Wheel Tread Defect Detection Based On Fourier Transform Profilometry

With the rapid development of modern industrial manufacturing technology, three-dimensional measurement have a wide range of demands for industrial automation monitoring, quality control, machine vision, reverse engineering, biomedical engineering, costume design and other fields. Due to advantages such as non-contact, high precision, high speed, Optical 3D measurement technology has become one of the research hot spots. As a technique of the 3D Optical measurement, Fourier Transform Profilometry (FTP) has high accuracy, and the method requires only one frame of the deformed fringe pattern to retrieve the surface of measured object, so it has faster measurement rate than other methods. The theory and application of Fourier transform profilometry were studied in this thesis, the main work of the paper is as follows:First, this thesis studies the basic theory of Fourier Transform Profilometry. The key technologies of FTP such as image preprocessing, frequency domain filtering, phase unwrapping were simulation experimented by computer. The experiment using the background elimination method to suppress zero frequency and remove specular interference, take orthogonal elliptic band-pass filtering to improve filtering accuracy, then the measurement accuracy of FTP improved.Secondly, for the issue that the projector was difficulty to calibration, but it’s a key equipment of optical 3D measurement system, this thesis studied a method based on the traditional model of camera calibration to calibrate the projector, the method relies on a camera and a checkerboard calibration plate, and combined with the perspective transformation correction method to get the 3D feature point coordinates.Finally, the thesis use the Fourier transform profilometry to achieve wheels tread defects detection, by the method the surface defects were accurately detected.