【作者】 朱坤；

【导师】 乔钢；

【作者基本信息】 哈尔滨工程大学 ， 水声工程， 2010， 硕士

【摘要】 声相关计程仪是基于“波形不变性”的一种测量船舶速度的设备,适合应用于远洋船舶、潜艇及自主水下运载器。与声多普勒计程仪相比,相关计程仪可以用更低的工作频率,垂直发射的宽波束以及较小的换能器尺寸保证更远的作用距离。因此它的研究对维护我国的海洋权益,科学开发海岛、利用海洋资源具有重大意义。本文首先细致讨论了声相关计程仪的基本工作原理——“波形不变原理”及其适用范围,着重分析了海底深度、接收器间距、船速及发射波束角对波形相似程度的影响。围绕声纳方程,论证了相关计程仪设计时应考虑的一些问题,如频率的选取,换能器间距等,讨论了多种发射信号的选择。从而为海底回波仿真的参数选择提供了理论依据。然后根据相关计程仪的测速特点,研究了一维、二维基阵的设计方法,在借鉴雷达虚拟阵元概念的基础上,给出了冗余因子、引入虚元、给出虚元位置重合度等概念,进而实现了应用于声相关测速需求的二维基阵的快速设计方法。以网格法建立的海底回波模型为基础,分别对时间、空间相关测速法进行了理论分析和仿真研究,并讨论了三次样条插值和多项式插值对空间相关函数的插值效果,给出了多种阵型的测速统计结果,测速精度较高。最后对时空相关测速法进行了理论分析和仿真研究,推导了海底回波的理论时空相关函数模型,建立了海底回波数据的相关矩阵,采用最大似然法对未知速度等参量进行了估计。论文引入单纯形算法实现了似然函数最优参数的搜索,但由于单纯形算法可能陷入局部最优,论文又采用模拟退火算法进行全局寻优,并将两种算法的结果进行了对比分析,证明了其有效性。更多还原

【Abstract】 The principle of“waveform invariance principle”is used for the velocity measurement among acoustic correlation log (ACL), which is suitable to be equipped on submarines and autonomous underwater vehicles (AUV). The ACL has striking advantages compared with the acoustic Doppler log (ADL). It can work with a single beam pointing directly down at the sea bed and the return signal is much larger than from the ADL because of the normal incidence. Furthermore the beam can be fairly broad and, for the same size of transmit transducer, this enables the use of lower acoustic frequencies for which the attenuation is less. The ACL has the potential therefore for operating on the sea bed echoes at much greater depths than is possible with the ADL. The design and utilization of ACL become more and more important both for the defense of the national ocean equity and for the scientific research and exploitation of islands and ocean resource.In this thesis, the basic principle of ACL and its applying area, is presented in detail. The correlation properties of seafloor reverberation signals between different hydrophones on receiving arrays are discussed which is determined by the oceanic depth and launching ankle. Some problems, such as the choice of frequency and distance between transducers, are discussed according to sonar equation, which should be considered in the design of ACL.The design method of transducer arrays assembly plays a key role in the velocity measurement for the ACL. A design method of one dimension and two dimension arrays for the ACL is studied in this dissertation. Based on the method of restricted minimum-redundancy linear array (RMRLA), the redundancy factor is got, an ideal virtual array map is built, the conception of virtual array coverage rate is proposed and a fast two-dimensional arrays design method is obtained.With sufficient advisement based on sonar equation, the seabed echo simulation model for acoustic correlation log is founded by gridding method, in which the result is basically consistent with the simulation. Then, the theoretical analysis and emulation study is taken on the spatial correlation according to the model, discussing the Hermite interpolation fit and cubic spline interpolation fit to the spatial correlation function or interpolation effect, the statistical velocity measurement result of beeline array and plane array have come out, the precision of velocity measurement is preferable.The theoretical analysis and emulation study is taken on the temporal and the spatial correlation according to the model, the theory of the temporal-spatial correlation is deduced in details, and data the correlation matrix is set up. Using the maximum likelihood estimation method to estimate the unknown velocity parameters. Nelder-Mead Method is introduced in the paper to find the likelihood function minimization. Due to the possibility to bet into local optimum with Nelder-Mead Method, the improved method is put forward with the Simulated Annealing algorithm. Simulation proves the effectivity of the improved method.更多还原