Real-Time Adjustment Underwater Positioning System for Submarines

A rapid real-time adjustment scheme is proposed for improving the precision of the conventional short-base line (SBL) positioning fix system used by submarines and other underwater vehicles. In the proposed approach, an initial position estimate is obtained by solving the conventional SBL tracking equations of the submarine given the assumptions of a constant speed of sound in water and a straight-line propagation path. In the first stage of the real-time adjustment procedure, this initial estimate is corrected using an iterative computation scheme based on a 3D geometry model. The improved position estimate is then used to compute a new, more accurate value of the speed of sound in water. Finally, in the second stage of the real-time adjustment procedure, the corrected speed of sound in water and the discrepancy between the original and corrected position estimates obtained in the first adjustment procedure are applied to update the coordinates of the submarine based on the second signal received from the pinger. The numerical results show that the proposed real-time adjustment system yields a significant improvement in the accuracy of the positioning fix estimates compared to those obtained from the conventional SBL method or the SBL method with the first adjustment procedure only.     

A Study of a Short-Baseline Acoustic Positioning System for Offshore Vessels

The underwater position of the beacon determined using the conventional mode of the short-baseline acoustic positioning system (SBL system) is usually incorrect due to the inaccuracy of underwater-measured sound speed, which is affected by the environment. This article presents a corrected mode of SBL system to offer a precise solution for the underwater beacon position. The corrected mode using the formulation of Euclidean geometry converges quickly and efficiently, obtaining the precise position of the beacon. Finally, a simulation of coring missions of a vessel is presented to verify the accuracy of the corrected mode of the SBL system.     

基于GPS的水下导航算法误差仿真研究

首先介绍了水下导航算法,采用GPS和水下参量测算相结合的方案,即当运行器在水下运行时,利用电子罗盘测量运行器的相对航向,水流传感器测算运行器的相对速度大小,利用学习阶段计算出海水流速,在水下运行器潜行时进行船位推算导航,用GPS精准的定位信号进行导航误差的校正。此算法精度的高低很大程度上取决于用来进行水下参量测算的传感器和用来方位校准的GPS。文中从各个传感器的误差着手,通过模拟仿真详细分析了电子罗盘、水流传感器和GPS的误差对导航精度的影响,对工程应用具有实际的指导意义。     

A precise and continuous monitoring system of the distance between the near-bottom instruments and the sea floor

A relatively simple and inexpensive distance monitoring system (DMS) was devised to monitor continuously and accurately the position of an underwater camera with an attached pinger relative to the sea floor. Although the precision graphic recorder (PGR) or precision depth recorder (PDR) have hitherto been used to record the pinger to bottom distance, these complicated and expensive instruments are not always expected on all vessels.This newly developed system, which measures with a counting timer the interval between the direct sound pulses generated by a pinger and the bottom echoes, yielded results equal to or better than that of the PGR. The distance information thus obtained was accurate within ±2.5% under good conditions (calm weather and flat and level topography) just above the sea bed. This system simplified the photographing operations and made it possible to obtain a precise and quantitative assessment of the epibenthic fauna with the use of a single camera.The DMS is also applicable for determining the precise location of a bottom water sampler, grab sampler, or other underwater oceanographic equipment as well as that of an underwater camera.A part of this research was supported by science research fund from the Ministry of Education.     

Tracking control for underwater vehicle-manipulator systems withvelocity estimation

In this paper, the problem of tracking a desired motion trajectory for an underwater vehicle-manipulator system without using direct velocity feedback is addressed. For this purpose, an observer is adopted to provide estimation of the system's velocity needed by a tracking control law. The combined controller-observer scheme is designed so as to achieve exponential convergence to zero of both motion tracking and estimation errors. In order to avoid representation singularities of the orientation, unit quaternions are used to express the vehicle attitude. Implementation issues are also considered and simplified control laws are suggested, aimed at suitably trading off tracking performance against reduced computational load. Simulation case studies are carried out to show the effectiveness of the proposed controller-observer algorithm. The obtained performance is compared to that achieved with a control scheme in which the velocity is reconstructed via numerical differentiation of position measurements. The results confirm that the chattering on the control commands is significantly reduced when the controller-observer strategy is adopted in lieu of raw numerical differentiation; this leads to lower energy consumption at the actuators and increases their lifetime     

A hydrostatic profiler for nearshore surveying

A portable beach-profiling system is described that utilizes the hydrostatic pressure principle to measure vertical differences between a pressure sensor that follows the profile and a reference sensor on the shoreline. The two instruments are connected by a fluid-filled tube. Horizontal distance is determined by measuring the extension of the tube. The complete profiling system, including a data-logging capability on magnetic tape, is carried in a small four-wheel-drive vehicle. Vertical accuracy in ocean surveys is estimated to be 2.5 cm and horizontal accuracy approximately 1 m. This accuracy is sufficient to resolve sediment transport volumes in most applications.Surveying the underwater portion of nearshore beach profiles has presented significant accuracy problems in the past. The highest accuracy is required at the greatest offshore distance to resolve sediment motions. Boat-supported surveying systems, using the sea surface as a horizontal datum, suffer from the presence in the record of surface waves with a broad range of periods which are difficult to remove from the profile.A number of systems have been developed to eliminate the sea-surface intermediate reference and to measure the submerged portion of the profile directly. These systems involve large vehicles that are propelled or pulled along the bottom and are restricted by portability limitations. The system described eliminates many of the portability problems.     

Monitoring moored instrument motion by optimal estimation

Many oceanographic applications require the positioning of the underwater sensor at measurement times. We consider here the case of subsurface moored tomographic instruments, where the distance between source and receiver must be known within a few meters. For that purpose, a long baseline array is deployed: this system includes a navigator, attached to the mooring element and an array of three transponders set on the ocean bottom. To process the navigation data collected with such system, we have developed a method based on optimal estimation. The triangulation problem is not a basic spherical constraints one and the specificity of deep underwater positioning, related to the variability of the ocean sound speed profile are pointed out. Correcting terms are proposed and introduced into the system. Simultaneous inversion of all data, defining an overconstrained problem allows to estimate biases and errors. The algorithm is applied here to a dataset collected in the Azores-Canary basin during CAMBIOS experiment.     

重力场辅助水下导航对惯导仪器的要求

水下重力测量的准确性是决定重力场辅助水下导航可行性的一个重要指标。从厄特弗斯改正公式出发,详细分析了纬度、航向、航速精度对厄特弗斯改正的影响方式和影响大小,并以当前海洋船测重力精度作为厄特弗斯改正的误差限定,分析了满足该条件下水下载体的航向、航速需要达到的精度指标,提出了利用惯性系统进行水下重力测量误差修正时对导航硬件的要求。     

一种基于视觉的水下机器人动力定位方法

以7 000 m载人潜水器的工程需求为背景,以水下单目摄像机为视觉传感器,进行了水下机器人动力定位方法研究。该动力定位方法利用视觉系统测量得到水下机器人与被观察目标之间的三维位姿关系,通过路径规划、位置控制和姿态控制分解,逐步使机器人由初始位姿逼近期望位姿并最终定位于期望位姿,从而实现了机器人的4自由度动力定位。通过水池实验验证了提出的动力定位方法,并且机器人能够抵抗恒定水流干扰和人工位置扰动。同时,该动力定位方法还可以实现机器人对被观察目标的自动跟踪。     

高精度测深侧扫系统在载人潜水器中的应用

为提升"蛟龙号"载人潜水器海底综合探测能力,介绍一种采用多子阵海底自动检测—子空间拟合的信号参数估计技术的高精度测深侧扫声纳系统。该系统安装于载人潜水器的两侧,能够测量海底的微地形地貌以及海底和水中的目标,同时获得探测区域高分辨率的地形图和地貌图。通过介绍该高精度测深侧扫系统的工作原理、技术指标及系统组成,结合"蛟龙号"载人潜水器试验性应用航次获得的高分辨率地形地貌数据,对该系统在载人潜水器中的应用和海底地形地貌探测结果进行了分析和展望。     

A study of increasing the precision of navigation position for submerged body

Currently, most submerged bodies use the long-baseline acoustic position system (LBL) to identify the navigation position for submerging. A precise navigation position is always the target pursued by underwater technology. The conventional long-baseline acoustic position systems normally use Kalman filter correction to handle the problem of positional errors. This article proposes a new modification, which is based on the periodically measured actual navigation distance, and associated with the three-dimensional geometrical relations between the transponder on the seabed and the navigation distance. This new modification employs the iterative approximation to modify the errors of the measured navigation position from the conventional long-baseline acoustic position system. In order to verify the availability of the modified model by the essay, the study uses the navigation position for an underwater surveying submerged body as the study object. After the numerical simulation analysis, the result shows that the modification was presented by the article can only use very few iterations to precisely modify the errors of the measured navigation position from the conventional long-baseline acoustic position system, which is highly applicable for positioning in long-term and long-distance submersion. Moreover, the modification method proposed by the paper can also help submersion positioning for the underwater vehicle, as well as the military submerged body.     

基于可重置联邦滤波器的水下运载体导航定位方法

单一导航系统无法满足水下运载体高精度、高可靠性的导航需求,文中根据常用水下导航系统的特点,提出基于可重置联邦滤波器的水下运载体导航定位方案,设计了以惯导系统(INS)为主参考系统,声学定位系统/深度计、多普勒计程仪(DVL)、罗经为子参考系统的联邦滤波器,并进行了仿真研究。结果表明文中设计的滤波器能有效融合各个传感器的导航信息,实现水下运载体高精度导航定位,并具有一定容错性。     

传感器测量衰减下的水下目标纯方位跟踪算法

为解决多传感器水下目标纯方位跟踪中的传感器测量衰减问题,建立水下目标静态多传感器纯方位跟踪模型,将传感器测量衰减建模为统计特性已知的随机变量,基于融合中心接收到的各水声传感器的原始测量值,设计了一种集中式状态估计器结构,利用最小方差方法推导出最优的集中式目标状态估计增益。通过算例仿真可以得出,所提出的算法能够在水声传感器不做机动的前提下跟踪目标,弥补了单个水声传感器观测性不足的缺点,对比传统的集中式Kalman估计器,具有更高的精度,能够有效解决传感器测量衰减问题。     

基于单水声信标距离量测的匹配定位方法

水声通信和测距能力是实现水下航行器准确定位的重要技术手段。当前基于水声定位的方法主要有利用测距和测向功能的水声定位技术以及水声测距辅助导航技术,二者的系统物理复杂度都比较高。本文提出了一种基于单水声信标距离量测的匹配定位方法,航行器在水声信标测距覆盖范围内,利用航行过程中多次测距信息构建测距圆序列形成位置约束,基于航位推算导航信息,将航行器在连续测距时间段内的相对航迹在圆序列上进行最优匹配,从而获得位置估计,通过对测距误差进行补偿可进一步提升定位精度。本方法所需物理系统结构复杂度低、可操作性强,仿真实验表明,该方法可以独立实现较高精度的定位。     

基于最小二乘法的超短基线水声定位系统校准方法

超短基线水声定位系统是海洋工程及水下无人系统中应用较广泛的精密仪器设备,为了提高对水下目标的定位精度,在使用前需对其进行校准。描述了一种基于最小二乘法迭代修正的超短基线水声定位系统校准方法,该方法以最小二乘法为基本原理,通过多次迭代修正的方式,修正基阵与GPS天线之间的平移偏差以及基阵与罗经之间的旋转偏差,从而提高系统的测量精度,最终通过湖上试验验证了该方法的有效性。     

机载激光测深系统研制中的关键技术

根据机载激光测深系统的工作机理,分析梳理了研制过程中涉及的主要关键技术,包括:高重复频率激光器研制、大动态范围微弱光信号提取、海底回波识别、海面波浪改正、浅水与深水分离测量、高速多通道数字采集、海陆分界识别、定位测姿、水位改正和测深数据质量控制等技术。只有成功突破上述关键技术,才能实现《海道测量规范》要求的测深精度指标。     

水下目标方位估计的一种新方法

矢量传感器是一种新型水声传感器。介绍了应用矢量传感器确定目标方位的理论和方法，给出了仿真和实验研究结果，讨论了矢量传感器具体体积小、输出信号多、抗各向同性干扰等特性。最后定性地分析了目标方位的方位估值误差。     

Design and analysis of a high-intensity LED lighting module for underwater illumination

Replacing traditional light sources with light-emitting diode (LED) light modules is a global trend, especially for underwater illumination. The light intensity is dispersed evenly at all emission angles in traditional underwater light sources that use the radiative transfer model, resulting in the inclusion of scattering factors in the attenuation coefficient. The high directionality of LED light source modules causes the light intensity transfer in water to vary according to varying emission angles. This renders traditional underwater optical transfer theory irrelevant as an underwater LED light module design reference. Therefore, this study constructs an underwater LED light source transfer model using the light-field average cosine and the light transfer scattering probability method, and imports the LED luminous intensity distribution curve (LIDC) and axial luminous intensity. Experimental results showed that the illumination intensity of the underwater LED illumination module was less than 10% of the simulation. Therefore, this design method can be used to design the required illumination light modules for different underwater environments. Finally, the LED light module has been used for under water fish attractor lighting and enhanced the illumination zone efficiency (m³ per Watt) of 81% compared to the traditional high intensity discharge (HID) underwater fish attractor lamp.     

用于水下潜器的惯性导航系统安装和初始对准技术

水下潜器通常采用捷联惯性导航和多普勒计程仪组合导航系统。为提高惯性导航系统的导航精度,保障水下潜器顺利作业,文章以高性能惯导系统PHINS为例,介绍其安装和初始对准技术。PHINS在安装时须计算其与船体的偏差以及与船体和外部传感器的力臂,尤其与多普勒计程仪组合时应执行传感器自动对准程序;PHINS的初始对准是其精确导航的前提,可在海上或静态时进行;惯导系统的安装误差和初始对准精度对于其导航精度具有决定性的影响。     

An ROV Stereovision System for Ship-Hull Inspection

Ship hulls, as well as bridges, port dock pilings, dams, and various underwater structures need to be inspected for periodic maintenance. Additionally, there is a critical need to provide protection against sabotage activities, and to establish effective countermeasures against illegal smuggling activities. Unmanned underwater vehicles are suitable platforms for the development of automated inspection systems, but require integration with appropriate sensor technologies. This paper describes a vision system for automated ship-hull inspection, based on computing the necessary information for positioning, navigation, and mapping of the hull from stereo images. Binocular cues are critical in resolving a number of complex visual artifacts that hamper monocular vision in shallow-water conditions. Furthermore, they simplify the estimation of vehicle pose and motion, which is fundamental for successful automatic operation. The system has been implemented on a commercial remotely operated vehicle (ROV), and tested in pool and dock tests. Results from various trials are presented to demonstrate the system capabilities