无合作目标激光测距中目标特性对测量影响研究

发布时间：2018-02-16 15:10

本文关键词： 调频连续波激光雷达无合作目标大尺寸测量散射特性测量不确定度　出处：《天津大学》2015年博士论文　论文类型：学位论文

【摘要】：基于连续激光调频测距技术的无合作目标大尺寸球坐标精密测量系统无需合作目标,测量安全快捷、范围大、精度高,能够满足目前大空间精密测量方面日益增长的需求。然而,与有合作目标的激光测距系统相比,被测目标表面的不确定性导致激光后向散射机理非常复杂,使得无合作目标激光测距系统的精度和测量范围均受到严重影响。因此,针对此问题,本文展开的一系列表面测量特性及其对测距影响的研究,是提高测量系统整体测量精度和范围的关键研究内容。论文的主要工作概况如下:1、研究了粗糙表面的散射特性,提出了一种制造表面粗糙度影响激光测量性能的试验方法,研制了试验装置,试验测量并分析了标准漫反射白板和标准粗糙度样块在红外激光照射下的散射特性,加强了对激光与物质相互作用机理的试验支撑和工程应用解释,为激光雷达中无合作目标问题的研究提供了理论与实验基础。2、对粗糙面后向散射系数的近似解析方法(积分方程方法、基尔霍夫近似方法和微扰法)进行了公式推导,数值计算了随机高斯粗糙面的后向散射系数。开展了实际加工表面的后向散射特性的实验研究,深入探讨了入射方位角、入射角、入射光偏振方向和表面微观形貌对实际加工表面后向散射特性的影响规律。3、在对真实加工表面后向散射特性进行大量实验研究与分析的基础之上,首先建立了基于神经网络的加工表面后向散射的网络模型,然后,结合遗传算法,构建了加工表面多维参数的反演模型,使能测范围得到大幅度地提高。4、建立了粗糙表面对激光雷达测量信号影响的数学模型,对理想信号、斜坡信号、突变信号以及随机粗糙面信号进行了模拟,分析了表面粗糙度、相关长度对测量信号的影响,通过对不同粗糙度样块的实际测量结果对比,验证了理论分析的正确性。5、推导了调频连续波激光雷达测距精度的理论模型,分析了影响激光雷达精度的因素,重点分析了表面特性对测距精度的影响。设计了大尺寸测距实验,对理论分析进行了验证。此外,针对表面微观形貌的特点,提出了减小测量不确定度的方法,减弱了粗糙表面的影响。
[Abstract]:Based on the continuous laser frequency modulation ranging technology, the large size spherical coordinate precision measurement system without cooperative target needs no cooperative target, and the measurement is safe, fast, wide range and high precision. However, compared with the laser ranging system with cooperative targets, the uncertainty on the surface of the measured target leads to a very complicated mechanism of laser backscattering. The accuracy and measurement range of the laser ranging system for non-cooperative targets are seriously affected. Therefore, a series of surface measurement characteristics and their effects on ranging have been studied in this paper. The main work of this paper is as follows: 1. The scattering characteristics of rough surface are studied, and a test method for the influence of surface roughness on laser measurement performance is proposed. A test device was developed. The scattering characteristics of standard diffuse white board and standard roughness sample were measured and analyzed under infrared laser irradiation, and the experimental support and engineering application explanation for the interaction mechanism between laser and matter were strengthened. This paper provides a theoretical and experimental basis for the study of non-cooperative target problem in lidar. The approximate analytical method of backscattering coefficient of rough surface (integral equation method, Kirchhoff approximation method and perturbation method) is derived. The backscattering coefficient of random Gao Si rough surface is numerically calculated. The experimental study on backscattering characteristics of practical machined surface is carried out, and the incident azimuth and incident angle are discussed in depth. The influence of the polarization direction of incident light and the micro-morphology of the surface on the backscattering characteristics of the real machined surface. 3. On the basis of a large number of experimental studies and analysis of the backscattering characteristics of the real machined surface, Firstly, a neural network-based model of backward scattering of machined surface is established, and then, combining with genetic algorithm, the inversion model of multi-dimensional parameters of machined surface is constructed. A mathematical model of the influence of rough surface on lidar measurement signal is established. The ideal signal, slope signal, abrupt signal and random rough surface signal are simulated, and the surface roughness is analyzed. The influence of correlation length on the measurement signal is verified by comparing the actual measurement results of different roughness samples, and the theoretical model of ranging accuracy of FM CW lidar is deduced. The factors that affect the accuracy of lidar are analyzed, and the influence of surface characteristics on ranging accuracy is analyzed. A large scale ranging experiment is designed and the theoretical analysis is verified. A method to reduce the uncertainty of measurement is proposed to reduce the influence of rough surface.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TN958.98

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