水下无人系统学报

Adaptive Bilateral Teleoperation Control Design in Task Space with Guaranteed Parameter Estimation

KUANG Rui, JIA Guotao, LUO Xin, LI Yantian, WANG Xian

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0060

[Abstract](21) [FullText HTML] (7) [PDF 1491KB](0)

Abstract:
In the framework of task-space, adaptive control techniques have been widely applied to bilateral teleoperation systems aiming at achieving precise synchronisation between master and slave robots in terms of Cartesian position and velocity. In order to improve the synchronisation of teleoperation systems, parameter estimation algorithms have been proposed in several studies to compensate for the effects of unknown dynamics. Nevertheless, designs based on traditional adaptive mechanisms have not yet achieved accurate estimation of the system parameters and therefore cannot fully compensate for the unknown dynamics. This paper proposes an adaptive control strategy for task-space teleoperation systems, which innovatively adopts the parameter error as the driving factor for parameter estimation update, and then designs a new adaptive law. The theoretical analysis proves that this strategy can not only achieve the position and velocity synchronization of teleoperation systems in task space, but also achieve the accurate estimation of system parameters at the same time. The convergence performance of parameter estimation is shown through simulation and theoretical analysis to significantly enhance the master-slave synchronization of teleoperation systems. Meanwhile, the effectiveness and superiority of this study are fully verified.

State-of-the-art of Flexible Robotic Arms and Their Underwater Application Prospects

DAI Yicheng, XU Yining, ZHANG Yuzhu, JIANG Zhehao, HE Xinyong, YUAN Han, QU Juntian

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0106

[Abstract](23) [FullText HTML] (8) [PDF 2747KB](3)

Abstract:
The constrained environments characterized by confined spaces and multiple obstacles significantly limit the operational capabilities of traditional rigid robotics. To address tasks in such specialized conditions, flexible robotic arms with slender structural profiles have increasingly become a research focus. This paper systematically reviews the current state of development in flexible robotic arms. It begins by summarizing the structural design of such robotic arms developed domestically and internationally, highlighting their advantages and disadvantages. Then, the discussion centers on modeling methodologies for these manipulators, including kinematics modeling based on geometric structures, dynamics modeling that accounts for force interactions, and model-free approaches. Subsequently, this paper reviews current methods for shape and force sensing in flexible robotic arms, primarily focusing on external sensor-based techniques, especially optical and vision-based shape sensing, as well as tactile sensing methods utilizing flexible sensors. Furthermore, recent advances in control strategies for flexible robotic arms are elaborated, examining the strengths and limitations of various approaches. Finally, this paper discusses the application potential and cases of flexible robotic arms in underwater environments, analyzes the problems to be solved for underwater applications, along with prospects for future research directions.

Damage prediction of reinforced concrete slab under underwater near-field explosion based on machine learning

XUE Zhengchun, Chen Jianyu, SHENG Longhan

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0059

[Abstract](9) [FullText HTML] (8) [PDF 2281KB](1)

Abstract:
Reinforced concrete (RC) slabs are typical load-bearing components of underwater structures, and accurately predicting their damage under underwater explosions remains a critical challenge in protective engineering. Such prediction is essential for structural health monitoring, blast-resistant design, and safety assessment. This study proposes a novel hybrid damage-prediction approach that integrates numerical simulation with machine learning. First, a fluid–structure coupling model was established in LS-DYNA using the Arbitrary Lagrangian–Eulerian (ALE) algorithm to simulate the dynamic response and damage evolution of concrete slabs subjected to different explosive charges and stand-off distances. Subsequently, a deep neural network (DNN)-based prediction model was developed, and its accuracy was significantly improved (exceeding 98%) through optimization of the hidden-layer architecture and neuron configuration, effectively avoiding overfitting. Furthermore, a convolutional neural network (CNN) was introduced for automatic recognition and quantification of damage regions from simulation images, greatly enhancing the efficiency of damage prediction. The results reveal that the damaged areas exhibit geometric regularity within specific loading conditions. The proposed methodology provides a new perspective for underwater explosion damage assessment and offers valuable guidance for the design of protective engineering structures.

Research Status and Application Prospect of Underwater Soft Gripper

LYU Yiwei, HU Haozhe, WANG Zeyu, ZENG Xinpei, WU Mingxin, WANG Chen, XIE Guangming

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0107

[Abstract](37) [FullText HTML] (13) [PDF 12309KB](4)

Abstract:
With the increasing demand for marine resource development and environmental protection, underwater robots have an urgent need for flexible, safe, and efficient soft grasping technology. This paper reviews the research status of underwater soft grippers, and firstly introduces the three actuation methods of underwater soft gripper technology: fluid variable pressure drive, cable drive and smart material drive. In addition, it summarizes the key technological advances of underwater soft grippers, such as bio-inspired design, stiffness adjustment, and underwater sensing. This paper also discusses the unique advantages of soft grippers in minimally invasive sampling, adaptability to multiple types of objects, and deep-sea precision operations. Finally, the future research directions of underwater gripping technology are prospected, which should focus on the development of high-performance underwater smart materials, the integration of multiple actuation methods, and the optimization of efficient energy systems and control systems, to promote the deep-sea and intelligent development of grippers and realize reliable operations in all underwater scenarios.

Design of a Crab-like Underwater Robot Control System

LI Pengji, TIAN Yutao, CHEN Zehan, ZHANG Dapeng

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0090

[Abstract](26) [FullText HTML] (14) [PDF 5342KB](1)

Abstract:
To address issues encountered by underwater robots during operations, such as damage or reduced efficiency due to complex underwater terrains and strong water currents, a robot inspired by the adaptability of crabs to various terrains has been designed. This robot employs a crab-like structure equipped with anti-displacement legs and utilizes superconducting magnetic fluid propulsion and sacrificial anode inspection devices to reduce underwater operation costs and enhance underwater working efficiency. The design aims to assist in the mid to late stages of oil and gas development exploration and maintenance, providing new guidance and recommendations for the laying, inspection, and maintenance of oil and gas pipelines.

Biomimetic Seal Whisker Sensors for Underwater Flow Field Sensing Technologies: A Review

WAN Xing-fu, ZHOU Xin-yue, WANG Si-yuan, WU Meng-Wei, XU Peng, XU Minyi

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0102

[Abstract](30) [FullText HTML] (9) [PDF 9969KB](4)

Abstract:
High-precision underwater flow field sensing is vital for marine resource exploration, autonomous undersea vehicle (AUV) operations, and national defense. However, under low visibility and complex disturbances, conventional optical and acoustic methods face severe limitations in performance and adaptability. Inspired by seal whiskers—whose undulated geometry suppresses vortex-induced vibrations (VIVs) and enhances signal-to-noise ratio (SNR), while the follicle-sinus complex (FSC) enables sensitive detection of subtle hydrodynamic cues—biomimetic whisker sensors have emerged as a promising solution to current bottlenecks. This review systematically summarizes recent progress in this field, covering the biological sensing principles of seal whiskers, as well as the design strategies, material choices, and performance optimization of biomimetic sensors based on optical, resistive, capacitive, piezoelectric, and triboelectric mechanisms. Representative applications on fixed and mobile platforms are discussed, followed by an overview of challenges in stability, miniaturization, and signal processing. This work aims to provide a comprehensive reference for advancing biomimetic flow sensing technologies in both theory and engineering practice.

Recent Advances in Underwater Flexible Sensors

WANG Tingyu, SHI Keyong, WU Mengwei, TANG Wei

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0093

[Abstract](31) [FullText HTML] (17) [PDF 1844KB](5)

Abstract:
With the increasing demand for ocean exploration, underwater flexible sensors have demonstrated significant potential in various underwater applications due to their exceptional compliance and environmental adaptability. In particular, the integration of underwater flexible sensors in complex environments, such as those with high hydrostatic pressure, large strains, and corrosion resistance, plays a crucial role in enhancing the perception capabilities of underwater soft robots, diving equipment, marine exploration devices, and other marine engineering systems. This review summarizes the latest advancements in the application of resistance, capacitance, piezoelectric, triboelectric, optical fiber, and electromagnetic sensing mechanisms in underwater environments. By comparing the advantages and challenges of different sensing mechanisms, this paper provides a comprehensive overview of their developments in underwater manned systems and soft robots, with a focus on innovative applications in deformation, posture, tactile, and flow field sensing. Furthermore, this paper highlights that overcoming the bottlenecks in adaptability and long-term reliability of underwater flexible sensors requires a focus on multimodal integration, intelligent decoupling, and biomimetic integration technologies. These findings offer new insights and potential solutions for the future development of underwater flexible sensors.

Optimization Technology of Combat Effectiveness Evaluation Indexes for the Underwater Equipment System

ZHANG Zhenhua, WANG Haining, SONG Xiaoxuan, BAI Jun

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0046

[Abstract](24) [FullText HTML] (9) [PDF 695KB](3)

Abstract:
Aiming at the effectiveness evaluation problems caused by the high complexity of the anti-submarine equipment system, the strong stage characteristics of tasks, and the dynamically changing battlefield environment, this paper proposes a hierarchical effectiveness evaluation method. By constructing an index normalization model for multiple scenarios, a dynamic mapping mechanism of "scenario-index-weight" is established. Redundant indicators are streamlined by combining with the maximum uncorrelated criterion, and the optimization of weights is achieved based on simple geometric calculations and the combination weighting method of maximizing the deviation. Experiments show that this method not only ensures the reasonable and accurate evaluation, but also significantly improves the calculation efficiency. It provides data-driven decision support for the system optimization and operational deployment of underwater equipment in complex combat environments, and has reference value.

Extraction Method for Multiple Feature Models of The Magnetic Field from Marine Targets

DONG Hao, ZHANG Yu, QIN Wei, CHEN Shuai

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0047

[Abstract](19) [FullText HTML] (13)

Abstract:
Maritime targets cause distortions in the surrounding magnetic field, forming the target's magnetic signature. This signature is widely used in target detection, ship stealth. Addressing the issue of multi-modal feature extraction for target magnetic fields, a magnetic anomaly signal model under an encounter scenario is established based on the magnetic signal generation mechanism. This model analyzes the characteristic differences between different source magnetic fields of the same target. A magnetic feature-based variational mode decomposition (VMD) method is proposed, which optimizes the parameters for decomposing the target's magnetic signal. Based on frequency characteristic differences, it separates the static magnetic field and the shaft-rate magnetic field signal. Actual marine interference signals are collected and combined with simulated target signals to validate the decomposition method. Compared with traditional algorithms, the proposed method achieves signals with a higher signal-to-noise ratio and lower error. Finally, the magnetic field of a ship was measured in practice. Using the measured data, the effectiveness of the proposed decomposition method for extracting maritime target features was validated.

Maximum efficiency tracking and wide power regulation composite control method for underwater MC-WPT system

LI Hao, QIAN Linjun, LI Shenghong, WANG Feng, LI Zhiqiang

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0065

[Abstract](15) [FullText HTML] (12) [PDF 2368KB](1)

Abstract:
Addressing the requirements of maximum efficiency transmission and varying power output for underwater unmanned vehicle wireless charging systems, a composite control method that can both achieve maximum efficiency tracking and adjust output power is proposed in this paper. Firstly, the influencing factors of transmission power and efficiency in underwater MC-WPT systems are analyzed. Focusing on the seawater medium environment, the issue of eddy current loss in the coupling mechanism needs to be considered. A joint simulation method of magnetic field and circuit is adopted to obtain the equivalent resistance of the coupling mechanism's eddy current, and the optimal load is calculated. Secondly, impedance matching is achieved by cascading Cuk converters at the receiving end to track maximum efficiency, while wide power range adjustment is realized by controlling the phase shift angle of the inverter at the transmitting end. In this composite control method, the efficiency and power control loops do not interfere with each other. Finally, a system simulation model was constructed, and an experimental prototype of the MC-WPT system was built. The correctness of the theoretical analysis and proposed methods in the paper was verified through simulation and experiment. The experimental results showed that after introducing the maximum efficiency tracking method, the optimal efficiency could be achieved under various load conditions. Taking the output of 2 kW and a load of 5 Ω as an example, the efficiency increased from 84.8% to 93.1%. In the experiment, when the input voltage varied, power output ranging from 1 kW to 3 kW was achieved at maximum efficiency by adjusting the phase shift angle. Both simulation and experiment demonstrate that the system can maintain high efficiency operation at all times and adjust the output power in real-time according to demand.

Construction of Intelligent Equipment Capability Evaluation System

PENG Jinghui, NI Yuantao, HOU Ping, ZHAO Miao, QU Lintao

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0063

[Abstract](20) [FullText HTML] (9) [PDF 623KB](7)

Abstract:
The development of artificial intelligence promotes the transformation of the form and mode of war, and intelligent equipment has become the protagonist of intelligent war. In order to measure the capability of equipment scientifically, aiming at the shortcomings of the current assessment of intelligent equipment, the research is carried out around the methods, indicators, elements and systems. Firstly, summarized the evaluation methods of equipment capability, and sorted out the ideas of intelligent equipment evaluation. Secondly, analyzed the capability index of intelligent equipment from the aspects of capability requirements, performance parameters and task capability. Then, refined the intelligent multi-dimensional capability, and given the elements of intelligent equipment capability evaluation. Finally, six standard modules are refined, and a capability evaluation system for intelligent equipment is constructed.

Underwater Adaptive End Effector Based on Biomimetic Grasping Mechanism of Soft-rigid Interaction

ZHONG Shuqiao, SONG Chaoyang, ZHOU Zhiyuan, WAN Fang, LIN Jian

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0092

[Abstract](26) [FullText HTML] (15) [PDF 1705KB](2)

Abstract:
Underwater unmanned systems, vital to national marine technology, are extensively used in resource exploration, research, and defense. The performance of their end-effectors-underwater grippers is crucial to mission success. Existing grippers often fail to combine high load capacity with adaptability, or to balance “non-destructive grasping” with “firm holding”. Inspired by lobster claws, this study proposes a novel bio-inspired hybrid rigid-soft gripper, the “LobSTER Gripper”. It uses a bionic reversed structure: soft fingers with passive compliance provide gentle initial contact, while internal rigid digits ensure secure holding, enabling phased stiffness adaptation without complex control. Tests show a 100% success rate under pose disturbances, significantly outperforming conventional rigid grippers (80%). The design offers a low-cost, reliable, and easily transferable solution for adaptive underwater grasping with broad application potential.

Analysis of Spatiotemporal Characteristics for Underwater Target's Comprehensive Magnetic Field

DONG Xinyu, WANG Honglei, YANG Yixin

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0073

[Abstract](39) [FullText HTML] (17) [PDF 1322KB](3)

Abstract:
The accurate modeling of the radiated magnetic field of underwater targets is of great significance to the development of magnetic detection technology. The target radiation magnetic field mainly consists of magnetic anomaly field and wake magnetic field, while the magnetic sensor usually receives the total magnetic field signal during detection. Current research mainly focuses on the simulation analysis of magnetic anomaly fields and wake magnetic fields respectively, lacking systematic studies on the radiation mechanism, propagation model, spatiotemporal characteristics and attenuation laws after their integration. This makes it difficult to effectively promote the development of underwater target magnetic detection technology. To this end, this paper proposes a method for analyzing the spatiotemporal characteristics of the comprehensive magnetic field of underwater targets. COMSOL and MATLAB software are used to model and study the magnetic anomaly field and wake magnetic field respectively. By integrating the two magnetic field models through vector superposition, the spatiotemporal characteristics and attenuation laws of the target's radiated magnetic field are comprehensively analyzed, which improves the solution efficiency and model accuracy of the comprehensive magnetic field. At the same time, it reveals the specific influence law of the target motion parameters on the comprehensive magnetic field, providing theoretical support for the high-precision modeling of underwater target magnetic detection.

Key Technologies of Underwater Wireless Optical Communication for UUV Cluster Applications

ZHU Yunzhou, HU Xujuan, WANG Xiaobo, YANG Yi, ZHANG Jianlei, HE Feng-tao

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0120

[Abstract](29) [FullText HTML] (12) [PDF 7617KB](3)

Abstract:
Unmanned undersea vehicle (UUV) swarm cooperation is a core capability for future marine operations, highly dependent on stable and efficient underwater communication technology. Underwater Wireless Optical Communication (UWOC), with its high bandwidth and low latency, serves as an ideal solution for medium-to-short-range underwater linking. However, the dynamic alignment and channel fading caused by high-speed UUV motion significantly restrict its practical application. To address these challenges, this study proposes an integrated UWOC system framework aimed at the “communication on the move” (COTM) requirement of UUV clusters. The system employs a cooperative design of wide-angle panoramic high-power transmission and multi-channel diversity high-sensitivity reception, overcoming the technical bottlenecks of link maintenance and stable signal reception under motion conditions. A prototype was developed and experimentally validated: in water with an attenuation coefficient of approximately 0.54 m⁻¹ over a distance of 15.5 m, the system achieved stable communication at 2 Mbit/s (bit error rate is less than 10⁻³); under conditions of 10 m distance, attenuation coefficient of about 0.85 m⁻¹, and UUV speed of 5 kn, the packet loss rate remained below 2%. This work demonstrates the preliminary application of UWOC technology on highly maneuverable multi-degree-of-freedom UUV platforms, providing effective technical support for UUV swarm coordination and high-speed information exchange.

Based on One-dimensional Attention Mechanism Convolutional Neural Network for Underwater Acoustic Target Recognition

ZHANG Yufei, ZHAO Mei, HU Changqing, GUO Zheng

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0053

[Abstract](20) [FullText HTML] (7) [PDF 1531KB](1)

Abstract:
To address the issues of complex network parameters and high computational costs in deep learning-based underwater acoustic target recognition models, this study proposes a lightweight one-dimensional convolutional neural network with an attention mechanism for underwater acoustic target recognition.First, during the feature extraction stage, spectral, Mel-spectrogram, chroma, spectral contrast, and tonal features are selected and reconstructed into a fused one-dimensional hybrid feature. Next, the hybrid feature is processed by a multi-scale residual convolution (MRC) module to enhance feature representation across different scales. Simultaneously, a Convolutional Block Attention Module (CBAM) is introduced to adaptively adjust feature importance through channel and spatial attention mechanisms, improving the model's focus on critical regions.Experimental results show that the proposed model achieves an average recognition accuracy of 98.58% on the ShipsEar dataset, demonstrating excellent classification performance. Compared to existing models, this model significantly reduces computational complexity. Further validation on real-world data from the East China Sea confirms its effectiveness.

Design and verification of end-face bidirectional self-sealing structure

LI Kaifu, GUAN Youliang, JIG Guotao, JIANG Quan, LIU Yunfan, JIAO Peng

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0020

[Abstract](16) [FullText HTML] (7) [PDF 4562KB](2)

Abstract:
In order to achieve the bidirectional sealing of the end face of underwater large-caliber hatch covers and solve the problem of large reaction force of the sealing ring during the closing process. Innovatively combining the good self-sealing advantage of the tongue-shaped cross-section and the anti-ejection structure of the dovetail structure, five specifications of "high-low tongue" bidirectional self-sealing rings were designed. The stress, deformation, contact pressure and other simulation analyses of the sealing rings were carried out using ABAQUS, and a prototype was trial-produced to conduct internal and external pressure sealing tests as well as loosening and tightening torque tests. The test results are consistent with the results of finite element analysis. The "high-low tongue" sealing ring can achieve bidirectional self-sealing of the end face under low reaction force. The larger the chamfer of the "tongue-shaped" structure, the higher the contact stress value between the sealing ring and the sealing surface, and the better the sealing effect; the smaller the difference in the height of the "tongue" on both sides of the sealing ring, the lower the height of the middle platform, and the easier it is for the sealing ring to be sucked out; reducing the maximum height and the middle platform height of the sealing ring can effectively reduce the sealing reaction force and extend the service life of the sealing ring. Based on the test results, the sealing ring was improved and optimized, and a large-caliber sealing ring was trial-produced. After closing and pressing the cover for more than a thousand times, it can still achieve self-sealing of internal air pressure, internal water pressure and external water pressure. The research results provide a reference for the design and application of end face sealing of large underwater pressure-bearing equipment.

Study on the Dynamic Interaction between Lower Limb Posture and Flow Field Environment during Underwater Diver Motion

ZOU Pengjun, LIN Xinghua, ZHANG Junxia, WANG Xinting, WANG Hao

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0052

[Abstract](12) [FullText HTML] (5) [PDF 1338KB](1)

Abstract:
In this paper, the dynamic coupling mechanism between the posture of the lower limbs and the flow field environment in the underwater movement of frogmen is deeply studied. Firstly, using the fluid-structure interaction simulation method, a numerical model of the frogman's lower limb dynamics with wearable assistive equipment was constructed, and the reliability of the numerical model was verified by comparing the experimental results with the simulation data. Secondly, based on the validated model, the influence of water flow impact on the posture of the frogman's lower limbs at different speeds was analyzed and the rule of joint angles was revealed. Finally, the Pareto optimal solution set of lower limb joint angles at different speeds was obtained based on the NSGA-II multi-objective optimization algorithm, the drag optimization strategy based on attitude compensation was proposed, and the optimization effect was verified through experiments. The results show that at a fixed speed, the lower limb posture experiences three phases: "maximum deformation - reverse adjustment - dynamic equilibrium." As the speed increases, the stable posture of the lower limb tends to flow field adaptive equilibrium point. Within the 1~3 kn speed range, the compensation between the posture stabilization angle and the optimal angle of resistance for the hip, knee, and ankle joints is −0.78°, 2.28°, and −1.05°. In the experimental verification of lower limb attitude optimization, the speed is increased by 9.09% compared with the free state, which indicates that the underwater kinematic performance can be improved by lower limb attitude angle constraints. This provides a quantitative basis for the closed-loop control of the joint module of the underwater assisted exoskeleton and the overall design of the flow field adaptation.

Research on the Extraction and Recognition of Space-Time-Frequency Features for Underwater Moving Targets

LIU Xiaochun, YANG Yunchuan, HU Youfeng, WANG Chenyu, LI Yongsheng

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0067

[Abstract](23) [FullText HTML] (11) [PDF 1231KB](2)

Abstract:
Aiming at the issue of inadequate bearing-angle adaptability in active sonar target recognition, this paper elaborates on the physical mechanism of active sonar target information perception from wave equation theory. Based on generalized multiple signal classification(MUSIC) spatial spectrum estimation, a novel method is proposed for acquiring the pseudo three-dimensional spatial feature of underwater targets by incorporating distance information, thereby effectively enhancing the adaptability of spatial features across different bearing angles. Additionally, research is conducted on methods to enhance Pseudo Wigner-Ville Distribution(PWVD) time-frequency features and extract Doppler frequency shift distribution features of moving targets. By leveraging the complementary advantages of these two algorithms, the bearing-angle adaptability is further improved. To address the challenge of scarce and imbalanced underwater target samples, the concept of meta-learning is integrated to construct a data-level fusion target recognition network that incorporates spatial, time-frequency, and Doppler domain features. The network is trained and tested using simulation and experimental data. The results demonstrate that the fusion features significantly improve the bearing-angle adaptability and anti-interference capability, providing a novel approach for the development of intelligent underwater target recognition technology.

A Review of Research Progress on Liquid Metal-Driven Soft Robotics

CAI Yueyao, WANG Shenlong

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0080

[Abstract](21) [FullText HTML] (5) [PDF 4002KB](4)

Abstract:
With the rapid advancement of key technologies in soft robotics, liquid metals have emerged as a focus in this field due to their unique properties, including low melting point, high electrical conductivity, superior thermal conductivity, and excellent fluidity. Gallium-based alloys have significantly enhanced their auxiliary application potential in actuation systems through approaches like magnetic reinforcement, electroactive enhancement, and structural optimization. As conductive materials and flexible electrodes, they demonstrate further promise in actuation, sensing, and multi-degree-of-freedom(multi-DOF) motion through approaches like magnetic reinforcement, electroactive enhancement, and structural optimization. This review systematically summarizes the functional characteristics, actuation mechanisms, and sensing technologies of liquid metals, with particular emphasis on their current applications and challenges in underwater soft robotics. To date, liquid metal-based actuators have achieved diverse actuation modes, including electrothermal, electrochemical, and magnetic driving mechanisms, while corresponding sensors have made breakthroughs in high-sensitivity strain detection, pressure sensing, and multimodal signal monitoring. Nevertheless, the realization of multi-DOF motion in underwater environments still faces technical challenges, such as complex actuation mechanisms, insufficient material stability, and imperfect control systems. Future research needs to further overcome these technical bottlenecks to advance the practical application of liquid metal-driven underwater soft robots.

An Engineering Approach for Obstacle Avoidance Path Planning of Unmanned Vessel Based on Optimized Artificial Potential Field

ZHANG Yabo, WANG Hongrui, ZHANG Haiyan, XIAO Qiang, LIU Yuxin

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0030

[Abstract](67) [FullText HTML] (20) [PDF 1259KB](8)

Abstract:
Aiming at the local path planning problem of obstacle avoidance for unmanned surface vessel, relying on the artificial potential field framework, a local path planning method for obstacle avoidance based on the dynamic construction of the water surface situation in longitude and latitude coordinates is proposed. Initially, the basic operations in the longitude and latitude coordinate system are sorted out and organized, and then the forms of the gravitational and repulsive force functions of the traditional potential function method are derived. The problems existing in the traditional potential function method and its improved methods, such as the difficulty in determining the virtual target point in the project and the inability to accurately predict the trajectory of the controlled object, are expounded. An improved potential function local path planning algorithm relying on the dynamic construction of the water surface situation is designed. Finally, the designed method is verified by simulation and sea trials. The simulation and test results show that the proposed engineering method of obstacle avoidance path planning can guide the unmanned surface vessel to complete the obstacle avoidance task, and has strong reliability and robustness.

Prediction method for buckling of deepwater explosion cylindrical shell based on random forest

FU Gaojun, MA Feng, ZHU Wei, JIA Xiyu, WANG Shuang

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0162

[Abstract](42) [FullText HTML] (19)

Abstract:
Under deep-water explosion conditions, pressure-resistant structures such as cylindrical shells will have a different failure mode from that in shallow water - instability buckling. In order to study the conditions for the occurrence of instability buckling of cylindrical shells under deep water explosion conditions and realize the prediction of the buckling state, a numerical simulation model was firstly established to simulate and analyze the results of the buckling of cylindrical shells under the conditions of different charge amount, blast distance and water depth. Based on the simulation results, a random forest model was designed to predict the buckling state. The results show that under the loading conditions of axial explosion in deep water environment, the cylindrical shell may present two macroscopic responses of unbuckling and buckling, and the prediction model constructed by the random forest algorithm can better realize the prediction of the instability state of the cylindrical shell under the specific structural parameters, and the prediction accuracies under the two structures reach 0.9375 and 0.875 respectively, which can provide references for the study of the buckling conditions of the cylindrical shell.

Analysis of the Impact of Shock Waves on the Safe Exit of the Rocket-assisted Vehicle Nose Cap during the Thermal Emission Process of a Concentric Canister Launcher

LIU Gangqi, YUAN Xin, GAO Shan, CUI Canli, HUANG Yuxuan

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0156

[Abstract](49) [FullText HTML] (23) [PDF 1755KB](7)

Abstract:
In response to the impact of shock waves on the safety of the rocket-assisted vehicle nose cap during the concentric tube thermal launch process, computational fluid dynamics (CFD) software was used to numerically simulate the ignition and launch process. The propagation process of shock waves and gas generated by solid rocket motors in the concentric tube was analyzed in detail, and the force variation curve of the nose cap under the action of shock waves was obtained, revealing the force mechanism of the nose cap inside the tube under the action of shock waves. The test data of the shock wave opening process during the field test of a certain product further illustrates the force variation process of the nose cap in the shock wave environment. The research results contribute to a clear understanding of the mechanism of force changes on the nose cap under the shock wave during the thermal emission process of concentric cylinders, and can be used to guide the safety design of the nose cap exiting the cylinder.

The 3D Reconstruction Method of Submarine Cables Based on High-Speed ROV Cruising with Multibeam Sonar

XU Haining, WANG Yong, JING Qiang, DING Tongzhen, YU Fei, SHEN Qingye, CAO Shengzhe

, Available online , doi: 10.11993/j.issn.2096-3920.2025-0036

[Abstract](76) [FullText HTML] (18)

Abstract:
Submarine cables, serving as the critical conduits for power transmission in offshore wind farms, are pivotal to the system's stability. However, due to their complex environments, three-dimensional (3D) reconstruction technology for these cables has become a key method for their inspection and maintenance. Currently, conventional 3D reconstruction methods for submarine cables are costly and less effective in deep-sea environments. Therefore, this paper proposes a 3D reconstruction method for submarine cables based on high-speed Remotely Operated Vehicle (ROV) cruising with sonar, drawing on the concept of synthetic aperture and simplifying calculations through spatial carving. This method comprehensively processes the multiple sonar observation information obtained during the ROV cruising to collectively reflect the spatial occupancy. In the simulation experiments of submarine cable 3D reconstruction, a comparison with mainstream methods was conducted. It is evident that the proposed method not only reduces the cost of submarine cable reconstruction by using conventional multibeam sonar but also achieves higher reconstruction accuracy, demonstrating significant application value and promotion potential.

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