水下无人系统学报

Development of Digital Twin Technology and Its Application Prospect in Unmanned Undersea System

ZHANG Ning, GUO Jun, YIN Shao-ping, GAO Zhi-yong

2022, 30(2): 137-146. doi: 10.11993/j.issn.2096-3920.2022.02.001

[Abstract](2922) [PDF 413KB](121)

Abstract:

To fill the gap of digital twin technology in the unmanned undersea system industry, this paper introduces the development process and status of digital twin technology at home and abroad and summarizes the characteristics. Subsequently, the connotation and key technologies of applying digital twins in unmanned undersea systems are discussed. The development and application of digital twin in the unmanned undersea system industry are prospected from different perspectives, including standard systems, design, testing, manufacturing, and operations. Finally, a typical application case of digital twin technology in an unmanned undersea system is presented based on a pump bench test. The results can provide a reference for the further application of digital twin technology in the unmanned undersea system industry.

Reinforcement-Learning Control for the High-Speed AUV Based on the Neural-Network State Estimator

GUO Ke-jian, LIN Xiao-bo, HAO Cheng-peng, HOU Chao-huan

2022, 30(2): 147-156. doi: 10.11993/j.issn.2096-3920.2022.02.002

[Abstract](3739) [FullText HTML] (41) [PDF 1658KB](73)

Abstract:
With the development of ocean research and exploitation, high-speed autonomous undersea vehicle(AUV) has attracted increasing attention as important unmanned underwater platforms. However, the high-speed AUV model is multi-input-multi-output(MIMO), strong-coupling, underactuated, and strongly nonlinear; therefore, the traditional control method that relies on the exact model is often limited in practical applications. To address these problems, a position-attitude controller based on reinforcement learning(RL) that does not rely on an exact model is proposed. The RL controller can not only regulate the attitude of the AUV but also the driver, as it reaches the target depth faster with the aid of the attitude and position loops. An improved state estimator of a high-speed AUV is designed based on a neural network(NN) to decrease the cost of collecting data, which is employed to train the RL controller. The improved state estimator can estimate the state at the next time instant according to the current state of the high-speed AUV and the control input. The simulation results demonstrate that the NN-state-estimator can estimate the state of a high-speed AUV with high precision, and the RL controller trained by the estimator achieves fast and steady performance, which verifies the feasibility and effectiveness of the proposed method. .

Analysis and Improvement of Supercavity Vehicle Planing Force Model

ZHOU Yu, SUN Ming-wei, ZHANG Jian-hong, LIU Le-hua, CHEN Zeng-qiang

2022, 30(2): 157-164. doi: 10.11993/j.issn.2096-3920.2022.02.003

[Abstract](147) [PDF 609KB](25)

Abstract:
The Dzielski benchmark and extended models have been widely applied in the study of supercavity vehicle control problems. At present, there are few comprehensive analyses of the differences between and rationale behind these models. In this study, these aspects were comparatively analyzed using numerical simulations of the state response and planing force of these models. The simulation results demonstrate that the cavity memory effect can reduce the peak value of the planing force, and cavity shift can affect the collision time and peak value of the planing force. Second, the unreasonable formulation of the planing force in the Balas model was improved. Finally, a new model is proposed based on the Mao model and its effectiveness is verified using numerical simulation. The comprehensive analysis and combination of supercavity vehicle models provide a reference for the design of a supercavity vehicle control system.

Rapid Determination Method of Critical Motion Conditions of Underwater Towing System

ZHANG Dan, LIANG Jian-tong, SONG Hai-sheng, LI Xiao-wei, XIE Shao-rong

2022, 30(2): 165-169. doi: 10.11993/j.issn.2096-3920.2022.02.004

[Abstract](155) [PDF 727KB](16)

Abstract:
The towing body is the main part of a towing profiler. It can realize waveform track movement and measure real-time multi-parameters of the ocean. Therefore, the period and amplitude of the preset trajectory determine measurement accuracy and range. To realize autonomous control of the towing profiler, it is important to determine the feasibility conditions of the preset trajectory. Based on the assumption of linearization of the tail swing angle and towing body attack angle, a dynamic model with tail swing control was established in this study by inverting the preset motion trajectory of the towing system and deriving the analytical expression of the tail swing angle. The theoretical results were in good agreement with the experimental data. Furthermore, the established model was used to determine the critical motion characteristics of the underwater towing system as well as the coordination relationship between the forward speed of the mother ship and the undulating motion of the towing body. The study verified that the Strouhal number can be considered as a condition for the realization of the preset trajectory, which is related to the speed of the mother ship as well as the amplitude and period of the preset trajectory and reflects the unsteady nature of motion. When the Strouhal number was less than 0.22, the trajectory could be reproduced autonomously by controlling the tail swing.

Element Matching Analysis Method for Underwater Towed Buoy Systems

ZHANG Zhen, ZHANG Tao, HE Wen-sheng, ZHU Min, SHAO Yong-yong, YANG Zhuang-tao

2022, 30(2): 170-177. doi: 10.11993/j.issn.2096-3920.2022.02.005

[Abstract](133) [PDF 632KB](15)

Abstract:
An underwater towed buoy system is an important means of undersea vehicle concealed communication and positioning. To utilize this system, it is crucial to match the buoy, tow cable, and towed vehicle. In this study, based on the classical method proposed by Ablow and Schechter for analyzing towed cable dynamics, we investigated the influence of towing velocity, towing vehicle depth, and buoy’s pitch angle on the tow cable’s shape and tension, considering an underwater towed buoy system as the research object. To meet the requirements of towing security and minimize the towing vehicle load, we established an analysis method for matching the buoy, tow cable, and towing vehicle, obtained the optimal matching law under different working conditions, and proposed the corresponding control expectation target of the winch and buoy. The results demonstrate that the buoy optimal pitch angle, which ensures that the underwater towed system fulfils the towing safety and minimum towing load requirements, increases with decreasing towing velocity and increasing towing depth.

Characteristics Simulation of Submarine Vortex Velocity

HE Xin-yi, ZHANG Di-zhou, ZHU Lin, CHEN Shuang, BAI Yi-hui

2022, 30(2): 178-183. doi: 10.11993/j.issn.2096-3920.2022.02.006

[Abstract](170) [PDF 682KB](27)

Abstract:
Submarine vortex detection technology has become a research hotspot for navies in various countries due to the characteristics of the vortex, including long duration, large scale, and inability to eliminate. The submarine vortex characteristics and the motion characteristics of the vortex generated by submarine maneuvering are discussed in this paper, along with some new ways to improve anti-submarine operational capability. A simulation analysis of three types of submarines was carried out, analyzing the vortex motion speed and ship speed with the same depth(200 m) and the vortex horizontal movement speed with depth under the same ship speed(10 kn). The simulation results show that the vortex motion speed is related to parameters such as the size, motion speed, diving depth, and buoyancy of submarines, among which the buoyancy is the most significant. The findings in this paper can provide references for the study of the submarine vortex velocity characteristics.

Analysis of Acoustic Scattering Characteristics of a Torpedo Based on Planar Elements Method

CAO Hao, FAN Shu-hong, ZHOU Jing

2022, 30(2): 184-189,196. doi: 10.11993/j.issn.2096-3920.2022.02.007

[Abstract](231) [PDF 1566KB](21)

Abstract:
To meet the demand for new anti-torpedo equipment for acoustic detection of incoming torpedoes, modeling and simulation of high-frequency acoustic scattering characteristics of torpedo physical structures are performed. A structural model of the torpedo target is established based on the planar element method. The analysis and calculation methods of the acoustic scattering characteristics of the torpedo are studied, and the acoustic scattering strength of the target is determined. In addition, the variation in the scattering strength of the torpedo with the direction of the acoustic signal is investigated. On this basis, the highlight features of the torpedo target are analyzed, and the temporal and spatial distribution of the highlight is obtained using simulation. The research results provide a reference for the accurate detection of anti-torpedo equipment.

Target Detection and Correction Method for Unmanned Surface Vehicles Marine Radar Based on Image Contour Features

LI Li-gang, LI Bo-ran, JIN Jiu-cai, LIU De-qing, DAI Yong-shou

2022, 30(2): 190-196. doi: 10.11993/j.issn.2096-3920.2022.02.008

[Abstract](185) [PDF 898KB](23)

Abstract:
Marine radar has the advantages of a wide detection range and all-weather operation, and it is the main method used by unmanned surface vehicles(USV) to detect obstacles on the sea. However, for large targets such as islands and freighters, marine radar cannot accurately describe the area in which they are located and may misjudge them as multiple scattered targets. For this reason, a method for correcting the target detection result of marine radar based on image contour features was proposed with the use of the radar image characteristics. First, the radar image is preprocessed to simplify the image data and enhance the detectability of related information. Second, the target contour is extracted according to the corresponding pixel coordinates of the target. If different targets correspond to the same contour, a misjudgment is considered to have occurred, and multiple scattered targets generated by the misjudgment are combined into one target. Finally, the area where the target was located was described using the distance and orientation characteristic parameters contained in the target contour. The results of the experimental tests demonstrate that this method can effectively solve the problem of misjudgment of large targets and reduce the distance error in the detection results of marine radar by more than 79%, and the azimuth error by up to 60%.

Construction Method of Unknown Environment Contour for Unmanned Undersea Vehicle

LI Yang, YU Hao-miao, GUO Chen, JIA Zhao-yan

2022, 30(2): 197-203. doi: 10.11993/j.issn.2096-3920.2022.02.009

[Abstract](157) [PDF 714KB](27)

Abstract:
The confidence level of data measured by multivariate ranging sonar in an unmanned undersea vehicle(UUV) in an underwater environment is generally low. Therefore, the mean shift clustering algorithm was used to preprocess the obtained data. First, the abnormal and normal data are divided into different data categories to obtain the set of boundary points. Second, the boundary points are connected with contour lines using the Alpha-Shapes algorithm. Furthermore, the Bézier curve is used to fit the constructed contour lines to obtain an ideal, smooth tracking path of the UUV. Finally, a control method was used to track the constructed map. Thus, the problem of UUV map construction in an unknown marine environment was effectively addressed.

Pseudo-color Enhancement Methods and Quality Evaluation of Sonar Image Based on the CIELab Color Space and HIS Color Space

LI Qiu-ju, XU Hai-ping, GOU Chun

2022, 30(2): 204-208,230. doi: 10.11993/j.issn.2096-3920.2022.02.010

[Abstract](110) [PDF 4099KB](21)

Abstract:
At present, pseudo-color enhancement methods for sonar images are based only on the RGB and HSV color spaces. To this end, two novel sonar image pseudo-color enhancement methods based on the CIELab color space and HIS color space are introduced in this study. The quality of the enhanced images obtained by the two methods was evaluated. First, a novel pseudo-color real-time enhancement method based on the CIELab color space is proposed. The enhanced image obtained using this method was clearer and had richer levels. Second, combined with the Otsu method and according to the grayscale distribution characteristics of sonar images, a novel adaptable pseudo-color enhancement method based on the HIS color space is introduced. This method has strong adaptability, and the enhanced image obtained using this method is information-rich. Finally, two objective evaluation methods were used to verify the effectiveness of the enhancement methods in conjunction with the subjective evaluation method.

Interior Ballistic Simulation of Underwater Steel Cable Towed Launch Torpedo

CHEN Zong-yang, LIAN Yong-qing, LI Ang

2022, 30(2): 209-215. doi: 10.11993/j.issn.2096-3920.2022.02.011

[Abstract](239) [PDF 640KB](19)

Abstract:
In view of the limitations of the existing torpedo scheme launched by unmanned undersea vehicles(UUVs), namely the low tube-exit speed of the torpedo, inability to ensure the smooth exit of the torpedo after start-up failure, and large instantaneous thrust on the torpedo, a basic structural scheme is proposed for the underwater steel cable towed launch torpedo. The proposed scheme is simple and compatible with the self-launching scheme. Based on the launch scheme, the internal ballistic model of the underwater steel cable towed launch torpedo was established, including the gas state model of the launching air bottle, mathematical models of the launch valve, air-water cylinder, and towing device, and torpedo motion model. A launch process simulation was performed. In addition, the factors influencing the internal ballistic path of the torpedo launch, such as the initial filling pressure of the launch air bottle, UUV speed, and elastic modulus of the steel cable, were analyzed. The simulation results demonstrate that the scheme meets the requirements of the UUV launch torpedo, is feasible in principle, and possesses a structure that can solve the problem of emergency torpedo launch when the torpedo fails to exit the tube owing to the failure of self-launching, thereby reducing the structural strength requirement of the torpedo tail to a certain extent.

Optimization Modeling of Gas Catapult Interior Ballistic Parameters Based on NSGA-II Algorithm

JIA Xuan, WU Yi-fan, DUAN Hao, YANG Gong-yi

2022, 30(2): 216-222. doi: 10.11993/j.issn.2096-3920.2022.02.012

[Abstract](114) [PDF 474KB](13)

Abstract:
Based on the classical catapult interior ballistic theory, a numerical analysis method was applied to solve the interior ballistic mathematical model and evaluate the effect of different interior ballistic parameters on the interior ballistic performance. The burning rate coefficient, burning rate pressure exponent, virtual quality coefficient, and thermal correction coefficient were used as optimization variables, and the consistency between the theoretical and experimental values was used as the optimization objective. The NSGA-II algorithm was used to optimize the interior trajectory parameters, the Pareto optimal solution of each optimization variable was obtained, and the optimal compromise solution was used to select a reasonable optimal solution. The optimization design results demonstrated that the theoretical calculations of the interior ballistics were in agreement with the experimental values, and the differences between the theoretical and experimental values of the maximum bore pressure and outlet velocity were smaller. The optimization method used in this study can effectively improve the calculation accuracy of the interior ballistic mathematical model and is of significance to interior ballistic optimization design.

A Low-speed MTPA High-Dynamic Response Control Method of Permanent Magnet Synchronous Motor

ZHANG Yuan, WEI Hai-feng, ZHANG Yi, LI Yuan-jiang, LIU Wei-ting

2022, 30(2): 223-230. doi: 10.11993/j.issn.2096-3920.2022.02.013

[Abstract](170) [PDF 823KB](14)

Abstract:
The permanent magnet synchronous motor(PMSM) used in undersea vehicles must have a fast torque current dynamic response capability to improve the control performance of the control system when running at low speed. Aiming at the poor dynamic response performance of the traditional low-speed maximum torque per Ample(MTPA) control method of PMSM used in underwater vehicles, this paper proposes a low-speed MTPA high-dynamic response control method. This method achieves MTPA control using a segmented fitting algorithm in the outer speed loop and predictive control in the current inner loop, and an algorithm for automatic segmentation based on motor parameters is proposed. Simulation and experimental results demonstrate that the control method proposed in this study has a faster dynamic response speed.

Investigation of the Storage Life of Lithium-ion Battery Based on the Metabolism GM(1, 1)-Neural Network

LI Ju-chen, HU Yu-li, HAO Ze-hua, ZHANG ZI-zheng, ZHENG Yi

2022, 30(2): 231-236. doi: 10.11993/j.issn.2096-3920.2022.02.014

[Abstract](629) [FullText HTML] (27) [PDF 1205KB](11)

Abstract:
Active torpedoes are in storage most of the time, and lithium-ion batteries are the main power sources. Therefore, it is important to study the storage life of lithium-ion batteries. In this study, a 18650 lithium cobalt oxide battery was used as the research object. Through the accelerated life test, the battery capacity and internal resistance change curves with time under different stress conditions are obtained, and the storage condition that is helpful to alleviate the attenuation of battery life is determined as 25℃ and 30% state of charge(SOC). This study integrates the advantages of the gray prediction method and neural network, and uses the metabolic GM(1, 1)-neural network method to predict the capacity of lithium-ion batteries. The combined prediction model was verified to be better than the gray prediction model and metabolic GM(1, 1). The prediction model has a higher accuracy and is more suitable for predicting the storage life of lithium-ion batteries under different stress conditions. This further verifies the storage conditions that are conducive to alleviating the attenuation of battery life.

Research on Hitting Probability of Supercavitating Torpedo Based on Dispersion of Miss Distance

XIE Chao, ZHOU Jing-jun, WAN Ya-min, SONG Shu-long, WANG Meng-hao

2022, 30(2): 237-244,253. doi: 10.11993/j.issn.2096-3920.2022.02.015

[Abstract](161) [PDF 745KB](22)

Abstract:
To evaluate the operational effectiveness of straight running torpedoes such as supercavitating torpedo, it is essential to clarify the hitting probability. In this paper, an analytical formula of the miss distance was proposed, which intuitively reveals the dispersion law of the torpedo when it is closest to the target. Simultaneously, considering the geometric size of surface target and the torpedo damage radius, a judgment model of the torpedo hits the target was established. Furthermore, the study analyzes the entire process of a straight running torpedo attack from the detection of the target to the hit target, extracts the source of the error in the process, and uses a Monte Carlo-based statistical method to evaluate the hitting probability of the supercavitating torpedo. The simulation test mainly analyzed the influence of the initial distance between torpedo and target, the initial target board angle, and the target’s speed on the hitting probability. The results show that the best shooting distance of the supercavitating torpedo is within 5 km, and it has a higher hitting probability when the initial target board angle is between 20° and 150°, and the advantage of attacking the low-speed target is mainly reflected in the range of the large target board angle.

Design and Implementation of Meteorological and Marine Unmanned Observation System for Sea-based Launching Missions

NIU Xiang-hua, ZHU Wen-hui, SUN Xiu-jun, ZHANG Peng-fei, YU Jiang-lin, SANG Hong-qiang, ZHOU Ying, LI Can

2022, 30(2): 245-253. doi: 10.11993/j.issn.2096-3920.2022.02.016

[Abstract](140) [PDF 3328KB](31)

Abstract:
In mid-September 2020, China successfully completed a sea-based launching mission on the Yellow Sea. Considering the difficulty of obtaining high-resolution meteorological and marine data in real time on the open sea, this study describes a method using a new unmanned mobile platform equipped with various sensors to provide refined meteorological and marine observations in the launch area. The optimal technical scheme was designed and implemented to ensure a smooth mission through the analysis of actual needs. Wave gliders equipped with weather, water temperature, and wave sensors were selected as the observation platform, and the fixed-point operation observation mode and Beidou communication module were used. The corresponding data transmission and processing system was designed to meet the needs of real-time observations for meteorological and marine forecasting. The stability and reliability of using the wave glider as an observation platform in the process of providing refined meteorological and marine support services were verified. Finally, this paper puts forward some thoughts on the mode and operation mechanism of meteorological observation support and provides a reference for follow-up tasks.

Design and Experimental Verification of Sidewall Sound Barrier Module of DFB Fiber Laser Hydrophone

ZHOU Xuan, SONG Wen-zhang, HUANG Jun-bin, GU Hong-can, ZHAO Hong-lin, CHEN Si-tong

2022, 30(2): 254-259. doi: 10.11993/j.issn.2096-3920.2022.02.017

[Abstract](116) [PDF 1305KB](17)

Abstract:
A small-scale side module was designed based on distributed-feedback(DFB) fiber laser hydrophone technology. An acoustical baffle model was designed using an elastic wave model in a layer media. After a reasonable selection of materials for the acoustic baffle, a four-array DFB fiber laser hydrophone side module was fabricated. The sensitivities and directivities of the side modules were tested. The experimental results demonstrated that the relative sensitivity of the hydrophone module was enhanced and the response was flat. The feasibility of the scheme was preliminarily verified.

Synthesis Assessment of Working Reliability for Electric Power Torpedo in Sea Trial Based on CMSR Method

ZHU Wen-zhen, TANG Shi-xuan, XIE Yong

2022, 30(2): 260-264. doi: 10.11993/j.issn.2096-3920.2022.02.018

[Abstract](131) [PDF 389KB](16)

Abstract:
Aiming at the problem of less test data for electric power torpedoes, this paper proposes an assessment method of electric power torpedoes working reliability in a sea trial based on the combined modified maximum likelihood(CMML) and sequential reduction(SR) method(CMSR). By analyzing the advantages and disadvantages of the reliability assessment method of the series system, combined with the improved electric power torpedo’s characteristics of less actual sailing data of primary batteries and different test samples of each subsystem, this paper proposes a three-series reliability test scheme and assessment method using the CMSR assessment model. This method can obtain a higher confidence level of assessment results for torpedo working reliability in sea trials and has better practicability.

2022 Vol. 30, No. 2

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