基于距离选通门控切片激光成像精度的实验研究

发布时间：2018-06-02 21:35

本文选题：距离选通 + 激光成像　；参考：《哈尔滨工业大学》2015年硕士论文

【摘要】：激光雷达经过多年的发展,形成了结合机械学、光电子学、数理统计、图像处理等学科具有各自独特性能的多种成像体制。高精度的三维目标像在工业设计与加工、逆向工程、探测勘探、目标建模及虚拟现实等应用中,都具有很广阔的前景。本文的研究方向为距离选通门控切片激光三维成像,通过理论分析及实验验证对这种体制的成像精度问题进行探讨。首先,通过较为详细的调研,对国内外距离选通技术的发展情况进行了综述。分析了不同研究机构的代表性成像系统的性能参数以及它们在实际应用当中的优势,引出了本文研究内容的必要性。其次,通过分析距离选通技术原理,对切片像的强度分布特性进行了matlab数值仿真。对比了二值化算法和质心算法对激光成像精度的影响,从理论上对成像距离精度的影响因素进行了分析。然后,以之前的理论分析为依据,设计并搭建了成像实验系统。完整系统主要由激光发射系统、同步控制系统、回波探测系统构成。对各分系统进行了必要的测试,掌握了设备的工作特性:光束发散角为4°,重频1-100Hz可调;系统固有延迟约13ns,可对1.95m以上的近距离目标成像;选通门宽3ns-DC可调;延迟步进达到ps量级,可以进行精细切片。最后对完整系统进行了调试使之工作在最佳状态。接下来,完成了厘米级精度的成像实验。对于9.5m及22m的目标,门宽为7ns时距离精度均可达到0.025m。通过不同条件下的多组实验,较为系统地分析了不同门宽下的成像距离精度,证实了较小的选通门宽对于保证成像精度具有一定的优势。最后,探讨了质心算法的适用性问题,提出了一种基于曲线拟合标定切片像强度质心的方法,并进行了实验验证。并通过实验对比验证了本文提出的这种方法在切片数量较少且切片分布不均匀的情况下,对于保证距离选通门控切片成像体制的适用性,提高距离像精度具有较大优势,通过分析指出了这种方法在门控切片成像体制下具有一定的普适性。
[Abstract]:After many years of development, lidar has formed a variety of imaging systems combining mechanical, optoelectronics, mathematical statistics, image processing and other disciplines with their own unique performance. High precision 3D target image has a broad prospect in industrial design and processing, reverse engineering, exploration, target modeling and virtual reality. The research direction of this paper is range gated slice laser 3D imaging. The imaging accuracy of this system is discussed by theoretical analysis and experimental verification. Firstly, the development of distance gating technology at home and abroad is reviewed through detailed investigation. The performance parameters of representative imaging systems of different research institutions and their advantages in practical applications are analyzed. Secondly, by analyzing the principle of distance gating, the intensity distribution of slice image is simulated by matlab. The effects of binarization algorithm and centroid algorithm on laser imaging accuracy are compared and the influence factors of imaging range accuracy are analyzed theoretically. Then, based on the previous theoretical analysis, an imaging experimental system is designed and built. The complete system consists of laser emission system, synchronous control system and echo detection system. The necessary tests of each subsystem are carried out, and the working characteristics of the equipment are mastered: the beam divergence angle is 4 掳, the repetition frequency 1-100Hz is adjustable, the inherent delay of the system is about 13ns, the imaging of the close target above 1.95m is possible, the gate width 3ns-DC is adjustable; Delay step up to PS order of magnitude, can be fine slicing. Finally, the whole system is debugged to make it work in the best condition. Next, the imaging experiment of centimeter accuracy is completed. For the target of 9.5m and 22m, the distance accuracy can reach 0.025m when the gate width is 7ns. The imaging distance accuracy under different gate widths is analyzed systematically through multi-group experiments under different conditions, and it is proved that smaller gate width has certain advantages in ensuring imaging accuracy. Finally, the applicability of the centroid algorithm is discussed, and a method of calibrating the centroid of slice image intensity based on curve fitting is proposed and verified by experiments. The experimental results show that the proposed method has the advantages of ensuring the applicability of the range gated slice imaging system and improving the range image accuracy when the number of slices is small and the section distribution is not uniform. Through analysis, it is pointed out that this method has certain universality under gated slice imaging system.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN958.98

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