水下无人系统学报

Current Situation and Technological Development of U.S. Navy’s MK48 Heavyweight Torpedo

GUO Zhi-qiang, SU Wen-guo, TANG Gui

2021, 29(2): 129-134. doi: 10.11993/j.issn.2096-3920.2021.02.001

[Abstract](736) [PDF 287KB](383)

Abstract:
The MK48 series heavyweight torpedo is a type of undersea weapon and it has gained considerable popularity from the U.S Navy. Furthermore, it has undergone considerable development in recent years. This paper reviews the development process and current situation of MK48 heavyweight torpedo and discusses the current progress of its research and development. Furthermore, the development routes of MK48 torpedo are analyzed, and the research results and application of three key developmental projects, namely: stealth torpedo enhancement program (STEP), torpedo advanced propulsion system(TAPS), and common broadband advanced sonar system(CBASS) are emphatically introduced. Finally, the main characteristic of its future development routes is preliminarily analyzed, and it is concluded that joint operations may be a novel application of MK48 torpedo.

Research on Wave Observation Technology of Wave Glider

QIN Yu-feng, QI Zhan-feng, ZHANG Shuang, HOU Er-hu, LI Guo-fu, FENG Zhi-tao

2021, 29(2): 135-146. doi: 10.11993/j.issn.2096-3920.2021.02.002

[Abstract](302) [PDF 2808KB](145)

Abstract:
At present, wave observation is mainly based on wave buoys for fixed-point observation, and few studies have been conducted on wave observation in navigation by using new ocean mobile observation platforms such as wave glider. The feasibility, method and capability of wave observation by using wave glider “Blue Whale” are studied in this paper. The structure, working principle and wave observation method of wave glider “Blue Whale” is introduced, and a comparison test on the basis of analyzing the different wave observation principles of wave glider and wave buoy is established. Based on the test results, the difference and correlation of the wave height, wave period, wave number and wave direction between the wave glider and the wave buoy are analyzed. The existence mechanism of the difference value is analyzed, and the theoretical basis of eliminating the difference value and correcting the observed data of wave glider is provided. According to the test analysis, compared with that of the wave buoy, the wave data of the wave glider has higher coincidence degree, smaller difference value and a high correlation. The average correlation coefficient is above 0.9 and the data quality is highly reliable. The accuracy of wave data observed by wave glider is verified, and the feasibility of wave observation by wave glider is proved.

Underwater Target Identification Based on Dolphin Auditory System Model

ZHOU Zhuo, LIANG Hong, YANG Chang-sheng, ZHAO Guo-gui

2021, 29(2): 147-152. doi: 10.11993/j.issn.2096-3920.2021.02.003

[Abstract](515) [PDF 1065KB](180)

Abstract:
Extracting feature information from the active sonar echo of target is an effective method to realize underwater target classification and identification. The excellent performance of animal sonar in underwater target identification provides a solution for artificial sonar. In this study, the click signal of bottlenose dolphin is used as the transmitting signal of active sonar. The echo characteristics of the target are extracted by wavelet transform and model of dolphin auditory system, and are classified as the input of support vector machine. In addition, this paper proposes an idea that the time spectrum obtained by the model based on dolphin auditory system is used as the input of convolution neural network to classify and identify the target. The results show that compared with that of the wavelet transform method, the feature extraction method based on the computer model of dolphin auditory system is better for target classification and identification. Combining with convolution neural network, using dolphin click signal and model of dolphin auditory system can obtain better results in underwater target identification.

Underwater Target Identification Method Based on Optimized 2D Variational Mode Decomposition and Transfer Learning

FU Tong-qiang, HU Qiao, LIU Yu, ZHENG Hui-wen

2021, 29(2): 153-163. doi: 10.11993/j.issn.2096-3920.2021.02.004

[Abstract](400) [PDF 882KB](165)

Abstract:
Intelligent identification of underwater targets using the traditional underwater acoustic target identification method has limitations owing to the complexity and variability of marine environments. The data sets that are constructed based on single-domain features cannot be used to characterize the global information of the target signal and the traditional machine learning and deep learning methods demonstrate a low generalization ability for small sample targets. To solve the problem of low accuracy and efficiency of traditional underwater acoustic target identification methods in complex marine environments, an underwater target identification method based on optimized two-dimen- sional variational mode decomposition(2D-VMD) and transfer learning is proposed herein. This method obtains the time-frequency map of the underwater target by wavelet transform and then uses the optimized 2D-VMD method to adaptively select the effective mode to achieve the separation of the target effective mode and the noise mode. The denoising of the time-frequency map is completed, and the classic texture features of the image are extracted for comparative analysis. Finally, through the transfer learning strategy being adopted, the model transfer learning verification based on InceptionV3 is realized, and the classification and identification for small sample data set of underwater targets are completed. Combined with the classification test experiment of five types of underwater targets in ShipsEar, the results show that: the underwater target identification method based on optimized 2D-VMD and transfer learning shows good feature extraction and denoising capabilities while taking into account the accuracy of underwater target identification and efficiency requirements. Moreover, it provides theoretical and technical support for the detection and identification of intelligent targets of marine equipment.

Weighted Histogram Method for DOA Estimation Using Single Vector Hydrophone

ZHANG Xiao-yong, ZHAGN Guo-jun, SHANG Zhen-zhen, WANG Shuai

2021, 29(2): 164-169. doi: 10.11993/j.issn.2096-3920.2021.02.005

[Abstract](352) [PDF 416KB](109)

Abstract:
Using vector hydrophone for direction of arrival(DOA) estimation in unmanned undersea system is advantageous, and this can be realized by the weighted histogram method with less computation using single vector hydrophone. In this study, the principle of acoustic energy flux detector is analyzed, the distribution of acoustic energy in the plane can be obtained from acoustic energy flux, which provides the theoretical basis for the weighted histogram method. It is observed that the energy of the sound source extends beyond the real orientation under low signal-to-noise ratio(SNR) through the analysis. Hence, the statistical interval of the weighted histogram method will segment the energy of the sound source and a DOA estimation error will occur. Aiming to the problem existing in the previous algorithm, an improved weighted histogram method based on energy search is proposed. In the new algorithm, the slide window method is used to find the range of sound source, and the center of gravity method is used to obtain the energy center which is the DOA estimation result. The simulation results show that the algorithm has better performance when the statistical interval is 10° and the SNR is within the range of 10 dB to 10 dB. Its root mean square error is 43.7% less than that of the previous algorithm and its DOA estimation results are comparatively accurate in a multi-target(interference) environment. The research in this paper provides a reference for improving the algorithm of DOA estimation using single vector hydrophone.

Influence on Nodes Movement to Holistic-network Performability of Multi-AUV Collaborative System

LIANG Qing-wei, ZHANG Xin, YAN Xiao-hang

2021, 29(2): 170-175. doi: 10.11993/j.issn.2096-3920.2021.02.006

[Abstract](147) [PDF 507KB](106)

Abstract:
The multi-AUV collaborative system(MAUVS) has a wide space range, strong functions and high efficiency. While facing the complex ocean environment, system nodes are required to adjust their movement during execution of tasks. The change in the movement of the nodes will affect communication distance between nodes, and Doppler frequency shifts, which will in turn affect the reliability of MAUVS. Based on the topology, considering the bit error rate and the delay characteristics of underwater communication, the reliability of communication performance is described herein in terms of holistic-network performability, and a method for calculation of holistic-network performability is discussed. The effect of communication distance on links under different motion states is analyzed using examples, and the effect of the movement of nodes on the holistic-network performability of the entire network is discussed. This study verifies the reliability of the MAUVS communication network described using holistic-network performability.

Multi-optical Buoys Joint Localization Algorithm and Simulation

GUO Jian-zhong, SUN Jian, WANG Kai-shuai

2021, 29(2): 176-182. doi: 10.11993/j.issn.2096-3920.2021.02.007

[Abstract](175) [PDF 518KB](120)

Abstract:
To solve the problem that single or double optical buoys cannot obtain all-elements information of a target, based on the technique of calculating the moving elements of acoustic target, an algorithm for multi-optical buoys joint localization is presented in this paper. A mathematical model is established for the observation of optical buoys including positioning error, observation time error, and optical observation blur error. Utilizing the Monte-Carlo simulation method, the localization accuracy index of different number of optical buoys for maneuvering target considering all the above-mentioned errors is provided, and the effect of each factor on the joint localization of multi-optical buoys is analyzed simultaneously. The research provides data support for the engineering application of optical buoy.

Side Lobe Control Method in Subarray Beamforming Based on Randomly Staggered Combination Array

ZHU Peng, DU Jin-xiang

2021, 29(2): 183-188. doi: 10.11993/j.issn.2096-3920.2021.02.008

[Abstract](199) [PDF 455KB](84)

Abstract:
In order to reduce the difficulty of engineering implementation of the underwater large-scale sonar array beamforming algorithm, a large planar array with element-level partitioned beam scanning mode can be adopted, without changing the weight of amplitude and phase of the array element in each scanning partition, and only the subarray-level digital beamforming is adopted, then the beam scanning of the array can be completed. However, this mode will bring high side lobe problems. To solve this problem, a new method of randomly staggered combination array based on regular subarray division is proposed, which breaks the limit of the existing research method that the offset is an integer multiple of the element spacing, and uses genetic algorithm to simultaneously optimize the offset of adjacent columns of the subarray and the subarray-level weight coefficients. The main side lobe ratio is used as the fitness function. Hence, the highest side lobe of the integrated pattern is the lowest and the grating lobe effect caused by the large element spacing at the subarray level is reduced. The simulation results show that the use of random staggered subarray structure, the optimized formation and weight coefficients can effectively avoid the high side lobe in large partitions and obtain a higher main side lobe ratio in different partitions. The control effect of the side lobes is better than that of the existing staggered combination array method, which verifies the effectiveness of the proposed method.

Underwater Bearings-Only Short Time Target Tracking Based on Initial Value Updating

ZHENG Yi, WANG Ming-zhou

2021, 29(2): 189-195. doi: 10.11993/j.issn.2096-3920.2021.02.009

[Abstract](698) [PDF 516KB](105)

Abstract:
Underwater passive bearings-only target tracking by single-observer has the advantages of simple layout and strong concealment. However, the filtering methods are sensitive to the initial value, and the actual engineering will encounter the situation of fast target speed, short observation time and less measurement data, which makes this problem significantly prominent. In view of this situation, this paper studies the causes and the effect of initial values on filtering, and presents an improved method of extended Kalman filter based on initial value update. By re-estimating and updating the initial values through backward iteration, the effect of the initial error on the filtering result is gradually reduced. The simulation results show that this method can reduce the dependence of the filter on initial value selection and the final estimation error.

Denoising Method for the Pulse Width Modulation Signal and Current Signal in the Control System of Underwater Robot Thruster

YIN Bao-ji, ZHOU Jia-hui, TANG Wen-xian, DONG Ya-peng

2021, 29(2): 196-202. doi: 10.11993/j.issn.2096-3920.2021.02.010

[Abstract](237) [PDF 1613KB](184)

Abstract:
With the aim of achieving thruster control and monitoring this control under operating conditions, a denoising method for the pulse width modulation(PWM) signal and current signal in the control system of underwater robot thruster is explored in this study. The ripple amplitude and duty cycle fluctuation of the PWM signal are large in a thruster control circuit based on typical series grounding. Therefore, to reduce the ripple amplitude and duty cycle fluctuation, a redundant grounding circuit is designed, in which an extra ground wire is added between the central processing unit(CPU) and the module converting analog voltage to PWM to avoid the interference of the ground signal of the power. However, the error between the denoised current data and the actual data has a large magnitude even after the current data is denoised using the wavelet decomposition method. Hence, to further denoise the current data, a coupling denoising method based on the cross coupling of wavelet decomposition and seven-point slip average is proposed. The water-tank experimental results obtained are as follows: The designed redundant grounding circuit has a smaller ripple amplitude and duty cycle fluctuation than those of the series grounding circuit. The proposed coupling denoising method has a smaller error between the denoised current data and the actual data when compared with that between the raw data and the denoised data as obtained via the wavelet decomposition. The effectiveness of the abovementioned methods is therefore verified by the experimental results.

Analytic Formula and Employment of the Hitting Probability for Sub-Launched Torpedo

WU Zhi-dong, YU Xue-yong, XU Zhao-peng

2021, 29(2): 203-209. doi: 10.11993/j.issn.2096-3920.2021.02.011

[Abstract](162) [PDF 429KB](178)

Abstract:
To establish the analytic formula of the hitting probability for sub-launched torpedo with a predetermined encounter situation, the geometric analysis method is adopted. Firstly, the influence of encounter situation on the hitting probability of sub-launched torpedo is analyzed, and the general calculation model of the torpedo hitting error in the two-time rotating angle shooting with different homing modes are established. On this basis, the analytic formula of torpedo hitting probability is es-tablished, and the values of model parameters are analyzed. Finally, based on the calculation results of examples, the torpedo hitting probability curves are analyzed quantitatively, the analytical calculation result and the simulation calculation results of torpedo hitting probability are compared, the feasibility of the analytical calculation method and the correctness of the model are verified. The influence of different elements errors on torpedo hitting result is compared and analyzed based on torpedo one-time and two-time rotating angle shooting.

Underwater Image Enhancement Algorithm Based on Constant Scattering Assumption and Homomorphic Filtering

WANG Dan, ZHANG Zi-yu, ZHAO Jin-bao, YANG Xie-liu, FAN Hui-jie, TANG Yan-dong

2021, 29(2): 210-217. doi: 10.11993/j.issn.2096-3920.2021.02.012

[Abstract](169) [PDF 7430KB](121)

Abstract:
Aiming at the problem of low contrast and color deviation in underwater image visual enhancement technology, an image enhancement algorithm based on constant scattering assumption and homomorphic filtering is proposed. Firstly, assuming the backscattering of the whole image is constant, the minimum pixel value of red, green and blue (RGB) three channels is searched in the foreground area of the image, and the difference between each channel and its corresponding minimum pixel value is determined to avoid backscattering. Subsequently, the image is transformed into a gray image and homomorphic filtering is performed to suppress the low-frequency information and enhance the high-frequency component of the image. Finally, color correction method is used to eliminated the interference of outliers to the image. Experimental results show that the proposed method can effectively improve the contrast and brightness of the image, and enhance the overall visual effect of the image.

The Application of Image Compressed Sensing in Joint Source-Channel Coding System

LIU Xu-han, ZHANG Shang-zhuo, LI Hai-qing, ZHANG Wei-jie, ZHANG Jian-song

2021, 29(2): 218-223. doi: 10.11993/j.issn.2096-3920.2021.02.013

[Abstract](220) [PDF 681KB](268)

Abstract:
This paper proposes a method which applies image compressed sensing based on the discrete wavelet transform(DWT) in the joint source-channel coding system. This method combines the double unequal error protection and dynamic rate allocation mechanism. According to the difference in the sub-band reconstruction information of each frequency after DWT of the image, unequal compression is performed using the compressed sensing(CS) algorithm to produce a progressive information flow in the source coding part. Consequently, the information flow is converted into binary codes which is comparably suitable for the channel transmission after the Huffman entropy coding. The rate of Turbo is distributed based on the progressive bit stream dynamically in the channel coding part, to achieve the unequal error protection of the channel. During instances when the channel resources are limited, the channel resource allocation can be optimized to achieve good end-to-end communication performance. Performing a simulation of the standard gray scale image of Lena and passing through the white Gaussian noise channel after coding, the result is as follows: When the SNR is 4 dB, the image reconstruction mean square error is 0.061 6 with good reconstruction performance. Meanwhile, the system obtains the compression ratio up to 4:1, reduces the system energy consumption and increases the transmission efficiency.

Prediction Design Method on Whole Working Process Co-Simulation of Torpedo Thermal Propulsion System

MA Wei-feng, LI Xin, HAN Xin-bo, WAN Rong-hua, HAN Yong-jun

2021, 29(2): 224-229. doi: 10.11993/j.issn.2096-3920.2021.02.014

[Abstract](168) [PDF 807KB](140)

Abstract:
In view of lack of a multi-disciplinary integrated design environment for torpedo thermal propulsion system and inability to achieve interdisciplinary cross-system coordination, this paper investigates the co-simulation prediction design method on the whole working process of torpedo thermal propulsion system based on the development status of torpedo thermal propulsion system simulation. This study provides a simulation and verification system of the thermal propulsion system using different dimensions, different professional simulation software and test data, and explores the prediction design method of the subsystem numerical simulation, scheme design optimization and the system numerical tests, in realizing the drive of the design parameters and interdisciplinary cross-system simulation, completes the digital verification and performance evaluation. The simulation examples show that the method enables the visual display of fluid field details and parameter changes, thereby facilitating the virtual validation of system performance. Using this method, the transfer from the conventional design to predicted design is achieved. As a result, design success rate and product reliability are enhanced while the design period is reduced, which is crucial for the research and development of torpedo thermal propulsion systems.

Effect of Explosion Network Output Synchronization on the Damage Power of Shaped Charge Warhead of Underwater Weapon

WANG Tuan-meng, HA Hai-rong, LU Hai-ling, WANG Xue-feng, LI Qin, XU Yang

2021, 29(2): 230-237. doi: 10.11993/j.issn.2096-3920.2021.02.015

[Abstract](197) [PDF 1013KB](109)

Abstract:
Aiming at the demand of underwater weapon shaped charge warhead adopting explosion network, the effects of the factors of multipoint output synchronization of explosion network are analyzed by using the mode of analysis tree, and the control method of multipoint output synchronization are proposed in this study. The effect of output synchronization of explosion network with one-in-eight-out on damage power of shaped charge warhead is studied by simulation method. The results show that the damage power of shaped charge warhead will not be significantly affected when the limit deviation of multi-point output synchronization of one-in-eight-out explosion network is controlled within 0.6 μs. However, if the technical index of output synchronization limit deviation of explosive network is continuously tightened and improved, the comprehensive damage power of shaped charge warhead will not be significantly improved. This research can provide theoretical basis for improving the damage caused by an underwater weapon shaped charge warhead.

Optimization of Regional Blockade Deployment of Underwater Preset Anti-ship Missiles Based on GA

SUN Fan, ZOU Qiang, PENG Ying-wu

2021, 29(2): 238-242. doi: 10.11993/j.issn.2096-3920.2021.02.016

[Abstract](3713) [PDF 456KB](272)

Abstract:
Underwater preset anti-ship missiles as a new type of underwater attack weapon will play an important role in future naval battles. Therefore, to improve the effectiveness of underwater preset anti-ship missile blockades, the deployment of underwater preset anti-ship missiles in regional blockade operations is studied by separating the target sea area into grids. This is combined with an analysis of weapon performance, environmental characteristics, operational requirements, and other factors, and a combination optimization model of underwater preset anti-ship missile regional blockade deployment is established. Finally, the genetic algorithm(GA) is used to verify the rationality and effectiveness of the model through simulation examples, whereby a reference is provided for the deployment of underwater anti-ship missiles in the future.

Collection and Application of Reliability Information for Torpedo

PANG Duo, CHENG Wen-xin, CHEN Huan, ZHANG Gong-yuan, ZHANG Yue-qing

2021, 29(2): 243-248. doi: 10.11993/j.issn.2096-3920.2021.02.017

[Abstract](188) [PDF 304KB](110)

Abstract:
Reliability information is crucial to improve product design and evaluate quantitative index. The collection of reliability information for torpedo is in the early phase, and the method and application of reliability information collection have not been systematically studied. Aimed at the actuality, this paper analyses the necessity of the collection of reliability information for torpedo, and gives the content, use, and method of information collection. Combined with engineering experience of information collection, the paper provides information collection forms for reference, and gives application examples combined with the calculation formula. It can supply mentality for information collection of torpedoes and accumulate reliability information of torpedo continually.

2021 Vol. 29, No. 2

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