Sonar Technology Research Articles

An Underwater Robot Inspection Anomaly Localization Feedback System Based on Sonar Technology

This article introduces an underwater robot inspection anomaly localization feedback system comprising a real-time water surface tracking, detection, and positioning system located on the water surface, while the underwater robot inspection anomaly feedback system is housed within the underwater robot. The system facilitates the issuance of corresponding mechanical responses based on the water surface’s real-time tracking, detection, and positioning, enabling recognition and feedback of anomaly information. Through sonar technology, the underwater robot inspection anomaly feedback system monitors the underwater robot in real-time, triggering responsive actions upon encountering anomalies. The real-time tracking, detection, and positioning system from the water surface identifies abnormal conditions of underwater robots based on changes in sonar images, subsequently notifying personnel for necessary intervention.

Ultrathin and pressure-resistant meta-coating with embedded tree-shaped acoustic black hole for broadband low-frequency underwater sound absorption

Acoustic coating is the main technical means to absorb incoming sound from detection sonars. Considering the advance of sonar technology to cope with low frequencies and the underwater working environment, acoustic coatings are required to provide effective broadband low-frequency sound absorption (SA) under hydrostatic pressure. However, current underwater acoustic coating materials have poor low-frequency broadband SA performance, especially under hydrostatic pressure. Herein, we propose an ultrathin meta-coating with tree-shaped acoustic black hole (ABH) units embedded in an elastomer matrix. Each tree-shaped ABH unit consists of multi-scale ABH plates as scatterers, a center-support column as “trunk” and a frame as “skeleton”. This design combines the rich dynamics of multi-scale ABH plates, the pressure-resistance characteristics of the frame and the column, and the damping of the matrix, to collectively lead to superior performance. Capitalizing on the rich local and coupled large-amplitude local resonances of the unit, and strong resistance to static-pressure-induced deformation, high and quasi-perfect SA is achieved in multiple and ultra-wide low-frequency bands at a deep subwavelength scale under different hydrostatic pressures. Notably, quasi-perfect SA (>0.92) is achieved at 500 Hz with a meta-coating whose thickness is 2 % of the sound wavelength. The quasi-perfect SA is also demonstrated experimentally within 1200–7500 Hz, which persists till 1.0 MPa. The SA is still above 0.6 from 3–10 kHz at 4.5 MPa. For SA model under hydrostatic pressures, hyperelastic constitutive model and pressurized dynamic mechanical parameters of the matrix were established. Numerical results are then verified by experimental tests under different hydrostatic pressures. With both high local-modal densities and hydrostatic-pressure resistance, this design represents a new type of acoustic metamaterials and promises broad underwater applications.

Bio-Inspired Cooperative Control Scheme of Obstacle Avoidance for UUV Swarm

The complex underwater environment poses significant challenges for unmanned underwater vehicles (UUVs), particularly in terms of communication constraints and the need for precise cooperative obstacle avoidance and trajectory tracking. Addressing these challenges solely through position information is crucial in this field. This study explores the intricate task of managing a group of UUVs as they navigate obstacles and follow a given trajectory, all based on position information. A new dynamic interactive topology framework utilizing sonar technology has been developed for the UUVs. This framework not only provides position information for the UUV swarm but also for the surrounding obstacles, enhancing situational awareness. Additionally, a bio-inspired cooperative control strategy designed for UUV swarms utilizing sonar interaction topology is introduced. This innovative method eliminates the need for velocity data from neighboring UUVs, instead relying solely on position information to achieve swarm cooperative control, obstacle avoidance, and trajectory adherence. The effectiveness of this method is validated through extensive simulations. The results show that the proposed method demonstrates improved sensitivity in obstacle detection, enabling faster trajectory tracking while maintaining a safer distance compared to traditional methods. Ultimately, this innovative strategy not only enhances operational efficiency but also enhances safety measures in UUV swarm operations.

Design of acoustic coating for underwater stealth in low-frequency ranges

In this study, it is aimed to protect underwater vehicles against active sonar systems by anechoic coating. A matrix material with close acoustic impedance to water, resistivity to hydrostatic pressure, suitability for the marine environment, and high material loss factor is selected. At low frequencies, the inclusions in different shapes and sizes are added to the matrix material. Since solid inclusions will increase the coating mass considerably, air cavities are preferred as inclusions. More attention is paid to low-frequency absorption, especially below 1 kHz, because of advancing sonar technology. The acoustic performance of the designed models is compared in three frequency ranges: low (below 3 kHz), middle (3–6 kHz), and high (6–10 kHz). The designed models are constructed by considering hydrostatic pressure; hence, volume of air cavities is tried to decrease, while absorption performance is aimed to increase. Therefore, a conical cavity which commonly used in the literature is optimized by chancing its dimensions and location. Also, novel approaches, gong shape cavity, and sandglass cavities are introduced. The results show that, not only cavity shape, but also its location and dimensions are highly influential on absorption performance. High-volume cavities increase the absorption performance at the low-frequency range, but they are not effective at high frequencies. The gong shape and sandglass air cavities show broadband absorption; also, gong shape cavity volume is less than literature models. Thus, its usability increases at deep waters. The results of this study provide novel underwater acoustic coating models for various applications.

Disaster zone human and animal detection using sonar

The research introduces a novel approach to animal and human detection using sonar technology in fields such as disaster management, and under water exploration. Unlike traditional visual methods, sonar systems emit soundwaves to analyze echoes, providing unique advantages in challenging environments. The proposed method involves collecting raw sonar data, followed by preprocessing techniques for noise reduction, signal normalization, and feature extraction. Sonar’s ability to penetrate various media, including water and dense fog, makes it valuable for detecting animals and humans in low-visibility conditions. Additionally, sonar operates effectively in both day and night settings, unaffected by lighting conditions. The proposed detection system will undergo comprehensive experiments using representative datasets and real-world scenarios. Performance metrics, such as detection accuracy, precision, recall, and computational efficiency, will be analyzed and compared with existing approaches. The study showcases the effectiveness and viability of employing sonar technology for animal and human detection tasks, highlighting its unique capabilities in challenging environments.

The Impact of Side-Scan Sonar Resolution and Acoustic Shadow Phenomenon on the Quality of Sonar Imagery and Data Interpretation Capabilities

Side-scan sonar is designed and used for a variety of survey work, in both military and civilian fields. These systems provide acoustic imageries that play a significant role in a variety of marine and inland applications. For this reason, it is extremely important that the recorded sonar image is characterized by high resolution, detail and sharpness. This article is mainly aimed at the demonstration of the impact of side-scan sonar resolution on the imaging quality. The article also presents the importance of acoustic shadow in the process of analyzing sonar data and identifying underwater objects. The real measurements were carried out using two independent survey systems: hull-mounted sonar and towed side-scan sonar. Six different shipwrecks lying in the Baltic Sea were selected as the objects of research. The results presented in the article also constitute evidence of how the sonar technology has changed over time. The survey findings show that by maintaining the appropriate operational conditions and meeting several requirements, it is possible to obtain photographic-quality sonar images, which may be crucial in the process of data interpretation and shipwreck identification.

Applications and analytical approaches using imaging sonar for quantifying behavioural interactions among aquatic organisms and their environment

Abstract For many aquatic animals, distributional patterns, trophodynamic relationships, and reproductive activity are driven by complex biotic and abiotic ecosystem interactions that influence behaviour. Linking behavioural information to environmental stimuli and stressors can, therefore, help to anticipate population and ecosystem responses to changing conditions and inform management. However, behavioural information is challenging to obtain because many sampling gears do not provide adequate spatial or temporal resolution, or potentially alter behaviours. Traditionally, most behavioural studies have been laboratory experiments, while behaviour in situ has often been inferred indirectly. Advancements in imaging sonar technology enable the study of in situ behaviours with the potential to address many understudied relationships. In this review we discuss applications of imaging sonar among a meta-analysis of 155 studies of aquatic organisms in their environments. We evaluate the performance of imaging sonar for studying inter- and intra-specific interactions, associations with complex and sensitive habitats and low-visibility environments, and to evaluate traditional fisheries sampling gears. We examine the data processing and analytical methods used to refine taxonomic resolution, manage time use and autocorrelation through sub-sampling, extract behavioural metrics applied to ecological processes, and for automating abundance estimates and image classification with the goal of providing a resource for researchers.

Assessment and Characterization of Woji Creek Riverbed in Port Harcourt, Rivers State, Nigeria, Utilizing Side Scan Sonar Technology

Woji Creek plays a crucial role in vessel navigation, supports diverse flora and fauna habitats, and sustains local livelihoods. However, human activities and natural events have led to changes in its riverbed over time. Given its significance for coastal stability and geomorphology, there is a pressing need to classify, evaluate, and ensure its environmental sustainability. The primary objective of this study is to employ side scan sonar technology to classify and assess the riverbed of Woji Creek in Port Harcourt, Nigeria. The study aims to classify the riverbed, analyze water depth variations, evaluate navigational suitability, and determine turbidity levels within the creek. To achieve these objectives, the methodology involved acquiring Side-Scan Sonar (SSS) and Sub-bottom profile data. These datasets underwent backscatter processing to create geocoded backscatter images. Feature points were extracted and matched from these images to derive riverbed classification, depth categories, water volume distribution, and river turbidity analysis. The riverbed classification revealed the presence of three primary sediment types: Clayey Silty Sand, Silty Clay, and Silty Sand, each with distinct implications for navigation. Shallow, Moderate, Deep, and Very Deep areas were identified within Woji Creek, each influencing navigational conditions. Additionally, the water volume distribution analysis provided essential insights into depth limitations and route planning.
 Moreover, the assessment of river turbidity identified low, moderate, and high turbidity zones, reflecting water clarity and suspended particle levels. These findings serve as invaluable decision support tools for navigation planning and management in Woji Creek, offering comprehensive insights into the riverbed, depth suitability, volume distribution, and water quality. Leveraging this data can enhance strategic decision-making processes and contribute to the sustainable management of this vital waterway.

Forward looking sonar applications for unmanned vehicles

Unmanned vehicles have the potential to greatly expand our ability to observe dynamic ocean environments. Whereas distributed acoustic sensors can monitor discrete measurement points in time and space, autonomous maritime platforms provide increased flexibility. Acoustic principles are a key component of this functionality and forward looking sonar (FLS) systems can acquire acoustically derived data products while enabling better informed autonomy behaviors based on enhanced situational and environmental awareness. This paper explores applications of forward look sonar technology when integrated with underwater vehicles. Utility of both interferometric and two-dimensional acoustic data products are examined to illustrate the impact on technologies associated with navigational drift mitigation and ocean observation. Results from sonar platform integration and in-water acquisition for development of an underwater terrain-aided navigation (UTAN) particle filter, an acoustic enabled simultaneous localization and mapping (SLAM) algorithm, obstacle avoidance techniques, and seabed observations are presented.

Laser-induced sonar: A promising approach for improved underwater acoustic sensing

This study presents the characteristics of acoustic pressure impulses generated by nanosecond laser-induced filamentation (ns-LIF) of water, focusing on the spatial, temporal, and spectral domains. In the time domain, the peak-to-peak (Pk-Pk) overpressures increase with higher incident optical energy while the arrival time remains constant. Notably, linearly polarized pulses exhibit higher Pk-Pk overpressures than circularly polarized pulses. Acoustic measurements of ns-LIF in water demonstrate a linear correlation between filament size and incident laser energy due to multiple plasma sources along the optical beam propagation. Alongside the temporal information, the spectrogram visualizes broad-spectrum underwater acoustic pressure impulses ranging from 10 to 800 kHz, perpendicular to the optical beam propagation. The low-frequency instantaneous underwater acoustic signals generated by ns-LIF is ∼90 kHz, offering advantages such as extended propagation distances and reduced attenuation in water. In addition to the experimental investigation, finite element analysis is employed to visualize the propagation and interaction of underwater acoustic signals across various interfaces. This integrated approach provides valuable insights into the behavior and characteristics of underwater signals. Eventually, our findings demonstrate the successful development of remote laser-induced sonar technology.

Evolution of performance metrics in the sonar world

The performance of sonar technology, including passive acoustic monitoring, environmental impact assessment and the monitoring of man-made noise sources, is typically characterized by the through-water detection range. This single performance measure depends on the characteristics of the sound sources, the underwater environment and sensing capabilities. Measuring sonar performance is considered critical in the deployment, operation and development of sonar systems, otherwise one is danger of investing in the wrong technology and/or operating this technology incorrectly. It is however already known that using detection range by itself may be insufficient, for instance where the detection and classification tasks are inseparable and counter-detection needs to be taken into account. This talk will describe the different aspects of sonar performance that need to be considered and correctly assessed. In particular, ongoing work to identify better metrics for detection, classification and localization will be outlined. This work is looking initially to borrow metrics from other domains and applications, both for speed of development and retention of cross-domain compatibility, in particular from the area of Machine Learning. Finally, this talk will identify the major areas where further work may still be required.

Subsea Power Cable Health Management Using Machine Learning Analysis of Low-Frequency Wide-Band Sonar Data

Subsea power cables are critical assets for electrical transmission and distribution networks, and highly relevant to regional, national, and international energy security and decarbonization given the growth in offshore renewable energy generation. Existing condition monitoring techniques are restricted to highly constrained online monitoring systems that only prioritize internal failure modes, representing only 30% of cable failure mechanisms, and has limited capacity to provide precursor indicators of such failures or damages. To overcome these limitations, we propose an innovative fusion prognostics approach that can provide the in situ integrity analysis of the subsea cable. In this paper, we developed low-frequency wide-band sonar (LFWBS) technology to collect acoustic response data from different subsea power cable sample types, with different inner structure configurations, and collate signatures from induced physical failure modes as to obtain integrity data at various cable degradation levels. We demonstrate how a machine learning approach, e.g., SVM, KNN, BP, and CNN algorithms, can be used for integrity analysis under a hybrid, holistic condition monitoring framework. The results of data analysis demonstrate the ability to distinguish subsea cables by differences of 5 mm in diameter and cable types, as well as achieving an overall 95%+ accuracy rate to detect different cable degradation stages. We also present a tailored, hybrid prognostic and health management solution for subsea cables, for cable remaining useful life (RUL) prediction. Our findings addresses a clear capability and knowledge gap in evaluating and forecasting subsea cable RUL. Thus, supporting a more advanced asset management and planning capability for critical subsea power cables.

Harmonizing multi-source backscatter data using bulk shift approaches to generate regional seabed maps: Bay of Fundy, Canada

ABSTRACT Advances in sonar technology have revolutionized our ability to map the seafloor, however, differences between legacy and modern data pose challenges when analysing multi-source datasets. Acoustic backscatter recorded via multibeam echosounder is commonly used to characterize the seafloor, but a lack of standardized calibration often yields relative rather than absolute backscatter measurements, hindering comparison between surveys. ‘Bulk shift’ methods have been developed for harmonizing legacy backscatter datasets using overlapping survey areas for relative statistical calibration. This becomes increasingly difficult, though, given many datasets collected over extensive time periods. Backscatter data were collected in the Bay of Fundy, Canada, using multiple sonar systems and vessels over an 18-year period. Here, we propose a reproduceable strategy for harmonizing this large volume of disparate backscatter data using the bulk shift method. A final, harmonized map is presented for the entire Bay of Fundy and is validated using in situ observations from seafloor imagery.

Guest editorial: recent advances in synthetic aperture sonar technology

Abstract[Correction added on 28‐July‐2023, after first online publication: The first affiliation has been changed and bio for Gary Heald has been added in this version.]Compared to traditional sidescan sonar, synthetic aperture sonar (SAS) or Interferometric synthetic aperture sonar (InSAS) systems can provide much higher resolution images across the whole swath. Due to the high resolution and fast mapping rate at a given speed, SAS/InSAS technology is gaining increasing interest within the field of underwater engineering. Navigation, autonomous underwater vehicles (AUVs), sonar technolog and electronics have achieved great progress in recent years. Thanks to these developments, the SAS/InSAS has also been pushed into a new stage. Firstly, the lightweight and compact SAS can be mounted on ever smaller, highly flexible platforms. Secondly, current algorithms are computationally more efficient. Thirdly, the SAS/InSAS images are further improved based on various methods. Last but not least, SAS/InSAS technology is preferred by underwater mapping users due to its high resolution. The current Special Issue is focused on research ideas, articles and experimental studies related to “Recent Advances in Synthetic Aperture Sonar Technology” for development, operating mode, algorithms and applications the various aspects of SAS/InSAS in applications.

Determination of the Canal Discharge Capacity Ratio and Roughness to Assess Its Maintenance Status: Application in Egypt

Waterlogging and soil salinity issues can be handled using surface or subsurface drainage networks, soil bed elevation, and soil and crop management patterns. A properly operating and maintained drainage system is important for both rural and urban inhabitants to protect lives and property from flooding and high groundwater levels, enhance health conditions, and safeguards water purity, soil salinity, and waterlogging. It also supports and increases crop yields and consequently rural incomes. This study assessed the maintenance condition of the main surface drains (Baloza and ELFarama) located in the Tina Plain (50,000 acres) and a portion of the Southeast El-Kantara regions (25,000 acres) in North Sinai, Egypt, based on the values of the Discharge Capacity Ratio (DCR) and Manning’s roughness (n). Ten measurement locations at the drain cross-section were used in the investigation. For the ELFarama Drain, the average values of n and DCR were found to be 0.029 and 86.2%, and for the Baloza Drain, they were 0.032 and 78.6%, respectively. Compared to the design values, the actual Manning’s roughness was higher, indicating that the drainage canals’ capacities had been reduced and that their upkeep was inadequate. In both drains, sedimentation is present and they need to be maintained, according to the hydrographic surveying results for the actual cross-sections compared to the planned cross-sections. A methodology for the channel maintenance method is presented. For removing vegetation and dredging sediment, a long-boom mechanical hydraulic excavator with a bucket is suggested and to be conducted every two years. To the results of this study, the amount of weed infestation in vegetated channels is the main factor that affects Manning’s roughness coefficient value. It is now easier to calculate the proportion of weeds that are submerged in vegetated channels using echo-sound sonar technology. The DCR is an affordable and simple methodology to assess the channel maintenance status for sustainable agriculture.

Research on Target Tracking Simulation System Framework for Multi-Static Sonar Buoys

In the modern war, with the improvement of the target mobility, the increase of the diversity of the target platform, the decrease in the radiation noise of underwater targets, active sonar technology is becoming increasingly important in the underwater target detection. The data processing has also been continuously improved. Especially with the development of information technology in the modern warfare, the target tracking technology is highly valued by various countries around the world, and it has now become a very important field of research. This article proposes a general tracking framework based on the Multi-Static Sonar Buoys System and a variety of tracking algorithms. It lays the foundation for further completing the multi-target tracking simulation system.

Coupling coefficient analysis of composite bar: A new idea for the design of multi-resonant longitudinal transducer

Multi-resonant longitudinal transducers are widely used in sonar technology by exciting multiple resonant modes to extend the operating bandwidth. However, the existing design methods of multi-resonant longitudinal transducers lack unified and effective theoretical guidance, and usually require extensive parameter searches and calculations, so it is not universal and difficult to popularize. Based on the one-dimensional longitudinal vibration theory, the mode analysis and harmonic analysis of the single piezoelectric bar and the composite bar are carried out, and the physical mechanism of the modes not being excited is revealed. Then, starting with the original definition of electromechanical coupling coefficient, the effective coupling coefficients of the composite bar at different resonant modes are given. Finally, a method to adjust the relative strength of resonant modes is proposed based on the relationship between dynamic conductance and effective coupling coefficient. In this paper, electromechanical coupling coefficient is taken as the core factor of transducer design, which holds the key point and provides a new idea for the design of multi-resonant longitudinal broadband transducers.

A High-Efficiency Side-Scan Sonar Simulator for High-Speed Seabed Mapping.

Side scan sonar (SSS) is a multi-purpose ocean sensing technology, but due to the complex engineering and variable underwater environment, its research process often faces many uncertain obstacles. A sonar simulator can provide reasonable research conditions for guiding development and fault diagnosis, by simulating the underwater acoustic propagation and sonar principle to restore the actual experimental scenarios. However, the current open-source sonar simulators gradually lag behind mainstream sonar technology; therefore, they cannot be of sufficient assistance, especially due to their low computational efficiency and unsuitable high-speed mapping simulation. This paper presents a sonar simulator based on a two-level network architecture, which has a flexible task scheduling system and extensible data interaction organization. The echo signal fitting algorithm proposes a polyline path model to accurately capture the propagation delay of the backscattered signal under high-speed motion deviation. The large-scale virtual seabed is the operational nemesis of the conventional sonar simulators; therefore, a modeling simplification algorithm based on a new energy function is developed to optimize the simulator efficiency. This paper arranges several seabed models to test the above simulation algorithms, and finally compares the actual experiment results to prove the application value of this sonar simulator.

Towards a cloud optimized data lake for archived water column sonar data

Due to their value to the ocean science and fisheries management communities, NOAA National Centers for Environmental Information (NCEI), with NOAA Fisheries and University of Colorado Cooperative Institute for Research in Environmental Sciences, established a national archive for water column sonar data. There are currently 210 TB of data freely and publicly available, and that volume is growing rapidly as sonar technology advances. The spatially and temporally diverse archive is accessible through its dedicated data portal and Amazon Web Services. Throughout 2023, we will develop a cloud-optimized data lake of echosounder files representing a ∼100 TB subset of the archive holdings. The echosounder files will be translated from their complex, binary and proprietary file format into zarr files following the Earth Science Information Partners analysis-ready cloud-optimized standards. The resulting data lake will serve as the foundation for building analytical capabilities that can cost-effectively tap into the archive’s sonar holdings, especially when coupled with compute power. The zarr stores will subsequently feed into EchoFish, the archive’s AWS-hosted interactive data visualization platform to facilitate subsetting and prevent the data lake from becoming a data swamp. The progress and potential applications of this NOAA Center for Artificial Intelligence funded project will be presented.

Recent advances in production of renewable energy by SONAR technology with optimized performance

Recent advances in production of renewable energy by SONAR technology with optimized performance