The Technology Of Part Measurement Based On Virtual Instrument And Machine Vision

The measurement based on machine vision is characteristic with rapid, high precision and flexibility. It has been studied and applied widely at home and abroad. The thesis aimed to measure the dimension of the circular and line features in machine parts.The performance parameters of the machine vision hardware are analyzed. All the parts of the machine vision system, including the camera, the lens, the illumination and the frame grabber, are chose and assembled. The flow chart of the software for the machine vision system is given.There are inevitable aberration, noise and blur in the images that are acquired by the camera because of the non-ideal lens and camera. The image enhancement, image filtering and edge detection were studied and applied. An image preprocessing method was raised. The Sobel operator and the medium filtering were used in the machine parts image processing. The camera calibration based on the pin-hole camera model is completed with the help of the IMAQ library. Using the camera calibration result parameter, the image rectification transforms the image to compensate lens distortion.The least-squares approximation sub-pixel edge location for the edge of circle are studied in this paper. System calibration is needed before the dimension of the object is measured. An effective method of system calibration is given.The software is developed using the Labview. In order to validate all algorithms above, the experiments are performed. The experiment shows that the system meets the needs of this thesis.