- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Development of the Underwater Robotics Complex for Laser Cleaning of Ships from Biofouling: Experimental Results
摘要： Periodic cleaning of a hull from biofouling provides high efficiency motion of a vessel. Inspection and cleaning of the underwater part of the vessel afloat is usually carried out by divers aimed with an underwater video system, non-destructive devices for hull structures monitoring, as well as tools for cleaning surfaces from biological fouling and corrosion products. The aim of the study was to develop a new technical tool for remote survey and cleaning of vessels based on the remotely operated uninhabited underwater vehicle (ROV) with build-in underwater laser cleaning equipment. As a result of the research, the prototype of an underwater robotic inspection and laser cleaning system for vessels afloat was designed and developed. The experimental results of the motion control system of the ROV with a hybrid propulsion system both in air and under water are presented. The efficiency of the laser cleaning equipment in stand-alone mode and as part of the vehicle was confirmed. The technical solutions obtained during the development of presented cleaning system allow efficiently and safely inspecting and cleaning the hull without docking of the vessel to be conducted.
关键词： underwater robotics,ships,laser cleaning,biofouling,experimental results
更新于2025-09-23 15:19:57
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High-Speed Plasmonic-Silicon Modulator Driven by Epsilon-near-zero Conductive Oxide
摘要： In this paper, closed-form expressions for the performance of the normalized matched ?lter (NMF) detector are developed speci?cally for the case of large time-bandwidth product, N . As a test case, the task of detecting underwater acoustic signals is considered. While the matched ?lter is the most common detector used, the NMF detector is used in cases where the ambient noise is fast time varying and is hard to estimate. While the performance of the NMF has been studied, no closed-form expressions are given for the detection and false alarm probabilities, and the accuracy of the available approximations greatly deteriorates with N . As a result, evaluating the detection threshold from the receiver operating characteristic requires signi?cant, and sometimes untraceable, numerical calculations. This is speci?cally important for underwater acoustic signals, where due to the low signal-to-noise ratio, N is very large. The analysis performed in this paper solves this problem. The analysis is based on the probability distribution of the NMF to give an exact closed-form (tabulized) expression for the false alarm probability, and a relatively accurate approximation for the probability of detection, both for the large N case. These approximations are found accurate in numerical simulations. Results from an experiment conducted in the Mediterranean sea at the depth of roughly 1000 m validate the analysis.
关键词： false alarm probability,detection probability,detection,Underwater acoustics,matched ?lter,receiver operating characteristic
更新于2025-09-23 15:19:57
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[ACM Press the Thirteenth ACM International Conference - Shenzhen, China (2018.12.03-2018.12.05)] Proceedings of the Thirteenth ACM International Conference on Underwater Networks & Systems - WUWNet '18 - Optical imaging study of underwater acousto-optical fusion imaging systems
摘要： Existing ocean visualization studies are usually conducted independently using either sonar or optical imaging. However, the two methods have their own shortcomings in different engineering applications. Acoustic imaging is not comprehensive enough to show the details of the target, and the perspective of the optical imaging is not extensive enough. Combining the advantages of optics and acoustics, this paper proposes a joint imaging method with acoustic communication-assisted decision-making and optical image stitching, aiming to improve information acquisition efficiency in the ocean visualization process. The joint imaging method relies on sonar technology as the decision-making layer to obtain the position information, then it sends instructions to AUV by acoustic communication and get the details of the target by the AUV-mounted camera which forms the executive layer. Finally, it conducts smoothing and mosaic processing on the optical image. The system can efficiently obtain complete, comprehensive, and detailed ocean visualization information through the advantages of agility of acoustic and accuracy of optics.
关键词： image mosaic,acousto-optical fusion,Underwater imaging,image enhancement
更新于2025-09-19 17:15:36
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[IEEE 2018 Eighth International Conference on Image Processing Theory, Tools and Applications (IPTA) - Xi'an, China (2018.11.7-2018.11.10)] 2018 Eighth International Conference on Image Processing Theory, Tools and Applications (IPTA) - A New Database for Evaluating Underwater Image Processing Methods
摘要： In this paper, we present a new, large-scale database on underwater image, which is called the NWPU underwater image database. This database contains 6240 underwater images of 40 objects. Each object is captured with 6 different levels of turbidity water, 4 lighting conditions and 6 different distances. Among them, we use the underwater images with turbidity value of 0 as Ground-truth. In addition, we captured the shadowless image of the object in the air and clear water. Different from other underwater databases, we capture underwater images with real high turbidity lake water instead of simulating the turbidity of water. This method ensures that the underwater images we captured are as close as possible to the real environment. We have given the database baseline which contains multi-scale Retinex with color restore (MSRCR) algorithms for enhancing images and four commonly used image quality evaluation criteria, including two full-references and two no-references methods. The four image quality evaluation methods include two no-reference and two full reference.
关键词： turbidity,underwater image,image quality evaluation,image enhancement and restoration
更新于2025-09-19 17:15:36
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[IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou, China (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - A combinding PAPR reduction method for DCO-OFDM UOWC
摘要： Optical orthogonal frequency division multiplexing (OFDM) has been adopted in underwater optical wireless communication (UOWC) system, to achieve high data rate and huge bandwidth, as well as to deal with the problem of inter symbol interference. However, it has the problem of high peak-to-average power ratio (PAPR) which will result in serious performance deterioration and increase equipment costs. In this paper, an SLM method is combined with μ-law companding method to reduce the PAPR of UOWC system, which reduce the signal PAPR by 6.8dB and is superior than both the traditional SLM and μ-law companding methods. As for the system bit error rate (BER), the proposed method has better performance than the μ-law companding method. With reasonable tradeoff with the BER, the proposed method has faster convergence than the traditional SLM method.
关键词： peak-to-average ratio,Orthogonal frequency division multiplexing,selective mapping,companding,underwater optical wireless communication
更新于2025-09-19 17:15:36
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[IEEE OCEANS 2018 MTS/IEEE Charleston - Charleston, SC, USA (2018.10.22-2018.10.25)] OCEANS 2018 MTS/IEEE Charleston - Geometric Distortion Correction for the Underwater Images
摘要： Non-metric cameras have been widely used in applications of obtaining geometric information of the underwater objects using either digital photogrammetric approaches or computer vision algorithms. All the underwater images exhibit significant geometric distortions caused by lens distortions and light refraction in underwater imaging, which must be geometrically corrected. In this paper, a geometric distortion correction method for the underwater images is proposed, which uses the sets of distortion parameters obtained through the iterative camera calibration to determine the position relationship between the original images and the final corrected images, and then the gray values of the final corrected images are directly resampled from the original images. The GoPro Hero 5 Black calibration results show that the final accuracies are close to 0 pixel after three iterations; all the final distortion parameters calculated with the iterative calibration method are decreased after several iterations and can be ignored. By contrast, the original image was corrected well with the three sets of distortion parameters calculated with the iterative calibration method. An example shows that the successful generation of point clouds illustrates the effectiveness of the geometric correction. The proposed correcting method provides a technique not only to greatly reduce the distortion through applying a series of distortion parameters but also preserve the image quality through a smart resampling way.
关键词： sets of distortion parameters,once resampling,iterative camera calibration,underwater images,geometric correction
更新于2025-09-19 17:15:36
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[IEEE OCEANS 2018 MTS/IEEE Charleston - Charleston, SC, USA (2018.10.22-2018.10.25)] OCEANS 2018 MTS/IEEE Charleston - Effective Local Backscattering Estimation for Underwater Image Enhancement
摘要： Due to absorption and scattering effects the underwater scenes are characterized by poor contrast, color shifting, additional noise and hazy appearance. In this paper we introduce a novel solution that estimates locally the backscattered light. While in general the existing solutions estimate a global backscattered light value over the entire scene, our local strategy is able to deal effectively to the more challenging non-uniform illumination generated by multiple light-sources. Our solution computes two complementary estimates of the local backscattered light, covering a large and a small patch size. The optimal local backscattered light is computed as the mean of the outputs processed with the small and the large patches while the transmission map, is estimated based on the dark-channel prior (DCP) [1]. Finally, our restored results are computed by simply inverting the optical model using the transmission and the local backscattered light estimates. The qualitative evaluation demonstrates the effectiveness of our approach compared with the recent underwater enhancing techniques.
关键词： enhancement,underwater,dehazing,backscattering
更新于2025-09-19 17:15:36
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[IEEE OCEANS 2018 MTS/IEEE Charleston - Charleston, SC, USA (2018.10.22-2018.10.25)] OCEANS 2018 MTS/IEEE Charleston - High-resolution structured light D sensor for autonomous underwater inspection
摘要： Sensors that can provide detailed 3D data underwater are a prerequisite for enabling autonomous inspection of e.g. seafloor integrity, ocean habitats and subsea installations with unmanned underwater vehicles. Sonars are currently the primary source of 3D data on moving platforms subsea but have limited depth and lateral resolution. Several optical approaches exist such as passive stereo, which have problems with textureless objects, and LIDARs which are slow and provide low lateral resolution. In this work we explore the use of structured light, to achieve high-resolution 3D of objects in an underwater environment. We have adapted a Gray Code Phase Stepping (GCPS) structured light approach to be more robust to the contrast degradation caused by the scattering and attenuation of light in water. The robustness towards increasing water turbidity has been verified in pool experiments. We achieve a depth resolution ranging from 1.4mm to 6.4mm depending on the turbidity when imaging an object at 1.1m distance with a pixel resolution of 1280x1024 at a framerate of 8Hz.
关键词： underwater,turbidity,Gray code,Structured light,3D
更新于2025-09-19 17:15:36
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An autodriven, solar fuel collection for a highly compact, biomimetic-modified artificial leaf without membrane
摘要： Hydrogen fuel generation from water splitting has recently attracted much attention due to its high potential as a clean, renewable energy source. To obtain pure H2 fuel, it is inevitably required to separate the H2/O2 product gas mixture, mainly relying on a membrane system at the current stage. However, this process has inherent durability and cost issues due to contamination, corrosion and its complex configuration. In our current work, we invented a highly compact gas separation and collection method in a water electrolysis system, which is set onto a biomimetically modified electrode without the use of a membrane or external convective flow. A key idea of this smart, compact and self-driven system is gas bubble manipulation by buoyant force and a slippery liquid infused porous surface (SLIPS). With the critical help of the biomimetic SLIPS wall by blocking bubble leakage, H2 and O2 product gases can be separately collected at the corresponding collection port. As a result, we achieved a remarkably improved H2 collection value of over 90 % with high purity using this membrane-free electrolysis system in which the product gases are separated only by their intrinsic buoyancy. This simple but effective gas separation/collection system is also applied to a highly compact, monolithic artificial leaf, in which the solar water splitting is practicably and conveniently conducted in a compact, floatable design.
关键词： artificial leaf,gas separation,underwater bubble manipulation,water splitting,biomimetic surface
更新于2025-09-19 17:15:36
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[IEEE 2019 Photonics North (PN) - Quebec City, QC, Canada (2019.5.21-2019.5.23)] 2019 Photonics North (PN) - Continuous-wave Nd:YVO <sub/>4</sub> laser with conical refraction output
摘要： A particle ?lter (PF)-based robust navigation with fault diagnosis (FD) is designed for an underwater robot, where 10 failure modes of sensors and thrusters are considered. The nominal underwater robot and its anomaly are described by a switching-mode hidden Markov model. By extensively running a PF on the model, the FD and robust navigation are achieved. Closed-loop full-scale experimental results show that the proposed method is robust, can diagnose faults effectively, and can provide good state estimation even in cases where multiple faults occur. Comparing with other methods, the proposed method can diagnose all faults within a single structure, diagnose simultaneous faults, and it is easily implemented.
关键词： fault tolerance,Fault diagnosis (FD),remotely operated underwater vehicle (ROV),switch-mode hidden Markov model (HMM),particle ?lter (PF),underwater navigation
更新于2025-09-19 17:13:59