水下无人系统学报

Research Progress in Foreign Underwater Vortex Detection Technology

HE Xin-yi, CHENG Shan-zheng, LU Jun, ZHU Lin

2021, 29(1): 001-5. doi: 10.11993/j.issn.2096-3920.2021.01.001

[Abstract](705) [PDF 2192KB](524)

Abstract:
Considering complex marine environments and the regular improvement of submarine stealth performance, developing a new non-acoustic detection technology to further improve the ability of submarine detection has become urgent. Accordingly, this study summarizes the research on foreign underwater vortex detection technology and explains both the mechanism of submarine vortex generation and the feasibility of detection. The characteristics of underwater vortex biomimetic detection, particle image velocimetry(PIV) detection, and laser detection technology are compared. Comparative results reveal that underwater vortex laser detection technology has good developmental potential because of its non-contact nature, high sensitivity, and simple structure, thus making it worthy of further study.

Preliminary Study of an Underwater Military Network Information System of Systems Based on Factor Capability Reorganization

DU Fang-jian, ZHANG Yong-feng, ZHANG Zhi-zheng

2021, 29(1): 006-13. doi: 10.11993/j.issn.2096-3920.2021.01.002

[Abstract](293) [PDF 718KB](257)

Abstract:
With the continual improvements to operational dimensions, the traditional centralized distributed system architecture and its attachment of informationized weapons and equipment have been unable to meet the operational requirements of future network system of systems(SoS). The construction of a super-system, super-network, capable-oriented, and service-oriented network information SoS should be created to address this situation. In addition, the innovation of strategic thinking and operational methods should be accelerated, and the operational form and operational force generation mode should be altered. In this study, the concept of a network information SoS based on factor capability reorganization is explained along with SoS characteristics and matching rules. Then, an underwater military network information SoS based on factor capability reorganization for underwater integrated joint operation is constructed. Based on analysis of SoS capabilities, SoS factors, and interaction mode, this study proposes the architectural design and service mode of an underwater military network information SoS and discusses some developmental directions that require major breakthroughs in terms of SoS factors. It is hoped that this study can be used as a reference for the future construction of underwater military network information SoS.

Trajectory Tracking Control Method of a Work-class ROV Based on a Super-twisting Second-order Sliding Mode Controller

HUANG Bo-lun, YANG Qi

2021, 29(1): 014-22. doi: 10.11993/j.issn.2096-3920.2021.01.003

[Abstract](1152) [PDF 963KB](150)

Abstract:
Time-varying external disturbances and system uncertainties affect the motion of work-class remote-operated vehicles(ROVs). The conventional sliding mode method for ROV motion control has the drawback of a chattering phenomenon, whereas the common method for eliminating chattering, namely, the saturation function combined with a boundary layer sliding mode controller(SatSMC), cannot guarantee control accuracy. To address these problems, a super-twisting second-order sliding mode controller(STSMC) is proposed to realize trajectory tracking of a work-class ROV. The Lyapunov method is used to analyze the stability of the system. It is proved that the proposed controller can ensure the convergence of a tracking error in finite time. A simulation experiment of the proposed STSMC and SatSMC methods and the proportional integral derivative(PID) control are compared. Results show that the STSMC method enables the ROV to complete the tracking of a predetermined path. This method also has stronger robustness, rapidity and accuracy. The chattering of the STSMC is also significantly reduced compared to that of the SatSMC. In addition, the control parameters are not increased, making the STSMC more suitable for actual use with ROVs.

Path Planning of a Large-scale Underwater Glider Swarm Area Coverage Detection

ZOU Jia-yun, QU Hong-yue, CHEN Zhi-peng

2021, 29(1): 023-29. doi: 10.11993/j.issn.2096-3920.2021.01.04

[Abstract](343) [PDF 599KB](207)

Abstract:
When search tasks in an underwater glider swarm are conducted, the detection efficiency of the swarm can be improved effectively by setting the search path of each platform reasonably, thereby maximizing the coverage of the detection area with the least platform. To solve the problem of large calculations in large-scale swarm mission planning, this study constructs a high-precision Boolean model based on the grid method to evaluate the coverage ability of an underwater glider swarm by delimiting the effective coverage area geometrically and inverting the grid number. With this as a support, a swarm intelligence algorithm can then be used to realize fast path planning of a large-scale swarm in a wide sea area. Accordingly, this research proposes a method for solving the minimum number of swarm platforms with only few calculations by using sequential thought. The feasibility of this method is verified through a simulation experiment. The proposed method can support mission planning for large-scale underwater glider swarms.

Research on AUV Dynamic Obstacle Avoidance Path Planning Based on the Rolling Speed Obstacle Method

ZHANG Fei, HU Chun-lei

2021, 29(1): 030-38. doi: 10.11993/j.issn.2096-3920.2021.01.005

[Abstract](463) [PDF 647KB](176)

Abstract:
To address the problem of poor path planning and the obstacle avoidance effect of autonomous undersea vehicles(AUVs) in dynamic environments, a feasible rolling speed obstacle method is proposed in this study. This method combines the rolling window method with the speed obstacle method and designs a suitable three-dimensional model predictive controller based on the rolling window method under a hybrid obstacle avoidance structure. Stable tracking of the reference path is achieved by optimizing the objective function. A three-dimensional collision cone and speed obstacle cone model is constructed while the window is rolling. If the collision avoidance condition is met, the critical collision point is calculated, and the AUV is guided to avoid obstacles safely by tracking the critical collision point. If collision avoidance ends, the AUV trajectory recovery is guided. Simulation results show that this method can effectively improve the dynamic obstacle avoidance ability of AUVs in real-time path planning.

Precise Control Method for Directional Swimming of a Robotic Fish Based on CPG and Fuzzy Control

HE Yan-hui, HU Qiao, WANG Chao-hui, YU Lei, CHEN Zhen-han, LI Yi-xin

2021, 29(1): 039-47. doi: 10.11993/j.issn.2096-3920.2021.01.006

[Abstract](348) [PDF 1336KB](239)

Abstract:
Robotic fish detection under water, waves, vortices, etc. can affect the accuracy of the swimming direction of a robotic fish, making it virtually for corresponding tasks to be completed. To solve the problem of ensuring the accuracy of the swimming direction of robotic fish, this study proposes an accurate control method based on the central pattern generator(CPG) theory and fuzzy controller. The proposed method can realize the directional swimming of a robotic fish of the genus Plover. In this method, a Hopf oscillator is used to build a CPG model of a robotic fish based on a limit cycle. In the early stage of robotic fish swimming, a small swing high-frequency CPG control signal is used to obtain a large propulsion force, and a large swing low-frequency CPG signal realizes stable swimming. Then, the attitude angle information of the robotic fish is obtained based on an attitude sensor, and the deviation of the robotic fish from the target direction is corrected in real time using the fuzzy controller. Finally, directional swimming and anti-interference experiments of the robotic fish are conducted to verify the feasibility and effectiveness of the precise directional swimming method. Results show that the proposed method has broad application prospects for precise directional swimming of robotic fish in complex environments.

Modeling and Simulation of Fully Actuated AUV Based on Modified ADRC

WANG Zhen, WANG Jun-xiong, NIU Xiao-chen, SU Wei

2021, 29(1): 048-53. doi: 10.11993/j.issn.2096-3920.2021.01.007

[Abstract](418) [PDF 1037KB](195)

Abstract:
Autonomous undersea vehicles(AUVs) are nonlinear, strongly coupled, and vulnerable to external disturbances. To improve the control accuracy of AUVs, a 6-degree-of-freedom fully actuated AUV is modeled, and a proportional integral derivative(PID) controller and auto disturbance rejection controller(ADRC) are built. A comparative analysis reveals that the traditional ADRC has too many parameters to adjust, and the tracking speed of each link of the tracking differentiator(TD) is slow. Therefore, the Asin function is used to simplify each link of the traditional ADRC, and the structure of the TD is improved to solve the problem of slow tracking speed. The control effect of the PID and modified ADRC is simulated under the same simulation conditions. Simulation results show that the modified ADRC has higher control accuracy and stronger anti-disturbance ability than PID when the motion of a multi-freedom system is controlled.

SINS/DVL/LBL-integrated Navigation Technology Based on Improved Variational Bayesian Filtering

ZHAO Jun-bo, GE Xi-yun, CHENG Yue, LI Jin

2021, 29(1): 054-59. doi: 10.11993/j.issn.2096-3920.2021.01.008

[Abstract](277) [PDF 551KB](175)

Abstract:
To solve the integrated navigation problem of an undersea vehicle strapdown inertial navigation system (SINS), Doppler velocity log(DVL), and long baseline(LBL) location equipment, a centralized filtering scheme is proposed in this study and a SINS/DVL/LBL-integrated navigation model is established. During integrated navigation, using the classical Kalman filtering method leads to the problem in which the filtering accuracy is reduced due to time-varying measurement noise variance and the interference of outliers. Accordingly, an improved variational Bayesian filtering method is proposed by combining a variational Bayesian filter with an IGGIII weight function. Integrated navigation simulation is conducting using MATLAB software, and results show that the proposed filtering method has strong self-adaptive and anti-outlier abilities as well as a higher filtering accuracy than the classical Kalman filtering and variational Bayesian filtering methods.

Ship-Radiated Noise Analysis Based on the Gammatone Frequency Cepstrum Coefficient

WU Yan-chen, WANG Ying-min

2021, 29(1): 060-64. doi: 10.11993/j.issn.2096-3920.2021.01.009

[Abstract](267) [PDF 742KB](155)

Abstract:
Acoustic feature extraction of ship-radiated noise has a major effect on target training and recognition. This research proposes a feature analysis method based on the gammatone frequency cepstrum coefficient(GFCC). The method uses the typical target feature extraction method——Mel frequency cepstrum coefficient(MFCC) algorithm for comparison and uses 5 122 samples with three types of targets, namely, small low-speed, small high-speed, and large vessels. The samples are extracted in two different underwater acoustic environments to generate a classification identification comparison test. Results show that the recognition rate of the two algorithms is greater than 80%. However, the recognition rate of GFCC in an ocean complex acoustic environment is found to be significantly higher than that of MFCC and is more sensitive to high-frequency targets. These results show that the GFCC algorithm has better noise resistance and a higher recognition rate for fast targets in oceanic and other strong interference environments as compared with the standard MFCC algorithm.

Method for Detecting and Ranging an Underwater Guided Light Source Based on Binocular Vision

ZHU Zhi-peng, ZHU Zhi-yu

2021, 29(1): 065-73. doi: 10.11993/j.issn.2096-3920.2021.01.010

[Abstract](386) [PDF 1694KB](249)

Abstract:
To meet the requirements of high accuracy, real-time performance, and robustness in autonomous underwater vehicle(AUV) underwater docking, this study proposes a binocular vision-based underwater guidance light source detection and ranging method. The main processes of this method includes underwater camera calibration, denoising of original images, detection of light sources, and location calculation. In the original image denoising stage, a Laplace operator is introduced to improve the mean denoising algorithm and enhance the image to highlight the light source. Then, an adaptive threshold binary image based on the dichotomy is used to effectively separate the light source from the background. Light sources on the left and right imaging planes are then detected and matched. Finally, according to the principle of binocular location, the relative position is solved by using the detected light source information. In this method, traditional mean denoising is improved for an underwater environment, and information of the guided light source is highlighted. The best image binary threshold is obtained by using the connected domain as the cyclic judgment condition, and the light source center is determined by weighted centroid detection method. The method is verified in specific experiments that meet the requirements of underwater docking accuracy. In addition, real-time performance is optimized.

Generation Method of Underwater Samples Based on a Generative Adversarial Network

LENG Ji-hua, LI Yong-sheng, Lü Lin-xia, LIU Li-wen

2021, 29(1): 074-79. doi: 10.11993/j.issn.2096-3920.2021.01.011

[Abstract](268) [PDF 474KB](144)

Abstract:
Neural network technology has become an application trend in the area of target detection of undersea high-speed vehicles, but the technology requires numerous training samples to ensure the accuracy of training results. As an important method used to solve the problem of sparse training samples, generative adversarial networks (GANs) are widely used in various fields. This study improves the classic GAN model based on the characteristics of underwater samples and proposes a generation method for underwater samples based on GAN for the purpose of augmenting training samples. First, a GAN model suitable for underwater samples is constructed, and the actual sea trial data are used to train the model and optimize the parameters. Finally, the model is used to simulate the generation of samples and verify the effectiveness of the results. Simulation results show that the generated and test samples are in good agreement and that data augmentation of the test samples can be realized. This method helps solve the problem of sparse underwater data samples and provides a reference for further application of neural networks to improve the efficiency and accuracy of undersea high-speed vehicle target detection

Flat Drag Reduction Method Based on Biomimetic Fish-body Structure

LI Guang-hao, FENG Na, LIU Gui-jie

2021, 29(1): 080-87. doi: 10.11993/j.issn.2096-3920.2021.01.012

[Abstract](289) [PDF 1708KB](153)

Abstract:
Ocean environments are complex, wherein the variation in flow velocity is wide and the general drag reduction mode with robots is unstable. In this study, a new drag reduction method is proposed for robots to better adapt to ocean environments. The effect of drag reduction is verified by numerical simulations and experiments. First, based on the principle of bionics, a robot fish operating under a body and/or caudal fin(BCF) mode is selected as the research object, and the model is reconstructed to duplicate the fish body. Second, the effects of model length, height, and thickness on drag reduction are studied by numerical simulation. The law of drag reduction is also summarized, and the mechanism of drag reduction is investigated intensively. The correctness of the numerical simulation is verified through a fluid experiment. Experimental results show that with an increase in the model length, the effect of drag reduction is gradually worsened. However, the flow velocity that preforms the best drag reduction effect is not affected by the length. The effect of drag reduction is greatly affected by the change in model height. With an increase in model thickness, the range of flow velocity that preforms drag reduction increases. The reconstructed model effectively reduces drag and has a wide range of flow velocity applications, thus enabling better adaptation to ocean environments

Numerical Simulation of Convective Condensation of Steam with Large Proportion of Non-condensable Gas under High Pressure

GENG Shao-hang, DANG Jian-jun, ZHAO Jia, ZHANG Jia-nan, SUN Jun-liang, QIN Kan

2021, 29(1): 088-96. doi: 10.11993/j.issn.2096-3920.2021.01.013

[Abstract](277) [PDF 607KB](155)

Abstract:
This study simulates the convection condensation heat transfer phenomenon of steam containing non-condensable gas(NCG) in the thermal power system of an underwater vehicle at a large sea depth. First, the condensation process is modeled by defining the source terms of the continuity, momentum, component transport, and energy equations. To verify the validity of the numerical model, classical Kuhn experimental conditions are then simulated, with results matching well with the experimental data. The maximum error of the heat-transfer coefficient is found to be less than 20%. Accordingly, the study then simulates the condensation heat-transfer process of different proportions of steam and NCG under 10 MPa pressure. During the simulation, the effect of the condensed liquid film is considered, and the influence of the NCG on the condensation heat transfer of steam under high pressure is analyzed in terms of heat flow density, liquid film thickness, saturation temperature, and condensation mass flow. Results show that the average heat flux of the steam condensation heat transfer is reduced by 50% until the NCG mass fraction reaches 30%. Finally, the simulation conditions are compared with the research on steam containing NCG under atmospheric pressure, with results showing that the inhibition effect of NCG on steam condensation heat transfer is reduced under high pressure.

Modeling and Simulation Verification of AUV Propulsion System Based on AMESim

ZHAO Chun-cheng, GUO Jia, XU Ke-wang, ZHANG Wei

2021, 29(1): 097-103. doi: 10.11993/j.issn.2096-3920.2021.01.014

[Abstract](347) [PDF 679KB](150)

Abstract:
To meet the requirement of early verification of autonomous undersea vehicle(AUV) propulsion system design, a simulation verification method of a virtual integration model of propulsion system is proposed. Through analysis of the composition of the AUV propulsion system and the principle of motor-propeller matching design, AMESim simulation models of AUV resistance characteristics, propeller characteristics, a propulsion motor, and power batteries are established, and a virtual integration of the propulsion system is realized. Using the integrated model as an AUV virtual navigation closed-loop test environment, a simulation analysis of AUV rapidity, motor-propeller matching characteristics, the influence law of electrical parameter change, and a power battery selection scheme is conducted. Simulation results verify the matching of the design plan of propulsion system, thus providing a reference for AUV propulsion system design optimization and component selection

Fault-Tolerant Control Method for an Underwater Robot Based on the CAM Matrix

QIU Shuai, Lü Rui, FAN Hui, WAN Ya-min, HUANG Hai, YANG Guan-jin-zi

2021, 29(1): 104-110. doi: 10.11993/j.issn.2096-3920.2021.01.015

[Abstract](300) [PDF 627KB](210)

Abstract:
The poor control effect of an underwater robot thruster after failure often prevents specific tasks from being completed and may even cause the loss of the robot. To address this problem, this study proposes a fault-tolerant control method for an underwater robot based on a control allocation machine(CAM) thrust distribution matrix. The CAM matrix is used to reconstruct the distribution to ensure stable navigation of the robot, and a thrust distribution strategy for achieving maximum resultant forces is identified using a sequential quadratic programming method. The effectiveness of the proposed method is verified through a simulation. Simulation results show that the proposed fault-tolerant control method can handle partial or complete failure of the thruster and can ensure that the robot achieves good performance and stable navigation

Underwater Sea Cucumber Identification and Localization Method Based on Image Processing

ZHANG Yun-feng, LI Juan, LI Ming

2021, 29(1): 111-123. doi: 10.11993/j.issn.2096-3920.2021.01.016

[Abstract](331) [PDF 11247KB](396)

Abstract:
An image processing algorithm for sea cucumber identification and localization is proposed to solve the problem of sea cucumber identification and localization in complex environment. First, based on image preprocessing, a fuzzy enhanced fusion RGB sea cucumber thorn and sea cucumber trunk prominent feature algorithm is designed to highlight sea cucumber target features. The outline of a sea cucumber is extracted using an improved image segmentation method, and the linked list method is used to remove false edges and morphological outline optimization, which is necessary to identify the sea cucumber target. The localization of sea cucumber target can be divided into two cases: a sea cucumber target with a regular shape that is located by one-time ellipse fitting, and a sea cucumber target with an irregular shape that is located by extracting the target direction feature of the sea cucumber and designing a quadratic fitting algorithm based on the least external rectangle direction ellipse. Simulation results reveal that the algorithm can effectively identify and locate sea cucumber target, determine the volume of sea cucumber, and ultimately provide an effective method for sustainable and automatic fishing of sea cucumbers.

Kinematics Simulation of Transmission Mechanism of Double DOF Steering Gear

WANG Zhong, ZHANG Xiong-ke, FAN Hui, YANG He-ran, WANG Jun-chang, TANG Wei-jiang

2021, 29(1): 124-128. doi: 10.11993/j.issn.2096-3920.2021.01.017

[Abstract](304) [PDF 749KB](180)

Abstract:
The working conditions of ultra-high-speed undersea vehicles become complicated during navigation, when the speed span is large and the steering changes significantly. Conventional steering gear cannot meet steering requirements, whereas a double-degree-of-freedom steering gear can improve the steering performance. This study considers the transmission mechanism of a steering gear as a research object. Specifically, the study uses UG software to establish a three-dimensional solid model and then imports it into ADAMS software to establish a mechanical simulation model based on the multi-body contact theory. A simulation is then conducted to obtain the gear speed and meshing force. Simulation results show that the relative errors of speed and meshing force are less than 1% and less than 6%, respectively, and the accuracy of the simulation model is verified. The simulation results provide a reference for design optimization of transmission mechanisms

2021 Vol. 29, No. 1

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