Artigos de revistas: "Underwater Experiments"

1

Chepurin, Yu A. "Experiments on underwater acoustic tomography". Acoustical Physics 53, n.º 3 (maio de 2007): 393–416. http://dx.doi.org/10.1134/s1063771007030141.

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Zhang, Meiyan, Wenyu Cai, Qinan Xie e Shenyang Xu. "Binocular-Vision-Based Obstacle Avoidance Design and Experiments Verification for Underwater Quadrocopter Vehicle". Journal of Marine Science and Engineering 10, n.º 8 (30 de julho de 2022): 1050. http://dx.doi.org/10.3390/jmse10081050.

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As we know, for autonomous robots working in a complex underwater region, obstacle avoidance design will play an important role in underwater tasks. In this paper, a binocular-vision-based underwater obstacle avoidance mechanism is discussed and verified with our self-made Underwater Quadrocopter Vehicle. The proposed Underwater Quadrocopter Vehicle (UQV for short), like a quadrocopter drone working underwater, is a new kind of Autonomous Underwater Vehicle (AUV), which is equipped with four propellers along the vertical direction of the robotic body to adjust its body posture and two propellers arranged at the sides of the robotic body to provide propulsive and turning force. Moreover, an underwater binocular-vision-based obstacle positioning method is studied to measure an underwater spherical obstacle’s radius and its distance from the UQV. Due to its perfect ability of full-freedom underwater actions, the proposed UQV has obvious advantages such as a zero turning radius compared with existing torpedo-shaped AUVs. Therefore, one semicircle-curve-based obstacle avoidance path is planned on the basis of an obstacle’s coordinates. Practical pool experiments show that the proposed binocular vision can locate an underwater obstacle accurately, and the designed UQV has the ability to effectively avoid multiple obstacles along the predefined trajectory.

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RAO, C. V. K. PRASADA, J. SWAIN, P. V. HAREESH KUMAR, P. V. NAIR, V. N. PANCHALAI e R. K. SHUKLA. "Underwater acoustic propagation experiments during ARMEX". MAUSAM 56, n.º 1 (19 de janeiro de 2022): 281–86. http://dx.doi.org/10.54302/mausam.v56i1.905.

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Two-ship acoustic propagation experiments were conducted in deep waters of the Arabian Sea between 22-25 July and 7-8 August 2002 from onboard INS Sagardhwani and ORV Sagarkanya during ARMEX-I phase. The aim of this experiment was to understand the spatial (up to 30 km) and temporal (up to 24 hr) fluctuations of acoustic intensities within the surface duct. The acoustic transmissions were made from 15m depth at 2.4 KHz and 620 Hz frequencies from one ship and the signals were received at 15m and 40m depths on the second ship. The data were recorded for 10 min duration during each transmission and 30 sec averages were taken for computing acoustic intensities. Simultaneous oceanographic data on temperature (CTD and XBT), currents (ADCP) and waves (SBWR) were also recorded. Steady and homogeneous mixed layer depths of 50-60m offered an ideal environmental condition for surface duct propagation. The sea-state was moderate with significant wave height ranging from 1.5 to 2.3m. The surface and sub-surface currents in the upper 125m water column revealed the predominance of tides with change of current direction at 6 hr intervals. The current speeds were ~ 50 cm/s. The analysis of acoustic data highlighted the importance of temporal variations compared to spatial variations. Around 20 dB fluctuations in acoustic intensity were noticed for temporal variability where as only 7 dB fluctuation was observed for spatial variability.

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Hostombe, Kevin, Tom Avsic e Delf Sachau. "Experiments with coated surfaces to generate sound waves in water". Journal of the Acoustical Society of America 154, n.º 4_supplement (1 de outubro de 2023): A355. http://dx.doi.org/10.1121/10.0023778.

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Sources for underwater sound have a wide range of applications, such as active sonar, navigation, and underwater communication. Particularly, sources with large dimensions l, such as a coating on a boat structure, can be suitable for generating low-frequency underwater sound. In this context, low-frequency refers to wavelength λ in water that fall within the range of 40 l > λ > 1,5 l. In this study, a sample of an active surface for generating underwater sound is created by attaching an array of 18 circular piezoelectric actuators to a glass-fiber reinforced plastic (GRP) plate. The array and the plate are coated with a potting compound that possesses the same acoustic properties as water. This coating physically separates the actuators from the water. The actuators can be individually controlled to analyze different configurations. The radiation characteristics of the active surface are investigated in an underwater test range with free field conditions, specifically for low-frequencies. Additionally, the interaction among the actuators and between the actuators and the GRP-plate are analyzed.

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Zhu, Jifeng, Xiaohe Pan, Zheng Peng, Mengzhuo Liu, Jingqian Guo, Tong Zhang, Yu Gou e Jun-Hong Cui. "A uw-Cellular Network: Design, Implementation and Experiments". Journal of Marine Science and Engineering 11, n.º 4 (13 de abril de 2023): 827. http://dx.doi.org/10.3390/jmse11040827.

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The most significant increase of current task is in the desire for operational flexibility and agility in large-scale underwater network application scenarios in recent years. In order to address the challenging problems in Underwater Wireless Sensor Networks (UWSNs), we propose a large-scale UWSN based on the cellular network architecture called Underwater Cellular (uw-Cellular) network. It is designed especially for application scenarios where a large number of both fixed and mobile network nodes exist in a wide area to monitor the underwater environment. We also design protocols in each network layer in order to ensure reasonable channel sharing, data forwarding path selection and data reliability. The purpose of the simulation study we implement is to evaluate the performance of the CLA routing strategy compared to the VBF and the MFLOOD protocols in the uw-Cellular network. We also deploy a twenty-node uw-Cellular network in the real-world environment as the field case study. The experimental results showed that the Data Rate between any nodes could reach above 500 bps, and the network Average Throughput was no less than 550 bps under various load situations.

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Dunbabin, Matthew, Peter Corke, Iuliu Vasilescu e Daniela Rus. "Experiments with Cooperative Control of Underwater Robots". International Journal of Robotics Research 28, n.º 6 (20 de maio de 2009): 815–33. http://dx.doi.org/10.1177/0278364908098456.

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Ellison, William T., e Karen S. Weixel. "Considerations for designing underwater acoustical playback experiments". Journal of the Acoustical Society of America 96, n.º 5 (novembro de 1994): 3316–17. http://dx.doi.org/10.1121/1.410748.

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Rajendran, R., J. K. Paik e J. M. Lee. "OF UNDERWATER EXPLOSION EXPERIMENTS ON PLANE PLATES". Experimental Techniques 31, n.º 1 (janeiro de 2007): 18–24. http://dx.doi.org/10.1111/j.1747-1567.2006.00130.x.

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Pau, Hans Wilhelm, Mareike Warkentin, Olaf Specht, Helga Krentz, Anne Herrmann e Karsten Ehrt. "Experiments on the mechanism of underwater hearing". Acta Oto-Laryngologica 131, n.º 12 (5 de setembro de 2011): 1279–85. http://dx.doi.org/10.3109/00016489.2011.607845.

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Buckingham, Michael J. "Light aircraft sound for underwater acoustics experiments". Journal of the Acoustical Society of America 140, n.º 4 (outubro de 2016): 3169. http://dx.doi.org/10.1121/1.4969951.

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Chen, Xiao, Mujiahui Yuan, Qi Yang, Haiyang Yao e Haiyan Wang. "Underwater-YCC: Underwater Target Detection Optimization Algorithm Based on YOLOv7". Journal of Marine Science and Engineering 11, n.º 5 (7 de maio de 2023): 995. http://dx.doi.org/10.3390/jmse11050995.

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Underwater target detection using optical images is a challenging yet promising area that has witnessed significant progress. However, fuzzy distortions and irregular light absorption in the underwater environment often lead to image blur and color bias, particularly for small targets. Consequently, existing methods have yet to yield satisfactory results. To address this issue, we propose the Underwater-YCC optimization algorithm based on You Only Look Once (YOLO) v7 to enhance the accuracy of detecting small targets underwater. Our algorithm utilizes the Convolutional Block Attention Module (CBAM) to obtain fine-grained semantic information by selecting an optimal position through multiple experiments. Furthermore, we employ the Conv2Former as the Neck component of the network for underwater blurred images. Finally, we apply the Wise-IoU, which is effective in improving detection accuracy by assigning multiple weights between high- and low-quality images. Our experiments on the URPC2020 dataset demonstrate that the Underwater-YCC algorithm achieves a mean Average Precision (mAP) of up to 87.16% in complex underwater environments.

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Ikeda, Masaaki, Shigeki Hikasa, Keigo Watanabe e Isaku Nagai. "Motion Analysis of a Manta Robot for Underwater Exploration by Propulsive Experiments and the Design of Central Pattern Generator". International Journal of Automation Technology 8, n.º 2 (5 de março de 2014): 231–37. http://dx.doi.org/10.20965/ijat.2014.p0231.

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Although, Autonomous Underwater Vehicles (AUVs) used for investigating underwater ecology have attracted the attention of underwater researchers, conventional AUVs moved underwater by screw propellers generate loud noise thatmay disturb the underwater environments and inhabitants to be observed. This paper discusses the development of an AUV that mimics the manta ray. Central Pattern Generators (CPGs) are also proposed to generate the motion of pectoral fins for Manta robot. The practicality of the robot is checked in underwater propulsion experiments, and the effectiveness of the proposed motion generation method is demonstrated in numerical simulations.

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Ji, Daxiong, Haichao Li, Chen-Wei Chen, Wei Song e Shiqiang Zhu. "Visual detection and feature recognition of underwater target using a novel model-based method". International Journal of Advanced Robotic Systems 15, n.º 6 (1 de novembro de 2018): 172988141880899. http://dx.doi.org/10.1177/1729881418808991.

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Imaging is an important means to explore the ocean for underwater robotics. The diffuse attenuation coefficient of light in water is one of the most important optical properties of seawater. This article presents a model-based method to analyze the causes of distortion of underwater images. We built a platform for underwater image acquisition and target recognition. The model coefficients were calibrated with images captured underwater and in air. Experiments were carried out to verify the designed algorithm and the transmission error model. The experiments show that the presented method works well in improving the accuracy of feature extraction and recognition of underwater targets.

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14

Wang, Di, e Yong Jie Pang. "Research on Disparity Map Generation Method of Underwater Target Based on the Improved SIFT Algorithm". Applied Mechanics and Materials 741 (março de 2015): 701–4. http://dx.doi.org/10.4028/www.scientific.net/amm.741.701.

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In order to obtain the depth information of the underwater target, it’s necessary to generate the disparity map based on binocular vision stereo matching. In the circulation water channel, the stereo matching experiments with underwater target were carried out by using the BM algorithm, SGBM algorithms and SIFT algorithm respectively. Then the characteristics of the disparity maps were analyzed for the three kinds of stereo matching algorithms. Compared with the BM algorithm and SGBM algorithms, the SIFT algorithm has been proved to be more suitable for underwater stereo matching. In order to obtain more feature points of underwater image, it is necessary to improved SIFT algorithm parameter. Underwater image matching experiments were made to determine the principal curvature coefficientγ. The results illustrated that the improvedγis better than the original value for underwater disparity map generation.

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15

Wang, Wuchao, Feihong Yun, Haiting Sun, Liquan Wang, Zheping Yan, Gang Wang, Haixia Gong, Kefeng Jiao, Dong Liu e Xiaoquan Hao. "The Research and Experiments on Contact Sealing Theory of the Underwater Clamp Connector". Machines 9, n.º 11 (30 de outubro de 2021): 262. http://dx.doi.org/10.3390/machines9110262.

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With regard to the sealing structure characteristics of the underwater clamp connector, based on the Hertz contact theory, this article studies the method of solving the extreme value of the radius of curvature on the two curved surfaces at the sealing contact point; first, the method of calculating the extreme value of the radius of curvature at any surface point of the rotary part is obtained, and then the equivalent radius of curvature is solved. Using finite element simulation to study the contact sealing characteristics without considering the edge thickness and width of the sealing gasket, it is verified that the Hertz contact theory is applicable to the metal contact theory of underwater clamp connectors. Then, the sealing simulation with the influence of the detailed dimensions of the sealing gasket is compared with the theoretical result of the direct application of the Hertz contact theory in the underwater clamp connector contact, and the theoretical correction coefficient of metal contact seal for underwater clamp connectors is introduced to solve the errors. The pressure sealing experiment is carried out on six-inch flange and metal sealing gasket, which proves that the coefficient can greatly enhance the theoretical calculation accuracy of the contact sealing of the underwater clamp connector.

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16

Podymova, T. M. "«CHERNOMOR»: TO THE 50th ANNIVERSARY OF THE LONGEST EXPERIMENT". Journal of Oceanological Research 49, n.º 3 (27 de dezembro de 2021): 122–32. http://dx.doi.org/10.29006/1564-2291.jor-2021.49(3).7.

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The work is devoted to a brief description of the preparation and conduct series of scientific experiments in the underwater laboratory “Chernomor” during the period of 1967–1972. The experiments were carried out at the depths from 8 to 30 meters. The place of the experiments is the Southern Branch of the Institute of Oceanology (Gelendzhik). It was unique experiments in the duration of a person’s stay underwater. The maximum depth for “Chernomor” was identified, the optimal methods of organizing work in underwater inhabited houses and the permissible depths for the use of nitrogen-oxygen breathing mixtures were determined. Specialized medical and physiological research was carried out to develop a methodology for the selection and training of aquanauts for future scientific crews. “Chernomor” was the only underwater house in the world that served on the seabed for five seasons in a row. More than 50 scientists from all over the country worked in it in different crews. The work is a tribute to the memory of all enthusiasts and dreamers: designers and developers, engineers and technicians, divers and scientists, everyone involved in those unforgettable events.

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Abdi, Ali, Erjian Zhang e Rami Rashid. "Multichannel signal transmission and reception using compact multichannel underwater communication devices: A unified theory and experimental results from different underwater media". Journal of the Acoustical Society of America 155, n.º 3_Supplement (1 de março de 2024): A317. http://dx.doi.org/10.1121/10.0027648.

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Simultaneous transmission of multiple signals over the same bandwidth allows for optimal utilization of the limited bandwidth in underwater systems and networks. To avoid using multiple spatially separated single-channel projectors, one compact multichannel device can be used instead [E. Zhang, R. Rashid, A. Abdi, “Particle velocity underwater data communication: Physics, channels, system and experiments,” IEEE J. Oceanic Eng. (2023); E. Zhang, R. Rashid, A. Abdi, “Underwater communication experiments for transmitting multiple data streams using a vector acoustic MIMO system: OFDM and FSK modulations,” Proc. Oceans (2023)]. Simultaneous reception of multiple signals using one compact multichannel device is also feasible and improves the communication performance, without using several spatially separated single-channel hydrophones [R. Rashid, E. Zhang, A. Abdi, “On the performance of a new wireless communication compact multichannel underwater receiver using a sphere vector sensor,” IEEE Transactions on Vehicular Technology (2023); R. Rashid, E. Zhang, A. Abdi, “Underwater acoustic signal acquisition and sensing using a ring vector sensor communication receiver: Theory and experiments,” Sensors (2023)]. In this paper, we present various experimental results using a number of compact multichannel underwater devices in different setups, and demonstrate their usefulness for underwater communication. [Work supported in part by NSF, Grant IIP-1500123].

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Kilfoyle, D. B., J. C. Preisig e A. B. Baggeroer. "Spatial Modulation Experiments in the Underwater Acoustic Channel". IEEE Journal of Oceanic Engineering 30, n.º 2 (abril de 2005): 406–15. http://dx.doi.org/10.1109/joe.2004.834168.

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Honary, Ehsan, Frank McQuade, Roger Ward, Ian Woodrow, Andy Shaw, Dave Barnes e Matthew Fyfe. "Robotic experiments with cooperative Aerobots and underwater swarms". Robotica 27, n.º 1 (janeiro de 2009): 37–49. http://dx.doi.org/10.1017/s0263574708004505.

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SUMMARYSciSys has been involved in the development of Planetary Aerobots (arial robots) funded by the European Space Agency for use on Mars and has developed image-based localisation technology as part of the activity. However, it is possible to use Aerobots in a different environment to investigate issues regarding robotics behaviour, such as data handling, limited processing power, and limited sensors. This paper summarises the activity where an Aerobot platform was used to investigate the use of multiple autonomous unmanned underwater vehicles (UUVs) by simulating their movement and behaviour. It reports on the computer simulations and the real-world tests carried out and the lessons learned from these experiments.

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Pu, Lina, Yu Luo, Haining Mo, Son Le, Zheng Peng, Jun-Hong Cui e Zaihan Jiang. "Comparing underwater MAC protocols in real sea experiments". Computer Communications 56 (fevereiro de 2015): 47–59. http://dx.doi.org/10.1016/j.comcom.2014.09.006.

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Caccia, M., G. Bruzzone e G. Veruggio. "Experiments in the Guidance of Unmanned Underwater Vehicles". Underwater Technology 24, n.º 4 (1 de janeiro de 2001): 143–52. http://dx.doi.org/10.3723/175605401783245525.

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Yasukawa, Shinsuke, Yuya Nishida, Jonghyun Ahn, Takashi Sonoda, Kentaro Yanagise, Keisuke Watanabe e Kazuo Ishii. "Field Experiments of Underwater Image Transmission for AUV". Proceedings of International Conference on Artificial Life and Robotics 25 (13 de janeiro de 2020): 171–74. http://dx.doi.org/10.5954/icarob.2020.os23-2.

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Alinei-Poiană, Tudor, David Reţe, Davian Martinovici, Vicu-Mihalis Maer e Lucian Buşoniu. "A BlueROV2-based platform for underwater mapping experiments". IFAC-PapersOnLine 58, n.º 20 (2024): 470–75. http://dx.doi.org/10.1016/j.ifacol.2024.10.098.

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24

Chen, Shuai, Jiadao Wang e Darong Chen. "Wetting Behaviors of an Underwater Oil Droplet on Structured Surfaces". MRS Advances 1, n.º 10 (2016): 667–73. http://dx.doi.org/10.1557/adv.2016.168.

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ABSTRACTIn this study, the wetting behaviors of an underwater oil droplet on structured surfaces were investigated using molecular dynamics simulations and experiments. The wetting states and contact angles of the underwater oil droplet on different hydrophobic surfaces were simulated. The simulation results showed that there were three kinds of equilibrium states on the pillar surfaces: the Wenzel, cross, and Cassie states. Moreover, the equilibrium state of the underwater oil droplet transformed from a Wenzel to Cassie state when the water contact angle decreased. The contact angle of the underwater oil droplet increased as the water contact angle decreased. Furthermore, the wetting behaviors of the underwater oil droplet on rough polytetrafluoroethylene and silicon surfaces were studied in experiments. The experimental results also indicated that the contact angle of the underwater oil droplet increased as the water contact angle decreased, which corresponded well with the simulation results.

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Kawabata, Kuniaki, Fumiaki Takemura, Shota Futenma e Tsuyoshi Suzuki. "On-Line Image Gathering Utilizing an Operated Underwater Movable Sensor Node". Journal of Robotics and Mechatronics 25, n.º 5 (20 de outubro de 2013): 772–77. http://dx.doi.org/10.20965/jrm.2013.p0772.

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The aim of our current research is to deploy a wireless sensor network for observing and collecting data on underwater environments. This paper describes the development of an underwater environment data collection system with a movable sensor node, and it details underwater data observation and collection experiments. Owing to their mobility, movable underwater sensor node can contribute to observation and to the collection of environmental data in small and hidden locations. The systemwe develop, with itsmovable sensor node platform, uses a mounted camera on a wireless network to capture underwater images. Collection experiments for the on-line underwater images with timestamps are carried out using the prototype system. Captured images with timestamps are sent to the host computer via a wireless network while the movable node is operated for the mission. In this paper, our fundamental attempts are discussed and collected data in the experiment are also shown as results.

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Lee, Phil-Yeop, Sung-Kook Park, Soon Tae Kwon, Sangwoong Park, Hunsang Jung, Min-Soo Park e Pan-Mook Lee. "Dynamic Modeling of Autonomous Underwater Vehicle for Underwater Surveillance and Parameter Tuning with Experiments". Journal of Ocean Engineering and Technology 29, n.º 6 (31 de dezembro de 2015): 488–98. http://dx.doi.org/10.5574/ksoe.2015.29.6.488.

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Centelles, Diego, Antonio Soriano-Asensi, José Vicente Martí, Raúl Marín e Pedro J. Sanz. "Underwater Wireless Communications for Cooperative Robotics with UWSim-NET". Applied Sciences 9, n.º 17 (28 de agosto de 2019): 3526. http://dx.doi.org/10.3390/app9173526.

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The increasing number of autonomous underwater vehicles (AUVs) cooperating in underwater operations has motivated the use of wireless communications. Their modeling can minimize the impact of their limited performance in real-time robotic interventions. However, robotic frameworks hardly ever consider the communications, and network simulators are not suitable for HIL experiments. In this work, the UWSim-NET is presented, an open source tool to simulate the impact of communications in underwater robotics. It gathers the benefits of NS3 in modeling communication networks with those of the underwater robot simulator (UWSim) and the robot operating system (ROS) in modeling robotic systems. This article also shows the results of three experiments that demonstrate the capabilities of UWSim-NET in modeling radio frequency (RF) and acoustic links in underwater scenarios. It also permits evaluating several MAC protocols such as additive links online Hawaii area (ALOHA), slotted floor acquisition multiple access (S-FAMA) and user defined protocols. A third experiment demonstrated the excellent capabilities of UWSim-NET in conducting hardware in the loop (HIL) experiments.

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Chen, Shanshan, Sheng Guan, Hui Wang, Ningqi Ye e Zexun Wei. "A New Method of Ship Type Identification Based on Underwater Radiated Noise Signals". Journal of Marine Science and Engineering 11, n.º 5 (30 de abril de 2023): 963. http://dx.doi.org/10.3390/jmse11050963.

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Ship type identification is an important basis for ship management and monitoring. The paper proposed a new method of ship type identification by combining characteristic parameters from the energy difference between high and low frequencies and the sensitive IMF variance mean value based on the modal decomposition of the underwater radiated noise signals using the Ensemble Empirical Mode Decomposition (EEMD) method. The comparison shows that the characteristic parameters of different types of ship, underwater radiated noises are different, whereas those of the same types of ship, underwater radiated noises fall in close range. Validation experiments based on randomly selected ship underwater radiated noise samples manifest that the method is of good separability for the four types of ship underwater radiated noises in the Deepship dataset. It has a higher identification rate than other methods within the distance range of ship underwater radiated noise detection in the dataset. The accuracy of this method tends to decrease with distance in the classification experiments of the ship underwater radiated noises at different distances.

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Praczyk, Tomasz, Piotr Szymak, Krzysztof Naus, Leszek Pietrukaniec e Stanisław Hożyń. "Report on Research with Biomimetic Autonomous Underwater Vehicle — Low Level Control". Zeszyty Naukowe Akademii Marynarki Wojennej 212, n.º 1 (29 de março de 2018): 105–23. http://dx.doi.org/10.2478/sjpna-2018-0006.

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Abstract The paper presents the first part of the final report on all the experiments with biomimetic autono-mous underwater vehicle (BAUV) performed within the confines of the project entitled ‘Autonomous underwater vehicles with silent undulating propulsion for underwater ISR’, financed by Polish National Center of Research and Development. The report includes experiments in the swimming pool as well as in real conditions, that is, both in a lake and in the sea. The tests presented in this part of the final report were focused on low-level control.

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Praczyk, Tomasz, Piotr Szymak, Krzysztof Naus, Leszek Pietrukaniec e Stanisław Hożyń. "Report on Research with Biomimetic Autonomous Underwater Vehicle — Navigation and Autonomous Operation". Zeszyty Naukowe Akademii Marynarki Wojennej 213, n.º 2 (1 de junho de 2018): 53–67. http://dx.doi.org/10.2478/sjpna-2018-0013.

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Abstract The paper presents the second part of the final report on all the experiments with biomimetic autonomous underwater vehicle (BAUV) performed within the confines of the project entitled ‘Autonomous underwater vehicles with silent undulating propulsion for underwater ISR’, financed by Polish National Center of Research and Development. The report includes experiments on the swimming pool as well as in real conditions, that is, both in a lake and in the sea. The tests presented in this part of the final report were focused on navigation and autonomous operation.

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Sakagami, Norimitsu, Mizuho Shibata, Tomohiro Ueda, Kensei Ishizu, Kenshiro Yokoi e Sadao Kawamura. "Numerical and Experimental Analysis of Portable Underwater Robots with a Movable Float Device". Journal of Robotics and Mechatronics 33, n.º 6 (20 de dezembro de 2021): 1234–47. http://dx.doi.org/10.20965/jrm.2021.p1234.

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This report describes a numerical and experimental study of a posture control device based on a movable float for portable underwater robots. We numerically analyzed the static stability using a stability curve and allowable spatial range of a center-of-gravity shift caused by a payload shift or manipulator configuration. Further, we proposed a feedback controller based on direct pitch and roll signals to change and maintain robot posture. We tested the feedback control using a numerical simulator and conducted experiments in a water tank using two portable underwater robots to demonstrate the effectiveness of the movable float device and proposed controller. The results of the field experiments showed that the device and proposed controller can be employed for effective underwater operations of portable underwater robots.

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Li, Guanqing, Shengxiang Huang, Zhi Yin, Nanshan Zheng e Kefei Zhang. "Analysis of the Influence of Refraction-Parameter Deviation on Underwater Stereo-Vision Measurement with Flat Refraction Interface". Remote Sensing 16, n.º 17 (4 de setembro de 2024): 3286. http://dx.doi.org/10.3390/rs16173286.

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There has been substantial research on multi-medium visual measurement in fields such as underwater three-dimensional reconstruction and underwater structure monitoring. Addressing the issue where traditional air-based visual-measurement models fail due to refraction when light passes through different media, numerous studies have established refraction-imaging models based on the actual geometry of light refraction to compensate for the effects of refraction on cross-media imaging. However, the calibration of refraction parameters inevitably contains errors, leading to deviations in these parameters. To analyze the impact of refraction-parameter deviations on measurements in underwater structure visual navigation, this paper develops a dual-media stereo-vision measurement simulation model and conducts comprehensive simulation experiments. The results indicate that to achieve high-precision underwater-measurement outcomes, the calibration method for refraction parameters, the distribution of the targets in the field of view, and the distance of the target from the camera must all be meticulously designed. These findings provide guidance for the construction of underwater stereo-vision measurement systems, the calibration of refraction parameters, underwater experiments, and practical applications.

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Liu, Minghao, Qirong Tang, Yinghao Li, Changhui Liu e Min Yu. "A Chattering-Suppression Sliding Mode Controller for an Underwater Manipulator Using Time Delay Estimation". Journal of Marine Science and Engineering 11, n.º 9 (5 de setembro de 2023): 1742. http://dx.doi.org/10.3390/jmse11091742.

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Underwater manipulators are pivotal in diverse applications, encompassing underwater pipeline repairs, salvage operations, and scientific sampling missions. However, attaining high-precision control mandates the establishment of precise mathematical models. Specifically, developing an accurate dynamic model for the underwater manipulator affixed to underwater robots proves exceptionally demanding, primarily attributed to the uncertainties arising from water currents and the perturbations induced by the vehicle’s motion. This paper presents a novel sliding mode controller with time delay estimation for the high-precision control of an underwater manipulator mounted on an underwater vehicle. The presented controller circumvents the requirement for an exact mathematical model of the underwater manipulator, enhancing its control precision even without detailed modeling information. Moreover, the proposed controller guarantees robustness against uncertain water flow disturbances, effectively preserving the performance of the underwater manipulator under challenging underwater conditions. The proposed controller comprises two key elements. Firstly, a time delay estimator is employed to estimate the system states using feedback from intentional time-delayed control inputs and a pre-designed matrix. Additionally, a specially designed reaching law is incorporated to reduce reaching time and prevent chattering in the sliding mode control. The controller offers several advantages, including easy implementation, insensitivity to model uncertainties, and robustness in the underwater environment. Simulations and experiments demonstrate the ability of the proposed controller to effectively mitigate disturbances, eliminate chattering, and ensure precise trajectory-tracking performance. The experiments are conducted on a fully self-developed 2-degree-of-freedom (2-DOF) underwater manipulator, showcasing the superiority of the proposed controller over other alternatives.

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Rashid, Rami, Erjian Zhang e Ali Abdi. "Underwater Acoustic Signal Acquisition and Sensing Using a Ring Vector Sensor Communication Receiver: Theory and Experiments". Sensors 23, n.º 15 (3 de agosto de 2023): 6917. http://dx.doi.org/10.3390/s23156917.

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Signal acquisition and sensing in underwater systems and applications is typically a challenging issue due to the small signal strength within the background noise. Here, we present a ring vector sensor communication receiver that can significantly improve signal acquisition, by utilizing the underwater acoustic vector field components, compared to the scalar component. The vector sensor receiver is a multichannel receiver that measures particle velocities, which are vector components of the underwater acoustic field, in addition to the scalar field component. According to the combination of our measured experimental data with our signal acquisition performance analysis, the introduced ring vector sensor receiver exhibits higher signal acquisition probabilities for the vector components compared to the scalar component. This can be attributed to certain characteristics of the vector field components. Another advantage of this multichannel receiver is that combining all of its channels can further increase the signal acquisition and packet detection probability in underwater communication systems compared to a single-channel approach.

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Yang, Shuang, e Xiangyang Zeng. "Combination of gated recurrent unit and Network in Network for underwater acoustic target recognition". INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, n.º 6 (1 de agosto de 2021): 486–92. http://dx.doi.org/10.3397/in-2021-1490.

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Underwater acoustic target recognition is an important part of underwater acoustic signal processing and an important technical support for underwater acoustic information acquisition and underwater acoustic information confrontation. Taking into account that the gated recurrent unit (GRU) has an internal feedback mechanism that can reflect the temporal correlation of underwater acoustic target features, a model with gated recurrent unit and Network in Network (NIN) is proposed to recognize underwater acoustic targets in this paper. The proposed model introduces NIN to compress the hidden states of GRU while retaining the original timing characteristics of underwater acoustic target features. The higher recognition rate and faster calculation speed of the proposed model are demonstrated with experiments for raw underwater acoustic signals comparing with the multi-layer stacked GRU model.

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Xu, Hao, Guo-cheng Zhang, Yu-shan Sun e Shuo Pang. "Energy-saving control of long-range autonomous underwater vehicle vertical plane based on human simulating intelligent control method". International Journal of Advanced Robotic Systems 17, n.º 5 (1 de setembro de 2020): 172988142094474. http://dx.doi.org/10.1177/1729881420944744.

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The long-range autonomous underwater vehicle is a new underwater vehicle with capability of stereoscopic observation of the ocean over a wide range of time series. This article proposed a novel control strategy for the long-range autonomous underwater vehicle considering the energy consumption. The vertical motion model of long-range autonomous underwater vehicle and the mathematical model of energy consumption of motion actuators are established in this article, and the maneuverability simulation experiments were carried out to analyze its motion and energy consumption characteristics. A hybrid controller based on human simulating intelligent control and S-plane control is designed. Considering the moment caused by the asymmetry of the hull in motion, an adaptive dynamic control allocation strategy is designed. Simulation experiments are conducted to demonstrate the performance of the scheme proposed.

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Liu, Tao, Lei Wan e Xing Wei Liang. "A Monocular Vision Measurement Algorithm Based on the Underwater Robot". Applied Mechanics and Materials 532 (fevereiro de 2014): 165–69. http://dx.doi.org/10.4028/www.scientific.net/amm.532.165.

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A monocular vision measurement system was proposed based on the underwater robot, which used a single camera as visual sensor and used inertial navigation system to measure position and attitude. In this paper, the processing of underwater target images and the parameter calibration algorithm for visual measurement system were discussed, and then the visual measurement mathematic model of underwater robot was derived using the pose information of the inertial navigation system. Vision measuring principle validation tests for underwater robot have been carried out to detect underwater targets. The experiments verify that the monocular vision measurement algorithm proposed for underwater robot is effective with a preferably accuracy.

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Fu, Qiang, Chao Dong, Kaikai Wang, Qingyi He, Xiansong Gu, Jianhua Liu, Yong Zhu e Jin Duan. "Underwater target laser polarization suppression scattering detection technology and verification". PLOS ONE 19, n.º 6 (25 de junho de 2024): e0305929. http://dx.doi.org/10.1371/journal.pone.0305929.

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The underwater laser polarization detection technology integrates the polarization characteristics of light into the detection and identification of underwater targets. Addressing the challenge of poor accuracy in identifying targets in strong underwater scattering environments, this article proposes an overall scheme for a laser polarization underwater detection device that suppresses scatter using polarized pulse signals. By overcoming key technological barriers in the design of polarization-preserving optical detection systems and utilizing the method of differential amplitude to measure polarization, a laser polarization underwater detection device was developed and underwater polarization detection experiments were conducted, achieving precise detection of underwater targets. The results indicate that the underwater detection device we designed has a root mean square error of less than 5.7% to detect the polarization of the target, demonstrating the accuracy and precision of the underwater detection device.

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Zhang, Bin, Fan Zhang, Yansen Sun, Xiaojie Li, Pei Liu, Liang Liu e Zelang Miao. "Underwater Target Recognition via Cayley-Klein Measure and Shape Prior Information in Hyperspectral Imaging". Applied Sciences 13, n.º 13 (4 de julho de 2023): 7854. http://dx.doi.org/10.3390/app13137854.

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Underwater target detection plays a vital role in various application scenarios, ranging from scientific research to military and industrial operations. In this paper, a detection method via the Cayley–Klein measure and a prior information of shape is proposed for the issue of hyperspectral underwater target identification. Firstly, by analyzing the data features of underwater targets and backgrounds, a background suppression algorithm based on Cayley–Klein measure is developed to enhance the differentiation between underwater targets and backgrounds. Then, a local peak-based algorithm is designed to discriminate potential underwater target points based on the local peak features of underwater targets. Finally, pseudo-target points are eliminated based on the priori shape information of underwater targets. Experiments show that the algorithm proposed is efficient and can effectively detect underwater targets from hyperspectral images.

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Du, Guangming, Wei Zhang, Puyang Zhang e Jingjing Liu. "Numerical Analysis and Experiments on Heavy Oil Heating of Shipwrecks". Journal of Physics: Conference Series 2445, n.º 1 (1 de fevereiro de 2023): 012007. http://dx.doi.org/10.1088/1742-6596/2445/1/012007.

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Abstract Analyze the change of oil temperature flow times during the heating process of wreck heavy oil and the temperature gradient change in the radiation area of the heating source. Using the result guide the heating process of low-temperature underwater oil recovery operations on the wreck. fluid software was used for the analysis process of the numerical simulation, and the physical model test is a simulation test of low temperature underwater electromagnetic heating of heavy oil. In this way, data related to the heating process of heavy oil can be obtained. from the numerical analysis results and the physical model test results, it can be concluded that the numerical simulation results are similar to the experimental verification results. The result can be used for engineering guidance. Due to the physical properties of heavy oil, the oil temperature decays faster during the heating process and the radiation effect of heat source is small, using the electromagnetic heater heats the heavy oil in the oil tank, and the heavy oil can be heated to meet the requirements of the pumping operation in a short time. The calculation model parameters are derived from actual operations. Numerical calculations and physical test results are of great significance to engineering guidance and can guide the underwater cryogenic oil pumping operation of shipwrecks.

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Morozov, Andrey K., e Douglas C. Webb. "Experiments with the Underwater Bubble Low Frequency Sound Resonator". Journal of the Acoustical Society of America 143, n.º 3 (março de 2018): 1762. http://dx.doi.org/10.1121/1.5035772.

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Monteiro, Martín, e Arturo C. Martí. "Using smartphones as hydrophones: two experiments in underwater acoustics". Physics Education 55, n.º 3 (13 de abril de 2020): 033013. http://dx.doi.org/10.1088/1361-6552/ab8102.

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Marino, Alessandro, e Gianluca Antonelli. "Experiments on sampling/patrolling with two Autonomous Underwater Vehicles". Robotics and Autonomous Systems 67 (maio de 2015): 61–71. http://dx.doi.org/10.1016/j.robot.2014.09.030.

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Farhat, C., K. G. Wang, A. Main, S. Kyriakides, L. H. Lee, K. Ravi-Chandar e T. Belytschko. "Dynamic implosion of underwater cylindrical shells: Experiments and Computations". International Journal of Solids and Structures 50, n.º 19 (setembro de 2013): 2943–61. http://dx.doi.org/10.1016/j.ijsolstr.2013.05.006.

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Yu, Jian-cheng, Ai-qun Zhang, Wen-ming Jin, Qi Chen, Yu Tian e Chong-jie Liu. "Development and experiments of the Sea-Wing underwater glider". China Ocean Engineering 25, n.º 4 (dezembro de 2011): 721–36. http://dx.doi.org/10.1007/s13344-011-0058-x.

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Yu, Li, Wenyong Guo, Hantao Chen, Zhe Wu, Chenghao Cao, Xiaofeng Li e Siyu Chen. "Fatigue Performance Analysis of an Underwater Vehicle Rudder Mechanism Considering Arctic Low Temperatures". Applied Sciences 14, n.º 3 (26 de janeiro de 2024): 1057. http://dx.doi.org/10.3390/app14031057.

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For underwater vehicles navigating in Arctic Sea ice-covered waters, fatigue damage is a crucial issue. Many scholars have conducted low-temperature fatigue analysis on low-temperature materials and substrate platforms for ships, and the results show that low temperature is beneficial for improving the mechanical properties of materials. However, they have mainly focused on low-temperature performance experiments and simulation analysis of standard components of materials, and there are very few fatigue life experimental studies on underwater vehicle mechanical structures. This paper conducts experimental investigations on a scaled model of an underwater vehicle rudder mechanism in a polar environment laboratory. Using a comparative analysis method involving simulations and experiments, the low-temperature fatigue test data of the scaled underwater vehicle rudder mechanism are analyzed, and the quantified analysis between fatigue and different low-temperature loading cycles, as well as the influence of icing on the fatigue life, is explored. It is indicated that the Arctic environment can decrease the fatigue life of the underwater vehicle rudder mechanism by deteriorating its material properties. The paper builds the foundation for the fatigue life of an underwater vehicle rudder mechanism in Arctic low-temperature environments.

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Xiong, Kuo, Xuefeng Sun e Qingxin Meng. "Modeling and Control Experiments of a Fishtail-Like Pneumatic Soft Actuator". International Journal of Robotics and Automation Technology 11 (30 de dezembro de 2024): 138–45. https://doi.org/10.31875/2409-9694.2024.11.12.

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As the exploration of deep-sea resources continues, underwater actuators with conventional motors as the main building blocks can no longer meet the increasingly demanding needs. Inspired by bionics, researchers have started to work on underwater actuators with bionic structures. In this study, we designed and implemented a novel Fishtail-like Pneumatic Soft Actuator (FPSA). This innovative actuator configuration is inspired by the tail structure of Body and/or Caudal Fin (BCF) mode fish. The actuator's motion is achieved by controlling the expansion and contraction of the pneumatic soft muscles on both sides. And by constructing an experimental platform, we conducted an in-depth performance characterization, revealing the existence of a frequency-dependent nonlinear hysteresis characteristic of the FPSA. In order to accurately characterize this property, we built a dynamic model of the FPSA and successfully identified the uncertain parameters in the model by applying the nonlinear least squares method. The validation results show that the constructed model can accurately describe the nonlinear hysteresis characteristics of the FPSA. Finally, we successfully realized the high-precision trajectory tracking control of the endpoint of the FPSA using a PID controller. This result provides relevant ideas for the research of novel underwater bionic actuators.

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Martinho, Laura, José Pio e Felipe Oliveira. "Deep Learning-Driven Parameter Adaptation for Underwater Image Restoration". Revista Eletrônica de Iniciação Científica em Computação 22, n.º 1 (6 de julho de 2024): 81–90. http://dx.doi.org/10.5753/reic.2024.4671.

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In this paper we propose a learning-based approach to enhance underwater image quality by optimizing parameters and applying intensity transformations. Our methodology involves training a CNN Regression model on diverse underwater images to learn enhancing parameters, followed by applying intensity transformation techniques. In order to evaluate our approach, we conducted experiments using well-known underwater image datasets found in the literature, comprising real-world subaquatic images and we propose a novel underwater image dataset, composed by 276 images from Amazon turbid water rivers. The results demonstrate that our approach achieves an impressive accuracy rate in three different underwater image datasets. This high level of accuracy showcases the robustness and efficiency of our proposed method in restoring underwater images.

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Wu, Nailong, Meng Wang, Tong Ge, Chao Wu, Deqing Yang e Rui Yang. "Experiments on high-performance maneuvers control for a work-class 3000-m remote operated vehicle". Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 233, n.º 5 (24 de outubro de 2018): 558–69. http://dx.doi.org/10.1177/0959651818806124.

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The challenge of high-performance maneuvers for a deep-ocean underwater vehicle is to design proper controllers and ensure the high accuracy of vehicle state measurements. Current underwater vehicle control solutions are considered to be a unique controller designed to reject the disturbance and noise. However, the controller is based on a precise hydrodynamic model. It requires multiple underwater experiments and complex theoretical analysis. In this article, a hybrid control strategy is presented for the work-class remote operated vehicle. It tries to compose several proportion–integral–differential controllers into one intelligent sequence in terms of task requirements. The proposed approach employs the iterative learning method to improve the performance of the depth holding and the way-point tracking. A remote operated vehicle system weighted about 1.5 tons is provided as a physical platform for scientific investigations using acoustic Doppler current profiler, inertial navigation system, depth sensor, and an altimeter. Results from the simulation and the experiment in the basin show that the proposed approach provides high accuracy at both conditions: tracking way-points with or without ocean currents and disturbances, which show the effectiveness of the proposed approach. In addition, the thrust vector defined for a propeller facilitates the control of underwater vehicle as the thruster configuration changes.

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Liu, Shuang, Hongli Xu, Yang Lin e Lei Gao. "Visual Navigation for Recovering an AUV by Another AUV in Shallow Water". Sensors 19, n.º 8 (20 de abril de 2019): 1889. http://dx.doi.org/10.3390/s19081889.

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Autonomous underwater vehicles (AUVs) play very important roles in underwater missions. However, the reliability of the automated recovery of AUVs has still not been well addressed. We propose a vision-based framework for automatically recovering an AUV by another AUV in shallow water. The proposed framework contains a detection phase for the robust detection of underwater landmarks mounted on the docking station in shallow water and a pose-estimation phase for estimating the pose between AUVs and underwater landmarks. We propose a Laplacian-of-Gaussian-based coarse-to-fine blockwise (LCB) method for the detection of underwater landmarks to overcome ambient light and nonuniform spreading, which are the two main problems in shallow water. We propose a novel method for pose estimation in practical cases where landmarks are broken or covered by biofouling. In the experiments, we show that our proposed LCB method outperforms the state-of-the-art method in terms of remote landmark detection. We then combine our proposed vision-based framework with acoustic sensors in field experiments to demonstrate its effectiveness in the automated recovery of AUVs.

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