Research On Data Acquisition Of3D Laser Point Scanner And The Algorithm Of Hole-repairing And Smoothing

3D laser scanner is one of the key equipment of digital design and manufacturing. The surface data of prototype sample can be obtained by using3D laser scanner which has been widely used in the field of product design and industrial inspection. By inputting the scanned measurement data into the reverse engineering software and building a CAD model of three-dimensional object from point cloud, the design cycle can be significantly shorten and achieve NC production, which can reduce the cost of product design and improve the production efficiency.Optical measurement technique has some perfect features of non-contraction and fast speed and easy-to-automation, which is especially suitable for the measurement of free-form surfaces. This thesis study3D laser line scanner of the servo control system to reduce the noise and vibration. The proposed scheme can improve both the measurement accuracy of scanning and the level of application of three-dimensional laser scanner in digital design and manufacturing. Besides that, it can also meet the demand of fine products.3D laser scanner measurement system is a system integrated optical, mechanical and electrical. It includes mechanical platform, motion control, CCD camera, a laser generator, optical imaging, laser spot image processing, object and image relation calibration, point cloud data processing and data interface. The main work done in this thesis is as follow:(1) The main components and parameters of3D laser scanner is introduced. The class CMoveCard, the class CImageCard, the class CMachine and the class CDataProcessFunc are designed by the object-oriented technology. The object of CMachine is built when scanner begins measure. While the measurement is over, the object is destructed. Release some computer resources to process the measured data conveniently.(2) Design the optical imaging parameters of the scanner based on the measurement depth of field, lens focal length and accuracy requirements.(3) The correspondence of the object and image is established by height lookup table method based on optical triangulation principle.(4) The imag core laser spot is extracted by the median filter and the floating threshold, and the centre of the core is calculated by the neighborhood weighted average method.(5)The single and sequence capture of the image acquisition collection is analyzed. Using the callback function based on cycle sequence acquisition method, we can achieve image acquisition and processing in parallel. Some experiments are done to further show that the proposed scheme can use the maximum speed of the camera, where the speed of the scanner to collect data is three times faster than that of serial mode. (6) The cause of the scanned blind is analysed, the hole with some neighborhood data is interpolated by the least squares method to fit the trend surface. Consider the constraint of the steep edge in the interpolating processing of hole edge extending to inside area.(7) In the smoothing processing of the measured data, we proposed a scheme of combing image edge detection and graphical edge detection. While ensuring the edge information is preserved, the non-edge measured data points is used to smooth process by using B-spline method.After the detection of experimental sample, the measurement accuracy of the proposed scheme is less than±0.015mm. Compared with the stepper control system based on laser line scanner, the measurement accuracy improves5to10um.