水下无人系统学报

Reliability Analysis of Torpedo Shell Based on Strength and Stability

GUO Jun, JIANG Zhong-liang, QIN Xiao-hui, LIU Jin

2011, 19(6): 401-405. doi: 10.11993/j.issn.1673-1948.2011.06.001

[Abstract](1668) [PDF 323KB](647)

Abstract:
The concept of reliability design is introduced into torpedo structure design to rectify the insufficiencies of the conventional safety coefficient method. A safety margin equation and the solving approach of torpedo shell structural reliability based on a theoretical formula are proposed by combining the classic theory of torpedo shell and the second-order second-moment method. Simulation of torpedo shell structure by using the probabilistic design system(PDS) module in software ANSYS is performed to achieve its reliability. The proposed scheme combines structure design with reliability design, which may facilitate the design of torpedo shell.

Influence of Cavitator Shape on Ventilated Supercavitation in Head Support Mode

YI Hui, ZHANG Yu-wen, YUAN Xu-long, WANG Rui

2011, 19(6): 406-410. doi: 10.11993/j.issn.1673-1948.2011.06.002

[Abstract](1093) [PDF 386KB](561)

Abstract:
The research on the influence of cavitator shape on supercavitation is usually conducted in the condition where the front flow of cavitator is not disturbed. However, when the front flow of cavitator is influenced by using of head support mode in water tunnel test, the changing law of ventilated supercavitation with the shape of cavitator is not clear. In this study, a series of simulation models in accordance with the experimental ones are built by means of the computational fluid dynamics (CFD) simulation software FLUENT. These models depend on the diameter of cavitator, the diameter of the connecting rod, and the cone angle of the cavitator. Simulation indicates that under certain ventilation, the length and the length to diameter ratio of the ventilated supercavitation increase with the diameter of connecting rod increasing, decrease with the diameter of cavitator increasing, or increase with the cone angle of cavitator decreasing. Moreover, the influencing laws of the cavitator shape on ventilated supercavitation are also investigated. This study may facilitate the design of cavitator shape for the water tunnel test of supercavitation in head support mode.

An Improved Method for Evaluating Torpedo′s Working Reliability in Sea Trial

HE Cheng-gang, YE Hao-jie, ZHANG Di

2011, 19(6): 411-414. doi: 10.11993/j.issn.1673-1948.2011.06.003

[Abstract](1514) [PDF 247KB](687)

Abstract:
Aiming at the limitation in evaluating torpedo′s working reliability only by success/failure type or index number type, an improved method for objectively and accurately evaluating torpedo’s working reliability in sea trial via combination of the two types is proposed. The evaluation result is a comprehensive one concerning test sample size, total voyage time, task time, fault number of success/failure type and index number type, etc. The variation of reliability level with task time is more significantly influenced by the fault of index number type than by the fault of success/failure type. The evaluation result of the proposed method is more objective and accurate than the conventional ones.

Joint Estimation of Source Number and DOA for Underwater Passive Target Based on RJMCMC Method

CHEN Zhao, LIU Zheng-guo, WANG Hai-yan, SHEN Xiao-hong, HE Bin

2011, 19(6): 415-422. doi: 10.11993/j.issn.1673-1948.2011.06.004

[Abstract](1339) [PDF 614KB](619)

Abstract:
Conventional wideband signal processing method of subspace class wideband requires more snapshots to get a better estimation result. We apply a Bayesian high resolution direction of arrival(DOA) estimation method based on the time-domain wideband signal model to underwater passive target DOA estimation. Compared with conventional subspace class methods, the proposed method can process signal directly in time-domain and needs remarkably less snapshots. We use a time-domain wideband signal model to construct a posterior probability density function(PDF) of the parameters according to Bayes law, and then use the reversible jump Markov chain Monte Carlo(RJMCMC) method for Bayesian estimation to search peaks of the posterior PDF. This method can jump among parameter spaces with different orders, thus can implement joint model order (i.e. source number) and DOA estimation. Simulation results show that the RJMCMC method exhibits good performance in joint estimation of model order and DOA.

Design of High-power VME Specification Power Supply System

HAO Bin

2011, 19(6): 423-427. doi: 10.11993/j.issn.1673-1948.2011.06.005

[Abstract](948) [PDF 360KB](574)

Abstract:
Military information processor requires a high performance power supply with stable output, load protection, and data protection to adapt the severe variation in output of fore-power. We designed a high performance and high-power Versa Module Eurocard(VME) specification power supply which can work in the input voltage range of 18V~50V according to the requirement of a certain military information processor, and analyzed the polarity protection module, the power keeping module, and the power supply monitoring module. Test on the information processor illustrates that this power supply gains excellent universality and reliability, and stable performance. The one-slot power supply possesses the virtues of higher power density, less weight, higher efficiency, and intelligence.

Optimum Localization Algorithm Based on the Linear Least Squares Estimate for Bistatic Sonar

LIU Ruo-chen, WANG Ying-min, ZHANG Qun

2011, 19(6): 428-432. doi: 10.11993/j.issn.1673-1948.2011.06.006

[Abstract](1536) [PDF 380KB](825)

Abstract:
In the view of the redundant information problem of a bistatic sonar system, an optimal localization algorithm based on the linear least squares estimation is proposed. A mathematical model of underwater positioning is established based on a certain bistatic sonar. Through numerical simulation with the software MATLAB, the effect of the system parameters on localization accuracy is investigated. Also, the algorithm is compared with the time-only-localization (TOL) method. Simulation results show that the proposed algorithm, taking full advantage of the redundant information of the bistatic sonar, can effectively improve the localization accuracy, especially in the neighborhood of baseline and the side area of the bistatic sonar. The algorithm is affected weakly by baseline length and station site error with engineering application. This study may provide a theoretical basis for localization optimization problem of multistatic sonar.

Underwater LPI Waveforms Design Based on LAS Code and Chaos

HONG Jia-xiang, YI Hong, ZHANG Juan, ZHANG Lin-rang

2011, 19(6): 433-437. doi: 10.11993/j.issn.1673-1948.2011.06.007

[Abstract](1371) [PDF 447KB](1047)

Abstract:
In view of the requirement for low probability of intercept (LPI) waveform characteristics in underwater detection, we serialize the chaotic sequences and use it to modulate the signal phase such that the basic waveform is obtained. Then the large area synchronized (LAS) codes are introduced for both interpulse and intrapulse modulations to design two new waveforms. Relying on the zero-delayed section and zero-Doppler section of an ambiguity function, we compare the discrimination property of the two new waveforms intuitively with four kinds of typical underwater detection waveforms, i.e. continuous waveform (CW), linear frequency modulation (LFM) waveform, binary phase shift keying (BPSK) waveform and Costas waveform. Quantification analysis is made by their time resolution constants and frequency resolution constants. In addition, nonzero-Doppler section of an ambiguity function is used to compare their Doppler sensitivity characteristics under the ideal background, followed by a further comparison of reverberation suppression capability via the Q function. The results show that two new waveforms have outstanding distance resolution, Doppler tolerance and reverberation suppression capability over whole velocity ranges required by practical use.

A CPG-based Method for Motion Control of Flapping-wing UUV

SHEN Chao, LIU Ming-yong, LIANG Qing-wei

2011, 19(6): 438-442. doi: 10.11993/j.issn.1673-1948.2011.06.008

[Abstract](1836) [PDF 458KB](612)

Abstract:
Traditional methods for robot motion control need complex dynamic and kinematic models, and are lack of real-time especially for the control tasks with multiple degrees of freedom (multi-dof). Central pattern generator (CPG) is good at dealing with multi-dof control tasks. This paper analyzes the flapping-wing’s influence on UUV’s motion, and proposes a CPG-based method for motion control of a flapping-wing UUV. The motion mode of the wings is controlled by using feedback signals, and two control laws for UUV′s straight and turning motions are designed by adjusting the relations among CPG parameters, feedback control input, and CPG output. Simulation result indicates that the CPG-based method is feasible and effective.

Nonlinear Transfer Alignment Model and Filtering Algorithm for Strapdown Inertial Navigation System of Shipborne Weapons

LI Na, WANG Xin-long

2011, 19(6): 443-450. doi: 10.11993/j.issn.1673-1948.2011.06.009

[Abstract](1544) [PDF 500KB](533)

Abstract:
To satisfy the requirement of fast reaction and high precision of initial alignment for shipborne weapons, and to enhance the transfer alignment for shipborne weapons with large misalignment, we present a method of combining the rapid transfer alignment model based on quaternion and the nonlinear unscented Kalman filter (UKF) algorithm, and establish a nonlinear error model for strapdown inertial navigation system(SINS) of shipborne weapons. This error model introduces quaternion to describe the attitude errors in order to enhance the speed and accuracy in calculating attitude. We select a velocity and attitude matching approach to improve the observability of the system, and solve the ill-condition of covariance matrix of the traditional nonlinear UKF filter by using singular value decomposition(SVD) to ensure the algorithm robustness. The simulation results show that the proposed method can effectively improve the precision and speed of transfer alignment for shipborne weapons with large misalignment, and its calculation accuracy and alignment time meet the design requirements of the system.

Application of Amplitude Limit Characteristic to Torpedo Control System Design

WANG Gai-di, HUANG Hua-hong, Lü Yan-hui

2011, 19(6): 451-454. doi: 10.11993/j.issn.1673-1948.2011.06.010

[Abstract](1475) [PDF 336KB](511)

Abstract:
The action mechanism of amplitude limit characteristic and system working principle are analyzed by taking an example of a torpedo depth pitch system with relay control. Based on the mathematical description of this system, the amplitude limit parameters are optimized and analyzed via simulation. The results show that the amplitude limit characteristic can realize the automatic transition of control status, maximize system capacity, and optimize the depth searching trajectory for torpedo to meet the requirement of torpedo usage in deep or shallow sea.

A Fast CPB Processing Method of Off-design Vibration and Noise Data from Multiple Channels

SUN Tao, GAO Ai-jun, WANG Yi, DU Zhi-guo

2011, 19(6): 455-458. doi: 10.11993/j.issn.1673-1948.2011.06.011

[Abstract](1468) [PDF 345KB](561)

Abstract:
To solve the time-consuming and laborious problem in processing the off-design vibration and noise data from multiple channels through the traditional constant proportional bandwidth (CPB) method, an improved CPB method is proposed. Firstly, the data from all channels are divided into multi-segment, and each segment is calculated via octave algorithm based on fast Fourier transform (FFT) algorithm. Secondly, technical parameter mean and average octave sequence are calculated according to the starting and ending time corresponding to the stable condition determined by the condition parameter curve. Finally, technical parameter mean and average octave sequence of the same working condition are adjusted to the adjacent columns by indexing the condition-determining parameters. Engineering application shows that the analysis efficiency and depth of test data are improved significantly.

Study on Starting Characteristics of Plunger Type Fuel Pump and Fuel Supply System

XU Xing-qin, BAI Zhao-gao

2011, 19(6): 459-462. doi: 10.11993/j.issn.1673-1948.2011.06.012

[Abstract](1569) [PDF 383KB](546)

Abstract:
To further enhance the starting reliability of torpedo thermal power system, the theoretical necessary condition of system starting is obtained in the view of physics by analyzing the structural feature of a plunger type fuel pump. By analyzing the data from test of the fuel pump and sea trial of a torpedo, a design criterion is offered to achieve better starting characteristics of the plunger type fuel pump and the fuel supply system, that is, the fuel pump′s design parameters must satisfy P1max/P0′1/K(V1/V0+1). It is found that the fuel pump can not start if the ratio of inlet to outlet pressure reaches a limit when the plunger type fuel pump works in starting phase and the fuel is in gaseous state.

Simulation Research on Roots Tri-propellant Proportion Controller

WANG Ying, WANG Yu-cai, PAN Guang

2011, 19(6): 463-467. doi: 10.11993/j.issn.1673-1948.2011.06.013

[Abstract](953) [PDF 464KB](515)

Abstract:
Tri-propellant proportion controller is a key part of underwater heat engine energy supply system, its proportional precision is very important for exploiting the energy efficiency of the propellant. And for Roots tri-propellant proportion controller, its proportional control precision is mainly affected by the leakage volume of each way. In this paper, based on the analysis of mechanics and leakage volume of Roots tri-propellant proportion controller, a mathematical model is established, and numerical simulations are performed via MATLAB. Consequently, the variation rules of the important parameters, such as the utilization factor of area, the interior diameter of stator, the total height of impeller, and the end face clearance, are obtained. And the influences of these parameters on proportional precision are analyzed. This study may be applied to the development of Roots tri-propellant proportion controller.

Development of Modern Acoustic Countermeasure Equipments and Its Effect on Sea Warfare

LI Ben-chang, LIU Chun-yue, ZHENG Yuan

2011, 19(6): 468-472. doi: 10.11993/j.issn.1673-1948.2011.06.014

[Abstract](1260) [PDF 314KB](564)

Abstract:
The main purpose of traditional tactic platform using acoustic countermeasure equipments is to achieve self-defense by keeping and resuming the self-covert evasion of tracking. With the enhancement of modern acoustic countermeasure equipments in function and performance, they can also implement other tactic aims on the platform and reach campaign purposes in higher level operational application. In this paper, based on the technical analysis and the operational application theory of the acoustic countermeasure equipments, the operational application of the modern acoustic countermeasure equipments are divided into three levels, i.e. platform defense, tactic cover, and campaign deceit. The tactic and technical characteristics of each level and their influences on sea warfare are discussed.

Optimum Torpedo-Dropping Parameter of Anti-submarine Patrol Aircraft

LI Ju-wei, ZHAO Zhi-yun, SUN Ming-tai

2011, 19(6): 473-478. doi: 10.11993/j.issn.1673-1948.2011.06.015

[Abstract](1645) [PDF 464KB](640)

Abstract:
In order to improve the hit probability of an aerial anti-submarine torpedo, the concept of optimum torpedo- dropping parameter with influencing factors and selection criterion are presented and analyzed. The arithmetic models based on Monte Carlo are established. The influences of torpedo-dropping parameter, target locating precision and torpedo-dropping dispersion on the detection probability in a circular search cycle are simulated. The results indicate that the torpedo-dropping parameter should be selected by considering the target locating precision and the torpedo-dropping dispersion comprehensively.

2011 Vol. 19, No. 6

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