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Walter J. Senus 《Marine Geodesy》2013,36(3):263-288
The current accuracy of sea‐going and airborne gravity measurements is not bounded by the precision of the gravimeter but by the precision with which external parameters such as vehicle velocity (speed), azimuthal heading, and geographic position can be determined. Uncertainties in these parameters are summed up in the Eötvös correction in the reduction of the measured data. This work investigates the suitability of baseline navigation systems, in particular Loran‐C and Omega, to further reduce the uncertainty of the Eötvös correction. Emphasis is placed on the velocity measurement error. A new algorithm is developed which derives velocity based upon the change in hyperbolic (or circular) grid readings, as opposed to the standard change in geographic position technique. A comparative analysis shows the new algorithm to be as precise as the currently used conventional calculation. Further, this simplified technique is accompanied with a 20‐fold reduction in computational complexity. Application of the results presented in this paper to the Loran‐C and Omega systems shows a velocity determination capability of 0.1 knot over a six minute integration time, and 0.05 knot for a 15 minute integration time for Loran‐C. The minimum error attainable in Omega is 0.1 knot when determined over a 17 minute measurement time. Further precision can be gleaned by applying the calculated error as a correction to subsequent velocity calculations. 相似文献
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Pan-Mook Lee Bong-Huan Jun Kihun Kim Jihong Lee Aoki T. Hyakudome T. 《Oceanic Engineering, IEEE Journal of》2007,32(2):327-345
This paper presents an integrated navigation system for underwater vehicles to improve the performance of a conventional inertial acoustic navigation system by introducing range measurement. The integrated navigation system is based on a strapdown inertial navigation system (SDINS) accompanying range sensor, Doppler velocity log (DVL), magnetic compass, and depth sensor. Two measurement models of the range sensor are derived and augmented to the inertial acoustic navigation system, respectively. A multirate extended Kalman filter (EKF) is adopted to propagate the error covariance with the inertial sensors, where the filter updates the measurement errors and the error covariance and corrects the system states when the external measurements are available. This paper demonstrates the improvement on the robustness and convergence of the integrated navigation system with range aiding (RA). This paper used experimental data obtained from a rotating arm test with a fish model to simulate the navigational performance. Strong points of the navigation system are the elimination of initial position errors and the robustness on the dropout of acoustic signals. The convergence speed and conditions of the initial error removal are examined with Monte Carlo simulation. In addition, numerical simulations are conducted with the six-degrees-of-freedom (6-DOF) equations of motion of an autonomous underwater vehicle (AUV) in a boustrophedon survey mode to illustrate the effectiveness of the integrated navigation system. 相似文献
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Abstract During May 1985, a comprehensive GPS and acoustic navigation data set was collected off the Monterey, California coast. Three types of GPS units, a LORAN‐C, and a Miniranger operated concurrently with an OCEANO acoustic system to resolve state‐of‐the‐art accuracies for at‐sea geodetic positioning. This report details the acoustic system which displayed baseline errors of only ±0.25 m over distances to 2600 m. Unfiltered point‐to‐point acoustic navigation errors had a standard deviation of ± 1.25 m, which included ship motion errors in addition to surveying errors. Ninety percent of the stations had navigation standard deviations below ±0.75 m The experiment showed that sub‐meter acoustic surveying is the state‐of‐the‐art. 相似文献
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Abstract The Canadian program for obtaining hydrographic data by aerial methods consists of merging laser bathymeter data with photogrammetric depth data. The main deficiency of the photogrammetric approach for bathymetric measurements is that incomplete stereomodels can occur in areas where little or no land appears. This problem is overcome by using an inertial navigation system (INS) hardmounted to the aerial camera to provide the orientation parameters of position and attitude for each photograph. In order to meet the high accuracy requirement, the INS and other complementary navigation data are processed through a post‐mission track recovery software package. The photogrammetric depths are improved further by merging them with the waterline height information and the laser bathymeter depths using a least‐squares adjustment algorithm. The photogrammetric compilation, depth measurements, shoreline plots, and laser bathymeter integration is done in an analytical stereoplotter. This instrument provides an on‐line refraction correction necessary because of the two‐media mode of operation. Results of a recent pilot project indicate that the integrated system is capable of obtaining depth measurements that agree with echo sounder depth measurements to a precision of .65 m (RMS), and that it can position measured depths to a precision of .74 m (RMS) relative to local control. 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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为了能够精确地拟合天然水域不规则的水陆边界,并能保持有限差分数值计算在矩形网格中进行,本文利用Thompson的数值网格生成技术,在长江口南支七丫口至横沙河段设计了一个椭圆型边界拟合坐标系,并在这个坐标系下建立了平面二维潮流数学模型。通过数值求解此数学模型,实现了计算区域内现状潮流的一个数值模拟,模拟结果表明,模式的设计是成功的。 相似文献
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ROV accurate path following is challenging due to system unmodeled dynamics, disturbances and navigation sensors error. The model uncertainty and disturbances are commonly treated using robust methods such as the sliding mode controller where by incorporating an integral action in the zero tracking error is also guaranteed. Practically, the ROV position data is often computed using low cost inertial measurement unit (IMU) with outputs contaminated with bias and noise. Failure of mission is an immediate consequence of employing such biased sensors. However, the problem can be circumvented using the concept of redundant measurements and data fusion. In this respect, a set of 12 measurements from IMU, magnetometer and Doppler velocity log (DVL) are employed where the last two are aided sensors. The set up is shown to be capable of providing ROV path following with zero (in average) steady state tracking error irrespective of its dynamic parameters, environmental disturbances and erroneous data; as if it enjoys the exact values of the position of the ROV. It means that the combined DVL and magnetometer are sufficient for filtering the IMU biased measurements. Various simulations conducted confirm the results. 相似文献
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Yun X. Bachmann E.R. McGhee R.B. Whalen R.H. Roberts R.L. Knapp R.G. Healey A.J. Zyda M.J. 《Oceanic Engineering, IEEE Journal of》1999,24(3):396-404
A Small Autonomous Underwater Vehicle Navigation System (SANS) is being developed at the Naval Postgraduate School. The SANS is an integrated Global Positioning System/Inertial Navigation System (GPS/INS) navigation system composed of low-cost and small-size components. It is designed to demonstrate the feasibility of using a low-cost strap-down inertial measurement unit (IMU) to navigate between intermittent GPS fixes. The present hardware consists of a GPS/DGPS receiver, IMU, compass, water speed sensor, water depth sensor, and a data processing computer. The software is based on a 12-state complementary filter that combines measurement data from all sensors to derive a vehicle position/orientation estimate. This paper describes hardware and software design and testing results of the SANS. It is shown that results from tilt table testing and bench testing provide an effective means for tuning filter gains. Ground vehicle testing verifies the overall functioning of the SANS and exhibits an encouraging degree of accuracy 相似文献
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Digital color logs of cores from leg 146, holes 893A and 893B, have been taken from images captured during January 1993, within days after the cores were split and described. The images were captured and color analyses performed on the Ocean Drilling Program (ODP) color digital imaging system, which was assembled from relatively inexpensive, off‐the‐shelf components. The images were used to calculate sedimentation rates by fitting chronological data from hole 893A to void‐corrected depths determined by eliminating all voids mapped from the images as >1 cm in length measured downcore. Color measurements were made at intervals between 0.22 and 1.0 mm in length, and then Commission Internationale de l'Eclairage (CIE) 1931 chromaticity values were computed. Results plotted within CIE chro‐maticity space lie in close proximity to the Munsell 5Y hue plane, confirming that the instrumental color analysis technique has produced results consistent with those of the human observers who described colors visually. Significant periodicities occurring at 12, 17, 31, and 90 years correlate with sunspot activity cycles, suggesting that color variations may reflect global climatic forcing functions. Linear correlation between color data sets from holes 893A and 893B suggests that as much as 1.2 m of material present at or near the top of hole 893B may not have been recovered from hole 893A, and that there is a 70‐cm depth discrepancy in the opposite direction at 51.5 m below seafloor (mbsf). The article recommends that the 1931 CIE chromaticity system be used routinely for describing colors of geological materials because it readily accommodates the mathematical manipulations required for statistical and time‐series analyses and avoids the subjectivity and other weaknesses inherent in the Munsell Color System. 相似文献
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文中关注水下潜航器导航定位时,电磁波传播途径中能量衰减、惯导系统长航时积累误差以及提高水下潜航器定位精度等问题。基于倒置的超短基线声学基阵,分析声波往返传播时间(RTT)、平面波近似方法和USBL导航解算方法及其坐标转换过程,结合INS误差方程,建立INS/USBL松组合模型。为进一步提高系统精度、动态性能和抗干扰性,考察USBL的原始斜距、斜距差以及声学基阵的空间分布信息,提出基于USBL原始输出信息的INS/USBL紧耦合组合导航方法。通过MATLAB仿真对导航算法进行验证,结果表明两种算法能充分抑制纯惯导误差随时间积累问题,且有效地估计出姿态、速度和位置误差角;其中紧耦合方法状态估计误差最小,导航参数精度相对松组合提高30%以上,对于提高水下载体导航定位精度、海洋探测具有重大意义。 相似文献
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This paper presents the design and development of an enhanced inertial navigation system that is to be integrated into the Morpheus autonomous underwater vehicle at Florida Atlantic University. The inertial measurement unit is based on the off-the-shelf Honeywell HG1700-AG25 3-axis ring-laser gyros and three-axis accelerometers and is aided with ground speed measurements obtained using an RDI Doppler-velocity-log sonar. An extended Kalman filter has been developed, which fuses together asynchronously the inertial and Doppler data, as well as the differential Global Positioning System positional fixes whenever they are available. A complementary filter was implemented to provide a much smoother and stable attitude estimate. Thus far, preliminary study has been made on characterizing the inertial navigation system-based navigation system performance, and the corresponding results and analyzes are provided 相似文献
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《Oceanic Engineering, IEEE Journal of》2009,34(3):294-306
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Many conventional ship autopilots use proportional integral and derivative (PID) control algorithms to guide a ship on a fixed heading (course-keeping) or a new heading (course-changing). Such systems usually have a gyrocompass as a single sensory input. Modern sea going vessels have a range of navigation aids most of which may be interconnected to form integrated systems. It is possible to employ the navigational data to provide best estimates of state vectors (Kalman filter) and optimal guidance strategies. Such techniques require powerful computing facilities, particularly if the dynamic characteristics of the vessel are changing, as may be the case in a maneuvering situation or changes in forward speed. This paper investigates the possibility of training a neural network to behave in the same manner as an optimal ship guidance system, the objective being to provide a system that can adapt its parameters so that it provides optimal performance over a range of conditions, without incurring a large computational penalty. A series of simulation studies have been undertaken to compare the performance of a trained neural network with that of the original optimal guidance system over a range of forward speeds. It is demonstrated that a single network has comparable performance to a set of optimal guidance control laws, each computed for different forward speeds 相似文献
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ABSTRACTThe rapid acquisition techniques of over- and under-water geoinformation is urgently needed. The Shipborne Over- and Under-water integrated Mobile Mapping System (SiOUMMS) applies plug-in and multi-process network technology to achieve integrated data acquisition and cooperative control of multi-sensors, such as Global Navigation Satellite System, Inertial Measurement Unit, laser scanner, and multi-beam echo sounder. The proposed system can meet the requirements of diverse application scenarios and sensors, allowing for flexibility and scalability. Meanwhile, coarse calibration based on a set of common points and fine calibration using the plane feature constraint are proposed for integratedly obtaining the exterior orientation elements of the laser scanner and the multi-beam echo sounder. Together, these methods provide theoretical support and technical help to the seamless integration of over- and under-water point clouds. Experiments are also described, proving that the root mean square error of over-water point clouds is 0.133 m, the average elevation clearance spacing between adjacent over- and under-water point clouds is less than 0.3 m, and the average horizontal clearance spacing is less than 0.2 m. At the same time, cases in this paper show that SiOUMMS has made important achievements in the integrated measurement of reefs, coastal zone, and inland waterways, and has broad prospects for future applications. 相似文献
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A. George Mourad 《Marine Geodesy》2013,36(4):293-313
Abstract Geographic Information Systems (GIS) have been developed during the last decade. Their land‐based applications range from land information management, urban planning, and environmental research to engineering design and management in the utility and oil industries, geological subsurface analysis, and others. However, applications of GIS in the marine environment are still in the initial stages. This may be due to, among other things, the large marine data sets, the demands of 3D data processing, and the difficulty of ocean data acquisition. This article presents the result of the development of an integrated Marine Geographic Information System (MGIS) for the exploration and development of the Exclusive Economic Zone (EEZ) in the U.S. Pacific Islands region by the Pacific Mapping Center, University of Hawaii. Features such as spatial marine data processing, integration of GIS and mapping systems, 3D data structures, and simulation and animation of marine operations are developed and applied in this system. Since MGIS applications in EEZ are related to many disciplines in marine sciences and engineering, an operational MGIS should be an integrated system in which both basic GIS and marine application systems are combined into a single geo‐referenced system, In addition to other applications, this MGIS has been used: (1) to select a potential deep‐water research site off the island of Hawaii for the State of Hawaii Department of Business, Economic, and Development (DBED); (2) to generate a three‐dimensional database and use it for the navigation and simulation of underwater operations of an underwater research vehicle; and (3) to produce two 2° × 2° mosaic sheets of sonar images, which meet the USGS standard for a sonar image atlas. 相似文献
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GyungNam Jo Hang S. Choi 《Oceanic Engineering, IEEE Journal of》2006,31(3):565-573
This paper discusses the problems related to constructing a receding horizon filter for underwater inertial navigation systems which are subject to external disturbances. Noises are assumed to be bounded, additive, and contained in both state and measurement equations. An estimator is designed according to the sliding-window strategy to minimize the receding horizon estimation cost function. The derived filter is applied to a velocity-aided inertial navigation system. Simulations show that the derived filter is more accurate than the standard Kalman filter (KF) for underwater navigation systems subject to temporary unknown disturbances 相似文献