Three-dimensional Design And Research Of High-speed Raster Projection System Hardware Real-time Measurements

With the development of computer technology and optical and electronic technologies, the new three-dimensional optical measurement methods are emerging. Structured light measurement method, the most representative of active three-dimensional measurement technique, projects structured light to the target object, and captures structured light image modulated by measured object surface, then calculates the three-dimensional topography data of the measured object from the images carrying three-dimensional morphology information of the object, which shows a strong vitality and great potential for applications in machine vision, reverse engineering, industrial automation and physical profiling, cultural heritage protection and other fields.Although the three-dimensional structure light measurement technique has been widely used in many fields, however, the existing research work focuses on measuring the topography of static objects or scenes graded. Currently a single measurement time of the commercially available structure light three-dimensional measurement system is generally more than0.5seconds, which makes it difficult to measure the dynamic object or changing scenes in real-time. For this research problem and market vacancy, this thesis aims to study high-speed real-time three-dimensional shape measurement techniques and corresponding system design, focusing on its hardware system design. This paper introduces the basic principles of three-dimensional grating measurement, including the phase shift method, phase unwrapping method, system calibration and coordinate conversion principle, etc. Then focus on the hardware design part of the high-speed real-time three-dimensional shape measurement system. The hardware system mainly uses the FPGA chip to achieve stripe encoding data storage and uses FPGA to control DLP projector projecting structural grating onto the target object. In this paper Quartus Ⅱ is used to develop FPGA chip and Verilog HDL hardware description language is used to control VGA timing and the synchronization between camera and projector. In support of the above basic theory and hardware platforms, the structures of high-speed real-time three-dimensional projection grating measurement system is completed. Based on the above hardware platform, the experiments on fringe projection system are carried on, which verifies that it can project the required grating strips as the timing required. In addition, we use the entire three-dimensional measurement system to measure more complex dynamic scenes in real-time. Experimental results show that the system can effectively reconstruct three-dimensional morphology information of complex scenes in real-time. Its measurement speed reached0.0083s and the relative accuracy of reconstruction reach0.05mm. Reconstruction effect is more ideal, basically meeting the requirements of real-time measurement. Finally, this paper gives some parameter index of the system.