Development of A Non-contact 3-D Free Form Surface Measuring System in Aid of The Maser Model Based Design

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In the case of the style design based on a master model which is made by clay or wood, the production of the CAD model by fitting the measured point data has been bottleneck in the design process. Measurement and fitting are the most important process for style design based on the master model. This report describes on development of a new non-contact 3-D free form surface measuring system in aid of the maser model based design. The artifacts we achieved in this study are summarized as follows.A high performance profile sensor for measuring the displacement of the free form surface is developed. The proposed profile sensor called "optical ring image sensor" has two major advantages. First, reflection light from a target surface in optical axis can be detected in all directions using a ring slit. Second, the radius of optical ring images is linearly proportional to the displacement of the surface in optical axis. The measurement principle of the optical ring image sensor is analyzed and … More the properties of this sensor are experimentally measured and discussed not only for both diffuse reflection surface and specular reflection surface with steep angles, but also for reduction of the laser speckle noise which has direst influence on the measurement accuracy and edge profile measurement by detecting the change of optical ring image.Non-cotact on-machine multi-functional measuring system which will be able to measure a 3-D free form surface with high performance. The measuring system is composed of the optical ring image sensor and the vigitizer displacement sensor. The multi-functional measuring method using these sensors is proposed. The sensor scanning offset path is processed and different measuring pitch is set in each area on the surface. It is shown by the measurements of fine free form surfaces that the measuring system make it possible to measure a free form surface in short time and with an accuracy of (]SY.+-[) 10mum.A new fitting method of 3-degree B-spline curve and surface onto the dense measured point data is developed. The method to determine knot location with taking account of curve length and curvature which is one of the important factors for the design concept is proposed. And the parameter is set in consideration of the knot location. Control points of 4-degree B-spline surface are calculated by the inverse translation based on the least-square method. The master model with free form surface is measured by using the developed non-contact 3-D digitizing system. It is shown that the B-spline curve and surface without waviness is fitted to the measured point data with high accuracy and in good condition.The new measurement strategy and fitting algorithm of Coons patch surface onto the measured point data of the master model is proposed. The master model is measured by using the non-contact laser displacement sensor with high density and high accuracy. Coons patches of C2 class are generated based on the B-spline curve fitted with taking account of curvature. The best fitted CAD model of measured point data is obtained. Moreover surface evaluation process for the strategic measurement is shown. Less