A low level supplementary heating system for free divers

A simple and effective method of heating divers in extreme cold water has been developed. The local heating concept utilizes a uniformly distributed granular mixture of magnesium and iron particles packed in small sachets. Upon activation by sea water, the two metal mixture behaves as a multitude of short-circuited electrolytic cells, producing thermal energy rather than electrical energy. The 45 mm-square sachets may be placed where heating is required on the diver's body, thus giving rise to the term “local heating”, obviously, the heating system requires no pumping device, or distribution network. Heating rate and duration of output of the sachets are controlled by particle size, and mixture ratio of the constituent Mg and Fe particles.This paper described the development, testing and performance of the heating sachets. Results of live tests in different dive situations are also presented and discussed.     

A self-heated second stage regulator for underwater divers

This article deals with the development, testing and performance evaluation of a new class of a self-heated breathing regulator for underwater divers.This class of regulators is introduced because of its capability of utilizing the energy of the compressed gas, used in supporting the lives of divers underwater, in heating the inhaled gases as well as in eliminating the problems of regulator freeze-up in cold waters.The paper presents the performance characteristics of the self-heated second stage regulators under different simulated dive temperatures, breathing frequencies and tidal volumes.Comparisons are also presented between the performance of the self-heated regulator and a conventional regulator in order to define the merits and limitations of each type under different dive conditions.The obtained results indicate that the self-heated regulator produced not only warm gases but performed successfully in zero°C waters while the conventional regulator has failed.This paper suggests the potential of the self-heated regulator as viable means for alleviating the problems of cold water diving.     

A self-heated first stage breathing regulator for underwater divers

This article presents a new class of first stage breathing regulators for underwater divers with built-in self-heating capabilities. In this class of regulators, the energy of the high pressure life support gas is used to heat both the inhaled gases and the regulator core in an attempt to combat problems of cold water diving.The thermal characteristics of this regulator are monitored and compared with those of a conventional regulator under different simulated dive temperatures, breathing frequencies and also under free flow conditions.The obtained results show that the self-heated first stage (SHFS) regulator delivered warm gases and performed successfully in zero°C water while the conventional regulator failed even when equipped with the environmental protection kit.This paper emphasizes the potential of the self-heated regulator as an essential part of cold water diving gear.     

Optimum design of a servo-controlled breathing regulator for underwater divers

This article deals with the analysis, synthesis and performance evaluation of the flow and dynamic characteristics of the new class of servo-controlled breathing regulators for underwater divers.Emphasis on such a class of regulators has been stimulated by their tremendous potential in extending the dive depth and duration because they reduce the diver breathing effort to a great extent. This would eliminate the unnecessary exhaustion of the diver under such extreme diving conditions and accordingly improve his work efficiency underwater.The study aims at developing rational design procedures and guides that would enable the regulator designers to select the optimal design parameters of this class of regulators. Such design guides are based on the analysis of the flow and dynamic characteristics of the servo-controlled regulator as well as the basic principle of the theory of optimum control.The study presents also experimental evaluation techniques of the dynamic characteristics of this class of regulators in order to provide common quantitative means for comparison with the conventional regulator designs.The presented results emphasize the merits and the potential of the servo-controlled regulators as essential tools of supporting the life of divers underwater.     

Portable acoustic tracking system for divers (PATS)

A portable acoustic tracking system (PATS) has been developed for the Navy to track underwater construction teams in water depths to 200 ft. The tracking system can be deployed and operated by the divers and is intended for use in remote areas and for nearshore survey, maintenance, and construction work. A self-calibrating system provides a geographically justified track for up to eight divers. Diver position coordinates are computed from acoustic measurements at periodic intervals and displayed for control purposes. The positions are also recorded for future reference.     

Acoustic telemetry system for underwater control

Underwater acoustic communication in the multipath environment encountered in shallow water is restricted mostly by signal fading. It degrades the signal detection and time synchronization required for reliable acoustic communication. An approach to time synchronization and to the frequency diversity method is presented. A communication algorithm for obtaining a reliable acoustic underwater link, and offering an easy-to-implement decoding scheme is introduced, and system realization is described     

A high-resolution pulse-Doppler underwater acoustic navigation system

A high-resolution underwater acoustic pulse-Doppler navigation system has been developed and tested at sea. The system provides continuous, highly accurate tracking of underwater and ocean-surface platforms in a fixed 50-km²navigation net. Three reference buoys, moored 20 m from the ocean bottom, provide the navigation net used by shipboard processing equipment. Each reference buoy contains an acoustic transponder, used to obtain the acoustic travel times from the transponder to the platform, and a continuous-tone beacon, used to obtain the Doppler shift due to platform motion. The system is capable of determining the position of a platform with respect to the reference net with an error of 2-3 m. The relative position of the platform on a fix-to-fix basis can be determined within several centimeters over short time intervals (approx 10min).     

A hydrodynamic model of a two-part underwater towed system

A three-dimensional model of a two-part underwater towed system is studied. In the model, the governing equations of cables are established based on the Ablow and Schechter method. The boundary conditions for the two-part underwater towed system are derived. The six-degrees-of-freedom equations of motion for submarine simulations are adopted to predict the hydrodynamic performance of a towed vehicle. The established governing equations for the system are then solved using a central finite difference method. In this paper several algorithms are used to solve this special form of finite difference equations. The results in this paper indicate that the two-part underwater towed system improves the dynamic behavior of the towed vehicle and is an easy way to decouple the towing ship motion from the towed vehicle. Because the model uses an implicit time integration, it is stable for large time steps and is an effective algorithm for simulation of a large-scale underwater towed system.     

水下机器人主动升沉补偿系统研究

介绍一种基于水下机器人常规液压收放绞车的主动升沉补偿系统,利用加速度传感器获得母船的升沉运动信号,控制绞车的运转来降低母船的升沉运动对水下机器人的影响。通过理论计算建立主动升沉补偿系统的数学模型,仿真分析绞车运动对水下机器人升沉运动的补偿效果,并利用主动升沉补偿系统实验台验证基于常规液压收放绞车的主动升沉补偿方案的可行性。     

Vision-based system of AUV for an underwater pipeline tracker

This paper describes a new framework for detection and tracking of underwater pipeline,which includes software system and hardware system.It is designed for vision system of AUV based on monocular CCD camera.First,the real-time data flow from image capture card is pre-processed and pipeline features are extracted for navigation.The region saturation degree is advanced to remove false edge point group after Sobel operation.An appropriate way is proposed to clear the disturbance around the peak point in the process of Hough transform.Second,the continuity of pipeline layout is taken into account to improve the efficiency of line extraction.Once the line information has been obtained,the reference zone is predicted by Kalman filter.It denotes the possible appearance position of the pipeline in the image.Kalman filter is used to estimate this position in next frame so that the information of pipeline of each frame can be known in advance.Results obtained on real optic vision data in tank experiment are displayed and discussed.They show that the proposed system can detect and track the underwater pipeline online,and is effective and feasible.     

An integrated sensory-intelligent system for underwater acoustic signal-processing applications

A generic integrated sensory-intelligent system (ISIS) is developed for underwater acoustic signal-processing applications. ISIS constantly monitors the current acoustic channel conditions and smoothly integrates the outputs of the most appropriate signal-processing procedures or algorithms available to it for those conditions. The system is based on a generalization of a tuneable approximate piecewise linear (TAPL) model derived from the modified probabilistic neural network (MPNN). This model was designed to seamlessly integrate a set of local linear signal-processing algorithms within a given multidimensional data space. Depending on the input signal distortions, which are determined by environmental effects, ISIS automatically weighs and adds the outputs from a set of processing algorithms working in parallel. The weighting is related to the "closeness" of each algorithm to the sensed input signal characteristics or some other measured environmental state. A single tuning parameter is used to smoothly and seamlessly select appropriately among the parallel processing algorithm outputs. A very small tuning-parameter value selects the closest most appropriate algorithm output. At the other extreme, a fixed weighted average of all the algorithm outputs is produced with a very large value. Otherwise, a dynamic weighed average of all algorithm outputs is achieved with values in between. Some features and benefits of ISIS are demonstrated with an illustrative linear sweep chirp signal-detector estimation problem characterized by extremely variable Doppler conditions.     

潜水器控制系统层次故障诊断模型设计

在潜水器控制系统的基础上,按照结构、功能和组件的关系,为潜水器控制系统进行故障诊断建模。依据基于模型的层次故障诊断技术,建立了适用于潜水器控制系统故障诊断的具体诊断和推理策略,开发了故障诊断软件系统,描述了故障诊断具体过程,并利用数字仿真验证系统设计的有效性。     

水下拖曳系统运动姿态仿真研究

采用凝集参数法建立了水下拖曳系统的三维离散模型,该模型由一系列的质量点和不计重量的弹簧组成.采用数学模型编程对NCEL浮球实验和四个典型拖曳系统进行了仿真计算.计算结果表明此数学模型具有一定的理论意义和工程实用价值.     

Geometrical aspects of a sonar-based navigation system for underwater vehicles

A novel self-contained navigation system has been devised for underwater vehicles operating in and around offshore installations. This system matches data from a sector-scanning sonar device to a computer model of the installation. The paper begins by highlighting the existing approaches to subsea navigation before outlining the main features of the proposed system. It then concentrates on a key component of this system which is a method for calculating the position and heading of an underwater vehicle navigating in the vincinity of tubular steel structures. An iterative solution method is presented which incorporates six degree of freedom vehicle motions and this is verified in a series of laboratory experiments with various arrangements of structural members and using a commercial sonar device. The key features, applications and performance of this method are discussed. The main conclusion is that the proposed method for calculating the position and heading of an underwater vehicle contributes towards achieving an accurate and reliable subsea navigation capability.     

MURS-300 MK II: A remote inspection system for underwater facilities of hydraulic power plants

While the civil engineering facilities of hydraulic power plants such as dam, water intake, waterway, etc., are usually submerged, there are few effective methods for their inspection. So we at Mitsui Ocean Development and Engineering Co., Ltd. (MODEC) have developed a new remote-controlled inspection system named "MURS-300 MK II" (MODEC Unmanned Remote-Controlled Submersible for 300-m water depth) in cooperation with Tokyo Electric Power Co., Inc. This MK II system, which consists of a submersible vehicle with a TV camera and a still camera, a handling system, a control van, and a composite cable with optical fibers, was designed, developed, and successfully evaluated at the end of 1984. This new system will find many applications to the inspection of nuclear and thermal power stations, offshore platforms, etc., as well as hydraulic power plants.     

A neural net controller for underwater robotic vehicles

Results of a study on the application of neural networks to the control system of underwater robotic vehicles (URVs) are presented. The robustness of the control system with respect to nonlinear dynamic behavior and parameter uncertainties is investigated by computer simulation. The results show the feasibility of using unpredictable changes in the dynamics of the vehicle and its environment     

用于水下通信的电磁耦合系统的优化设计

提出了一种评定电磁耦合通信效果的方法,并给出了一种最优的电磁耦合系统的设计方法。讨论了影响电磁耦合系统通信距离的因素,提出了用通信系数,即互感和载波频率来评定电磁耦合的通信效果,并据此提出了电磁耦合圆线圈的优化设计方法。实验测试证明了通信效果评定方法和优化设计方法的正确性。通过该方法可以针对需要的通信距离设计出最小尺寸...     

Enhancement of the inertial navigation system for the Morpheusautonomous underwater vehicles

This paper presents the design and development of an enhanced inertial navigation system that is to be integrated into the Morpheus autonomous underwater vehicle at Florida Atlantic University. The inertial measurement unit is based on the off-the-shelf Honeywell HG1700-AG25 3-axis ring-laser gyros and three-axis accelerometers and is aided with ground speed measurements obtained using an RDI Doppler-velocity-log sonar. An extended Kalman filter has been developed, which fuses together asynchronously the inertial and Doppler data, as well as the differential Global Positioning System positional fixes whenever they are available. A complementary filter was implemented to provide a much smoother and stable attitude estimate. Thus far, preliminary study has been made on characterizing the inertial navigation system-based navigation system performance, and the corresponding results and analyzes are provided     

水下机械手接近觉系统研究

根据水下机械手的工作需要,设计了一套高精度的水下超声波定位系统.采用超声波检测距离、三探头阵列检测方位的方案,使用超低功耗单片机MSP430精确计算超声波往返时间和控制三探头轮流工作,通过对三个探头的测量数据进行处理,实现目标测距及定位.经过实验室及水池实验表明,该系统在水下工作稳定,精度及灵敏度高,是水下机器人及机械手自主探测目标的有效手段之一.