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

在基于粘土或木材制成的主模型进行样式设计的情况下，通过对测量点数据进行拟合来生成CAD模型一直是设计过程中的瓶颈。测量和适配是基于主模型进行款式设计的最重要的步骤。本文介绍了一种新的基于脉泽模型的非接触式三维自由曲面测量系统的研制。本文的主要研究成果如下：1.研制了一种用于自由曲面位移测量的高性能轮廓型传感器。该轮廓传感器被称为“光学环形图像传感器”，具有两大优点。首先，使用环形狭缝可以从各个方向检测来自目标表面在光轴上的反射光。其次，光学环像的半径与表面在光轴上的位移成正比。分析了光学环形图像传感器的测量原理和…对该传感器的性能进行了实验测量和讨论，不仅对漫反射表面和镜面反射表面进行了实验测量，而且通过检测光学环像的变化来减小对测量精度和边缘轮廓测量有直接影响的激光散斑噪声。非接触式在机多功能测量系统将能够高性能地测量三维自由曲面。该测量系统由光学环形图像传感器和激振器位移传感器组成。提出了利用这些传感器实现多功能测量的方法。处理传感器扫描偏移路径，并在表面上的每个区域设置不同的测量节距。通过对精细自由曲面的测量表明，该测量系统可以在短时间内对自由曲面进行测量，测量精度可达10 mm。提出了一种将三次B-样条曲线曲面拟合到密集测点数据上的新方法。提出了考虑曲线长度和曲率的节点位置确定方法，这是设计理念的重要因素之一。并且该参数是在考虑结位置的情况下设置的。采用基于最小二乘法的反变换方法计算四次B-Spline曲面的控制点。利用研制的非接触式三维数字化系统对自由曲面母模进行了测量。结果表明，不含波纹度的B-Spline曲线曲面能够较好地拟合测量点数据，且精度较高。提出了一种新的基于主模型测量点数据的Coons曲面片测量策略和算法。采用高密度、高精度的非接触式激光位移传感器对母模进行测量。基于考虑曲率的B-样条曲线，生成C2类的Coons曲面片。得到了测点数据的最佳拟合CAD模型。此外，还给出了战略度量的表面评价过程。较少

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