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Underwater Localization for Multiple AUVs Based on Bearing and Range Measurements
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作者 李闻白 刘明雍 郭千桥 《Defence Technology(防务技术)》 SCIE EI CAS 2009年第4期267-272,共6页
A novel underwater localization algorithm for autonomous underwater vehicle(AUVs) is proposed. Taking aim at the high cost of the traditional "leader-follower" positioning,a "parallel" model is ado... A novel underwater localization algorithm for autonomous underwater vehicle(AUVs) is proposed. Taking aim at the high cost of the traditional "leader-follower" positioning,a "parallel" model is adopted to describe the localization problem. Under an unknown-but-bounded assumption for sensor noise,bearing and range measurements can be modeled as linear constraints on the configuration space of the AUVs. Merged these constraints,a convex polyhedron representing the set of all configurations consistent with the sensor measurements can be induced. Estimates for the uncertainty in the position of a single AUV or the relative positions of two or more AUVs can then be obtained by projecting this polyhedron into appropriate subspaces of the configuration space. The localization uncertain region for each AUV can be recovered by an approximation algorithm to realize underwater localization for multiple AUVs. The deduced theoretically and the simulated results show that it is an economical and practical localization method for the AUV swarm. 展开更多
关键词 automatic control technology multiple AUVs underwater localization approximation algorithm uncertain region
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UnderwaterWaste Recognition and Localization Based on Improved YOLOv5 被引量:3
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作者 Jinxing Niu Shaokui Gu +1 位作者 Junmin Du Yongxing Hao 《Computers, Materials & Continua》 SCIE EI 2023年第8期2015-2031,共17页
With the continuous development of the economy and society,plastic pollution in rivers,lakes,oceans,and other bodies of water is increasingly severe,posing a serious challenge to underwater ecosystems.Effective cleani... With the continuous development of the economy and society,plastic pollution in rivers,lakes,oceans,and other bodies of water is increasingly severe,posing a serious challenge to underwater ecosystems.Effective cleaning up of underwater litter by robots relies on accurately identifying and locating the plastic waste.However,it often causes significant challenges such as noise interference,low contrast,and blurred textures in underwater optical images.A weighted fusion-based algorithm for enhancing the quality of underwater images is proposed,which combines weighted logarithmic transformations,adaptive gamma correction,improved multi-scale Retinex(MSR)algorithm,and the contrast limited adaptive histogram equalization(CLAHE)algorithm.The proposed algorithm improves brightness,contrast,and color recovery and enhances detail features resulting in better overall image quality.A network framework is proposed in this article based on the YOLOv5 model.MobileViT is used as the backbone of the network framework,detection layer is added to improve the detection capability for small targets,self-attention and mixed-attention modules are introduced to enhance the recognition capability of important features.The cross stage partial(CSP)structure is employed in the spatial pyramid pooling(SPP)section to enrich feature information,and the complete intersection over union(CIOU)loss is replaced with the focal efficient intersection over union(EIOU)loss to accelerate convergence while improving regression accuracy.Experimental results proved that the target recognition algorithm achieved a recognition accuracy of 0.913 and ensured a recognition speed of 45.56 fps/s.Subsequently,Using red,green,blue and depth(RGB-D)camera to construct a system for identifying and locating underwater plastic waste.Experiments were conducted underwater for recognition,localization,and error analysis.The experimental results demonstrate the effectiveness of the proposed method for identifying and locating underwater plastic waste,and it has good localization accuracy. 展开更多
关键词 underwater image enhancement detection of waste underwater target localization RGB-D camera
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A Survey of Ranging Algorithms and Localization Schemes in Underwater Acoustic Sensor Network 被引量:4
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作者 QU Fengzhong WANG Shiyuan +1 位作者 WU Zhihui LIU Zubin 《China Communications》 SCIE CSCD 2016年第3期66-81,共16页
Underwater Acoustic Sensor Network(UASN) has attracted significant attention because of its great influence on ocean exploration and monitoring. On account of the unique characteristics of underwater environment, loca... Underwater Acoustic Sensor Network(UASN) has attracted significant attention because of its great influence on ocean exploration and monitoring. On account of the unique characteristics of underwater environment, localization, as one of the fundamental tasks in UASNs, is a more challenging work than in terrestrial sensor networks. A survey of the ranging algorithms and the network architectures varied with different applications in UASNs is provided in this paper. Algorithms used to estimate the coordinates of the UASNs nodes are classified into two categories: rangebased and range-free. In addition, we analyze the architectures of UASNs based on different applications, and compare their performances from the aspects of communication cost, accuracy, coverage and so on. Open research issues which would affect the accuracy of localization are also discussed, including MAC protocols, sound speed and time synchronization. 展开更多
关键词 underwater acoustic communication underwater acoustic sensor network localization
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Study of gas shielding stability for underwater local dry welding based on FLUENT 被引量:1
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作者 高辉 焦向东 +1 位作者 周灿丰 朱加雷 《China Welding》 EI CAS 2010年第1期70-75,共6页
The research of gas shielding stability technology, playing a key role in underwater local dry welding, was introduced in this paper. The study includes shielding cup design, gas flow simulation, draining and welding ... The research of gas shielding stability technology, playing a key role in underwater local dry welding, was introduced in this paper. The study includes shielding cup design, gas flow simulation, draining and welding experiments. The commercial computational fluid dynamics ( CFD ) software FLUENT was applied to get and compare the speed and pressure contour images of gas in the three kinds of cup with different intake mode. The computed results show that the cup with stilling chamber on the top has the best shielding performance. The underwater welding experiment of 15 meters proves that the shielding cup with stilling chamber can offer a good dry space, the welding arc can burn stably in it and the weld quality is perfect. The research will facilitate the application of underwater local dry welding technology in the maintenance of nuclear power station widely. 展开更多
关键词 shielding cup gas shielding stability FLUENT underwater local dry welding
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Theory of passive localization for underwater sources based on acoustic ray modeling 被引量:2
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作者 SUN Zhenge (National Laboratory of Acoustics Beijing 100080)MA Yuanliang TU Qingping and JIANG Xiaoquan(College of Marine Engineering, NPU Xi’an 710072) 《Chinese Journal of Acoustics》 1997年第3期250-259,共10页
The theory of passive localization for underwater sources based on acoustic ray channel modeling is discussed. The principles of channel modeling in Ray-theory, determination of eigenrays which connect source and rece... The theory of passive localization for underwater sources based on acoustic ray channel modeling is discussed. The principles of channel modeling in Ray-theory, determination of eigenrays which connect source and receiver, analysis of DOA arriving structure and time delay spectrum arriving structure, their relationship to source location are given in the paper. Source location is estimated by matching measured DOA and TDS to their calculated counterparts. The method of Ray-theory based passive localization features its simplicity, less calculation, short array aperture and robust performance to environment parameters, as compared with those methods based on Normal Mode theory. 展开更多
关键词 Theory of passive localization for underwater sources based on acoustic ray modeling
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