共查询到19条相似文献,搜索用时 171 毫秒
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低空无人机遥感系统应用日益广泛,其一般搭载传感器为非量测型数码相机,为了保证测量精度必须进行相机检校,以确定其内方位元素和畸变差系数。采用室外三维控制场的DLT(直接线性变换)方法,编制了基于三维DLT方法的非量测型相机的检校软件,该软件具备相机检校参数解算和物方空间坐标解算功能。对于室外三维控制场的测量数据和一海岛的无人机航摄数据,分别使用和不使用相机检校参数进行处理,试验结果显示使用检校参数可以获得更好地测量精度,表明了室外三维检校场方案和编制的相机检校软件是正确可行的,可实现非量测数码相机的检校。 相似文献
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为了解决水下航行器惯性导航误差随时间积累问题,利用地形辅助导航技术进行导航位置修正。由于水下地形的非线性,对基于扩展卡尔曼滤波(EKF)、无迹卡尔曼滤波(UKF)和粒子滤波(PF)3种非线性滤波方法的水下地形辅助导航算法进行研究。针对传统基于单波束声纳量测模型在小起伏地形区域导航精度低、易发散问题,从提高量测地形信息量角度,建立了基于多波束测深声纳的量测模型。使用多波束实测地形数据进行仿真试验,结果表明:无论在粗糙地形区域还是较平坦地形区域,多波束量测模型有效缓解了3种方法易发散问题,提高了导航精度。 相似文献
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针对海洋测量水下拖曳设备位置确定问题,综合考虑拖缆受力、海流影响以及水下拖体的运动性质,建立了水下拖曳设备的位置计算模型,并仿真计算分析了测量船在不同航行状态下拖曳设备位置确定的规律,探讨了不同海流效应对拖曳设备位置确定的影响。仿真计算结果表明,在海洋动态环境作用下,拖缆各方向的偏移明显呈曲线形状,非简单几何运算所确定。测船各方向的运动均可对水下拖体的位置在相应方向产生一定影响,而水下拖体位置的变化量小于测船拖点位置的变化量。海流对水下拖曳设备定位可造成数米的偏差,需进行相应改正。建议可考虑采取船载式ADCP实时测流辅助水下拖曳设备定位的工作模式。 相似文献
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阐述了全站仪在公路施工中的施工平面控制点加密,中桩测设,构造船桥梁施工工细部控制的方法以及精精度,指出了全站仪使用注意事项。 相似文献
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超短基线水声定位系统是海洋工程及水下无人系统中应用较广泛的精密仪器设备,为了提高对水下目标的定位精度,在使用前需对其进行校准。描述了一种基于最小二乘法迭代修正的超短基线水声定位系统校准方法,该方法以最小二乘法为基本原理,通过多次迭代修正的方式,修正基阵与GPS天线之间的平移偏差以及基阵与罗经之间的旋转偏差,从而提高系统的测量精度,最终通过湖上试验验证了该方法的有效性。 相似文献
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为解决多传感器水下目标纯方位跟踪中的传感器测量衰减问题,建立水下目标静态多传感器纯方位跟踪模型,将传感器测量衰减建模为统计特性已知的随机变量,基于融合中心接收到的各水声传感器的原始测量值,设计了一种集中式状态估计器结构,利用最小方差方法推导出最优的集中式目标状态估计增益。通过算例仿真可以得出,所提出的算法能够在水声传感器不做机动的前提下跟踪目标,弥补了单个水声传感器观测性不足的缺点,对比传统的集中式Kalman估计器,具有更高的精度,能够有效解决传感器测量衰减问题。 相似文献
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Rongxin Li Haihao Li Weihong Zou Smith R.G. Curran T.A. 《Oceanic Engineering, IEEE Journal of》1997,22(2):364-375
This paper presents a photogrammetric model for digital underwater video imagery, which has been mostly applied to qualitative analysis in the marine environment. With this model, quantitative analysis of underwater images is possible, e.g., to locate positions, calculate sizes, and measure shapes of objects from image features. The underwater photogrammetric model is based on a three-dimensional optical ray tracing technique which rigorously models imaging systems with multilens configurations and multiple refractions. The calibration procedure with two independent phases has been proven to be efficient in simplifying the computation and improving the calibration accuracy. With the current imaging system configuration and photogrammetric model, an accuracy of 0.8 cm in lateral directions and 1.2 cm along the depth direction for objects located about 2-3 m from the camera system in the object space is attainable. A PC-based digital underwater photogrammetric prototype system has been developed to implement the underwater photogrammetric model 相似文献
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In this paper, we experimentally perform the measurement of the backscattered light intensity from the underwater targets with different size. We develop a simple system, which can easily measure the intensity of the backscattered light, after the laser is scattered at the target underwater. We find that, the signal period is related to the particle size, and the stability of the intensity (standard deviation) varies linearly with changing the particle size. After the calibration, our system can be used to precisely determine the particle size of arbitrary targets. Our method could open a new opportunity for the future underwater detection using femtosecond pulse laser. 相似文献
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电化学方法是测量海水pH值的主要方法之一。针对自主研发的基于铱金属及其氧化物电极的pH传感器,建立了海水环境下仪器标定和数据校正的方法,并在近岸和大洋环境中进行了原位测试的应用。仪器标定包括:(1)依照海水pH分析的标度要求选取适当的标定缓冲试剂;(2)以标准海水替代常用的2-氨基吡啶(AMP)溶液制备标定缓冲体系。数据校正主要包括温度背景校正及误差校正。海区原位测试应用以及与其他同类仪器对比表明,标定体系差异带来的误差可达1.00 pH单位,数据校正可提升测试精度0.10~3.00 pH单位不等。仪器的标定与数据校正方法能有效提高该自研pH传感器的测量精度。 相似文献
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文章依据相关国家标准,结合海洋环境监测站的实际工作需求,针对环境自动观测系统的盐度传感器,提出新的现场校准方法,即直接比较法;根据不确定度来源,分别计算由测量重复性、盐度标准器、测量环境、测量人员和恒温水槽引入的不确定度分量并合成标准不确定度,据此计算扩展不确定度和合成标准不确定度的有效自由度,由此得出盐度传感器现场校准测量结果的不确定度为0.17。本研究提出的盐度传感器现场校准方法更契合海水盐度的变化规律,可实现盐度分量的量值溯源,具有准确度高和溯源途径清晰的特点;不确定度评定方法科学合理,且具有一定的推广价值。 相似文献
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多波束测深技术是目前水下地形测量的主要技术手段,测量平台的瞬时姿态及方位是影响多波束测深系统最终成果准确度的重要因素。GNSS方位辅助惯性导航系统,作为目前应用较为广泛的方位、姿态、及位置综合测量系统,不仅能够提供高精度位置信息,同时也能提供测量平台的瞬时姿态及方位数据,而且因为具有GNSS方位辅助测量,使得最终方位测量结果比传统方位测量精度大大提高,这对于多波束最终测量成果精度提高具有重要意义。文中从GNSS方位辅助惯性导航系统原理及技术优势出发,结合Trimble RTX后处理技术,从姿态测量、方位测量及辅助高程测量方面分析了在多波束水下地形测量中的应用,并以实际测量成果来展现其在水下地形精密测量技术方面的优势,结果显示,定位精度可以达到优于2 cm级别,方位精度可以优于0.01°(依赖于双GNSS天线之间的基线长度),该技术对水下地形测量准确度提升作用显著。 相似文献
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In this paper, a hierarchical system, in which each level is composed by a neural-based classifier, is proposed to recognize objects in underwater images. The system has been designed to help an autonomous underwater vehicle in sea-bottom survey operations, like pipeline inspections. The input image is divided into square regions (macro-pixels) and a neural tree is used to classify each region into different object classes (pipeline, sea-bottom, or anodes). Each macro-pixel is then analyzed according to some geometric and environment constraints: macro-pixels with doubt classification are divided into four parts and re-classified. The process is iterated until the desired accuracy is reached. Experimental results, which have been performed on a large set of real underwater images acquired in different sea environments, demonstrate the robustness and the accuracy of the proposed system 相似文献
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《中国海洋工程》2015,(6)
To achieve accurate positioning of autonomous underwater vehicles, an appropriate underwater terrain database storage format for underwater terrain-matching positioning is established using multi-beam data as underwater terrainmatching data. An underwater terrain interpolation error compensation method based on fractional Brownian motion is proposed for defects of normal terrain interpolation, and an underwater terrain-matching positioning method based on least squares estimation(LSE) is proposed for correlation analysis of topographic features. The Fisher method is introduced as a secondary criterion for pseudo localization appearing in a topographic features flat area, effectively reducing the impact of pseudo positioning points on matching accuracy and improving the positioning accuracy of terrain flat areas. Simulation experiments based on electronic chart and multi-beam sea trial data show that drift errors of an inertial navigation system can be corrected effectively using the proposed method. The positioning accuracy and practicality are high, satisfying the requirement of underwater accurate positioning. 相似文献