【作者】 李壮；

【导师】 乔钢；

【作者基本信息】 哈尔滨工程大学 ， 信号与信息处理， 2013， 博士

【摘要】 21世纪是海洋世纪，基于声波探测的水声技术是获取和传递水下信息最有效的手段。本文主要研究短基线高精度定位技术,是为解决水下探测和作业的机器人提供高精度定位装备。由于水声信道的多途特性，严重影响了水声定位系统的时延估计精度。信号直达声与多途反射声混在一起影响了声呐检测器的判决。本文利用时间反转聚焦信道多途的特性，提出一种抑制信道多途的新方法，即对短基线定位系统加以改进，提出短基线与单阵元时间反转镜相结合的方法。采用基于单阵元的非同步主动应答式、同步虚拟信标式的时间反转定位方式，达到抑制信道多途提高定位精度。并且提出利用时间反转信道聚焦的功能解决多目标定位中的若干问题。本文针对短基线声呐的检测问题，理论分析推导常规匹配滤波检测器、时间反转匹配检测器、常规最大似然估计器及时间反转最大似然估计器的性能特点。针对在水下存在多途、混响及噪声边缘等非平稳背景条件下声呐检测器的检测性能，给出了一种变异指数的恒虚警检测器—VI-CFAR检测器，其具有较强的自适应性及抗干扰能力，且在噪声边缘背景下有较好的虚警概率控制能力且运算量小，是一种稳健的检测器。本文详尽分析了基阵误差对定位精度的影响，提出一种快速随机布放的水声短基线定位系统。针对短基线基阵校准问题，本文从系统的总体误差角度入手，以基阵扰动矢量最小化为目标，提出采用约束最小二乘算法来抑制扰动误差的影响，并且针对在短基线定位中具有相同误差源的特性，提出利用邻近辅助基阵节点做为差分参考节点，用参考节点去修正未知节点测距，然后结合最小二乘技术迭代求解，该算法结构简单，工程应用性高。最后本文论证并且实现了一套应用于水下机器人的短基线定位系统，详细介绍了各模块的软、硬件设计思想和实施方案。给出了该系统经过水池、多功能造波水池、海试的试验结果。通过实验验证，该系统定位精度可达到0.5%以内，并且工作稳定，性能可靠，通过园筛法、中值滤波及卡尔曼滤波等后置处理手段对定位过程中的间断点和野点进行处理，轨迹平滑效果良好，满足系统要求。更多还原

【Abstract】 21stcentury is a century of ocean, and the underwater acoustic technology based on sounddetecting is the most effective means to achieve and transform underwater information. Thisarticle mainly deals with short-baseline based high-precision location technology, whichprovides high-precision location devices for robots detecting and working underwater.Multi-path time delay estimation error is one of the important factors that affect theprecision of a location system. Due to the multi-path feature of the underwater acousticchannel, direct sound signal mixes with multi-path reflected sound, which affects the sonardetector’s judgment. Utilizing the multi-path characteristic of a time-reversal focusingchannel, this paper proposes a new strategy to mitigate the multi-path effect of the underwateracoustic channel, namely an improvement of short-baseline location system. A technologycombining short-baseline and single array time-reversal mirror method is raised. Also, thefocusing gain of the proposed method is analyzed. In this paper, time-reversal locationmethods, asynchronous initiative respond and single array based synchronous virtual beacon,are used to mitigate the multi-path effect and improve precision of location. A method basedon the channel focus function of time-reversal mirror to resolve problems such as near-fareffect and multi-target distinguish of multi-target location system is also proposed.Focused on detection issue of the short-baseline sonar, the paper analyses and deduces theperformance of the common matching filtering detector, time-reversal matching detector,common maximum likelihood estimator and time-reversal maximum likelihood estimator.Especially, for the detection performance of the sonar detectors in unstable background suchas multi-path effect of the underwater acoustic channel, reverberation and noise edge, it putsup with a CFAR detector of varying index, namely VI-CFAR detector. The VI-CFAR detectorhas strong capacity of self-adaptation and anti-interference. It not only does well in falsealarm probability control, but also requires small calculating amount, which makes it a steadydetector.The paper analyses the influence of the base array to location precision in detail, and putsforward a high speed random placed short-baseline underwater acoustic location system. Asfor the short-baseline array’s correction, the paper aiming at minimizing the array interference vector, starts from the factor of total error and proposes a method to mitigate the influence ofinterference error by utilizing restraint Least Square Method. Due to the characteristic of thesame error source in locating system, the paper uses adjacent array nodal point as differentialreference nodal point to correct unknown nodal points. Then combine Least Square Methodfor iterative solution. The proposed method has simple structure and high engineeringapplicability.At last the paper demonstrates and realizes a short-baseline location system used forunderwater robots. The design idea and implementation plan of software and hardware ineach module are also introduced carefully. In addition, the test results of the system underdifferent condition such as pool, multifunction wave-producing pool and the sea are provided.It is proved that the system is of great reliability in various circumstances and its locatingprecision even ranges within0.5%, which satisfies the system requirements. It copes with thebreakpoints occurred in the process of locating through some manners like round filter,mid-value filtering and Kalman filtering, which contributes to its good effect for pathsmoothing.更多还原