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1.
Initial alignment technology is directly related to the navigation accuracy and startup time of the strap-down inertial navigation system (SINS), and has always been regarded as a challenging focal point in the research field of inertial navigation. This paper makes a comprehensive survey of SINS initial alignment technology, briefly introduces the basic principles of initial alignment without latitude, coarse alignment with known latitude and precise alignment, and points out their advantages, disadvantages and applicable conditions. The research and effects of existing initial alignment error suppression techniques are then analyzed and discussed. Finally, according to the problems of existing initial alignment methods and the development requirements of the carrier, the future research direction of SINS initial alignment technology is predicted. © 2022 Journal of Clinical Hepatology. All rights reserved. 相似文献
2.
[目的]系统地研究初始横倾角对随机横浪下船舶横摇运动响应的影响。[方法]以路径积分法为基础,通过数值求解控制横摇运动微分方程概率属性的Fokker-Planck方程,得到横摇运动响应的概率分布。[结果]结果显示,初始横倾角对船舶横摇运动响应谱的影响有限,但对横摇角概率分布以及横摇运动响应极值分布的影响十分明显,且会造成船舶安全性的显著恶化。[结论]路径积分法可作为研究随机海浪下船舶横摇运动特性的有效数值方法。 相似文献
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红黏土因其具有孔隙比大、易压缩等不良工程特性,常在工程建设中引起一列工程问题.为此,采用聚丙烯纤维对红黏土进行加固,并采用核磁共振(NMR)技术和无侧限抗压强度试验对不同含量纤维加固后土体的宏微观特性进行测试,得到以下结论:1)不同含量纤维加固后红黏土的T2谱形态基本保持一致,均在弛豫时间为1 ms附近出现峰值,且纤维含量为0.2%时,试样内部信号最强;不同含量纤维加筋土内部的孔径主要分布在0.01μm到0.05μm之间,且0.02μm孔径所占比例最大;试样的孔隙度和T2谱峰值面积随纤维含量的增加表现出先增加后减小的趋势,且均在纤维含量为0.2%时到达最大值;2)纤维能够明显增加红黏土的抗压强度,加筋土的抗压强度与纤维含量保持良好的线性增加关系;且随着纤维含量的增加,试样由脆性破坏逐渐表现为韧性破坏特征.3)纤维在土体中起到加筋作用,显著增加了土体间的连接力,且纤维相互交叉连接形成了空间网状结构,限制了土体的变形,使得加筋土抗压强度增加并表现出韧性破坏特征. 相似文献
5.
PANG Yong-jie YOU Guang-xin 《船舶与海洋工程学报》2005,4(4):1-6
Oceanographic survey, or other similar applications should be the applications of multiple AUVs. In this paper, the skill & simulation based hybrid control architecture (S^2BHCA) as the controller's design reference was proposed. It is a multi-robot cooperation oriented intelligent control architecture based on hybrid ideas. The S^2BHCA attempts to incorporate the virtues of the reactive controller and of the deliberative controller by introducing the concept of the "skill". The additional online task simulation ability for cooperation is supported, too. As an application, a multiple AUV control system was developed with three "skills" for the MCM mission including two different cooperative tasks. The simulation and the sea trials show that simple task expression, fast reaction and better cooperation support can be achieved by realizing the AUV controller based on the S^2BHCA. 相似文献
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7.
D. W. Shuttlewood D. A. Crolla R. S. Sharp I. L. Crawford 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1993,22(5):383-396
The development of a mathematical model of a limited bandwidth hydro-pneumatic suspension that is incorporated into a vehicle handling model is described. The combined model is used to evaluate a suitable control strategy for eliminating body roll during a cornering manoeuvre. The philosophy behind the roll control strategy has been to use feedback measurements of the body motions which do not compromise the ride control. A study of the influence of the position of the body motion feedback transducer on the effectiveness of the system to reduce the body roll is presented. Non-linear modelling of the suspension components for a 0.8g cornering manoeuvre has revealed performance limitations. Conclusions are drawn as to the effectiveness of the control scheme. 相似文献
8.
GPS动态定位中自适应卡尔曼滤波模型的建立及其算法研究 总被引:1,自引:0,他引:1
采用描述机动载体运动的“当前”统计模型,建立了一种新的GPS动态定位自适应卡尔曼滤波模型。为了进一步提高滤波器的动态性能,提出一种改进的自适应滤波算法,大大提高了GPS动态定位卡尔曼滤波器的跟踪能力,改善了滤波效果。计算机仿真结果验证了该算法的有效性。 相似文献
9.
ZONG Zhi DONG Guo-hai 《船舶与海洋工程学报》2007,6(2):1-5
Among all environmental forces acting on ocean structures and marine vessels, those resulting from wave impacts are likely to yield the highest loads. Being highly nonlinear, transient and complex, a theoretical analysis of their impact would be impossible without numerical simulations. In this paper, a pressure-split two-stage numerical algorithm is proposed based on Volume Of Fluid (VOF) methodology. The algorithm is characterized by introduction of two pressures at each half and full cycle time step, and thus it is a second-order accurate algorithm in time. A simplified second-order Godunov-type solver is used for the continuity equations. The method is applied to simulation of breaking waves in a 2-D water tank, and a qualitative comparison with experimental photo observations is made. Quite consistent results are observed between simulations and experiments. Commercially available software and Boundary Integral Method (BIM) have also been used to simulate the same problem. The results from present code and BIM are in good agreement with respect to breaking location and timing, while the results obtained from the commercial software which is only first-order accurate in time has clearly showed a temporal and spatial lag, verifying the need to use a higher order numerical scheme. 相似文献
10.
ZHUANG Yuan LIU Zu-yuan 《船舶与海洋工程学报》2007,6(1):53-57
At present, the method of calculating the turbulent flow width around the bridge pier is not given in the "Standard for Inland River Navigation" (GB50139-2004) in China, and the bridge designer usually increases the bridge span in order to ensure the navigation safety, which increases both of the structural design difficulty and the project investments. Therefore, it is extremely essential to give a research on the turbulent flow width around the bridge pier. Through the experiments of the fixed bed and the mobile bed, the factors influencing the turbulent flow width around the bridge pier have been analyzed, such as the approaching flow speed, the water depth, the angles between the bridge pier and the flow direction, the sizes of bridge pier, the shapes of the bridge pier, and the scouring around the bridge pier, etc. Through applying the dimension analytic method to the measured data, the formula of calculating the turbulent flow width around the bridge pier is then inferred. 相似文献