Optimization Design Of Structural Parameters Of Visual Sensors & Calibration Technology

In virtue of the advantages of large measuring range, non-contact measurement, fast measuring speed, flexibility for kinds of products and medium measuring precision, visual inspection technology is getting more and more applications in modern industry production area. How to improve the precision, speed, and reliability of vision inspection system is its important research aspect. The structural parameters of visual sensors and calibration technology will affect the performance of an inspection system directly. In this thesis, researches are mainly focused on the following aspects:Firstly, the perfect project transform mode of video cameras in visual sensors is introduced. The lens distortions having influence on the quality of images grabbed by sensor are studied and a few math models of usually used visual sensors are presented.Secondly, the structure design of visual sensors is analyzed in details. The measurement accuracy of visual sensors in relation to the values of the sensor structure parameters and their errors is probed. Then the principle and method of visual sensors design are derived.Thirdly, the method and step of visual sensors calibration and measuring system global calibration is introduced. Three well-known calibration methods of CCD camera, which are non-linear minimization, direct linear transformation method and radial alignment constraint method are stressed. The target forms for camera calibration and their characteristics are introduced.Lastly, adjusting the visual sensors and control-circuits self-designed, a set of visual measuring experimental system is established. The performance of the calibrated device is tested and analyzed by series of experiment, meanwhile, some feasible improving measures are put forward.