A method of multi-channel reference signals acquiring in broadband ANC

In a flank array on an unmanned underwater vehicle （UUV）, self-generated noise which has broadband and colored spectrum property in frequency and spatial domain is the main factor affecting the performance of weak signal detection, so the technique of adaptive noise cancellation （ANC） as well as physical denoising and active noise cancellation are often used in practice. Because ANC is based on correlations, improvements in performance come from better correlation between reference signals and primary signals. Taking full advantage of the characteristics of flank arrays and the characteristics of information obtained from hydrophones, a new method for reference signal acquisition for adaptive noise cancellation is proposed, in which the multi-channel reference signals are obtained by accurate delaying for a given direction of arrival （DOA） and differencing between adjacent outputs of array elements. The validity of the proposed method was verified through system modeling simulations and lake experiments which showed good performance with little additional computational burden.     

Numerical analysis of transient fluid-structure interaction of warship impact damage caused by underwater explosion using the FSLAB北大核心CSCD

［Objectives］This paper aims to address the numerical simulation problems of the dynamic response of ships subject to near-, medium- and far-field underwater explosions by establishing several numerical methods and calculation models. ［Methods］First, load and fluid-structure interaction models are established on the basis of the Eulerian finite element method and acoustic finite element method using the field-split technique, and FSLAB fluid-structure interaction software is developed. Next, near-, medium- and far-field underwater explosions are numerically simulated respectively. The shock wave propagation law, bubble shape and load evolution characteristics of near free-surface and near-wall underwater explosions are obtained, and the shock response characteristics of a spherical shell and ship subject to far-field underwater explosions are analyzed. Finally, the FSLAB software results are compared with the analytical solutions, reference solutions and experimental data. ［Results］The results show that the FSLAB fluid-structure interaction software developed in this paper is effective and accurate in simulating the impact damage of underwater explosions on warships. ［Conclusion］This study can provide a basis and support for the power assessment of underwater anti-explosion and shock design of warships. © 2022 Journal of Clinical Hepatology. All rights reserved.     

Application of ML to System Identification for Underwater Vehicle

In this paper, maximum-likelihood (ML) and its relaxation algorithm, which are used to identify the mathematicsmodel of an underwater vehicle(UV), arc discussed. With the trial data of zigzag tests, the hydrodynamic derivatives of theUV were estimated, and the relaxation algorithm is confirmed to have better astringency from the contrast between the twomethods.Then a simulation environment based on these parameters is established to verify the validity and effect of these meth-ods. The result shows the model is credible and the methods are very useful for the research of maneuverability and adaptivecontrol of underwater vehicles.     

Analytical and experimental study of free vibration of beams carrying multiple masses and springs

The structures in engineering can be simplified intoelastic beams with concentrated masses and elastic spring supports.Studying the law of vibration of the beams can be a help in guidingits design and avoiding resonance. Based on the Laplace transformmethod, the mode shape functions and the frequency equations ofthe beams in the typical boundary conditions are derived. Acantilever beam with a lumped mass and a spring is selected toobtain its natural frequencies and mode shape functions. Anexperiment was conducted in order to get the modal parameters ofthe beam based on the NExT-ERA method. By comparing theanalytical and experimental results, the effects of the locations ofthe mass and spring on the modal parameter are discussed. Thevariation of the natural frequencies was obtained with the changingstiffness coefficient and mass coefficient, respectively. The findingsprovide a reference for the vibration analysis methods and thelumped parameters layout design of elastic beams used inengineering.     

Application of A* algorithm for real-time path re-planning of an unmanned surface vehicle avoiding underwater obstacles

This paper describes path re-planning techniques andunderwater obstacle avoidance for unmanned surface vehicle （USV）based on multi-beam forward looking sonar （FLS）. Near-optimalpaths in static and dynamic environments with underwaterobstacles are computed using a numerical solution procedure basedon an A algorithm. The USV is modeled with a circular shape in 2degrees of freedom （surge and yaw）. In this paper, two-dimensional（2-D） underwater obstacle avoidance and the robust real-time pathre-planning technique for actual USV using multi-beam FLS aredeveloped. Our real-time path re-planning algorithm has beentested to regenerate the optimal path for several updated frames inthe field of view of the sonar with a proper update frequency of theFLS. The performance of the proposed method was verifiedthrough simulations, and sea experiments. For simulations, theUSV model can avoid both a single stationary obstacle, multiplestationary obstacles and moving obstacles with the near-optimaltrajectory that are performed both in the vehicle and the worldreference frame. For sea experiments, the proposed method for anunderwater obstacle avoidance system is implemented with a USVtest platform. The actual USV is automatically controlled andsucceeded in its real-time avoidance against the stationary underseaobstacle in the field of view of the FLS together with the GlobalPositioning System （GPS） of the USV.     

水下爆炸空化效应作用下全船响应的并行计算(英文)

As well as shock wave and bubble pulse loading, cavitation also has very significant influences on the dynamic response of surface ships and other near-surface marine structures to underwater explosive loadings. In this paper, the acoustic-structure coupling method embedded in ABAQUS is adopted to do numerical analysis of underwater explosion considering cavitation. Both the shape of bulk cavitation region and local cavitation region are obtained, and they are in good agreement with analytical results. The duration of reloading is several times longer than that of a shock wave. In the end, both the single computation and parallel computation of the cavitation effect on the dynamic responses of a full-scale ship are presented, which proved that reloading caused by cavitation is non-ignorable. All these results are helpful in understanding underwater explosion cavitation effects.     

欠驱动ODINs的全局逆最优循迹控制（英文）

This paper presents a design of optimal controllers with respect to a meaningful cost function to force an underactuated omni-directional intelligent navigator(ODIN) under unknown constant environmental loads to track a reference trajectory in two-dimensional space. Motivated by the vehicle’s steering practice, the yaw angle regarded as a virtual control plus the surge thrust force are used to force the position of the vehicle to globally track its reference trajectory. The control design is based on several recent results developed for inverse optimal control and stability analysis of nonlinear systems, a new design of bounded disturbance observers, and backstepping and Lyapunov’s direct methods. Both state- and output-feedback control designs are addressed. Simulations are included to illustrate the effectiveness of the proposed results.     

海底犁式挖沟机犁体曲面优化设计(英文)

The plow of the submarine plowing trencher is one of the main functional mechanisms, and its optimization is very important. The design parameters play a very significant role in determining the requirements of the towing force of a vessel. A multi-objective genetic algorithm based on analytical models of the plow surface has been examined and applied in efforts to obtain optimal design of the plow. For a specific soil condition, the draft force and moldboard surface area which are the key parameters in the working process of the plow are optimized by finding the corresponding optimal values of the plow blade penetration angle and two surface angles of the main cutting blade of the plow. Parameters such as the moldboard side angle of deviation, moldboard lift angle, angular variation of the tangent line, and the spanning length are also analyzed with respect to the force of the moldboard surface along soil flow direction. Results show that the optimized plow has an improved plow performance. The draft forces of the main cutting blade and the moldboard are 10.6% and 7%, respectively, less than the original design. The standard deviation of Gaussian curvature of moldboard is lowered by 64.5%, which implies that the smoothness of the optimized moldboard surface is much greater than the original.     

Research on vibration and near-field soundradiation of ring-ribbed cylindrical shell coated deadening and decoupling materials

The research on structural vibration and sound radiation of underwater ring-ribbed cylindrical shell, which is coated with a kind of deadening and decoupling materials, becomes a focus in recent years. This paper analyzes the problem on two aspects: model experiment and numerical calculation. The model experiment is carried out including three cases firstly, in which the structural vibration response and radiating acoustic field are measured respectively, and the results gained in these three cases are analyzed to discuss the effect of reducing structural vibration and radiating noise of the deadening and decoupling materials. The coupling FEM/BEM and the SEA methods are both used in numerical calculation, i.e. the arithmetic of the coupling FEM/BEM method is adopted to calculate the low frequency characteristics and the SEA method is adopted to calculate the medium-high frequencies characteristics of the model. By comparing experimental results with numerical calculation results, it is proved that the algorithm adopted in this paper is reasonable.     

Virtual prototype simulation on underwater hydraulic impingement shovel

The virtual prototype technology is applied to the design of the hydraulic impingement shovel, which is to increase the reliability of the design. The work principle of hydraulic impingement shovel is expatiated, and its dynamic equations are established. The 3D model of virtual prototype is built by PRO/E. Then the couple between the mechanical body of prototype and the hydraulic system is completed by virtue of ADAMS. Finally, the simulation is made on the virtual prototype. The simulation results show that the design of underwater hydraulic impingement shovel is rational. The virtual prototype technology could lay sound foundation of successful manufacturing of physical prototype for the first time and offer highly effective and feasible means for the design and production of underwater equipments.     

基于M估计的多UUV协同定位算法

为解决多水下无人航行器(UUV)协同定位系统因水声环境复杂,水声距离观测信息受异常噪声干扰,导致采多UUV协同定位效果变差的问题,本文将M估计算法应用于UUV协同定位中,提出一种基于M估计多UUV协同定位算法。半实物仿真试验结果表明,相较于传统基于扩展卡尔曼滤波算法,所提算法可将定位精度提升30%左右。     

水下航行体降噪艉翼填角的数值模拟与试验研究

为降低水下航行体噪声,研究了艉翼填角的降噪效果。分析了水下航行体艉翼接合部马蹄涡影响螺旋桨伴流场的特征,认为马蹄涡对水下航行体噪声产生了不利影响。针对某无人水下航行体(UUV)设计了一种艉翼填角,运用CFD方法对该艉翼填角优化螺旋桨伴流场的效果进行了数值模拟,结果显示伴流场轴向速度的周向不均匀度系数下降35%-62%。将艉翼填角应用于该UUV,开展航行辐射噪声测量试验,结果显示艉翼填角使UUV航行噪声总声源级降低3.4 d B,尤其对低频噪声抑制较好。     

无人水下航行器控制系统CAN总线通信设计与仿真研究

由于水下环境的复杂性及无人水下航行器自身特点,对其实施实时高效控制需处理大量数据。文章采用CAN总线对UUV控制系统通信网络进行设计和分析,讨论了CAN总线网络数据帧在系统中的具体应用设计和传输参数设置,并使用CANoe仿真软件对所设计的UUV控制系统CAN网络进行了仿真,通过仿真验证了UUV控制系统CAN网络通信设计的正确性。该方法应用于UUV控制系统通信网络设计,将有效提高UUV系统控制性能和特征模拟性能。     

军用UUV使命任务和装备性能分析

无人潜航器(UUV)作为一种独具特色的水下作战力量,正在成为一种新型作战平台,受到各国海军的关注。综述军用UUV的基本概念、作战使命、装备性能及其发展趋势。介绍世界各国海军的战略需求、UUV的级别、任务及其优先级和能力需求。     

水下战场UUV侦察与监视研究

UUV由于自身特点非常适合完成侦察与监视任务。论文介绍了水下战场UUV侦察与监视的意义,描述了UUV常见通信侦察传感器类型,对UUV可提供的情报类型进行了深入分析,提出了UUV情报、监视与侦察体系结构,阐述了从UUV侦察与监视到情报保障的工作过程,对实现水下战场的侦察与监视具有一定的参考作用。     

一种改进的指令调节自适应控制器在无人水下航行器深度控制中的实验研究（英文）

Command governor-based adaptive control(CGAC) is a recent control strategy that has been explored as a possible candidate for the challenging task of precise maneuvering of unmanned underwater vehicles(UUVs) with parameter variations.CGAC is derived from standard model reference adaptive control(MRAC) by adding a command governor that guarantees acceptable transient performance without compromising stability and a command filter that improves the robustness against noise and time delay.Although simulation and experimental studies have shown substantial overall performance improvements of CGAC over MRAC for UUVs,it has also shown that the command filter leads to a marked reduction in initial tracking performance of CGAC.As a solution,this paper proposes the replacement of the command filter by a weight filter to improve the initial tracking performance without compromising robustness and the addition of a closed-loop state predictor to further improve the overall tracking performance.The new modified CGAC(M-CGAC) has been experimentally validated and the results indicate that it successfully mitigates the initial tracking performance reduction,significantly improves the overall tracking performance,uses less control force,and increases the robustness to noise and time delay.Thus,M-CGAC is a viable adaptive control algorithm for current and future UUV applications.     

无人水下航行器外热源热机用无气体产生燃料

无人水下航行器(UUV)在军事领域正得到愈发广泛的应用,动力装置是其技术难点之一。无人水下航行器采用外热源热机,在续航力和航速上,都优于其他类型动力装置,且使用无气体产生燃料,可从根本上解决水下气体排放问题,提高航行隐蔽性,具有良好的军事应用前景。本文根据无人水下航行器的使用条件和技术要求,对适用于无人水下航行器外热源热机的无气体产生燃料进行了广泛考察,给出了可用于无人水下航行器外热源热机的无气体产生燃料和氧化剂的组合。     

水下机器人结构形式及其发展趋势分析

水下机器人的结构是影响其运动性能的重要因素。按框架式、刚性外壳仿生式、柔性外壳仿生式、球形、滑翔式和链式6类结构,对水下机器人结构形式的发展现状和存在的关键技术问题进行分析。重点分析各类结构的驱动速度、加装载重和运动灵活性,以及在水下环境中的运动性和适应性。研究结果表明,水下机器人的结构形式正朝着高度柔性化、整体与局部结构之间高度变形化和多体结构可分离化的方向发展。     

多无人水下航行器协同导航与定位研究

提出一种基于移动长基线的多无人水下航行器协同导航与定位方法.多无人水下航行器协同导航与定位方法对于解决大水深和远航程问题至关重要,在移动长基线算法中,主UUV装备高精度导航设备作为移动长基线节点,而从UUv装备低精度导航设备,两者之间通过水声装置米相互定位,利用传统几何关系解算从UUV,位置的算法将产生很大误差.基于扩展卡尔曼滤波的移动长基线算法能有效融合内部和外部传感器信息,提高导航精度.仿真试验对此进行了验证.     

基于iSIGHT的UUV优化设计平台

水下航行体(UUV)外形设计的优劣对UUV的最终性能有着举足轻重的影响。传统的设计方法是通过反复的选型-计算-修改来实现的,这种方法不但效率低下,而且由于选型范围有限,常导致得不到最优解。为解决这一问题,本文研究了UUV的参数化设计方法,并通过自编程序实现了在SolidWorks中的参数化建模。利用iSIGHT优化设计平台强大的过程集成能力和各种寻求最优参数的技术,实现了iSIGHT集成并驱动SolidWorks,Gridgen,CFX等软件并寻求最优参数的设计流程。并针对某UUV,以最小阻力为目标,利用NLPQL优化算法进行了优化设计。结果表明,本设计平台达到了实现UUV参数化设计并优化的目的,提高了设计效率。