【作者】 李宇翔；

【导师】 曹益平；

【作者基本信息】 四川大学 ， 光学， 2007， 硕士

【摘要】 位相测量轮廓术(PMP)是一种基于条纹投影和位相测量的光学三维面形测量技术，由于其具有非接触、全场性、速度快、高精度、自动化程度高等特点，这种技术已在工业检测、机器视觉、逆向工程等领域获得广泛应用。在PMP测量中，常采用数字投影仪通过计算机VGA视频接口控制产生正弦相移光栅投影，并用专用图像采集卡采集变形条纹图，由于计算机显示器与投影仪共用一个VGA视频接口，当投影正弦光栅时，计算机难以同时操作测量软件与采集图像，目前解决的办法由两种，一种方法是采用另一台计算机专门控制投影仪，主计算机控制应用软件系统，实现数据获取与处理，这种系统不宜实现仪器化；另一种方法是采用专用的双频显卡，用VGA视频接口控制显示器，而用DVI接口控制投影仪，并通过编制专用应用软件，实现显示器信息与投影仪信息的分离显示，这种系统由于需要采用专用的硬件和软件，兼容性不是很好。为此，从仪器化角度出发，对传统的PMP测量系统进行了改进，利用TI公司TMS320C6000系列DSP的高性能图象处理芯片TMS320DM642实现PMP系统，投影仪完全不依赖计算机视频接口，而是直接由DM642的视频显示端口控制实现相移图像的投影，同时由DM642视频采集端口直接与CCD相连接实现图像采集以获取变形条纹图像，不再需要传统的嵌入在PC机端的图像采集卡及PC机，实现了仪器化设计。本文研究的主要内容如下：1．比较了几种PMP系统的结构，提出了对传统的PMP系统的改进。2．介绍了基于DM642的PMP系统核心模块的实现，DM642的视频采集与视频显示端口、UART以及它们驱动程序设计，介绍了系统的自启动设计和相移图像产生的算法实现。3．从强度传递函数出发，分析了它对PMP测量系统精度的影响。通过强度传递函数补偿方法可得到正弦性很好光场分布，减小了位相测量误差。4．考虑到投影光场不稳定性对PMP测量系统的影响，利用DM642的高速图像处理性能，在DM642的内部对采集到的图像进行多次平均，以减小投影光场的不稳定影响给测量带来的误差。并用实验进行了对比验证，表明平均算法减小了投影光场的稳定性给系统带来的测量误差，提高了本系统的测量精度。更多还原

【Abstract】 Phase measuring profilometry (PMP)is an important technique in the 3-D shape measurement, which is based on fringe patterns projection and phase measurement. It has been widely used in industrial inspection, machine vision, inverse engineering etc because of its merits of noncontact, full-field, high-precision and high-speed.In PMP measurement system, the digital projector is often adopted to produce the phase-shift sinusoid fringes through the computer VGA video interface, and a special image captured card embedded in computer must be applied to obtain the corresponding deformed patterns , because the display and projector share a VGA video interface, while a phase-shift Sinusoid fringe need to be projected onto the measured object ,both the digital projector and the display are producing the information which makes the computer difficult to operate the measuring software and capture image data at the same time. Usually, there are two methods to solve this conflict problem, One is to adopt another computer specially for controlling the projector so as to let the master computer operate the application software and accomplish the image data captured and processed, this kind of system is unsuitable to be instrument; The other is to adopt special-purpose display card, controlling the display with VGA interface, and controlling the projector with DVI interface, besides the special-purpose application software is required to realize the separated display of the projector and computer display, because this kind of system needs to adopt the special-purpose hardware and special-purpose software, it may not be compatible enough. So an improved PMP measuring system of making use of the high-performance image processing chip of TI Company’s TMS320C6000 series DSP named TMS320DM642 has been developed instrumentally in which the projector is connected to the video display port of DM642 rather than the computer, and CCD is linked to the video capture port of DM642 without any other image captured card. Some instrumental design has been researched. The main tasks are as follows:1. Having compared several kinds of structure of PMP system, the improved PMP system has been proposed.2. The key modules based on DSP of the improved PMP system have been developed such as the video image capture control, the phase-shift sinusoid fringes generator realization and UART communication program design. Finally, the related algorithms and self-starting program in this system have been accomplished.3. In order to analyze the accuracy of PMP system, the intensity transmit . function (ITF) is used to improve the quality of the projected sinusoidal fringe, experimental results show its feasibility.4. Because of the unstable projected field caused by pixel scanning, which may influence the precision of PMP system ,a faster image data processing method with several frames mean arithmetic has been done inside of the high performance DM642 to reduce the instability of the field. Contrastive experiments have been proved that the measuring precision has been improved remarkably.更多还原