A workpiece measurement point sampling offline planning method and system

Abstract

The present invention provides a method and system for off-line planning of workpiece measurement point sampling, the method comprising: obtaining a plurality of contour intersection lines by discretizing a part model; constructing a plurality of contour intersection lines by fitting based on a fitting reconstruction algorithm to obtain a mathematical model of the intersection lines; extracting arc lengths of adjacent feature points in the same contour intersection line based on the mathematical model of the intersection lines, and judging whether the arc lengths and a preset arc length threshold meet preset conditions; if not, supplementing feature points of the intervals of adjacent feature points based on a dichotomy method to obtain a final morphological feature point set of a plurality of contour intersection lines; converting the position information of the data points in the final morphological feature point set in the measurement plane into a sensor electrical signal sampling signal, and triggering adaptive sampling according to a discrete pre-planned sampling signal. The present invention can obtain the morphology of irregular parts, and trigger adaptive sampling according to a discrete pre-planned sampling signal, thereby achieving rapid and accurate batch quality detection of parts by a pre-planned adaptive sampling strategy.

Description

Technical Field

[0001] The present invention relates to the technical field of measuring point sampling, and in particular to an offline planning method and system for workpiece measuring point sampling. Background Art

[0002] In modern manufacturing, effective evaluation of parts processing quality is a strong guarantee for subsequent product remanufacturing and assembly reliability. For large and complex surface detection, traditional contact methods (such as three-coordinate detection equipment) are limited by geometric features such as sudden changes in curvature, which makes it difficult to improve sampling efficiency. Therefore, current engineering applications mostly use "point laser displacement sensor + two-dimensional precision moving mechanism" to construct non-contact detection methods. Among them, the rationality of measurement point sampling planning is the key to achieving the coordinated improvement of accuracy and efficiency. Too dense sampling points will inevitably consume more data preprocessing time, and too few sampling points will not meet the new requirements of high-precision detection.

[0003] Among the existing technologies, the commonly used sampling planning methods include: equal interval, equal arc length, equal chord height, and adaptive methods based on a single shape feature (curvature or normal vector distribution). Among them, the implementation process of the first three is based only on pre-set threshold parameters, without considering the geometric shape characteristics of the parts, and therefore they are mostly used in scenes with relatively simple morphological structures of the workpieces to be measured. Adaptive adjustment of sampling density based on shape features is widely used in free-form surface sampling because it reasonably utilizes the topological structure of the surface to be measured to adjust the number and distribution of sampling points. However, for complex and changeable curved surface parts, single feature constraints are often not applicable. Summary of the invention

[0004] Based on this, an object of the present invention is to provide a method and system for off-line planning of workpiece measurement point sampling, so as to at least solve the above-mentioned deficiencies in the prior art.

[0005] In a first aspect, the present invention provides a workpiece measurement point sampling offline planning method, the method comprising:

[0006] Discretize the part model to obtain several contour intersection lines;

[0007] Based on the fitting reconstruction algorithm, a plurality of the contour intersection lines are fitted and constructed to obtain a mathematical model of the intersection lines;

[0008] Extracting arc lengths of adjacent feature points in the same contour intersection line based on the intersection line mathematical model, and determining whether the arc length and a preset arc length threshold satisfy a preset condition;

[0009] If not, then adding feature points to the intervals adjacent to the feature points based on the binary method until the arc length and the preset arc length threshold meet the preset condition, so as to obtain a final morphological feature point set of the plurality of contour intersection lines;

[0010] The position information of the data points in the final morphological feature point set in the measurement plane is converted into a sensor electrical signal sampling signal, and the adaptive sampling is triggered according to the discrete pre-planned sampling signal.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: a mathematical model of the intersection line is obtained by fitting a number of contour intersection lines, and the arc lengths of adjacent feature points on the contour intersection lines are extracted. By supplementing the intervals of adjacent feature points, a final set of morphological feature points can be obtained, thereby obtaining the morphology of irregular parts. By converting the position information of the data points in the final morphological feature point set into a sensor electrical signal sampling signal, and triggering adaptive sampling according to discrete pre-planned sampling signals, the pre-planned adaptive sampling strategy can achieve rapid and accurate batch detection of part quality.

[0012] Furthermore, the step of obtaining a plurality of contour intersection lines by discretizing the part model comprises:

[0013] Obtain the STL model of the complex surface part to be tested;

[0014] Discretizing the STL model into a series of mutually parallel contour intersection lines according to the decomposition order from surface to curve to point, so as to obtain a theoretical discrete point cloud of the complex surface part to be measured;

[0015] The single cross section of the complex curved surface part to be measured is segmented on the measuring plane based on the preset discrete density, and the theoretical discrete point cloud is made to meet the preset judgment condition on the measuring plane for the single cross section, so as to obtain the contour discrete point cloud of the single cross section.

[0016] Furthermore, the expression of the contour intersection line is:

[0017] ;

[0018] In the formula, represents the contour intersection line, express Axis coordinate components, express Axis coordinate components, Indicates the number of cross sections, Indicates The first contour intersection line discrete points, Represents the total number of discrete points on the corresponding contour intersection line.

[0019] Furthermore, after the step of obtaining the mathematical model of the intersection line, the method includes:

[0020] Extracting differential information of the cross section of the part model based on the intersection line mathematical model to search for extreme curvature points and zero-crossing points of the cross section of the part model;

[0021] The curvature extreme point and the zero-crossing point are recorded on the position information to obtain an initial morphological feature point set.

[0022] Furthermore, the step of extracting arc lengths of adjacent feature points in the same contour intersection line based on the intersection line mathematical model and judging whether the arc length and a preset arc length threshold satisfy a preset condition comprises:

[0023] Calculate the arc lengths of adjacent feature points on the same contour intersection line based on the intersection line mathematical model, and extract the arc lengths of adjacent feature points;

[0024] Determine whether the arc length is greater than the preset arc length threshold.

[0025] Furthermore, before the step of obtaining a final set of morphological feature points of a plurality of contour intersection lines, the method further comprises:

[0026] Based on the bisection method, feature points are supplemented for intervals of other adjacent feature points on the same contour intersection line.

[0027] In a second aspect, the present invention further provides a workpiece measurement point sampling offline planning system, the system comprising:

[0028] Discretization module, used to discretize the part model to obtain several contour intersection lines;

[0029] A fitting module, used for fitting and constructing a plurality of the contour intersection lines based on a fitting reconstruction algorithm to obtain an intersection line mathematical model;

[0030] An extraction module, used for extracting arc lengths of adjacent feature points in the same contour intersection line based on the intersection line mathematical model, and determining whether the arc length and a preset arc length threshold satisfy a preset condition;

[0031] A supplementation module, used for determining that if the arc length and the preset arc length threshold do not satisfy the preset condition, then supplementing feature points of the intervals adjacent to the feature points based on a binary search method until the arc length and the preset arc length threshold satisfy the preset condition, so as to obtain a final morphological feature point set of the plurality of contour intersection lines;

[0032] The conversion module is used to convert the position information of the data points in the final morphological feature point set in the measurement plane into sensor electrical signal sampling signals, and trigger adaptive sampling according to the discrete pre-planned sampling signals.

[0033] Furthermore, the discretization module includes:

[0034] An acquisition unit is used to acquire the STL model of the complex surface part to be tested;

[0035] A discretization unit, used for discretizing the STL model into a series of mutually parallel contour intersection lines according to the decomposition order from surface to curve to point, so as to obtain a theoretical discrete point cloud of the complex surface part to be measured;

[0036] The segmentation unit is used to segment the single section of the complex curved surface part to be measured on the measurement plane based on a preset discrete density, and to make the theoretical discrete point cloud satisfy a preset judgment condition on the measurement plane for the single section, so as to obtain the contour discrete point cloud of the single section.

[0037] Furthermore, the system also includes:

[0038] An extraction and search module, used for extracting differential information of the cross section of the part model based on the intersection line mathematical model, so as to search for the curvature extreme value point and zero-crossing point of the cross section of the part model;

[0039] A recording module is used to record the curvature extreme point and the zero-crossing point on the position information to obtain an initial morphological feature point set.

[0040] Furthermore, the extraction module includes:

[0041] A calculation unit, used for calculating arc lengths of adjacent feature points on the same contour intersection line based on the intersection line mathematical model, and extracting arc lengths of adjacent feature points;

[0042] A judging unit is used to judge whether the arc length is greater than the preset arc length threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a flow chart of the workpiece measurement point sampling offline planning method in the first embodiment of the present invention;

[0044] Figure 2 Schematic diagram of segmentation of the STL model surface in the first embodiment of the present invention;

[0045] Figure 3 Schematic diagram of extracting initial morphological feature points in the first embodiment of the present invention;

[0046] Figure 4 A supplementary schematic diagram of feature points between adjacent feature points in the first embodiment of the present invention;

[0047] Figure 5 It is a structural block diagram of the workpiece measurement point sampling offline planning system in the second embodiment of the present invention.

[0048] Description of main component symbols:

[0049] 10. Discretization module;

[0050] 20. Fitting module;

[0051] 30. Extraction module;

[0052] 40. Supplementary modules;

[0053] 50. Conversion module.

[0054] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0055] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0056] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0058] Embodiment 1

[0059] See also Figure 1 , which shows a workpiece measurement point sampling offline planning method in a first embodiment of the present invention, the method comprises steps S1 to S5:

[0060] S1, discretize the part model to obtain several contour intersection lines;

[0061] Specifically, the step S1 includes steps S11 to S13:

[0062] S11, obtaining an STL model of the complex curved surface part to be tested;

[0063] S12, discretizing the STL model into a series of mutually parallel contour intersection lines according to the decomposition order from surface to curve to point, so as to obtain a theoretical discrete point cloud of the complex surface part to be measured;

[0064] S13, segmenting a single cross section of the complex curved surface part to be measured on a measuring plane based on a preset discrete density, and making the theoretical discrete point cloud satisfy a preset discrimination condition on the measuring plane for the single cross section, so as to obtain a contour discrete point cloud of the single cross section;

[0065] It should be explained that the model of the complex surface part to be tested is an STL model. The three-dimensional model of the part is decomposed by the decomposition order from surface to curve to point. For details, please refer to Figure 2 , which is a schematic diagram of the segmentation of the STL model surface, can obtain a series of mutually parallel contour intersection lines. In this embodiment, the expression of the contour intersection line is:

[0066] ;

[0067] In the formula, represents the contour intersection line, express Axis coordinate components, express Axis coordinate components, Indicates the number of cross sections, Indicates The first contour intersection line discrete points, Represents the total number of discrete points on the corresponding contour intersection line;

[0068] Among them, the discrete points are projected on the XOY plane , obtained by the principle of equal intervals, corresponding to the coordinate components It is calculated using the geometric relationship between the space point and the triangle patch;

[0069] Taking the cross-sectional profile as the processing unit, in the measurement plane, that is, the XOY plane, firstly, the single cross section is divided along the X-axis based on a certain discrete density, and for the single cross section, the expression of the single cross section is: According to the theoretical discrete point cloud, the coordinate component in the X-axis direction meets the discrimination condition, and the expression of the coordinate component in the X-axis direction is In this embodiment, the judgment condition is , It indicates that the preset distance threshold is adjusted to complete the rapid extraction of discrete point cloud of single section contour.

[0070] S2, constructing a plurality of the contour intersection lines by fitting based on a fitting reconstruction algorithm to obtain an intersection line mathematical model;

[0071] It should be explained that each contour intersection line is constructed by fitting through a fitting reconstruction algorithm. In this embodiment, a B-spline interpolation algorithm can be used to fit each contour intersection line, and then a mathematical model of the intersection line is obtained.

[0072] It is worth noting that after obtaining the mathematical model of the intersection line, the method further includes steps S21 and S22:

[0073] S21, extracting differential information of the cross section of the part model based on the intersection line mathematical model to search for extreme curvature points and zero-crossing points of the cross section of the part model;

[0074] S22, recording the curvature extreme point and the zero-crossing point on the position information to obtain an initial morphological feature point set;

[0075] It can be understood that the cross-sectional curvature differential information of the part model is further obtained from the intersection line mathematical model to search for the curvature extreme points and zero-crossing points, and the cross-sectional sharp feature point set is obtained from the curvature extreme points and zero-crossing points. The expression of the cross-sectional sharp feature point set is:

[0076] ( ;

[0077] In the formula, represents the set of sharp feature points of the cross section, represents the characteristic points on the cross section, represents the location of the feature point, Represents the horizontal coordinate of the feature point, Represents the ordinate of the feature point, Represents the total number of initial feature points;

[0078] See also Figure 3 , which is a schematic diagram of extracting initial morphological feature points.

[0079] S3, extracting arc lengths of adjacent feature points in the same contour intersection line based on the intersection line mathematical model, and determining whether the arc length and a preset arc length threshold satisfy a preset condition;

[0080] Specifically, the step S3 includes step S31 to step S32:

[0081] S31, calculating arc lengths of adjacent feature points on the same contour intersection line based on the intersection line mathematical model, and extracting arc lengths of adjacent feature points;

[0082] S32, determining whether the arc length is greater than the preset arc length threshold;

[0083] It is understandable that further Adjacent feature points on the same intersection line , Arc length Extraction is performed and the arc length threshold is compared with the preset Compare.

[0084] S4, if not, then supplement feature points for the intervals adjacent to the feature points based on the binary method until the arc length and the preset arc length threshold meet the preset condition, so as to obtain a final morphological feature point set of the plurality of contour intersection lines;

[0085] It is understandable that if When this judgment condition is met, feature points are added to this interval based on the dichotomy method until , and finally obtain a new set of morphological feature points: ( , );

[0086] In the specific implementation, further calculation The arc length between adjacent feature points on the same section and by comparing with the preset arc length threshold Compare, when the judgment conditions are met: When , based on the dichotomy method, the section line contour model is used to supplement the feature points of the arc length. For details, please refer to Figure 4 , so that the arc length between the characteristic points (including supplementary points) in this arc length satisfies: This judgment condition is then repeated until the feature points of the cross-section contour line are supplemented, and the updated cross-section sharp feature point set is obtained. ;

[0087] In addition, when the arc length is equal to the preset arc length threshold If the preset conditions are met, no additional morphological feature points will be added.

[0088] It is worth noting that the step S4 includes step S41:

[0089] S41, supplementing feature points of intervals of other adjacent feature points on the same contour intersection line based on the dichotomy method;

[0090] It can be understood that by continuing to supplement the feature points of other adjacent feature points on the same contour intersection line, the feature points of the contour intersection line are supplemented, thereby obtaining an updated cross-section sharp feature point set.

[0091] It is also necessary to explain that, since there are several contour intersection lines, the feature points of all contour intersection lines are supplemented by repeatedly extracting other adjacent feature points and supplementing the feature points of the intervals of the adjacent feature points.

[0092] S5, converting the position information of the data points in the final morphological feature point set in the measurement plane into a sensor electrical signal sampling signal, and triggering adaptive sampling according to the discrete pre-planned sampling signal;

[0093] It needs to be explained that the position information of the data points in the final morphological feature point set in the measurement plane is converted into a sensor electrical signal sampling signal, so that the external timer triggers the sensor head to complete adaptive sampling according to the discrete pre-planned sampling signal.

[0094] In summary, the workpiece measurement point sampling offline planning method in the above-mentioned embodiment of the present invention adopts the sampling idea of ​​section planning from surface to curve to point, and first extracts discrete point cloud for the part model by equal interval sampling method through breaking the whole into parts. Then, according to the single-point sampling characteristics of point laser, the single-section discrete point cloud is fitted and reconstructed, and then the single-section morphology contour feature points are extracted by the section model and the geometric characteristics of curvature and arc length, that is, the greater the density (curvature), the smaller the distance between two adjacent points; the smaller the density (curvature), the greater the distance between two adjacent points. In this way, the position information of the morphology feature point on the measurement plane is converted into electrical signal sampling information, and adaptive sampling is achieved by external timing triggering. The present invention combines the measured part morphology features with the technical characteristics of the measuring instrument itself to establish the correlation between the measurement information and the identification features, so as to achieve rapid and accurate batch quality detection of parts by pre-planning adaptive sampling strategies.

[0095] Embodiment 2

[0096] See also Figure 5 , which is a workpiece measurement point sampling offline planning system in a second embodiment of the present invention, and the system comprises:

[0097] A discretization module 10 is used to discretize the part model to obtain a plurality of contour intersection lines;

[0098] The expression of the contour intersection line is:

[0099] ;

[0100] In the formula, represents the contour intersection line, express Axis coordinate components, express Axis coordinate components, Indicates the number of cross sections, Indicates The first contour intersection line discrete points, Represents the total number of discrete points on the corresponding contour intersection line;

[0101] A fitting module 20, for fitting and constructing a plurality of the contour intersection lines based on a fitting reconstruction algorithm to obtain an intersection line mathematical model;

[0102] An extraction module 30, for extracting arc lengths of adjacent feature points in the same contour intersection line based on the intersection line mathematical model, and determining whether the arc length and a preset arc length threshold satisfy a preset condition;

[0103] A supplementation module 40 is used to determine if the arc length and the preset arc length threshold satisfy the preset condition, then supplement feature points of the intervals adjacent to the feature points based on the dichotomy method until the arc length and the preset arc length threshold satisfy the preset condition, so as to obtain a final morphological feature point set of the plurality of contour intersection lines;

[0104] The conversion module 50 is used to convert the position information of the data points in the final morphological feature point set in the measurement plane into sensor electrical signal sampling signals, and trigger adaptive sampling according to the discrete pre-planned sampling signals.

[0105] In some optional embodiments, the discretization module includes:

[0106] An acquisition unit is used to acquire the STL model of the complex surface part to be tested;

[0107] A discretization unit, used for discretizing the STL model into a series of mutually parallel contour intersection lines according to the decomposition order from surface to curve to point, so as to obtain a theoretical discrete point cloud of the complex surface part to be measured;

[0108] The segmentation unit is used to segment the single section of the complex curved surface part to be measured on the measurement plane based on a preset discrete density, and to make the theoretical discrete point cloud satisfy a preset judgment condition on the measurement plane for the single section, so as to obtain the contour discrete point cloud of the single section.

[0109] In some optional embodiments, the system further comprises:

[0110] An extraction and search module, used for extracting differential information of the cross section of the part model based on the intersection line mathematical model, so as to search for the curvature extreme value point and zero-crossing point of the cross section of the part model;

[0111] A recording module is used to record the curvature extreme point and the zero-crossing point on the position information to obtain an initial morphological feature point set.

[0112] In some optional embodiments, the extraction module includes:

[0113] A calculation unit, used for calculating arc lengths of adjacent feature points on the same contour intersection line based on the intersection line mathematical model, and extracting arc lengths of adjacent feature points;

[0114] A judging unit is used to judge whether the arc length is greater than the preset arc length threshold.

[0115] In some optional embodiments, the supplemental module includes:

[0116] The supplementation unit is used to supplement feature points of intervals of other adjacent feature points on the same contour intersection line based on the bisection method.

[0117] The functions or operation steps implemented when the above modules and units are executed are generally the same as those in the above method embodiments, and will not be repeated here.

[0118] The workpiece measurement point sampling offline planning system provided in the embodiment of the present invention has the same implementation principle and technical effects as those of the aforementioned method embodiment. For the sake of brief description, for matters not mentioned in the system embodiment, reference may be made to the corresponding contents in the aforementioned method embodiment.

[0119] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0120] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A workpiece measurement point sampling offline planning method, characterized in that: The method comprises: Discretize the part model to obtain several contour intersection lines; The step of obtaining a plurality of contour intersection lines by discretizing the part model comprises: Obtain the STL model of the complex surface part to be tested; Discretizing the STL model into a series of mutually parallel contour intersection lines according to the decomposition order from surface to curve to point, so as to obtain a theoretical discrete point cloud of the complex surface part to be measured; The single section of the complex curved surface part to be measured is segmented on the measuring plane based on the preset discrete density, and the theoretical discrete point cloud is made to meet the preset discrimination condition on the measuring plane for the single section, so as to obtain the contour discrete point cloud of the single section, wherein the expression of the contour intersection line is: ； In the formula, represents the contour intersection line, express Axis coordinate components, express Axis coordinate components, Indicates the number of cross sections, Indicates The first contour intersection line discrete points, Represents the total number of discrete points on the corresponding contour intersection line; Based on the fitting reconstruction algorithm, a plurality of the contour intersection lines are fitted and constructed to obtain a mathematical model of the intersection lines; Extracting arc lengths of adjacent feature points in the same contour intersection line based on the intersection line mathematical model, and determining whether the arc length and a preset arc length threshold satisfy a preset condition; The step of extracting arc lengths of adjacent feature points in the same contour intersection line based on the intersection line mathematical model and judging whether the arc length and a preset arc length threshold satisfy a preset condition comprises: Calculate the arc lengths of adjacent feature points on the same contour intersection line based on the intersection line mathematical model, and extract the arc lengths of adjacent feature points; Determining whether the arc length is greater than the preset arc length threshold; If not, then adding feature points to the intervals adjacent to the feature points based on the binary method until the arc length and the preset arc length threshold meet the preset condition, so as to obtain a final morphological feature point set of the plurality of contour intersection lines; The position information of the data points in the final morphological feature point set in the measurement plane is converted into a sensor electrical signal sampling signal, and the adaptive sampling is triggered according to the discrete pre-planned sampling signal.

2. The workpiece measurement point sampling offline planning method according to claim 1 is characterized in that: After the step of obtaining the mathematical model of the intersection line, the method comprises: Extracting differential information of the cross section of the part model based on the intersection line mathematical model to search for extreme curvature points and zero-crossing points of the cross section of the part model; The curvature extreme point and the zero-crossing point are recorded on the position information to obtain an initial morphological feature point set.

3. The workpiece measurement point sampling offline planning method according to claim 1 is characterized in that: Before the step of obtaining a final set of morphological feature points of a plurality of contour intersection lines, the method further comprises: Based on the bisection method, feature points are supplemented for intervals of other adjacent feature points on the same contour intersection line.

4. A workpiece measurement point sampling offline planning system, characterized in that: The system comprises: Discretization module, used to discretize the part model to obtain several contour intersection lines; The discretization module comprises: An acquisition unit is used to acquire the STL model of the complex surface part to be tested; A discretization unit, used for discretizing the STL model into a series of mutually parallel contour intersection lines according to the decomposition order from surface to curve to point, so as to obtain a theoretical discrete point cloud of the complex surface part to be measured; The segmentation unit is used to segment the single section of the complex curved surface part to be measured on the measurement plane based on a preset discrete density, and for the single section, the theoretical discrete point cloud satisfies a preset discrimination condition on the measurement plane to obtain the contour discrete point cloud of the single section, wherein the expression of the contour intersection line is: ； In the formula, represents the contour intersection line, express Axis coordinate components, express Axis coordinate components, Indicates the number of cross sections, Indicates The first contour intersection line discrete points, Represents the total number of discrete points on the corresponding contour intersection line; A fitting module, used for fitting and constructing a plurality of the contour intersection lines based on a fitting reconstruction algorithm to obtain an intersection line mathematical model; An extraction module, used for extracting arc lengths of adjacent feature points in the same contour intersection line based on the intersection line mathematical model, and determining whether the arc length and a preset arc length threshold satisfy a preset condition; The extraction module comprises: A calculation unit, used for calculating arc lengths of adjacent feature points on the same contour intersection line based on the intersection line mathematical model, and extracting arc lengths of adjacent feature points; A judging unit, used to judge whether the arc length is greater than the preset arc length threshold; A supplementation module, used for determining that if the arc length and the preset arc length threshold do not satisfy the preset condition, then supplementing feature points of the intervals adjacent to the feature points based on a binary search method until the arc length and the preset arc length threshold satisfy the preset condition, so as to obtain a final morphological feature point set of the plurality of contour intersection lines; The conversion module is used to convert the position information of the data points in the final morphological feature point set in the measurement plane into sensor electrical signal sampling signals, and trigger adaptive sampling according to the discrete pre-planned sampling signals.

5. The workpiece measurement point sampling offline planning system according to claim 4 is characterized in that: The system further comprises: An extraction and search module, used for extracting differential information of the cross section of the part model based on the intersection line mathematical model, so as to search for the curvature extreme value point and zero-crossing point of the cross section of the part model; A recording module is used to record the curvature extreme point and the zero-crossing point on the position information to obtain an initial morphological feature point set.

Images