水下无人系统学报

Obstacle Avoidance Control of AUV Based on DVFH+ in Ocean Current Environment

ZHU Zhongben, ZHANG Jiahao, XUE Yifan, QIN Hongde

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0077

[Abstract](9) [FullText HTML] (8) [PDF 1315KB](6)

Abstract:
Aiming at the problem that the improved vector field histogram (VFH) algorithm VFH+ ignores dynamic performance of autonomous undersea vehicle (AUV) and the impact of ocean current environment, and is sensitive to threshold setting, dynamic-based VFH+ (DVFH+) is proposed in this paper. The dynamic parameters of AUV are used to limit the output of the expected heading, which solves the problem of the expected output hopping of the original algorithm and improves the tracking performance of AUV; considering the drift angle compensation in the real ocean current environment, the obstacle avoidance algorithm is optimized to improve its robustness and adaptability; according to the obstacle information, the threshold value can be adjusted adaptively, and the planning instructions can be calculated according to the environmental characteristics around AUV, so as to ensure the efficiency and safety of navigation. The REMUS 100 AUV model is used for simulation and the results show that DVFH+ proposed in this paper can provide a smoother and more feasible obstacle avoidance route, which is suitable for obstacle avoidance of AUV in complex environment, and effectively avoids the path detouring and planning failure caused by the unreasonable threshold setting of the original algorithm.

A Review of Terrain Elevation Matching Algorithms for Underwater Vehicles

XIONG Lu, LI Jingshu, RAO Zhe, HUO Zhifan

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0152

[Abstract](10) [FullText HTML] (6) [PDF 1997KB](0)

Abstract:
The inertial guidance error of underwater vehicles accumulates over time, and the terrain elevation matching technology, which is based on terrain features, can provide the required continuous position correction information for the inertial guidance system according to the measured terrain, and is a hot spot of research in the field of domestic and foreign underwater navigation aid. This paper takes the development of terrain matching elevation algorithm for underwater vehicles as the research object, firstly, points out the problems faced by the navigation and positioning of underwater vehicles, and then introduces the basic principle and system composition of terrain matching for underwater vehicles on the basis of this, and takes the development of underwater terrain matching algorithm as the vein, and then expounds the main stages in the development of terrain matching algorithm and typical algorithms, the principle, the advantages and disadvantages in the order of order. Then, the principle improvement and experimental application of underwater terrain matching algorithm are introduced from foreign and domestic aspects respectively. Comparing with the current research status at home and abroad, effective ways to improve the performance of the matching algorithm are proposed for the reference of related researchers. Finally, the similarities and differences between domestic and international research on underwater terrain matching algorithms was briefly summarized, and by combining the technological development of parallel computing, multibeam sonar, and underwater terrain characterization, the effective ways to improve the performance of underwater matching algorithms was discussed so as to provide reference for researchers of this field.

Profile Design, Airfoil Preference and Variable Wing Camber Impact Analysis for Trans-Medium Fixed-Wing Vehicles

LU Jixin, SONG Wenbin, CAO Runzhen, LIANG Yifan, FENG Liuzhu, QI Yang

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0125

[Abstract](10) [FullText HTML] (7) [PDF 2146KB](2)

Abstract:
To achieve controlled trans-medium flight for trans-medium fixed-wing vehicles, it is essential to conduct a dynamical analysis for various working conditions within the typical mission configuration. Initially, the airfoil design for trans-medium fixed-wing vehicles primarily derives from seaplane wings, unmanned aerial vehicle (UAV) folding wings, and biomimetic wings. It remains unclear how traditional airfoil designs optimized for aerial cruising perform under underwater powered propulsion and gliding conditions. This paper proposed a profile for trans-medium fixed-wing vehicles based on an integrated design of traditional fixed-wing aircraft and underwater gliders. Utilizing typical NACA 00 and NACA 44 series airfoils, numerical simulations were conducted to compare aerodynamic and hydrodynamic properties such as lift-to-drag ratios, lift and drag coefficients, and moment coefficients in air and water environments. After summarizing performance evaluation criteria for existing UAV airfoils and underwater glider wings, key typical operational states were identified by combining the mission profile of trans-medium vehicles. This led to the establishment of design objective functions and constraints for trans-medium fixed-wing vehicle airfoils. Based on these conditions and the mission profile of trans-medium vehicles, recommendations for trans-medium vehicle airfoil designs were provided. Some best airfoils from the NACA 4-digit series and corresponding motion parameters were also suggested for this small-scale platform and its underwater navigation profile. The analytical methods used in this work are based on the Fluent compressible flow model, with parametric airfoil definitions and a combination of boundary layer and hybrid mesh techniques. After analyzing mesh sensitivity, numerical analysis of standard airfoils was conducted, establishing a procedure for airfoil parameter sensitivity analysis, which can facilitate further parameter optimization studies.

Application of Image Fusion Method Based on Structural Tensor in Marine Exploration

MA Xiaoyi, CHEN Yihong, WANG Fei, XIE Shuo

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0066

[Abstract](13) [FullText HTML] (6) [PDF 1298KB](0)

Abstract:
Single sensor cannot achieve well results in marine detection. Infrared and visible light have strong complementarity, and fusing them can obtain high-quality fused images, enabling more accurate and comprehensive perception of maritime targets. However, existing fusion methods have not been applied in the field of maritime detection, and they lack specificity, poor fusion effects, and a lack of deep learning datasets for maritime fusion. This article studies the deep learning image fusion method based on structural tensors, improves and optimizes the characteristics of maritime targets, adds multi-scale convolution, and fuses images according to channels, aiming to obtain high-quality color fusion images with significant targets and comprehensive information. The data set used for marine fusion is constructed from the data collected in the Taihu Lake Lake. The collected data are used for experiments, and a variety of evaluation indicators are comprehensively selected for comparative simulation experiments. The research results indicate that the improved image fusion method performs better than the original algorithm in six indicators, and its overall performance is better than the other ten commonly used image fusion algorithms. The generalization of the improved method has been verified on other public datasets. The improved image fusion method based on structural tensors has excellent performance in sea perception, with fusion results highlighting target features and better fusion performance than other methods.

Investigation of acoustic target strength of a cylindrical shell partially coated with anechoic layers

MA Qi, NI Shifeng, GENG Hao, YANG Haibin

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0105

[Abstract](7) [FullText HTML] (4) [PDF 1367KB](2)

Abstract:
In order to study the characteristics of the acoustic target strength of a cylindrical shell partially coated with anechoic layers, a dimensionality reduction method is proposed for analysis of the anechoic coating embedded with transverse cylindrical cavities, greatly reducing computational complexity. Based on the Kirchhoff-Helmholtz integral formula, the dimensionality reduction method is established through two-dimensional approximation and axial integration of differential elements of the cylinder. Using this method, the target strength reduction properties of the anechoic coating to the cylindrical shell is further analyzed. The results show that in the case of partially coated shell, the sound absorption of the anechoic coating, the coupling resonance between the coating and the shell, and the cancellation interference between the scattering waves from different regions can significantly reduce the target strength. As a consequence, the target strength reduction beyond the sound absorption effect can be achieved by regulating the coating area, which provides useful reference for the engineering applications of anechoic coatings.

Research on seakeeping of unmanned hydrofoil based on LQR and ZOA

SHUI Xinhua, DUAN Fuhai

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0083

[Abstract](12) [FullText HTML] (5) [PDF 1424KB](0)

Abstract:
In this paper, the motion amplitudes of roll, pitch and heave were selected as the indexes to measure seakeeping. LQR controller was adopted, and the parameters of LQR controller were optimized by ZOA. Firstly, the kinematics and dynamics models of unmanned hydrofoil were established with the differential flap rotation angle and motor thrust as the control variables, and the mathematical models were linearized. Then, the particle vertical acceleration and wave angle of irregular waves were taken as interference, and LQR controller simulation was carried out by Simulink. The objective was to reduce the motion amplitude of unmanned hydrofoil during navigation, and the parameters of LQR controller are optimized and compared by ZOA and PSO optimization algorithms respectively under different sampling frequencies and population numbers. Finally, the seakeeping index is simulated under the random wave interference of different encounter angles to verify the effectiveness and feasibility of LQR and ZOA methods, and to give the reasonable heading Angle of the outwater wing vehicle, which provides a theoretical reference for the attitude control and seakeeping research of the unmanned hydrofoil vehicle.

A Holographic Surface Wave Antenna Based on the Surface Transmitter

REN Ming

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0122

[Abstract](8) [FullText HTML] (6) [PDF 1700KB](0)

Abstract:
In this paper, the semi-open guided wave structure of half-band ground medium is selected to improve the design of TM0 mode surface wave emitter, and the surface wave field generated by TM mode surface wave emitter is simulated and analyzed. Based on the improved surface wave transmitter, the corresponding holographic modulation surface is designed, and then a holographic surface wave antenna based on the surface transmitter is designed. Fourier analysis of the surface wave transmitter and holographic surface wave antenna is carried out to verify the correctness of the theoretical design.

Fixed-Time Formation Control for Multiple Unmanned Surface Vessel Systems with Input Delay

LI Jianxiang, ZHANG Wenle, LI Ming

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0039

[Abstract](12) [FullText HTML] (9) [PDF 1548KB](0)

Abstract:
In recent years, fixed-time formation control is a research hotspot for multi-unmanned surface vessel (USV) systems, and the input delay problem is one of the key scientific issues to be solved in the fixed-time formation process of multi-USV systems. In view of this, under the general directed interaction topology, this paper carries out an in-depth study on the fixed-time formation control problem of multi-USV systems containing input delay. Firstly, the Artstein reduction method is applied to transform a multi-USV system with input time delays into a disturbance-containing control system with a second-order integral form. Secondly, in order to overcome the effect of system disturbances, a fixed-time state observer is constructed to estimate the system state. It is worth mentioning that this state observer uses only the relative position information of the USV. On this basis, a distributed fixed-time formation control protocol is proposed in combination with the backstepping method to realize the fixed-time formation control of multi-USV systems containing input delays. Finally, the correctness of the proposed theoretical results is verified by simulation experiments.

Passive Localization Of Underwater Broadband High-Frequency Targets Based on frequency Difference Matching Field

LI Jiayi, ZHOU Jianbo, LI Shaomeng, SHI Min, WANG Yafen

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0136

[Abstract](14) [FullText HTML] (8) [PDF 5351KB](0)

Abstract:
High frequency signals are easily affected by environmental uncertainty during propagation, leading to degradation of traditional matching field methods in high-frequency localization performance. To improve this problem, this article proposes a passive high-frequency signal localization method based on frequency difference matching field, which performs quadratic product processing on the received data of arrays with different frequencies within the high-frequency bandwidth to construct a sound field structure at the difference frequency much smaller than the original frequency. Apply the established matching field positioning algorithm at the difference frequency to reduce the broadband high-frequency signal to the low-frequency range for processing. Firstly, the principle of frequency difference method is presented and the grazing angle of shallow sea multipath propagation is accurately estimated. Based on this, physical models of frequency difference matching fields suitable for shallow sea and deep sea are proposed. Finally, simulation results show that the proposed method has significantly better localization performance for high-frequency signals in uncertain environments than traditional methods.

Reflections on Anti-Sea-Buried Target Destruction Techniques

LI Weichen, KANG Songyi, CAI Yi, GAO Yuan, JIA Xiyu

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0124

[Abstract](13) [FullText HTML] (5) [PDF 906KB](0)

Abstract:
This paper discusses the technologies and methods for the effective destruction of submarine buried targets in modern warfare and maritime security. As these targets are highly concealed and difficult to destroy, they are mainly dealt with by kinetic energy penetrators and blasting loads. Due to its efficient penetration capability and design simplicity, kinetic energy penetrator is more suitable to deal with deeply buried targets and enhance the destruction effect through secondary explosion. The article analyzes the influence of different submarine media on the penetration effect, and optimizes the design of the penetrator through numerical simulation and experimental research. Blast load is widely used because of its wide range of action and high hit rate. The article also discusses the effects of shock wave propagation characteristics, cratering effect, blast cavity characteristics and liquefaction effect on target destruction. Future research recommendations include strengthening the basic research on the penetration and explosion mechanism of submarine media, establishing high-precision models, and developing experimental platforms to simulate submarine environments, in order to enhance the capability of destroying submarine-buried targets.

Research on Application of Anti-submarine Method based on Ship-Aircraft Coordination

ZHANG Xuelun, PENG Junyu, GUO Kun, ZHANG Huaying

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0141

[Abstract](9) [FullText HTML] (6) [PDF 1199KB](0)

Abstract:
Based on the complex security situation in China's surrounding waters and the large number of submarines, building a complete and coordinated anti submarine system and designing reasonable and efficient anti submarine warfare methods have become the key issues that urgently need to be addressed. This article takes ocean anti submarine warfare as the research background, and conducts research and exploration on anti submarine warfare methods based on ship aircraft coordination. Firstly, analyzation was conducted on the collaborative anti submarine systems and weapons and equipment of various countries. Then, the application of ship aircraft collaborative anti submarine warfare methods was analyzed. Finally, through partial effectiveness simulation analysis, reference was provided for the development and improvement direction of ship aircraft collaborative anti submarine warfare methods.

Underwater image enhancement method based on light compensation and pyramid fusion

YUE Chenghai, XU Huixi, LÜ Fengtian, SHAO Gang, ZHU Baotong, YIN Zhongxun

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0082

[Abstract](9) [FullText HTML] (4) [PDF 3348KB](0)

Abstract:
The existing enhancement methods based on deep learning and underwater imaging models still have insufficient adaptability due to the problems of color deviation, scattering blur, and uneven brightness in underwater optical imaging. In response to the above issues, this article proposes a single underwater image enhancement method that combines lighting compensation and pyramid detail fusion. Firstly, the global illumination and color channel characteristics are combined to estimate and compensate lighting intensity at pixel level, achieving intensity correction for each color channel. Then, Gaussian blur is used to estimate the scattered components of the image and multi-scale gaussian filter residual method is used to remove scattering. Finally, a multi image pyramid detail fusion brightness equalization method that combines edge enhanced image, adaptive Gamma corrected image, and brightness balanced image is proposed, which effectively preserves image detail information while solving the problem of uneven brightness in the image. Subjective evaluation and objective analysis have demonstrated the effectiveness of the method proposed in this paper.

Fuzzy Model Based Sliding Mode Control for AUVs

LI Rongchang, BAI Huajun, ZHANG Jingxi, ZHANG Yi

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0149

[Abstract](12) [FullText HTML] (8) [PDF 1538KB](0)

Abstract:
Autonomous underwater vehicles (AUVs) have many characteristics such as highly nonlinearities、strongly coupling of variables and parameter uncertainties of the model, meanwhile it is also affected by unmeasurable disturbances in the marine environment, which makes it difficult to design the controller for AUVs. In addition, most existing results adopt AUV simplified linear models or only consider single dimensional models. Since the strongly coupling of variables, the designed controllers are only suitable for simplified systems and cannot be extended to original complex AUV systems. To solve the above problems, this paper proposes a T-S fuzzy method based adaptive sliding mode controller for AUV system. The controller has high versatility and strong robustness, and is suitable for complex AUV systems. Firstly, the T-S fuzzy modeling method is used to linearize the AUV systems, and a global linearized model is obtained. Meanwhile, the parameters of the system that are difficult to obtain are transformed into uncertainties, and their reconstruction expressions are obtained. Secondly, considering the presence of internal actuator faults and external environmental disturbances, an adaptive sliding mode controller is designed, which can estimate unknown parameters and adaptively update the control law to stabilize the system. Finally, the stability and state reachability of the closed-loop system are ensured through the Lyapunov stability theory. Simulations verified the effectiveness of the designed controller.

Research on Simulation of Unmanned Undersea Vehicle Anti-Submarine Warfare Model

CAO Chi, SHI Wentao, WANG Baihe, ZHANG Qunfei

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0116

[Abstract](13) [FullText HTML] (7) [PDF 1010KB](3)

Abstract:
Aiming at the requirement of establishing underwater weapon simulation system in anti-submarine warfare scenario, this paper analyzes the tactical characteristics of underwater unmanned vehicle (UUV) weapons, this paper gives the sub-modules of the whole flow of UUV for anti-submarine warfare operations and strike missions, including launch control, wire-guided, target detection, target search and tracking, and underwater target attack modules. By modeling the various functional sub-modules, a comprehensive model of an UUV anti-submarine warfare simulation model is constructed. After simulation verification, the constructed UUV simulation model can realize the underwater anti-submarine strike combat mission according to the user's information such as enemy and self position, acoustic parameters and battlefield environment, and provide technical support for the establishment of underwater weapon countermeasure simulation system.

An underwater WIFI-acoustic dual link cooperative control AUV for confined water applications

Zhang Meng, Wei Bowen, Jin Junhao, Tong Feng, Zhang Fumin

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0117

[Abstract](11) [FullText HTML] (10) [PDF 2816KB](0)

Abstract:
In recent years, Autonomous Underwater Vehicle (AUV) has been widely used in various marine tasks such as environmental monitoring, resource exploration, underwater rescue, pipeline inspection and underwater construction, and its underwater control link generally adopts underwater acoustic communication link. For confined waters with complex terrain such as shallow shoals, reservoirs, lakes, canals and caves, strong multipath has a serious impact on the performance of high-speed underwater acoustic communication, and the limited water depth provides the possibility of wireless links. For this kind of application, a micro-sized AUV: SubseaBuddy-3 is jointed developed by Xiamen University(XM) and Hongkong University of Science and Technology (HKUST), which adopts the cooperative control of underwater acoustic and WIFI dual-link, in which the underwater acoustic link adopts the low-rate spread spectrum underwater acoustic communication mode to ensure the communication reliability under the strong multi-path condition, while the high-rate WIFI link can work in shallow water area, or the function debugging test before deployment, as well as the control and observation at the recovery stage. The underwater acoustic link and WIFI link can cooperate in different working depths and different information acquisition/return states, which can meet the needs of reliable accusation and real-time/quasi-real-time underwater image return under restricted water conditions. At the same time, the AUV is equipped with an IMU and depth sensor for attitude and depth control. The effectiveness of the dual link AUV is verified by the pool experiment.

Mechanism Design and Simulation Analysis of Underwater Dredging Series-Parallel Hybrid Manipulator

XIA Yin, SU Wenbin, HU Qiao, ZHANG Jian, SHI Lin

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0067

[Abstract](14) [FullText HTML] (9) [PDF 4103KB](1)

Abstract:
In recent years, using underwater robots to clean the sediment at the bottom of reservoirs has gradually become a new solution plan for underwater dredging, and underwater manipulators are the main tool for underwater dredging robots to achieve dredging operations. This paper designs an underwater series-parallel hybrid manipulator by combining series and parallel manipulator to solve the problem of low structural stiffness and poor reliability of the series manipulator during dredging. Firstly, a hybrid mechanism was designed using screw theory and the structure design of manipulator was completed. Then, strength verification and static stiffness simulation analysis were completed by using finite element software. The results indicate that the series-parallel hybrid manipulator has higher structural stiffness compared to the series manipulator. This research result can provide theoretical and technical support for improving and optimizing the design of underwater manipulator.

Threshold Segmentation Method for Underwater Moving Luminous Targets Combined with Background Modeling

WANG Jia, GUAN Xia-wei, ZHANG Hao, FU Shao-bo, ZHANG Yu-ang, SONG Qing-hua

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0107

[Abstract](16) [FullText HTML] (11) [PDF 1223KB](0)

Abstract:
This paper presents an adaptive threshold segmentation algorithm combined with background modeling for the visual positioning of underwater moving luminous targets. Initially, background modeling is conducted based on the Gaussian Mixture Model to roughly screen out several regions with dynamic characteristics in the image. Subsequently, the features of the pixels within these regions are analyzed in the HSV color space to determine the presence of a target. After identifying regions containing the target, the Otsu method is applied to calculate the segmentation threshold within these regions. Finally, binarization processing is performed on the regions containing the target based on the calculated threshold to achieve target extraction. The algorithm is designed to alleviate the impact of brightness variations and clutter interference on visual positioning in complex underwater scenes. It fully utilizes the target’s motion state as well as its color and brightness attributes, combining background modeling with threshold segmentation to enhance the precision and stability of the segmentation process. Experimental results indicate that the algorithm demonstrates strong adaptability to common issues in underwater visual positioning, such as changes in brightness, halo blur, and bubble interference, and it is not dependent on the selection of initial parameters, making it suitable for engineering applications.

A Deep Learning-Based Solver for Underwater Explosion Shock Response Spectrum

Wang Shuang, Lv Feng, Ma Feng, Chen Si, Zhu Wei, Han Feng, Huang Qinyi

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0144

[Abstract](35) [FullText HTML] (14) [PDF 1490KB](6)

Abstract:
Due to the short-duration and complexity of shock responses, Shock Response Spectrum(SRS) is commonly used as a tool for analyzing these responses. To address the trade-off between calculation speed and accuracy inherent in traditional SRS solving methods, this paper proposes a deep learning-based fast solver for shock response spectra. An adaptive threshold selection mechanism tailored to the characteristics of shock response spectra is designed to improve the solver's accuracy. A comparison between the SRS obtained by the proposed solver and the results calculated using traditional methods demonstrates a high degree of consistency, validating the effectiveness of the solver. Additionally, L2 regularization is introduced in the solution process, effectively preventing overfitting and further enhancing the robustness of the solver.

Multi-Degree-of-Freedom Equipment Shock Response Model Based on Deep Learning

HUANG Qinyi, ZHU Wei, MA Feng, CHEN Si, WANG Shuang

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0143

[Abstract](50) [FullText HTML] (41) [PDF 1516KB](4)

Abstract:
To address the challenge of analyzing the response of multi-degree-of-freedom naval equipment under explosive shock loads, this study proposes a deep learning-based shock response prediction model. Traditional single-degree-of-freedom models cannot effectively analyze the complex shock responses of multi-degree-of-freedom systems. Leveraging deep learning technology, particularly the data feature extraction and nonlinear modeling capabilities of neural networks, this model learns the relationship between the shock spectrum and input shock loads from numerical simulation data, achieving efficient and accurate calculation of shock response spectra at critical points within naval structures. This approach fills the gaps of existing models in handling multi-degree-of-freedom equipment and meets the demand for rapid, accurate analysis of complex system shock responses. Experimental results demonstrate that the model can accurately predict the shock response spectra of multi-degree-of-freedom equipment, with a relative error of less than 8% compared to simulation data, effectively overcoming the limitations of traditional models in multi-degree-of-freedom system analysis.

Research on Underwater Positioning Method Based on Vision-Inertia-Pressure Fusion

ZHANG Jian, HU Qiao, XIA Yin, SHI Lin, LI Yangyang

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0061

[Abstract](67) [FullText HTML] (33) [PDF 2158KB](17)

Abstract:
In underwater unstructured environments, robots face difficulties in relying on external base stations for localization. Therefore, autonomous localization using multi-sensor fusion has significant application value in such settings. This paper addresses issues such as poor stability in visual localization and substantial drift in inertial navigation within underwater multi-sensor fusion localization. We propose a tightly integrated multi-sensor fusion localization method that combines visual, inertial, and pressure sensors. By utilizing graph optimization techniques for multi-sensor fusion and identifying errors in visual-inertial data based on depth information, the quality of the fused data is enhanced. To address drift and localization loss during the fusion localization process, a depth sensor is employed for weight allocation to provide more detailed system initialization. Additionally, loop closure detection and relocalization methods are introduced to effectively mitigate drift and localization loss. Experimental validation demonstrates that the proposed fusion localization algorithm improves accuracy by 48.4% compared to visual-inertial fusion localization methods, achieving superior precision and robustness.

Adaptive Neural Network Control of ROV under Ocean Current Disturbance

LI Xiangheng, YAN Zhaokun, LOU Jiankun, WANG Hongdong

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0045

[Abstract](140) [FullText HTML] (58) [PDF 1664KB](17)

Abstract:
Aiming at the motion control problem of remotely operated unmanned vehicles (ROV) under uncertain model parameters and ocean current disturbance, an adaptive back-stepping control system is designed based on the limited time command filter and feedback base Radial Basis Function (RBF) neural network. Firstly, construct a stochastic ocean current model based on the Markov process, and construct a ROV mathematical model of velocity under ocean current disturbance; secondly, introduce command filtering technology for the desired speed to reduce the amount of calculation caused by the iterative derivative of the traditional back-stepping method; thirdly, use radial basis neural network to estimate the uncertainty terms and external unknown disturbances of the ROV model, and design an adaptive neural network controller; finally, Lyapunov stability theory is used to prove the stability of the closed-loop control system. The simulation results show that the controller designed in this paper can achieve precise control of ROV navigation, and can realize the uncertainty term of the effective stagnation model and the impact of sea current disturbance on ROV motion.

UUV threat assessment method based on EBM

LIU Shuwei, CHENG Jianqing, LIU kai

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0121

[Abstract](38) [FullText HTML] (39)

Abstract:
In order to solve the problems of lack of data mining ability and insufficient explanatory nature of neural network algorithms when traditional threat assessment methods process complex battlefield situation data, this paper proposes an innovative solution: unmanned undersea vehicle(UUV) threat assessment model based on Explainable Boosting Machine(EBM). As an advanced machine learning technology, EBM cleverly integrates gradient boosting and generalized additive model to achieve the perfect combination of high interpretability of linear model and accuracy of gradient boosting algorithm. In this study, the performance of the EBM model was comprehensively evaluated and compared with several other mainstream machine learning methods, including CatBoost, AdaBoost, and Deep Learning. Through simulation experiments, we found that the EBM model not only maintained high interpretability, but also showed excellent accuracy, the accuracy of the EBM model reached 98.10% in the identification of threat levels. This result not only verifies the effectiveness of the EBM model in complex battlefield situation analysis, but also provides a solid theoretical foundation and technical support for UUV's autonomous decision-making.

Design of Control System for Underwater Hexapod Robot Based on Inverse kinematics and Foot Trajectory Optimization

LU Gangtai, YANG Ke, CHEN Hui

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0087

[Abstract](67) [FullText HTML] (37) [PDF 1865KB](11)

Abstract:
The underwater hexapod robot has strong carrying load ability and terrain adaptability, which is very suitable for near-earth observation and sampling in complex and changeable seabed environments. The control system is the key technology to realize the stable walking of underwater hexapod robots. In this paper, a control system design methodology for underwater hexapod robot based on inverse kinematics and foot trajectory optimization is proposed. The D-H coordinate system was established to derive the analytical relationship between the foot trajectory and the joint angle (positive kinematics). Through polynomial optimization, a smooth foot trajectory is planned, and then the corresponding joint angle (inverse kinematics) is solved. With PC104 as the main control unit, the foot trajectory optimization and inverse kinematics solving was designed in the ROS2 environment, and the synchronous tracking of the joint motor was realized through EtherCAT technology, and the control system suitable for the underwater hexapod robot was designed. The typical movement patterns of the underwater hexapod robot (straight and turning) were verified in the pool. Experimental results show that the control system designed in this paper can realize the stable walking of the underwater hexapod robot.

Current status of structural research in impact protection of naval structures

ZHANG Tao, SUN QingZhen, ZHANG Lei, LI XiangMei

, Available online , doi: 10.11993/j.issn.2096-3920.2024-0072

[Abstract](93) [FullText HTML] (34)

Abstract:
As modern naval threats become increasingly complex, the structural protection of ships has become key to enhancing survivability and combat effectiveness. This paper reviews the research progress in ship impact protection structures, particularly focusing on the evolution from traditional homogeneous protection structures to multilayer composite protection structures. In the face of modern high-energy attacks such as missiles and torpedoes, traditional robust steel plates and alloy materials have become inadequate to meet protection needs, prompting researchers to turn to composite materials and their layered structures. By utilizing ceramics, metals, fiber-reinforced materials, and polymers, and integrating advanced design concepts such as gradient design, embedded design, lattice structures, and sandwich technologies, not only has superior impact resistance been achieved but also structural lightweighting. The article also discusses challenges related to the strength of material interfaces, complexity of structures, and manufacturing difficulties, noting that poor interlayer bonding under extreme impact conditions may lead to material layer separation or cracking, weakening the protective efficacy. Future research should focus on the development of nanomaterials, polymer materials, and smart materials, as well as the implementation of multifunctional integrated designs to enhance the stealth, anti-detection, and active defense functions of protective structures. It also emphasizes the central role of simulation technology in design optimization and performance prediction, as well as the potential of additive manufacturing and laser processing technologies to improve production efficiency and product quality. Through technological innovation and material development, the comprehensive performance of composite protective structures can be effectively enhanced, meeting the needs of modern military and civil sectors for high-performance protective materials.

Latest Articles

Journal News> >

Download> >