Research For3D Visual Measurement System With Light-Pen

With the development of large-scale equipment manufacturing industry and the increasing requirements of large-size measuring tools, gradually traditional measurement tools could not adapt to complex environment and structure, and they are inconvenient to move. The paper carried on the research of3D visual measurement system towards the the precise measurement of the large size workpieces. The main works are as follows:(1) With the camera perspective transformation principle, a binocular vision model is built. The model contains the effects of the second-order radial distortion.Equations to get parameters of camera have been established. These mathematical model and equations can be directly used in the programming of the binocular vision system software.(2) Performance and cost of the hardwares are taken into consideration to make a reasonable choice,and it makes sure that the translation of image data from equipments to the software and the relationship among all the hardwares have good function.(3) The structure with plane and holes makes the location of the light-pen to be simple, and a new material, a kind of aluminum alloy is used to reduce the weight of light-pen, thus the difference between the light-points and background is increased. The design of the light-pen results in a more accurate calculating for the tip position of light-pen.(4) For the extracting process of LED spot center, a new judging process is proposed wich simplifies the calculation of process,and the running time of system is reduced at the same time. A new method called the Gauss Cumulative Distribution Fitting is used for the extracting of LED spot center and with using of it the system is more precise.(5) Results of measurement experiments and precision analysis show that the system is with high precision in measuring range.