Method for determining inflection point of contour line of element to be detected

Abstract

The invention discloses a method for determining inflection points of a contour line of a to-be-detected element, and the method comprises the following steps: collecting an image of the to-be-detected element through an industrial camera, and extracting contour points of the to-be-detected element; according to a preset fitting straight line area, all contour point fitting straight lines falling into the fitting straight line area are selected; according to the set searching direction, the distance between each contour point on one side of the fitting straight line area and the fitting straight line is calculated, and the contour point with the first distance larger than a set threshold value is marked as an inflection point. Whether the distances from other contour points to the fitting straight line exceed a set threshold value or not is judged, due to the fact that judgment is conducted through the distance, the bending shape of the edge of the element to be detected has little influence on the judgment result, and the inflection point can be stably determined.

Description

[Technical Field]

[0001] This invention relates to the field of measurement technology, and more specifically, to a method for determining the inflection point of the contour line of an element to be detected. [Background Technology]

[0002] In the industrial field, using industrial cameras to acquire images of components under inspection, followed by obtaining the component's outline and performing dimensional inspection, is a well-established technology. However, the principle for confirming the inflection points (such as the positions of rounded or right-angled corners) of the component under inspection remains unclear. Figure 1 As shown, the sensitivity curve is obtained by calculating the angle between adjacent regions of points on the contour line and then filtering. Whether the sensitivity curve corresponding to a point on the contour line exceeds a set sensitivity threshold is used to determine if it is the desired inflection point. This method is more effective for rigid materials with high edge processing precision (such as machined rigid components). However, when the edge processing precision is low or the material contour lines are irregular, such as solder paste, the above method will lead to a large deviation in the sensitivity curve calculation, making it difficult to determine the inflection point. [Summary of the Invention]

[0003] The purpose of this invention is to provide a method for determining the inflection point of the outline of a component to be detected, so as to solve the problem that it is not easy to determine the inflection point of the outline of materials with low edge processing accuracy or irregular outline in the prior art.

[0004] To achieve the above objectives, the method for determining the inflection point of the outline of the component to be detected according to the present invention includes the following steps:

[0005] Step 1: Use an industrial camera to acquire images of the component to be tested and extract the contour points of the component;

[0006] Step 2: Based on the pre-set fitting line area, select all contour points falling within this fitting line area to fit a straight line.

[0007] Step 3: According to the set search direction, calculate the distance from each contour point on one side of the fitted line area to the fitted line, and mark the first contour point whose distance is greater than the set threshold as an inflection point.

[0008] Based on the above main features, the pre-set fitting line area in step two is pre-set by the user on the vision software according to the shape of the element to be detected.

[0009] To achieve the above objectives, the method for determining the inflection point of the outline of the component to be detected according to the present invention includes the following steps:

[0010] Step 1: Use an industrial camera to acquire images of the component to be tested and extract the contour points of the component;

[0011] Step 2: Based on the preset direction, select a predetermined number of contour points to fit a straight line;

[0012] Step 3: Calculate the distance from each contour point to the fitted line in sequence according to the direction. If it is less than the set threshold, refit the line with the contour point selected in Step 2. Repeat this process until the distance of a contour point exceeds the threshold, then mark it as an inflection point.

[0013] Compared with the prior art, the present invention uses contour points to fit a straight line, and then judges whether the distance of other contour points to the above-mentioned fitted straight line exceeds a set threshold. Because the judgment is made by distance, the bending shape at the edge of the detected element has little impact on the judgment result, and the inflection point can be stably determined. [Attached Image Description]

[0014] Figure 1 This is a schematic diagram of a method for determining the inflection point of a component to be detected in the prior art.

[0015] Figure 2 A schematic diagram illustrating the working principle of the method for determining the inflection point of the outline of the component to be detected according to the present invention.

[0016] Figure 3 This is a flowchart illustrating the first embodiment of the method for determining the inflection point of the outline of the component to be detected according to the present invention.

[0017] Figure 4 This is a flowchart illustrating the second embodiment of the method for determining the inflection point of the outline of the component to be detected according to the present invention.

Detailed Implementation Methods

[0018] Please see Figure 3 The diagram shown is a flowchart illustrating a first embodiment of the method for determining the inflection point of the outline of a component to be detected according to the present invention. The method for determining the inflection point of the outline of a component to be detected according to the present invention includes the following steps:

[0019] Step 1: Use an industrial camera to acquire images of the component to be tested and extract the contour points of the component;

[0020] Step 2: Based on the pre-set fitted line region (e.g., Figure 2 As shown in the figure, select all contour points that fall within this fitted line area to fit a straight line.

[0021] Step 3: According to the set search direction, calculate the distance from each contour point outside the fitted line area to the fitted line, and mark the first contour point whose distance is greater than the set threshold as an inflection point.

[0022] In practice, the pre-set fitting line area in step two is pre-set by the user on the vision software according to the shape of the element to be detected. If a part of the element to be detected is a straight line edge, the position where this straight line edge appears is directly defined as the fitting line area.

[0023] In practice, the search direction in step three is set according to the actual production needs. For example, for a groove in the middle of the edge of the component to be tested, the search directions on both sides of the groove are set relative to each other. For a right-angled edge of the component to be tested, the search direction is only the direction pointing to the right-angled edge.

[0024] Please see Figure 4 The diagram shown is a flowchart illustrating a second embodiment of the method for determining the inflection point of the outline of a component to be detected according to the present invention. The method for determining the inflection point of the outline of a component to be detected according to the present invention includes the following steps:

[0025] Step 1: Use an industrial camera to acquire images of the component to be tested and extract the contour points of the component;

[0026] Step 2: According to the preset direction (e.g.) Figure 2 (From left to right), select a predetermined number of contour points to fit a straight line;

[0027] Step 3: Calculate the distance from each contour point to the fitted line in the direction described above (i.e., judge the contour points other than the predetermined number of contour points one by one in the direction described). If it is less than the set threshold, refit the contour point with the contour points selected in Step 2 as a whole. Repeat this process until the distance of a contour point exceeds the threshold, then mark it as an inflection point.

[0028] In practice, the remaining possible straight line segments can be processed in the two ways described above to obtain all the inflection points, and the user can select the desired inflection point.

[0029] Compared with the prior art, the present invention uses contour points to fit a straight line, and then judges whether the distance of other contour points to the above-mentioned fitted straight line exceeds a set threshold. Because the judgment is made by distance, the bending shape at the edge of the detected element has little impact on the judgment result, the inflection point can be stably determined, and the amount of calculation is small and easy to implement.

[0030] It is understood that those skilled in the art can make equivalent substitutions or modifications to the technical solution and inventive concept of the present invention, and all such substitutions or modifications should fall within the protection scope of the appended claims.

Claims

1. A method for determining the inflection point of the outline of an element to be detected, characterized in that... The method includes the following steps: Step 1: Use an industrial camera to acquire images of the component to be tested and extract the contour points of the component; Step 2: Based on the pre-set fitting line area, select all contour points falling within this fitting line area to fit a straight line. Step 3: According to the set search direction, calculate the distance from each contour point on one side of the fitted line area to the fitted line, and mark the first contour point whose distance is greater than the set threshold as an inflection point.

2. The method for determining the inflection point of the outline of the component to be detected as described in claim 1, characterized in that: The pre-set fitting line area in step two is pre-set by the user on the vision software according to the shape of the element to be detected.

3. A method for determining the inflection point of the outline of a component to be detected, characterized in that... The method includes the following steps: Step 1: Use an industrial camera to acquire images of the component to be tested and extract the contour points of the component; Step 2: Based on the preset direction, select a predetermined number of contour points to fit a straight line; Step 3: Calculate the distance from each contour point to the fitted line in sequence according to the direction. If it is less than the set threshold, refit the line with the contour point selected in Step 2. Repeat this process until the distance of a contour point exceeds the threshold, then mark it as an inflection point.

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