共查询到19条相似文献,搜索用时 125 毫秒
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在目标定位过程中,采取窗口分数维方法对初至波进行拾取,确定其到达时刻;采用五元十字阵的传感器阵列布局方式,用提取的初至波建立方程组,通过方程组求解目标所在位置.针对水下目标的测向和测距进行了分析和仿真实验.结果表明,将五元十字阵应用于水下目标被动定位的方法是可行的,其定位误差较小,能够获得较精确的定位结果. 相似文献
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本文根据实际情况建立多途信道和传播模型,由此模型提出了一种利用单水听器进行目标距离事先预知,事后修正的被动测距方法,文章分析了测距误差,在此基础上又提出了利用3个水听器组成的基阵进行运动目标被动跟踪定位的方案,根据该方案建立的定位系统进行海上试验,数据处理结果令人满意,海上试验表明,该方案是一种易于实现而又非常实用的方法。 相似文献
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在测距雷达与经纬仪组成的测量网络中,为了提高目标的跟踪定位能力和获取更多的弹道数据,提出了雷达与经纬仪的联合定位方法.根据雷达与经纬仪实时跟踪目标时的几何关系,推导出目标定位的计算公式.将经纬仪的测角信息和雷达测距信息进行数据融合,得到目标相对于经纬仪的距离,进而确定目标的三维位置信息.分析了定位误差的主要来源,明确了该方法的适用范围.在雷达与经纬仪跟踪远距离目标过程中加以应用.结果表明,雷达与经纬仪间的测量基线越小,该方法的定位误差越接近雷达的测距误差. 相似文献
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提出了装配机器人系统中一种基于视觉引导和超声测距的运动目标跟踪和抓取方法,介绍了运动目标的跟踪原理,采用图像雅可比矩阵进行机器人运动控制,跟踪运动的目标,利用视觉引导技术,获取目标在图像平面中的位置与方位,进行平面跟踪,然后引导超声波测距装置测取目标深度信息。实验结果验证了本文提出的这种方法的可行性和有效性。 相似文献
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多阵方位-频率目标运动分析算法研究 总被引:1,自引:0,他引:1
利用两接收阵的大空间跨度,可以得到对同一个目标有较大差异的DOA估计,利用这些角度差可直接对目标进行三角定位和跟踪。在多阵条件下,即使只有一种目标方位参量,也能在不需要本艇机动下对目标进行跟踪。但当目标处于两阵连线上时,目标仍容易发散。为解决这一问题,我们提出了多阵方位.频率目标运动分析算法,对其可观察性进行了分析。理论分析证明多阵方位-频率TMA的不可观察性条件在多阵纯方位TMA的不可观察性条件[θ1(t)-θ2(t)]=kπ上增加了一个附加条件θ1′=0。这个附加条件不仅弱化了不可观察性的约束条件,还在一定程度上增加了目标跟踪的稳定性。最后给出了三种情况下的计算机模拟.并与多阵纯方位目标运动分析算法作了比较。 相似文献
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针对常规被动声纳的非对称阵布阵方式,对常规的互谱法被动测距进行改进研究,推导出适合远近程测距的测距公式,解决了近程测距模糊问题,进而实现了互谱法改进研究算法的DSP硬件处理。并研究了后置滤波技术,采用基于自适应抵消的参数估计器取代传统的Kalman滤波器。实现了被动声纳的150m和15km之间的全程测距(传统被动声呐仅能对3km~4km以外的目标测距)和对快速目标的跟踪。在近程测距中,实现了潜艇尾部测距缩小盲区。原测距系统在30°~150°范围测距。改造后的互谱测距在3km时,能对20°~160°范围测距,在300m时,能对10°~170°范围测距。测距相对误差小于5%。在近程提高了潜艇的机动性。 相似文献
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单台雷达的定位精度低,致使多台雷达的融合定位精度较低.在多台雷达实时跟踪目标过程中,雷达的测角误差随距离的增加而增大,而测距误差变化较小.为了提高远距离目标的跟踪定位精度,本文提出了组网雷达的交会定位方法.利用至少3台雷达的测距信息,依据雷达与目标的空间几何关系,推导出该方法的数学模型,分析了定位精度的影响因素.利用组网雷达的实际测量数据进行试验,仿真结果表明,距离目标较近时交会法与融合法的定位精度相当,距离目标较远时交会法优于融合法. 相似文献
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运动目标空间位置激光跟踪测量是计量测试领域的前沿课题,该测量系统集激光干涉测距、光电检测、精密机械、计算机及控制系统和现代数值计算于一体,对空间运动目标进行跟踪并实时测量其坐标和姿态。测量范围1-10m,测量精度50μm/m。采用多个激光干涉仪进行冗余设计,对测点造成过定位,通过解最小二乘方程组计算出被测点的坐标。文中论述了多站法跟踪测量的原理并建立了计算坐标的数学理论模型。 相似文献
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基于圆孔阵列调制的“猫眼”目标隐身技术 总被引:2,自引:1,他引:1
针对激光主动探测技术对光电装备造成的探测威胁,在不改变光电装备光学结构以及有限"牺牲"成像质量的前提下,提出利用圆孔阵列的光强调制作用降低光电装备的"猫眼"效应,实现隐身。基于单孔衍射成像原理及空间平移效应,从理论上给出并仿真分析了圆孔阵列远场夫琅和费衍射的光强分布特性,利用实验的方法对圆孔阵列用于"猫眼"目标隐身的效果进行了验证。结果表明,利用圆孔阵列可实现对典型"猫眼"目标回波的光强调制并造成回波损耗,"猫眼"目标隐身效果明显。 相似文献
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利用圆孔阵列光强调制作用可以有效减弱光学窗口的“猫眼”效应,同时也会对“猫眼”目标成像质量产生一定不利影响.考虑到利用调制传递函数(MTF)可对光电仪器成像质量进行综合评价,分别给出了测试望远系统和微光夜视系统MTF的数学模型,利用自行研制的光学仪器MTF数字化检测系统,实现了这两种典型“猫眼”目标MTF的数字化检测.结果表明,圆孔阵列在全空间频率上均使“猫眼”目标的MTF有所下降,且孔径较小、孔阵较密的圆孔阵列对“猫眼”目标MTF的影响较小,这为合理设计圆孔阵列结构以减小对“猫眼”目标成像质量的影响提供了可靠的实验数据. 相似文献
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Zhang J Drinkwater BW Wilcox PD 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2008,55(10):2254-2265
Ultrasonic nondestructive evaluation is used for detection, characterization, and sizing of defects. The accurate sizing of defects that are of similar or less size than the ultrasonic wavelength is of particular importance in assessing structural integrity. In this paper, we demonstrate how measurement of the scattering coefficient matrix of a cracklike defect can be used to obtain its size, shape, and orientation. The scattering coefficient matrix describes the far field amplitude of scattered signals from a scatterer as a function of incident and scattering angles. A finite element (FE) modeling procedure is described that predicts the scattering coefficient matrix of various cracklike defects. Experimental results are presented using a commercial 64-element, 5 MHz array on 2 aluminum test samples that contain several machined slots and through thickness circular holes. To minimize the interference from the reflections of neighboring defects, a subarray approach is used to focus ultrasound on each target defect in turn and extract its scattering coefficient matrices. A circular hole and a fine slot can be clearly distinguished by their different scattering coefficient matrices over a specific range of incident angles and scattering angles. The orientation angles of slots directly below the array are deduced from the measured scattering coefficient matrix to an accuracy of a few degrees, and their lengths are determined with an error of 10%. 相似文献
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经典方位角估计算法中未考虑阵列安装支架对阵列接收信号的影响,实际中阵列安装支架必然会对阵列接收信号产生影响。以环绕在刚性球上的均匀圆阵为阵列模型。在对声场特性的分析中将声学原理和阵列信号处理技术相结合,探讨了存在刚性球形障碍物时的声源方位角估计问题。首先从声学理论出发,分析了刚性球体散射声场及声场分解,讨论了刚性球体对圆阵响应的影响;进而结合阵列信号处理技术,在对声场分解所得到的特征波束空间,利用实值MUSIC算法实现了声源方位角估计。计算机仿真表明,该算法能较好地估计出空间多个声源的方位角,且计算量小,估计精度高,具有解相关声源的能力。 相似文献
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Ozgurluk A Atalar A Köymen H Olçum S 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2012,59(6):1301-1308
The radiation impedance of a capacitive micromachined ultrasonic transducer (CMUT) array is a critical parameter to achieve high performance. In this paper, we present a calculation of the radiation impedance of collapsed, clamped, circular CMUTs both analytically and using finite element method (FEM) simulations. First, we model the radiation impedance of a single collapsed CMUT cell analytically by expressing its velocity profile as a linear combination of special functions for which the generated pressures are known. For an array of collapsed CMUT cells, the mutual impedance between the cells is also taken into account. The radiation impedances for arrays of 7, 19, 37, and 61 circular collapsed CMUT cells for different contact radii are calculated both analytically and by FEM simulations. The radiation resistance of an array reaches a plateau and maintains this level for a wide frequency range. The variation of radiation reactance with respect to frequency indicates an inductance-like behavior in the same frequency range. We find that the peak radiation resistance value is reached at higher kd values in the collapsed case as compared with the uncollapsed case, where k is the wavenumber and d is the center-to-center distance between two neighboring CMUT cells. 相似文献
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Stephens D Kruse D Qin S Ferrara K 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2011,58(8):1590-1602
As the applications of ultrasonic thermal therapies expand, the design of the high-intensity array must address both the energy delivery of the main beam and the character and relevance of off-target beam energy. We simulate the acoustic field performance of a selected set of circular arrays organized by array format, including flat versus curved arrays, periodic versus random arrays, and center void diameter variations. Performance metrics are based on the -3-dB focal main lobe (FML) positioning range, axial grating lobe (AGL) temperatures, and side lobe levels. Using finite-element analysis, we evaluate the relative heating of the FML and the AGLs. All arrays have a maximum diameter of 100λ, with element count ranging from 64 to 1024 and continuous wave frequency of 1.5 MHz. First, we show that a 50% spherical annulus produces focus beam side lobes which decay as a function of lateral distance at nearly 87% of the exponential rate of a full aperture. Second, for the arrays studied, the efficiency of power delivery over the -3-dB focus positioning range for spherical arrays is at least 2-fold greater than for flat arrays; the 256-element case shows a 5-fold advantage for the spherical array. Third, AGL heating can be significant as the focal target is moved to its distal half-intensity depth from the natural focus. Increasing the element count of a randomized array to 256 elements decreases the AGL-to-FML heating ratio to 0.12 at the distal half-intensity depth. Further increases in element count yield modest improvements. A 49% improvement in the AGL-to-peak heating ratio is predicted by using the Sumanaweera spiral element pattern with randomization. 相似文献