidar for compensation measurement. This not only significantly improves the accuracy of the radius measurement of the groove cylinder, but also greatly shortens the measurement time through fully automated measurement. In addition, the measurement system of the present invention can be extended to terminal actuators such as grinding and spraying of groove cylinder workpieces to realize the closed-loop operation of measurement and repair. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the system measurement for illustrating an embodiment of the present invention.

[0022] Figure 2 It is Figure 1 The enlarged view of part A of

[0023] In the figure, 1 is the groove cylinder, 2 is the slide rail, 3 is the support, 4 is the lidar, 5 is the laser tracker, 6 is the target ball assembly, and 61 is the target ball. Detailed Embodiments

[0024] The following further elaborates the present invention in conjunction with the drawings.

[0025] The high-precision measurement system for the radius of the groove cylinder of the present invention includes a hardware part and a software part. The system mainly has the following characteristics: Multi-sensor dynamic collaboration: Through the real-time feedback of the 6D pose of the radar by the laser tracker and the combination of the target ball 61 calibration technology, the dynamic unification of coordinates during the mobile measurement is realized, and an independent error adjustment module eliminates the cumulative error caused by the displacement of the equipment.

[0026] Fully automated measurement process: Integrating G-code control, path planning, and data analysis, reducing manual intervention and improving the measurement efficiency of complex curved surfaces by more than 50%.

[0027] Intelligent damage analysis: Based on the fitting of the reference axis from point cloud data, quantify the depth and position of surface damage, providing direct input for subsequent processing (grinding, inkjet printing, laser marking).

[0028] Ultra-thin tooth surface data fitting algorithm: The purpose is to calculate the radius. The result is denoised. The data of the tooth surface is intercepted transversely along the axial length and the radius / diameter. It is intelligently adapted (1. For tooth tips from 0.15 to 0.1 mm, the radar can scan a lot of data, forming a parabola between the teeth. Process the parabola, intercept a part of the data on both sides, and do not take the data in the middle, and take the average of a small surface to obtain a super-high-definition result; 2. Obtain a circular curve. According to the calculated length and combined with error analysis, the length of a tooth can be obtained. Determine how much length represents the radius / diameter, intelligent radius algorithm). Such as Figure 1 And Figure 2 As shown, based on the above characteristics, the system hardware part of an embodiment of the present invention includes a lidar 4, a laser tracker 5, an axial motion module and a target ball assembly 6.

[0029] The above-mentioned lidar 4 is used for high-speed non-contact scanning to obtain three-dimensional point cloud data of the surface of the grooved cylinder (groove surface, tooth tip surface, base circle, etc.). It is installed on the support 3, and the support 3 is installed on the slide rail 2. The slide rail 2 is used to penetrate the grooved cylinder 1 along the axial direction of the grooved cylinder 1. And the above-mentioned target ball assembly 6 is also installed on the support 3. The target ball assembly 6 is used to reciprocate linearly on the slide rail 2 synchronously with the lidar 4. That is, the axial motion module controls the support 3 to reciprocate linearly on the slide rail 2, and further makes the lidar 4 and the target ball assembly 6 on the support 3 reciprocate linearly on the slide rail 2 synchronously.

[0030] The above-mentioned laser tracker 5 is used to measure the positions of the respective target balls 61 in the target ball assembly 6, thereby obtaining the 6D pose of the lidar, and calibrating through the target ball 61 to make the three-dimensional coordinates of the laser tracker 5 and the lidar 4 unified. And the support 3 drives the lidar 4 and the target ball assembly 6 to move to a preset position on the slide rail 2. Specifically, the above-mentioned axial motion module drives the support 3 to move on the slide rail 2 by parsing the G-code instruction according to the preset path and distance.

[0031] In this embodiment, preferably, just as Figure 2As shown, the above-mentioned target ball assembly 6 has three target balls 61, and the three target balls 61 are based on the rotation axis of the lidar 4, and the angles between them are 120 degrees; the rotation axis of the lidar 4 is the same as the extension direction of the axis of the groove cylinder 1, and it is best to adjust the two to coincide with each other, or to make the two in an approximately coincident state. The three target balls 61 are all fixed on the base of the lidar 4, so that the laser tracker 5 can provide real-time pose feedback and align the initial coordinate systems of the groove cylinder workpiece and the ground target ball seat.

[0032] The above-mentioned lidar scanning paths (such as spiral lines, axial layering) and the G-code execution logic are as follows: The position to be measured is obtained from the workpiece coordinate system of the groove cylinder, and the lidar 4 is driven to the position to be measured by a programmable motor. The lidar 4 rotates one week on the support 3 to complete the scanning of the specified path and obtain the point cloud data of the measured parts of the groove cylinder workpiece (i.e., the partition base surface, shroud, gland teeth, etc.).

[0033] The software part of the system in this embodiment includes a measurement network adjustment module, a coordinate fusion module, a motion control module, and a point cloud processing module.

[0034] The above-mentioned measurement network adjustment module is used to eliminate the cumulative error between the coordinates of the lidar and the laser tracker according to the calibration of the position of the target ball 61 by the laser tracker.

[0035] The above-mentioned coordinate fusion module is used to dynamically align the three-dimensional point cloud data obtained by the lidar with the workpiece coordinate system obtained by the laser tracker through the position of the target ball 61.

[0036] The above-mentioned motion control module is used to drive the support to drive the lidar and the target ball assembly 6 to move to the preset measurement position.

[0037] The above-mentioned point cloud processing module is used to calculate the geometric relationship between the measured part of the groove cylinder and the central axis in the three-dimensional point cloud data.

[0038] Specifically, the way for the point cloud processing module to calculate the geometric relationship between the measured part of the groove cylinder and the central axis, that is, the above-mentioned ultra-thin tooth surface data fitting algorithm. This algorithm realizes the accurate calculation of the inner tooth surface radius of the workpiece through the analysis of three-dimensional point cloud data, and it is realized as follows: The whole circle tooth surface is segmented. Based on the preset scanning path, the annular tooth surface on the inner wall of the groove cylinder is divided into multiple equal-length small arc segments, and each small arc segment contains complete tooth profile features; the segmentation parameter satisfies: θ_segment = 360° / N (N is generally 4 or 8).

[0039] Feature region data interception. Define the feature extraction region as 60% of the tooth surface width, symmetrically distributed along the center of the tooth surface. Three axial scan lines are intercepted at the starting end, middle position, and ending end of each arc surface respectively.

[0040] Multi-order data fitting. Use the least squares method to fit the scan line through the point cloud into points, and simultaneously execute: a) Validity verification: Calculate the fitting residual RMS value, and set the threshold ε ≤ 0.05 mm. The aforementioned RMS value is the root mean square value (Root Mean Square).

[0041] b) Outlier rejection: Establish a sliding window filter, and the window size W = 5%L (L is the length of the scan line).

[0042] Cylindrical coordinate radius calculation. Define the coordinate system of the groove cylinder as a cylindrical coordinate system, and then record the radius values ρ_i of the starting point, midpoint, and ending point of each small arc segment respectively, and generate the radius change function of formula (1).

[0043] Full-circle analysis graph generation. Output a statistical graph including the radius range Δρ_max and the roundness deviation δ; the aforementioned radius range Δρ_max is calculated by formula (2): ρ(θ)=aθ² + bθ + c (1) Δρ_max = max(ρ_i) - min(ρ_i) (2) The above roundness deviation δ is calculated by formula (3): δ = |ρ_avg - ρ_design| (3) In the above formula (1), ρ is the radius value, θ is the azimuth angle, a is the quadratic coefficient of θ, b is the linear coefficient of θ, and c is the constant term; in formula (3), ρ_avg is the average radius of each small arc segment, and ρ_design is the designed radius of each small arc segment.

[0044] Specifically, when recording the radius values ρ_i of the starting point, midpoint, and ending point of each small arc segment above, define the coordinate system of the cylinder as a cylindrical coordinate system, where the points in the cylindrical coordinate system are represented as (ρ, φ, z), where ρ is the radial distance from the point to the central axis of the cylinder, φ is the azimuth angle, and z is the axial distance of the cylinder.

[0045] Preferably here, in the software part of this embodiment, there is also a damage analysis module, which is used to calibrate the damaged position of the inner wall of the groove cylinder through the statistical graph of the radius range Δρ_max and the roundness deviation δ, and combine the corresponding camera photos to generate a digital report on the damage of the groove cylinder.

[0046] Furthermore, for the spliced tooth spaces, an ultra-high-resolution camera can be used to identify the tooth profile, mark red dots at the damaged areas, and photos are also provided on the subsequently generated model. New measurement areas can be added according to the measurement trend. Using real-time feedback to assist in assembly debugging and processing, it has good data real-time performance and can make quick responses.

[0047] Meanwhile, in the system of this embodiment, lidar scan path adaptive control can also be utilized to plan and correct the path in real time. Specifically, the dynamic optimization of the scan path is achieved through real-time pose compensation. The specific implementation process is as follows: Real-time acquisition of 6D pose. Establish a target ball group measurement model, use 3 non-coplanar target balls 61 to form a measurement array, obtain position data (P1 - P3) through a laser tracker, and solve the pose matrix of the lidar body.

[0048] Error compensation mechanism, construct a mechanical deformation compensation system.

[0049] Dynamic transformation of coordinate systems, develop a dedicated coordinate transformation algorithm library to realize the conversion of path planning data formats (.path →.cyl); Parametric representation of space curves, represent the scan path as: R(θ)={ρ(θ),z(θ),α(θ)} Pose compensation calculation, that is, establish a transformation matrix chain.

[0050] In this embodiment, the lidar and the target ball assembly 6 move synchronously along the radial direction of the groove cylinder on the slide rail 2, enabling the lidar to continuously measure and scan radially to obtain the three-dimensional point cloud data of each part of the groove cylinder. And the laser tracker obtains the 6D pose of the lidar through the target ball assembly 6 that moves synchronously with the lidar for compensation measurement. This not only significantly improves the measurement accuracy of the radius of the groove cylinder, but also can greatly shorten the measurement time through fully automated measurement. The measurement system of the present invention can also be extended to end effectors such as grinding and spraying of groove cylinder workpieces to realize the closed-loop operation of measurement and repair.

[0051] In a preferred embodiment test by the inventor, it can be known that the present invention has the following technical effects: Precision improvement: 6D pose compensation makes the measurement accuracy reach ±0.02 mm, suitable for high-precision manufacturing scenarios. Efficiency optimization: The fully automated process shortens the single measurement time to 30% of the traditional method. Strong scalability: The system can be adapted to end effectors such as grinding and inkjet to realize the closed-loop of "measurement - repair".

[0052] As mentioned in the above method, in actual use, the system of the above embodiment executes the following process.

[0053] 1. System initialization Fix the target ball assembly 6 on the ground or the slide rail 2 along the axial direction of the workpiece, measure its spatial coordinates using a laser tracker, complete the alignment of the initial coordinate systems of the laser tracker and the radar, and simultaneously complete the coordinate adjustment.

[0054] Scan the reference base surface (such as the end face or flange face) of the grooved cylinder workpiece through the lidar to establish a workpiece coordinate system with the central axis as the reference.

[0055] 2. Dynamic pose tracking The axial module moves the radar to the target position according to the G-code instruction, and the tracker collects the 6D pose data of the target ball 61 at the radar base in real time to update the transformation matrix between the radar coordinate system and the workpiece coordinate system.

[0056] 3. Data acquisition and processing The lidar scans the surface of the workpiece along the preset path to obtain high-density point cloud data.

[0057] The software automatically removes noise points, fits feature curves such as grooves and tooth tips, and calculates their radial deviations from the central axis.

[0058] 4. Result output Generate a digital report containing a color map, an error table, and processing marks, which can be directly imported into a numerical control machine tool or a robot to perform repair operations.

[0059] Another embodiment of the present invention is a method for high-precision measurement of the radius of a grooved cylinder, and this method includes the following steps.

[0060] S1. The support drives the lidar and the target ball assembly 6 to move linearly on the slide rail 2 synchronously, and the slide rail 2 penetrates the grooved cylinder along the axial direction of the grooved cylinder. The motion control module drives the support to drive the lidar and the target ball assembly 6 to move to the preset measurement position.

[0061] S2. The lidar and the target ball assembly 6 move along the slide rail 2, and the lidar performs non-contact scanning measurement along the radial direction of the grooved cylinder to obtain the three-dimensional point cloud data of the grooved cylinder. The coordinate fusion module dynamically aligns the three-dimensional point cloud data obtained by the lidar with the workpiece coordinate system obtained by the laser tracker through the position of the target ball 61.

[0062] S3. The laser tracker measures the positions of the target balls 61 in the target ball assembly 6, thereby obtaining the 6D pose of the lidar, and making the three-dimensional coordinates of the laser tracker and the lidar unified through the calibration of the target ball 61. The measurement network adjustment module eliminates the cumulative error between the coordinates of the lidar and the laser tracker according to the calibration of the position of the target ball 61 by the laser tracker.

[0063] S4. The point cloud processing module calculates the geometric relationship between the measured part of the groove cylinder body and the central axis in the three-dimensional point cloud data. In this step, preferably, the method by which the point cloud processing module calculates the geometric relationship between the measured part of the groove cylinder body and the central axis is as follows: S41. Based on a preset scanning path, the annular tooth surface of the inner wall of the groove cylinder body is divided into multiple small arc segments of equal length, and each small arc segment contains a complete tooth profile feature.

[0064] S42. Three axial scanning lines are intercepted at the starting end, middle position, and ending end of each small arc segment respectively.

[0065] S43. The least squares method is used to fit the points passed by the scanning lines into points through the point cloud.

[0066] S44. The coordinate system of the groove cylinder body is defined as a cylindrical coordinate system, and then the radius values ρ_i of the starting point, midpoint, and ending point of each small arc segment are recorded respectively, and a radius change function of the following formula is generated.

[0067] ρ(θ)=aθ² + bθ + c In the formula, ρ is the radius value, θ is the azimuth angle, a is the quadratic coefficient of θ, b is the linear coefficient of θ, and c is the constant term.

[0068] S45. Output a statistical chart including the radius range Δρ_max and the roundness deviation δ; where the radius range Δρ_max is calculated through the following formula: Δρ_max = max(ρ_i) - min(ρ_i) The roundness deviation δ is calculated through the following formula: δ = |ρ_avg - ρ_design| In the formula, ρ_avg is the average radius of each small arc segment, and ρ_design is the designed radius of each small arc segment.

[0069] Furthermore, the method of this embodiment further includes: Step S5. The damage analysis module calibrates the damaged position of the inner wall of the groove cylinder body through the statistical chart of the radius range Δρ_max and the roundness deviation δ, and combines the corresponding camera photos to generate a digital report on the damage of the groove cylinder body.

[0070] It should be noted that the lidar, laser tracker, axial motion module, target ball assembly 6, etc. used in the above embodiments of the present invention are all commercially available laser measurement instruments. The present invention only uses their inherent functions and does not improve their own structures. Therefore, the structures and principles of the foregoing system components will not be described in detail, which will not affect those skilled in the art from achieving the same or similar technical effects as the present invention through the existing technical solutions of the present invention.

[0071] In addition to the above, it should also be noted that the "one embodiment", "another embodiment", "embodiment" and the like mentioned in this specification refer to the specific features, structures or characteristics described in connection with that embodiment being included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in connection with any embodiment, it is intended that the implementation of such feature, structure or characteristic in combination with other embodiments also fall within the scope of the present invention.

[0072] Although the present invention has been described herein with reference to various illustrative embodiments of the invention, it should be understood that those skilled in the art can devise many other modifications and embodiments that will fall within the scope of the principles of this application as disclosed. More specifically, within the scope of the present application as disclosed, the drawings and the claims, various variations and improvements can be made to the components and / or layout of the subject combination layout. In addition to the variations and improvements made to the components and / or layout, other uses will also be apparent to those skilled in the art.

Claims

1. A high-precision measurement system for groove cylinder radius, characterized in that The measuring system comprises a laser radar and a laser tracker, wherein the laser radar is mounted on a support, and the support is mounted on a slide rail, and the slide rail is used to penetrate the groove cylinder along the axial direction of the groove cylinder; A target ball assembly is also mounted on the support; the target ball assembly is used to reciprocate linearly on the slide rail synchronously with the laser radar; The laser tracker is placed on one end of the slide rail, and the tracking direction of the laser tracker is used to correspond to the target ball assembly; in: The laser radar is used to move along the slide rail and perform non-contact scanning measurement along the radial direction of the groove cylinder to obtain three-dimensional point cloud data of the groove cylinder; The laser tracker is used to measure the position of each target ball in the target ball assembly, thereby obtaining the 6D position and posture of the laser radar, and the three-dimensional coordinates of the laser tracker and the laser radar are kept consistent through target ball calibration; The support is used to cooperate with the laser tracker to drive the laser radar and the target ball assembly to move synchronously to a preset measurement position.

2. The high-precision measurement system for groove cylinder radius according to claim 1 is characterized in that: The target ball assembly has three target balls, and the three target balls use the rotation center axis of the laser radar as a reference line, and the angle between them is 120 degrees; the rotation center axis of the laser radar is close to or coincides with the center axis of the groove cylinder.

3. The high-precision measurement system for groove cylinder radius according to claim 1 is characterized in that: The measurement system further comprises a measurement data unit, wherein the measurement data unit comprises: The measurement network adjustment module is used to eliminate the cumulative error between the coordinates of the laser radar and the coordinates of the laser tracker according to the calibration of the target sphere position by the laser tracker; The coordinate fusion module is used to dynamically align the three-dimensional point cloud data obtained by the laser radar with the workpiece coordinate system obtained by the laser tracker through the target ball position; The motion control module is used to drive the support to move the laser radar and target ball assembly to a preset measurement position; The point cloud processing module is used to calculate the geometric relationship between the measured part of the groove cylinder and the central axis in the three-dimensional point cloud data.

4. The high-precision measurement system for groove cylinder radius according to claim 3 is characterized in that The point cloud processing module calculates the geometric relationship between the measured part of the groove cylinder and the central axis in the following way: Based on a preset scanning path, the annular tooth surface of the inner wall of the groove cylinder is divided into a plurality of small arc segments of equal length, and each small arc segment contains a complete tooth shape feature; Three axial scanning lines are intercepted at the starting end, middle position and end of each small arc segment; The scan lines are fitted into points through the point cloud using the least squares method; The coordinate system of the groove cylinder is defined as a cylindrical coordinate system, and then the radius values ​​ρ_i of the starting point, midpoint and end point of each small arc segment are recorded respectively, and the radius variation function of the following formula is generated; ρ(θ)=aθ²+bθ+c In the formula, ρ is the radius value, θ is the azimuth angle, a is the quadratic term coefficient of θ, b is the linear term coefficient of θ, and c is the constant term; Then output a statistical chart containing the radius range Δρ_max and the roundness deviation δ; The radius range Δρ_max is calculated by the following formula: Δρ_max=max(ρ_i)-min(ρ_i) The roundness deviation δ is calculated by the following formula: δ=|ρ_avg-ρ_design| Where ρ_avg is the average radius of each small arc segment, and ρ_design is the design value of the radius of each small arc segment.

5. The high-precision measurement system for groove cylinder radius according to claim 4 is characterized in that: The measurement data unit also includes a damage analysis module, which is used to calibrate the damage position of the inner wall of the groove cylinder through a statistical diagram of the radius range Δρ_max and the roundness deviation δ, and generate a digital report on the damage of the groove cylinder in combination with the corresponding camera photos.

6. A high-precision measurement method for groove cylinder radius, characterized in that The method comprises the following steps: The support drives the laser radar and the target ball assembly to move linearly on the slide rail synchronously, and the slide rail penetrates the groove cylinder along the axial direction of the groove cylinder; The motion control module drives the support to move the laser radar and the target ball assembly to a preset measurement position; The laser radar and the target ball assembly move along the slide rail, and the laser radar performs non-contact scanning measurement along the radial direction of the groove cylinder to obtain three-dimensional point cloud data of the groove cylinder; The coordinate fusion module dynamically aligns the three-dimensional point cloud data acquired by the laser radar with the workpiece coordinate system acquired by the laser tracker through the target sphere position; The laser tracker measures the position of each target ball in the target ball assembly, and then obtains the 6D pose of the laser radar. The target ball is calibrated to keep the three-dimensional coordinates of the laser tracker and the laser radar consistent. The measurement network adjustment module eliminates the cumulative error between the laser radar and laser tracker coordinates according to the calibration of the target sphere position by the laser tracker; The point cloud processing module calculates the geometric relationship between the measured part of the groove cylinder and the central axis in the three-dimensional point cloud data.

7. The high-precision measurement method for groove cylinder radius according to claim 6 is characterized in that The point cloud processing module calculates the geometric relationship between the measured part of the groove cylinder and the central axis in the following way: Based on a preset scanning path, the annular tooth surface of the inner wall of the groove cylinder is divided into a plurality of small arc segments of equal length, and each small arc segment contains a complete tooth shape feature; Three axial scanning lines are intercepted at the starting end, middle position and end of each small arc segment; The scan lines are fitted into points through the point cloud using the least squares method; The coordinate system of the groove cylinder is defined as a cylindrical coordinate system, and then the radius values ​​ρ_i of the starting point, midpoint and end point of each small arc segment are recorded respectively, and the radius variation function of the following formula is generated; ρ(θ)=aθ²+bθ+c In the formula, ρ is the radius value, θ is the azimuth angle, a is the quadratic term coefficient of θ, b is the linear term coefficient of θ, and c is the constant term; Then output a statistical chart containing the radius range Δρ_max and the roundness deviation δ; The radius range Δρ_max is calculated by the following formula: Δρ_max=max(ρ_i)-min(ρ_i) The roundness deviation δ is calculated by the following formula: δ=|ρ_avg-ρ_design| Where ρ_avg is the average radius of each small arc segment, and ρ_design is the design value of the radius of each small arc segment.

8. The high-precision measurement method for groove cylinder radius according to claim 7 is characterized in that The method further includes: the damage analysis module calibrates the damaged position of the inner wall of the groove cylinder through the statistical diagram of the radius range Δρ_max and the roundness deviation δ, and generates a digital report on the groove cylinder damage in combination with the corresponding camera photos.

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