Measurement algorithm of notch length of vehicle accessories based on contour points

Accurate and rapid measurement of the notch of vehicle accessories produced in real time on the assembly line is an important way to reduce labor cost and improve production efficiency. The current dimension measurement algorithms pay attention to the extraction of edge high-precision contour which needs complex parameter adjustment and despise the extraction of contour corner information. It is difficult to be used in industrial real-time detection environment because of its large amount of calculation, easy to be disturbed by the environment and weak robustness. In order to realize the noncontact, high-precision and wide application range of notch length measurement based on machine vision, an algorithm is proposed to extract corner points with contour point features and contour edges with geometric restrictions, so as to finally obtain the length of notch. The algorithm uses moments to estimate the centroid coordinates and overall direction of the accessory, and calculates the distance to the centroid and the offset angle from the overall direction for each side of the accessory one by one. The results show that compared with the traditional corner extraction and line detection algorithms, the algorithm can extract the accessory corner and the notch length more accurately. The average processing time for the accessory image with a resolution of 200 pixels (vertical) × 600 pixels (horizontal) is 15 milliseconds, and the notch length can still be extracted for the slight shaking generated in the manufacturing process. The relative error of the extracted notch length is less than 1%, which is suitable for the industrial field environment with high requirements for real-time and robustness. It has the characteristics of strong adaptability and low cost.