Application Of Contact Zone Measurement For Hypoid Gear Based On Stereo Vision

It still remains unchanged today that the traditional approach that detection of the contact zone of hypoid gear is done through binocular by experienced engineers. In general, the engineer observes the location, size and shape of contact zone by binocular. However, the approach will take engineers much time. As a result, precision decreases because of human factors. Therefore, it is urgently needed for engineers to seek a real-time measurement approach.In this thesis, the measurement approach based on stereo vision is mainly dealt with. According to this approach, twin cameras acquire 2D digital image of contact zone. Computer is used to analyze and process 2D digital image of contact zone to reconstruct 3D information of it and finally realize digital analysis. The key issues such as camera calibration, feature points obtaining and matching, image processing and 3D information calculation, are systemically studied in the thesis. A newer and more flexible method, which goes between the traditional calibration and self-calibration based on the camera linear model, was presented by Zhang Zhengyou calibrate 3D measurement system. A refining strategy is adopted in corner detection. Harris operator is used to estimate the rough location and finally quadratic surface fitting is used to acquire the precise location. The advanced image matching technique based on SIFT (Scale Invariant Feature Transform) is used to extract and match feature point. Finally, all technologies which are introduced in this thesis are employed comprehensively to reconstruct 3D information. In addition, an experimental platform based on binocular stereo vision is established and a set of measuring program is developed under the MATLAB architecture. All the experiments including camera calibration and 3D measurements of contact spot on the system show that the designed 3D measurement system succeeds in the 3D information reconstruction of contour curves on contact spot.In the research, the stereo vision technology has been applied to the gear measurement. With its full advantages, this measurement technique, with high measurement precision, will be expected to advance the level of gear-detection.