【作者】 叶修松；

【导师】 黄谟涛；

【作者基本信息】 解放军信息工程大学 ， 大地测量学与测量工程， 2010， 博士

【摘要】 机载激光水深探测技术是当今海洋测绘领域研究的热点与难点之一。虽然该技术的广阔应用前景早已引起人们的极大关注,且硬件设备在国外已相当成熟,有关探测系统集成方面的许多关键问题也已得到解决,诸多机构利用这种系统获得了大量的海上实测数据,并在很多领域得到具体的应用,但机载激光水深测量数据后处理技术在国际上仍处于研究发展阶段,还有许多难点问题有待研究解决。为此,本文围绕机载激光水深探测数据处理中的几项关键技术进行研究,取得的主要成果和创新点如下:(1)系统总结了机载激光水深测量技术的研究背景和发展概况,以及机载激光测深数据处理技术的发展现状,分四个阶段详细介绍了国内外机载激光测深技术的发展历程,指出了机载激光测深技术,特别是其中的数据处理技术面临的主要问题和挑战,进一步明确了本文的研究方向和目标。(2)在简要介绍机载激光测深系统组成和工作原理基础上,给出了机载激光水深测量计算模型和测深能力估算模型;全面细致地分析了机载激光测深信号传输的特点,提出了使用不变矩确定机载激光水深测量激光回波信号峰值位置的计算方法,同时采用平移矩的方法校正海底回波信号的偏移;通过采用高斯函数模拟海底的反射信号,研究探讨了海底反射信号振幅随光谱宽度控制参数变化的规律,建立了激光测深低通滤波器最佳截止频率与光谱控制参数的函数关系式,设计出了最优的激光回波信号滤波器,并利用海上试验数据具体实现了激光脉冲回波信号的有效识别和提取。(3)详细推导了动态差分GPS定位的计算模型,提出了将精密单点定位技术应用于机载激光测深定位定向的新思路,具体推导了精密单点定位的数学模型,给出了基于传统计算模型的PPP解算方法,提出了解决实际应用该方法几个关键问题的技术途径;提出了INS/GPS组合导航系统改进方案和惯性测量单元标定与传递对准方法。利用航空重力测量导航定位数据和国内外计算软件,对以上三种定位定向技术的适用性和计算模型进行了比较充分的数值计算验证,得出了一些有益的结论,为下一步的工程化应用奠定了必要的技术基础。(4)根据脉冲式激光发射器的工作原理,给出了码盘周期和激光脉冲记录数据的处理方法;定义了各类传感器观测坐标系统,并确定了不同坐标系之间的转换关系,在此基础上,提出了激光测深、GPS定位、电子罗盘等多源观测数据的集成和同步处理方法;提出了通过求解反射镜法线及反射光线在各个平面的投影,确定海面及海底激光入射点坐标的计算方法,详细推导了海面激光入射点坐标的严密计算模型。通过仿真和实际观测数据计算分析,有效验证了上述各种处理方法的可行性和正确性。(5)详细分析了机载激光测深各类观测数据的误差源,从定性和定量两个方面探讨了各类误差源对激光测深成果的影响规律。具体分析了机载激光测深深度归算改正的三种计算模型,得出了惯导辅助修正模型是三种深度归算改正模型的首先方案。针对机载激光测深出现异常数据比较多的特点,提出了基于抗差M估计选权迭代法的异常数据检测方法,给出了异常数据检测的判别模型和计算流程。根据机载激光测深条带连接必须有部分重叠的要求,给出了机载激光测深数据系统偏差的趋势面模型,提出采用两步法解决机载激光测深数据中的系统偏差补偿问题,极大地简化了机载激光测深条带数据融合计算过程。(6)提出了采用单波束测深成果检核机载激光数据质量的技术方法和计算流程,并以我国自行研制的机载激光测深系统为例,给出了该系统在某海区试验数据的外部检核结果。针对两种测深手段之间明显存在系统性偏差的基本事实,提出了以单波束测深成果为控制,对机载激光测深数据系统偏差进行校正和补偿的精细化处理新方案。更多还原

【Abstract】 Airborne laser bathymetric technique is a hot and difficult problem in the field of present marine surveying and mapping. The promising prospect of the application of the technique has greatly attracted people’s attention. With the maturing of bathymetric hardware in foreign countries, and the solution of many key problems on hardware and system integration, many organizations and consortiums have obtained enormous ocean observations using bathymetric system and applied the system into a lot of fields. However, the post processing methods of bathymetric observations are still in the phase of research and development, and there are still many problems that have not been well solved. Under such background, the dissertation performed research on some key problems of airborne laser bathymetric system (ALBS). The main work completed is as follows.(1) The history and development of Airborne Laser Bathymetry (ALB) technology as well as the current status of ALB data processing techniques were summarized in general. The development of ALB technology in the world within four periods was introduced in detail, and the major problems and challenges faced by ALB especially the data processing techniques were illustrated. Then the work scheme and target of the dissertation were briefed.(2) Mathematical models for ALB computations and bathymetric capability assessment were presented on the basis of the system structure and work mechanism of ALB. Through a detailed analysis of the characteristics of ALB signal transmission, a computation method for the determination of the summit position of ALB laser echo signal using invariant moment was proposed, and the method for shift correction of seabed echo signal using translating moment translation was also proposed. By simulating the reflection signal from seabed using Gauss Function, the variation of the amplitude of seabed reflection signal with the control parameter of spectral width was researched, and the function model of the optimal truncation frequency of laser bathymetric FIR and the spectral control parameter was set up, and thus the optimal filter of laser echo signal was designed. As a result, the effective recognition and extraction of laser pulse echo signal were implemented with shipboard test data.(3) The computation model for dynamic differential GPS was derived, based on which the new idea that applied the Precise Point Positioning (PPP) technique to the positioning and orientation of ALB was put forward, and the mathematical model for PPP was derived, and the PPP solution method using conventional solution was presented, and furthermore the technical approaches to some key problems of the application of the method were provided. The scheme for the improvement of INS/GPS integrated navigation system as well as the calibration and transferring-and-alignment method for the inertial measuring unit were also presented. Using navigation positioning observations from airborne gravimetry and state-of-the-art software, numerical tests were made on the applicability and computation model of the above three positioning and orientation methods, from which some beneficial conclusions were drawn, which lays the foundation for future engineering applications.(4) The processing method for encoder cycle and laser pulse record was presented on the basis of the principle on which the pulse-type laser emitter works. The coordinate systems for different sensor observations were defined and the transformations between the systems were determined, and then the integration and synchronous processing method for multi-source observations from ALB, GPS and electronic compass was proposed. A method was given for the determination of the incidence points at sea surface and seabed by computing the projections of the reflector normal and reflected laser beams onto device planes, and the strict model for the computation of the incidence point coordinates on sea surface was derived in detail. Simulation and actual observations processing effectively demonstrated the applicability and correctness of the proposed methods.(5) Error sources that have effect on the observations of ALB were given through a thorough analysis, and the effects of different error sources on ALB were discussed from a quantitative and a qualitative view respectively. The three computation models for the reduction and correction of depths from ALB were given material analyses, from which the conclusion that the inertial navigation aided correction model is the most preferred scheme of the three models. Then, aiming at the characteristics that more outliers than common appears in ALB, the outlier detection method based on weight-selection iteration of robust M-estimation, along with the judgment model and computation flow for outlier detection was brought forward. According to the requirement that for the stripe conjunction of ALB there must be some overlapped area, the trend surface model that suits ALB data system bias was provided, and the two-step method was recommended to solve the system bias compensation within the ALB observations, which greatly simplifies the fusion process of ALB stripe data.(6) The technique and processing steps for the back-check of ALB data quality using single beam bathymetric data were proposed, which were implemented on the ALB system developed by China. The results for the exterior check of the system were given from experiments at sea. To overcome the prominent systematic bias between the two bathymetric techniques, a new processing scheme was proposed for making corrections and compensations to the systematic bias of ALB data with single beam bathymetric data as control.更多还原