Dynamics Modeling and Simulation of Autonomous Underwater Vehicles with Appendages

To provide a simulation system platform for designing and debugging a small autonomous underwater vehicle＇s （AUV） motion controller, a six-degree of freedom （6-DOF） dynamic model for AUV controlled by thruster and fins with appendages is examined. Based on the dynamic model, a simulation system for the AUV＇s motion is established. The different kinds of typical motions are simulated to analyze the motion performance and the maneuverability of the AUV. In order to evaluate the influences of appendages on the motion performance of the AUV, simulations of the AUV with and without appendages are performed and compared. The results demonstrate the AUV has good maneuverability with and without appendages.

A large eddy simulation of flows around an underwater vehicle model using an immersed boundary method

A large eddy simulation （LES） of the flows around an underwater vehicle model at intermediate Reynolds numbers is performed. The underwater vehicle model is taken as the DARPA SUBOFF with full appendages, where the Reynolds number based on the hull length is 1.0x 105, An immersed boundary method based on the moving-least-squares reconstruction is used to handle the complex geometric boundaries. The adaptive mesh refinement is utilized to resolve the flows near the hull, The parallel scalabilities of the flow solver are tested on meshes with the number of cells varying from 50 million to 3.2 billion, The parallel solver reaches nearly linear scalability for the flows around the underwater vehicle model, The present simulation captures the essential features of the vortex structures near the hull and in the wake, Both of the time-averaged pressure coefficients and srreamwise velocity profiles obtained from the LES are consistent with the characteristics of the flows pass an appended axisymmetric body. The code efficiency and its correct predictions on flow features allow us to perform the full-scale simulations on tens of thousands of cores with billions of grid points for higher-Reynolds-number flows around the underwater vehicles.

Simulation platform of navigation system for autonomous underwater vehicle

In view of the characteristics of underwater navigation, the simulation platform of navigation system for autonomous underwater vehicle has been developed based on Windows platform. The system architecture, net communication and the information flow are discussed. The methods of software realization and some key techniques of the Vehicle Computer and the Navigation Equipment Computer are introduced in particular. The software design of Terrain Matching Computer is introduced also. The simulation platform is verified and analyzed through simulation. The results show that the architecture of the platform is reasonable and reliable, and the mathematic models and simulation algorithms of sub-systems are also valid and practicable.

Study on Simulation of Remotely Operated Underwater Vehicle Spatial Motion

In order to analyze the spatial maneuverability of the remotely operated underwater vehicle(ROV),the 6-DOF motion mathematic model of the ROV was founded.Hydrodynamics were analyzed by using the Taylor series.The thrusters on the ROV were discussed.This paper considers three cases of motion simulation:vertical motion,rotational motion and Z-shape motion.A series of simulation experiments showed that the 6-DOF motion mathematic model was correct and reliable,and also fit with the scene simulation.

Maneuverability simulation of a mini autonomous underwater vehicle

In order to simulate the under water motion of a mini autonomous underwater vehicle( AUV) and an- alyze its maneuverability,the dynamical characteristic of the mini AUV was researched. The 6-DOF motion equations were founded. Through model experiment with accessory bodies,the hydrodynamics of AUV body including resistance,main inertial and viscous hydrodynamic coefficients was obtained. The hydrodynamics of rudders was gained through theoretical calculation. Simulation computation of the vehicle was carried out through numerical integration of the motion equations. A motion simulation system was constructed. Four typical maneuvers in horizontal and vertical planes were simulated and the maneuverability of the mini AUV was forecasted. The simulation results reflect the basic motion characteristic of mini AUV and validate the feasibility and correctness of the whole system. The simulation system can be a testing platform for the design and debugging of motion controller and an effective tool for the development of AUV.

Semi-physical simulation of AUV pipeline tracking

Before the task of autonomous underwater vehicle(AUV) was implemented actually,its semi-physical simulation system of pipeline tracking had been designed.This semi-physical simulation system was used to test the software logic,hardware architecture,data interface and reliability of the control system.To implement this system,the whole system plan,including interface computer and the methods of pipeline tracking,was described.Compared to numerical simulation,the semi-physical simulation was used to test the real software and hardware more veritably.In the semi-physical simulation system,tracking experiments of both straight lines and polygonal lines were carried out,considering the influence of ocean current and the situation of buried pipeline.The experimental results indicate that the AUV can do pipeline tracking task,when angles of pipeline are 15°,30°,45° and 60°.In the ocean current of 2 knots,AUV could track buried pipeline.

Adaptive PID control system for an autonomous underwater vehicle

The control system of an autonomous underwater vehicle （AUV） is introduced. According to control requirements of the AUV, a simple but practical adaptive PID control method is designed The semi-physical simulation is done to test the feasibility of the control system. The neural network idea and the structure of PID controller are referred to design the adaptive PID controller. An intelligent integral is introduced to improve control precision. Compaed with traditional PID con- trollers, the adaptive PID controller has simple structure, good online adjusting ability, fast convergence and good robustness. The simulation experiments also show that the adaptive PID control system has high precision and fine antijamming ability.

Design and Research on the Two-Joint Mating System of Underwater Vehicle

In the 21st century, people have come to the era of ocean science and ocean economy. With the development of ocean science and technology and the thorough research on the ocean, underwater mating technique has been widely used in such fields as sunk ship salvage, deep ocean workstation, submarine lifesaving aid and military affairs. In this paper, researches are made home and abroad on mating technology. Two-joint mating system of underwater vehicle is designed including plane system, three-dimensional assembly system and control system in order to increase the capacity of adapting platform obliquity and adopting rotational skirt scheme. It is clear that the system fits the working space of underwater vehicle passageway and there is no interference phenomenon in assembly design. The finite element model of the system shell and the pressurization of the joint are established. The results of the finite element computing and the pressing test are accordant, and thus it can testify that the shell material meet the need of intension and joint pressurization is reliable. Modeling of the control system is accomplished, and simulation and analysis are made, which can provide directions for the controller design of mating system of underwater vehicles.

A Numerical and Experimental Study on the Hull-Propeller Interaction of A Long Range Autonomous Underwater Vehicle

Range is an important factor to the design of autonomous underwater vehicles (AUVs), while drag reduction efforts are pursued, the investigation of body-propeller interaction is another vital consideration. We present a numerical and experimental study of the hull-propeller interaction for deeply submerged underwater vehicles, using a proportional-integral- derivative (PID) controller method to estimate self-propulsion point in CFD environment. The hydrodynamic performance of hull and propeller at the balance state when the AUV sails at a fixed depth is investigated, using steady RANS solver of Star-CCM+. The proposed steady RANS solver takes only hours to reach a reasonable solution. It is more time efficient than unsteady simulations which takes days or weeks, as well as huge consumption of computing resources. Explorer 1000, a long range AUV developed by Shenyang Institute of Automation, Chinese Academy of Sciences, was studied as an object, and self-propulsion point, thrust deduction, wake fraction and hull efficiency were analyzed by using the proposed RANS method. Behind-hull performance of the selected propeller MAU4-40, as well as the hull-propeller interaction, was obtained from the computed hydrodynamic forces. The numerical results are in good qualitative and quantitative agreement with the experimental results obtained in the Qiandao Lake of Zhejiang province, China.

Design and simulation of ex-range gliding wing of high altitude air-launched autonomous underwater vehicles based on SIMULINK

High altitude air-launched autonomous underwater vehicle （AL-AUV） is a new anti-submarine field, which is designed on the Lockheed Martin＇s high altitude anti-submarine warfare weapons concept （HAAWC） and conducts the basic aerodynamic feasibility in a series of wind tunnel trials. The AL-AUV is composed of a traditional torpedo-like AUV, an additional ex-range gliding wings unit and a descending parachute unit. In order to accurately and conveniently investigate the dynamic and static characteristic of high altitude AL-AUV, a simulation platform is established based on MATLAB/SIMULINK and an AUV 6DOF （Degree of Freedom） dynamic model. Executing the simulation platform for different wing＇s parameters and initial fixing angle, a set of AUV gliding data is generated. Analyzing the recorded simulation result, the velocity and pitch characteristics of AL-AUV deployed at varying wing areas and initial setting angle, the optimal wing area is selected for specific AUV model. Then the comparative simulations of AL-AUV with the selected wings are completed, which simulate the AUV gliding through idealized windless air environment and gliding with Dryden wind influence. The result indicates that the method of wing design and simulation with the simulation platform based on SIMULINK is accurately effective and suitable to be widely employed.

A Potential Flow Based Flight Simulator for an Underwater Glider

Underwater gliders are recent innovative types of autonomous underwater vehicles （AUVs） used in ocean exploration and observation. They adjust their buoyancy to dive and to return to the ocean surface. During the change of altitude, they use the hydrodynamic forces developed by their wings to move forward. Their flights are controlled by changing the position of their centers of gravity and their buoyancy to adjust their trim and heel angles. For better flight control, the understanding of the hydrodynamic behavior and the flight mechanics of the underwater glider is necessary. A 6-DOF motion simulator is coupled with an unsteady potential flow model for this purpose. In some specific cases, the numerical study demonstrates that an inappropriate stabilizer dimension can cause counter-steering behavior. The simulator can be used to improve the automatic flight control. It can also be used for the hydrodynamic design optimization of the devices.

Three-dimensional Numerical Simulation of Combustion Field in the Combustion Chamber

In order to study the effect of rotation on the combustion in the underwater vehicle,a two-phase turbulent combustion process is described with Reynolds stress turbulence model,eddy-dissipation turbulent combustion model,P-1 radiation model and particle tracking model of liquid. The flow in the rotating combustion chamber is simulated at two different working speeds,0?r/min and 1?000?r/min by Fluent software. The temperature,gas velocity,static pressure of wall and fuel concentration are computed and compared. The results show that the combustion in rotating combustor is faster and more effective.

基于MATLAB/SIMULINK与FLUENT的协同仿真方法研究

以水下机器人的动态行为仿真为背景,针对单一环境下仿真水下机器人动态行为和流体动力学问题存在的局限性,提出了基于MATLAB/Simulink与FLUENT协同仿真的解决方案。首先介绍了MATLAB/Simulink与FLUENT的运行机制,分析了两个仿真环境实现协同仿真的技术可行性并提出了三种可行的接口方式。以此为基础,重点研究了FLUENT中嵌入MATLAB/Simulink与MATLAB/Simulink中嵌入FLUENT两种嵌入式协同仿真方式以及并行协同仿真方式的基本思想和具体实现方法。此协同仿真方法不仅对于研究流体环境中物体运动与流体动力紧密耦合的问题提供了有效手段,也为研究其它与流体紧密耦合的物理现象提供了解决思路。

基于Adams与Matlab/Simulink的水下自航行器协同仿真

针对传统水下自航行器(Autonomous underwater vehicle,AUV)仿真中图形界面、实时性和动力学性能难以兼顾的问题,提出利用虚拟样机分析软件Adams和控制仿真软件Matlab/Simulink联合建立AUV虚拟样机系统的方法。在分析虚拟样机系统运动学、动力学和水动力数学模型的基础上,给出虚拟样机物理模型及控制模型的建立过程,并利用该虚拟样机系统对设计的AUV空间动态定位控制算法进行基于动力学基础的仿真分析。仿真试验的过程及结果表明,该虚拟样机系统具备智能控制与动态控制交互仿真演示和功能验证的能力,可为AUV图形仿真研究提供一种新的解决思路,对研究水下自航行器的操纵与控制有重要的现实意义。

基于Simulink/VRML的自主水下航行器编队控制仿真

针对多自主水下航行器编队协同控制问题,建立了基于Leader-Follower编队的数学模型,设计了编队控制律,并从理论上证明了控制律的稳定性。为了直观地表达自主水下航行器编队控制的效果,利用MATLAB的Simulink/VRML工具箱构建了水下航行器的编队控制的可视化仿真模型。仿真结果表明,提出的编队控制算法是有效的,所构建的仿真平台直观地表达了自主水下航行器的编队效果,该仿真模型易于扩展,且可以验证其它编队控制算法。

基于Matlab/Simulink的水下航行器建模与仿真

为便于对水下航行器的运动弹道和运动控制进行计算机仿真,建立一种基于Matlab/Simulink的水下航行器模型。利用矢量化建模方法,给出水下航行器6自由度空间运动数学模型,详细论述Simulink建模过程和S函数的实现方法,并应用所建立的Simulink模型,对水下航行器的开环运动、操纵性以及闭环运动控制相关问题进行仿真。仿真结果表明,该系统符合水下航行器的实际运动规律。

Motion Analysis and Trials of the Deep Sea Hybrid Underwater Glider Petrel-Ⅱ

A hybrid underwater glider Petrel-II has been developed and field tested. It is equipped with an active buoyancy unit and a compact propeller unit. Its working modes have been expanded to buoyancy driven gliding and propeller driven level-flight, which can make the glider work in strong currents, as well as many other complicated ocean environments. Its maximal gliding speed reaches 1 knot and the propelling speed is up to 3 knots. In this paper, a 3D dynamic model of Petrel-II is derived using linear momentum and angular momentum equations. According to the dynamic model, the spiral motion in the underwater space is simulated for the gliding mode. Similarly the cycle motion on water surface and the depth-keeping motion underwater are simulated for the level-flight mode. These simulations are important to the performance analysis and parameter optimization for the Petrel-II underwater glider. The simulation results show a good agreement with field trials.

Research on simultaneous localization and mapping for AUV by an improved method:Variance reduction FastSLAM with simulated annealing

At present,simultaneous localization and mapping(SLAM) for an autonomous underwater vehicle(AUV)is a research hotspot.Aiming at the problem of non-linear model and non-Gaussian noise in AUV motion,an improved method of variance reduction fast simultaneous localization and mapping(FastSLAM) with simulated annealing is proposed to solve the problems of particle degradation,particle depletion and particle loss in traditional FastSLAM,which lead to the reduction of AUV location estimation accuracy.The adaptive exponential fading factor is generated by the anneal function of simulated annealing algorithm to improve the effective particle number and replace resampling.By increasing the weight of small particles and decreasing the weight of large particles,the variance of particle weight can be reduced,the number of effective particles can be increased,and the accuracy of AUV location and feature location estimation can be improved to some extent by retaining more information carried by particles.The experimental results based on trial data show that the proposed simulated annealing variance reduction FastSLAM method avoids particle degradation,maintains the diversity of particles,weakened the degeneracy and improves the accuracy and stability of AUV navigation and localization system.

Evaluation on safety performance of a millimetre wave radar-based autonomous vehicle

This paper presents a method using range deception jamming to evaluate the safety performance of the autonomous vehicle with millimetre wave(MMW)radar.The working principle of this method is described.Combined with a waveform edition software,an experimental platform is developed to generate a deceptive signal that contains false distance information.According to related theories and its principle,the configuration parameters of the experimental setup are calculated and configured.The MMW radar of evaluated vehicle should identify an objective when it receives the deceptive signal from the experimental setup.Even if no obstacle,the evaluated vehicle can immediately brake in order that its braking distance is measured.The experimental results show that the proposed method can meet the requirements of the safety performance evaluation for the autonomous vehicle with MMW radar,and it also overcomes some deficiencies of previous methods.

A Lagrangian Particle Random Walk Model for Simulating A Deep-Sea Hydrothermal Plume with both Buoyant and Non-Buoyant Features

This paper presents a computational model of simulating a deep-sea hydrothermal plume based on a Lagrangian particle random walk algorithm. This model achieves the efficient process to calculate a numerical plume developed in a fluid-advected environment with the characteristics such as significant filament intermittency and significant plume meander due to flow variation with both time and location. Especially, this model addresses both non-buoyant and buoyant features of a deep-sea hydrothermal plume in three dimensions, which significantly challenge a strategy for tracing the deep-sea hydrothermal plume and localizing its source. This paper also systematically discusses stochastic initial and boundary conditions that are critical to generate a proper numerical plume. The developed model is a powerful tool to evaluate and optimize strategies for the tracking of a deep-sea hydrothermal plume via an autonomous underwater vehicle （AUV）.