水下无人航行器壳体抗毁伤性能的数值仿真研究

应用ABAQUS通用有限元软件中的声固耦合算法,对水下无人航行器壳体在远场水下爆炸冲击波作用下的抗毁伤性能进行了数值仿真研究。在数值仿真中,计算出在三硝基甲苯炸药爆炸时,不同方向及爆距条件下航行器壳体结构的动态响应过程,确认了航行器壳体的易损舱段及位置,得出抗爆炸毁伤的安全距离,为水下无人航行器的结构设计和抗毁伤性能指标考核提供了参考。     

无人水下航行器悬停过程分析与仿真

通过对无人水下航行器悬停过程的分析,和对悬停过程中运动进行的研究,建立了无人水下航行器悬停的纵向运动方程,并运用Matlab中的仿真模块Simulink对悬停过程进行仿真。通过对仿真结果的分析,得出无人水下航行器悬停过程的基本运动规律。     

某型无人水下航行器建模与仿真研究

为研究无人水下航行器的控制系统设计,建立其一般动力学模型。因为模型具有较高的非线性特征,采用小扰动原理及摄动原理对模型简化。根据简化的模型设计航速、航向、纵倾和深度控制器,并分别进行仿真,仿真结果证明了设计的鲁棒性和稳定性。     

无人水下航行器陆地模拟试验系统

为弥补海洋模拟试验数据采集困难、数据量大、环境复杂等不足,设计了无人水下航行器陆地模拟试验系统。这一试验系统由池体、水深模拟模块、障碍物模拟模块和检测系统组成。池体、水深模拟模块和障碍物模拟模块用于模拟试验对象的运行环境,通过可升降假底模拟水深变化,通过池底滑块和滑道模拟障碍物。检测系统包括测量单元、数据采集和处理单元、数据传输单元、控制单元和数据输出单元。这一试验系统通过测定俯仰角、偏航角及横滚角等参数,为无人水下航行器的设计和改进提供技术参考。     

水下高速航行器壳体联结强度分析

随着超空化技术被用于水下航行器减阻提速,水下高速舷行器的结构设计也成为热点.为了确保在设计范围内航行器可以正常运行,采用分析软件ANSYS对水下高速舷行器壳体的卡箍连接强度进行了研究.考虑到实际问题的复杂性,首先建立了整个壳体的三维有限元模型,初步分析了壳体应力的大致分布;然后利用子模型技术以及非线性有限元技术,建立了壳体卡箍连接部位的有限元子模型,进一步分析了壳体间连接的接触强度.以有限的计算机资源,得到较为准确的结果.分析结果表明在常态下壳体结构联结强度较好,并进一步预估了壳体的极限载荷.为航行器壳体的结构设计以及优化提供了理论依据.     

无人水下航行器摆式发电装置设计与研究

针对海洋无人水下航行器能源供给需求,设计了一款小型化摆式发电装置,该装置搭载在无人水下航行器内部,受波浪、海流、潮汐等影响,航行器产生摆动,获取海洋动能,并将其转换成稳定的电能。详细论述了摆式发电装置的工作原理、系统结构和设计方案,建立了系统机电耦合动力学仿真平台进行仿真分析,并开展了样机试验验证。研究结果表明：该摆式发电装置设计是可行的,实现了电能稳定输出,有效发电效率达到了24.40%。     

水下航行器壳体外形优化设计

同时把阻力和噪声作为目标函数,建立了低阻低噪回转体形水下航行器外形的多目标优化设计数学模型。水洞试验数据和计算结果表明,优化外形阻力有较大降低,自噪声性能有一定改善。     

浅水域探测型无人水下航行器波浪能发电系统设计

为了实现浅水域探测型无人水下航行器(Unmanned underwater vehicle,UUV)探测设备水下长时间工作,提出波浪能发电系统,可以将近水面的波浪能收集转化为电能。详细叙述永磁发电机的原理结构及设计参数;根据Lagrange方程建立系统的数学模型;采用Runge-Kutta方法求解简化的运动方程,研究不同海况条件下对发电性能的影响。研究结果表明提出的波浪能发电系统是合理可行的,在一般海况下,能够满足探测设备的能源需求。同时表明频率与幅度以及耦合横摇对发电性能影响比较大,而耦合垂荡对其影响基本可以忽略。研究结果将为后期波浪能发电系统的工程试验提供一定的理论依据。     

无人水下航行器用双转子无刷直流电机的控制

根据无人水下航行器的任务特点,研制出无位置传感器的双转子对转无刷直流电机推进动力装置。介绍了无刷直流电机利用专门设计的转换电路,直接检测电机绕组线电压获得功率管驱动信号的方法,研究了无位置传感器无刷直流电机的起动方法,通过样机实验验证了系统设计的合理性。     

小型水下视频检查机器人方案设计

小型机器人已成为各国研究的热点,介绍小型水下视频检查机器人的结构和工作原理．探讨密封方式的选用及电机的选择等问题。     

基于CAD的自主式水下航行器几何模型参数化建模

为满足自主式水下航行器(AUV)多学科设计优化对几何模型创建过程自动化的要求,研究了基于CAD技术的AUV几何模型的参数化建模方法。首先对AUV几何模型特征进行具体分析,建立了AUV参数化的几何模型;然后在此基础上,以UG NX7.0软件作为开发平台,结合VC++工程应用,采用内部开发模式,驱动UG/Open API库函数,创建了AUV几何模型参数化建模的应用程序,并最终通过具体实例验证了该方法的可行性。     

Cooperative path planning of multiple autonomous underwater vehicles operating in dynamic ocean environment

This paper presents a two-stage cooperative path planner for multiple autonomous underwater vehicles operating in dynamic environment. In case of static environment, global Legendre pseudospectral method is employed for collision-free paths of vehicles for the purpose of minimum time consumption and simultaneous arrival. Moreover, in order to keep the multiple autonomous underwater vehicles safe from collisions on the path segments connecting two adjacent control nodes, an adaptive intermediate knots insertion algorithm is introduced. In the on-line planning stage, the local re-planning strategy aims at avoiding collisions with unexpected dynamic obstacles by two consecutive avoidance maneuvers, and the differential flatness property of autonomous underwater vehicle is utilized, which can help the vehicles react fast enough to avoid moving obstacles.     

Study on denoising filter of underwater vehicle using DWT

In the step processing a digitalized signal,noises are generated by internal or external causes of the system.In order to eliminate these noises,various methods are researched.Among these noise elimination methods,Fourier fast transform （FFT） and short-time Fourier transform （STFT） are widely used.Because they are expressed as a fixed time-frequency domain,they have the disadvantage that the time information about the signal is unknown.In order to overcome these limitations,by using the wavelet transform that provides a variety of time-frequency resolution,multi-resolution analysis can be analysed and a varying noise depending on the time characteristics can be removed more efficiently.Therefore,in this paper,a denoising method of underwater vehicle using discrete wavelet transform （DWT） is proposed.     

Containment control of networked autonomous underwater vehicles: A predictor-based neural DSC design

This paper investigates the containment control problem of networked autonomous underwater vehicles in the presence of model uncertainty and unknown ocean disturbances. A predictor-based neural dynamic surface control design method is presented to develop the distributed adaptive containment controllers, under which the trajectories of follower vehicles nearly converge to the dynamic convex hull spanned by multiple reference trajectories over a directed network. Prediction errors, rather than tracking errors, are used to update the neural adaptation laws, which are independent of the tracking error dynamics, resulting in two time-scales to govern the entire system. The stability property of the closed-loop network is established via Lyapunov analysis, and transient property is quantified in terms of L₂ norms of the derivatives of neural weights, which are shown to be smaller than the classical neural dynamic surface control approach. Comparative studies are given to show the substantial improvements of the proposed new method.     

多轴工程车辆油气悬架系统参数仿真

建立了多轴越野车辆的平面力学模型,对其参数进行了计算机仿真,仿真参数包括悬架弹簧变刚度和变阻尼,分析涉及的车辆模型有弹簧悬置的车体和4个车桥,研究了车辆系统的6个自由度的运动方程及动态特性,分析了车辆在粗糙路面上的油气弹簧刚度和阻尼特性的非线性变化规律,获得了多轴车辆的悬架系统在路面激励下的响应特性,提出提高车辆平顺性的途径．     

A simplified signal analysis algorithm for the development of a low cost underwater echo-sounder

In the literature survey, most of the signal analysis techniques for underwater acoustic information rely on complex mathematical models, which are impractical for a small real time application such as an underwater echo sounder. The purpose of this work is to introduce a modified signal process algorithm which can be easily implemented into a microprocessor and to determine the distance an obstacle from a moving underwater vehicle. This simplified acoustic signal analyzer uses a series of ‘mask shading’, ‘3-time majority’ and ‘echo-duration threshold’ signal process steps to increase the accuracy of distance measurement for the self-developed underwater echo sounder. Experiment result shows that the proposed algorithm can ignore the erroneous signal cased by environment noise at sea and transient noise from the circuit board. This work has been proven valuable when used with an auxiliary solar-powered boat to measure the slurry accumulation at a local An-Ping Harbor in southern Taiwan.     

光度数据反演临近空间低速点目标形状尺寸信息

为了获取临近空间低速点目标的形状尺寸信息,进行了高空气球光学观测实验,研究了如何从光度数据中反演低速点目标形状尺寸信息。利用孔径测光技术处理地基探测装备所拍摄的实验图像数据获取目标光度数据。在反演过程中,采用球谐函数法和细分控制点法两种形状描述方法来参数化描述目标形状,利用球谐函数法的正则化函数、三角面元正则化函数和基于目标物理特性的正则化函数约束目标的形状变化,在对目标光度数据以及由两种形状描述方法产生的模型数据进行傅里叶变换的基础上,结合光学系统点扩散函数来反演空间目标形状尺寸信息。结果表明:两种形状描述方法反演的目标形状主要特征相似,表明这种形状特征是从光度数据提取到的。球谐函数法和细分控制点法反演出的目标等效直径相对误差分别为11.3%和22.6%,长度相对误差分别为11.6%和21.8%。由此表明:球谐函数法反演的临近空间低速目标形状误差较小,更能准确地反演出临近空间低速目标形状。     

The use of computational fluid dynamics to study furnace effects in ITS-90 fixed points realizations

Together with the impurities, the thermal fluxes are one of the major sources of uncertainty during the realization of the International Temperature Scale of 1990 (ITS-90) defining fixed points. The use of computational fluid dynamics (CFD) is a valuable tool to develop models that describe the time evolution of the phase transformation (essentially the evolution of the solid–liquid interface) as a function of given theoretical assumptions and given parameters (furnace thermal gradients, freezing initiation, ambient temperature and insulation). The models can be validated by observing the impact of the selected parameters on the observed corresponding melting curves and used to achieve a full understanding of these thermal effects and their impact on uncertainty. This paper proposes an ITS-90 metallic fixed points CFD model together with some results about the influence of the furnace thermal gradients and the freezing initiation techniques.     

A study on dynamic performance of closed-loop commuted stepping motor to improve precision motion control

To achieve precision movements, a motor with very low speed ripple and torque ripple is required. A motor with more poles will normally give higher ripple frequency and hence lower ripple magnitude. The hybrid stepping motor when commuted in closed-loop mode will behave in the form of a multi-pole brushless DC servo motor with each step similar to one pole. To reduce torque ripple further, the commutation of the coils requires careful adjustment of the lead angle in order to compensate for the time constant of the coils at different speeds. This article establishes an accurate dynamic model for the closed-loop commuted hybrid-type stepping motor, which takes into account the drive circuit and the effect of magnetic saturation. Simulations have been performed on the model using the stiff system numerical method for higher accuracy. The results show a good match between the numerical solution and the actual measurement. The dynamic model developed can be used to predict speed ripple of the motor system under various commutation methods. This provides a means of minimizing speed ripple by using software to improve the accuracy of motion control systems on high-precision machines.