視覺檢測系統中尺寸測量的原理及人工無法比擬的優點
發布時間：
2023-02-10 11:30
在大規模的自動化生產中，傳統的尺寸測量方法已經不能滿足需求，這時候機器視覺檢測系統尺寸測量具有檢測精度高、速度快、成本低、安裝簡單等優點，可以檢測零件的各種尺寸，如長度、圓、角度、線弧等測量。本文將詳細介紹視覺檢測系統技術中尺寸測量的知識介紹。
In the large-scale automatic production, the traditional size measurement method has been unable to meet the needs. At this time, the machine vision inspection system has the advantages of high detection accuracy, fast speed, low cost, simple installation and so on. It can detect various dimensions of parts, such as length, circle, angle, line arc and so on. This paper will introduce the knowledge of dimension measurement in visual inspection system technology in detail.
工件檢測的基本流程圖
Basic flow chart of workpiece inspection
機器視覺尺寸測量應用實例
Application of machine vision dimension measurement
角度測量
Angle measurement
如何進行邊緣檢測
How to detect edge
（1）投影處理
Projection processing
投影處理是相對于檢查方向進行垂直掃描，然后計算各投影線的平均濃度。
Projection processing is to scan vertically relative to the inspection direction, and then calculate the average concentration of each projection line.
投影線平均濃度波形被稱為投影波形。
The average concentration waveform of projection line is called projection waveform.
算投影方向的平均濃度可以減少區域內的噪點造成的檢查錯誤。
Calculating the average concentration of the projection direction can reduce the error caused by the noise in the region.
（2）微分處理
Differential processing
根據投影波形進行微分處理。可能成為邊緣的、濃淡變化較大的部位，其微分值也較大。可以消除區域內濃度絕對值的變化所導致的影響。例：沒有濃淡變化的部位的微分值是0，白色（255）→黑色（0） 時的值是-255。
Differential processing is carried out according to the projection waveform. The differential value of the part which may be the edge and the change of the shade is larger. It can eliminate the influence caused by the change of absolute value of concentration in the region. For example: the differential value of the part without the change of shade is 0, and the value of white (255) → black (0) is - 255.
（3）通過校正使微分最大值達到100%
The maximum differential value is 100% by correction
對于微分波形中最大部分的中心附近的3個像素，根據這3個像素形成的波形，進行修正演算。以1/100像素為單位測算邊界位置（次像素處理）。
For the three pixels near the center of the largest part of the differential waveform, the correction calculation is performed according to the waveform formed by these three pixels. The boundary position is measured in 1 / 100 pixel (sub-pixel processing).
對于微分波形中最大部分的中心附近的3個像素，根據這3個像素形成的波形，進行修正演算。以1/100像素為單位測算邊界位置（次像素處理）。
For the three pixels near the center of the largest part of the differential waveform, the correction calculation is performed according to the waveform formed by these three pixels. The boundary position is measured in 1 / 100 pixel (sub-pixel processing).
邊緣檢測的代表性檢測應用
Representative application of edge detection
（1）利用邊緣位置的各種檢查
Use various checks of edge position
在多個部位設置邊緣位置模式，測量檢測對象的X座標或Y 座標。
The edge position mode is set in multiple parts to measure the x-coordinate or y-coordinate of the detected object.
（2）利用邊緣寬度的各種檢查
Various checks using edge width
利用邊緣寬度的“ 外部尺寸”模式，檢測金屬板的寬度、孔洞的X方向/Y方向孔徑等。
Using the "external size" mode of edge width, the width of metal plate and the hole diameter in X direction / Y direction are detected.
（3）利用邊緣位置圓周區域的各種檢查
Various inspection of peripheral area by edge position
以圓周作為檢測區域，檢測切缺部位的角度（相位）。
Taking the circumference as the detection area, the angle (phase) of the missing part is detected.
（4）利用趨勢邊緣寬度的各種檢查
Various checks using trend edge width
利用“圓周”區域的“趨勢邊緣寬度”模式，掃描環狀工件的內徑、評價扁平度等。
Using the "trend edge width" mode of the "circumference" area, the inner diameter of the annular workpiece is scanned and the flatness is evaluated.
趨勢邊緣模式
Trend edge model
趨勢邊緣位置（ 寬度）模式是指在掃描檢查區域內較窄的邊緣窗口的同時檢測邊緣位置。利用這種檢查模式，可以對于一個窗口內的多個點進行邊緣位置（ 寬度） 檢查，因此可以確保捕獲工件的微小變化。
The trend edge position (width) mode is to detect the edge position while scanning the narrow edge window in the inspection area. With this inspection mode, edge position (width) can be checked for multiple points in a window, so as to ensure that minor changes of the workpiece can be captured.
檢測原理：使小范圍內的分割以小間距進行移動，檢查各點的邊緣寬度或邊緣位置。
Detection principle: make the segmentation in a small range move with a small space, and check the edge width or edge position of each point.
提高位置檢測精度的方法：縮小分割尺寸。
The method to improve the accuracy of position detection is to reduce the segmentation size.
縮短處理時間的方法：縮小分割移位幅度（移動量）。
The method to shorten the processing time is to reduce the range of segmentation shift (the amount of movement).
趨勢方向：分割移動的方向。
Trend direction: the direction of the split movement.
視覺檢測系統的尺寸測量技術屬于非接觸式的測量，不僅速度快而且測量出來的數值準確度高，相對于傳統的自動化生產過程中，典型的測量尺寸的方法是千分尺、游標卡尺、塞尺等，這些測量方法測量出的結果準確度低，速度慢。
The size measurement technology of visual inspection system belongs to non-contact measurement, which is not only fast but also has high accuracy. Compared with the traditional automatic production process, the typical measurement methods are micrometer, vernier caliper, feeler gauge, etc., the accuracy and speed of these measurement methods are low.
視覺檢測系統,視覺檢測技術