声学多普勒流速测量关键技术研究

发布时间：2018-05-03 03:22

本文选题：声学多普勒流速剖面仪 + 波束散射模型　；参考：《哈尔滨工程大学》2010年博士论文

【摘要】：声学多普勒流速剖面仪(Acoustic Doppler Current Profiler,以下简称为ADCP)是一种既可以测量相对水底速度,同时又可以兼顾测量相对水流速度的声纳设备。ADCP既可以用于舰船的定位导航,又可以广泛应用于海洋及内陆河流的测流领域。作为一种测速仪器ADCP在河流和海洋工程中得到了越来越多的应用,对于声学多普勒测流技术的研究日益受到了人们的关注。本文的主要工作是对声学多普勒测流过程中所涉及到的几个关键技术进行研究,主要包括测流信号形式分析与回波建模、流速测量方式的差异与性能估计、宽带束控技术以及换能器安装校准技术等。具体的研究内容和得到的结果如下: (1)基于分辨理论对发射信号形式进行了研究。分析了单载频矩形脉冲、相干脉冲串和编码相干脉冲串等3种信号形式在多普勒测流中的适用情况。流速测量是指波束空间内大量散射体的多普勒频移信息的感知和处理,基于此提出了旨在分析接收回波的波束散射模型,并对水底回波和流层回波进行了仿真。与试验数据的分析对比结果说明了波束散射模型的正确性。以上的工作为多普勒测流的性能评估打下了基础。 (2)总结了多普勒流速测量的三种方式,即非相干、相干和宽带方式。可以看到,非相干方式适合于层厚要求不高以及大作用距离的测流应用场合;相干方式适合于浅水高分辨的测流应用场合;宽带方式则集中了两者的优点,它可看成是非相干方式与相干方式的结合体。以建立的波束散射模型和快速灵活的复自相关方法为基础,对不同的测流方式进行了仿真统计,结果表明:非相干方式的标准误差在几十厘米/秒;相干方式的测速标准误差可以达到毫米/秒的量级;而宽带方式的标准误差可以达到几厘米/秒的量级。相比于非相干方式,宽带方式由于增大了信号时宽带宽乘积而使得测流精度得到了改善。 (3)研究了束控技术。可以看到相移束控技术利用了窄带信号的周期性,此时窄带信号的相移等效为声程差对应的时间延迟。当涉及到宽带信号时,相移束控展宽了束宽且产生了信号失真。针对于此提出了宽带信号时延束控解决方案。仿真结果表明,时延束控技术可以不失真地收发窄带和宽带信号,这就使得ADCP利用束控技术实现换能器宽带信号的收发成为了可能。 (4)研究了走航式ADCP声学换能器的安装误差校准技术。利用走航式ADCP的水底回波数据、姿态仪数据与DGPS数据,提出了基于DGPS的最小二乘方法对声学换能器的三维安装偏角误差进行校准,并建立了完整的参数解算公式。从中可以看出三个安装偏角在坐标转换时是以旋转矩阵的方式起作用,因此没有必要解出具体安装偏角,而是将该旋转矩阵作为未知数直接求解并进一步进行航迹推算。试验结果表明,基于DGPS的最小二乘方法极大地减小了因换能器安装偏角引入的系统误差,可以使测流精度显著提高。
[Abstract]:The acoustic Doppler flow profiler (Acoustic Doppler Current Profiler, hereinafter referred to as ADCP) is a kind of sonar device, which can both measure relative water velocity and measure the relative flow velocity of the sonar equipment,.ADCP can be used for ship positioning and navigation, and can be widely used in the field of ocean and inland river flow measurement. A speed measuring instrument, ADCP, has been used more and more in the river and ocean engineering. The research of acoustic Doppler flow measurement has attracted more and more attention. The main work of this paper is to study several key technologies involved in the acoustic Doppler flow measurement, including the analysis and return of the flow measurement signal. Wave modeling, velocity measurement mode difference and performance estimation, broadband beam control technology and transducer installation calibration technology, etc. specific research content and results are as follows:
(1) based on the theory of resolution, the form of the emission signal is studied. The application of 3 signal forms, such as single carrier frequency rectangular pulse, coherent pulse string and coded coherent pulse string, in Doppler flow measurement is analyzed. The velocity measurement refers to the perception and processing of the Doppler shift information of a large number of scatterers in the beam space. Based on this, the aim is to put forward the purpose. The beam scattering model of the received echo is analyzed, and the underwater echo and the flow layer echo are simulated. The result of analysis and comparison with the experimental data shows the correctness of the beam scattering model. The above work lays a foundation for the performance evaluation of Doppler flow measurement.
(2) the three ways of Doppler flow measurement are summed up, namely, incoherent, coherent and wide-band methods. It can be seen that incoherent modes are suitable for a current application where the thickness requirements are not high and the distance is large. The coherent mode is suitable for shallow water and high resolution flow measurement applications; the broadband mode concentrates the advantages of both. The combination of coherent mode and coherent mode. Based on the established beam scattering model and fast and flexible complex autocorrelation method, the simulation of different flow measurement methods is carried out. The results show that the standard error of the incoherent mode is tens of centimeters per second; the standard error of the coherent mode can reach the magnitude of millimeter / second; and the wideband is wide. The standard error of the method can reach the magnitude of a few centimeters per second. Compared to the incoherent mode, the broadband method improves the accuracy of the flow measurement due to the increase of the wide band width of the signal.
(3) the beam control technology is studied. It can be seen that the phase shift control technology uses the periodicity of the narrow band signal. At this time, the phase shift of the narrow band signal is equivalent to the time delay corresponding to the sound path difference. When the wideband signal is involved, the phase shift beam broadens the beam width and produces the signal distortion. The real results show that the time-delay beam control technology can transmit and receive narrowband and wideband signals without distortion, which makes it possible for ADCP to use beam control technology to transmit and receive broadband signal of the transducer.
(4) the installation error calibration technique of the navigable ADCP acoustic transducer is studied. Using the underwater echo data of the navigable ADCP, the attitude instrument data and the DGPS data, the least square method based on DGPS is proposed to calibrate the three-dimensional installation deflection error of the acoustic transducer, and a complete parameter calculation formula is set up. From this, we can see that three It is not necessary to solve the specific installation deflection, but to solve the rotation matrix as an unknowns and to further carry out the trajectory calculation. The results show that the least square method based on DGPS greatly reduces the system introduced by the installation deflection angle of the transducer. The error of the system can improve the accuracy of the flow measurement.

【学位授予单位】：哈尔滨工程大学
【学位级别】：博士
【学位授予年份】：2010
【分类号】：TB565

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