基于高阶滑模控制器的水下潜器运动控制

水下环境复杂多变,由于水流的不可预知性和多变性,潜器的水动力系数往往无法准确获取,使得依赖这种参数的潜器运动控制算法的应用受到了很大的局限。为了解决控制器对模型参数的依赖,设计了一种基于高阶滑模控制算法的模型无关控制器,并通过设置合理的过渡过程,解决了这种控制算法依赖初值的弊端。仿真结果表明,位置和姿态的控制能够快速的收敛,误差很小并且不依赖于初始条件,控制器需调节参数很少,并且算法简单,适用于工程的实际需要。     

重力辅助匹配惯性导航系统研究

常规的航位推算方法无法满足水下潜器长时间工作的导航要求,惯导设备的定位误差随时间积累,重力异常数据和重力梯度数据进行匹配辅助导航可以连续的对惯性导航系统积累误差进行校正。 文章介绍了利用重力辅助惯导的思想和原理,对重力辅助惯性导航进行了讨论,建立包含重力异常/ 重力梯度数据的 Kalman 滤波算法,并采用改进的 ICCP 算法对重力异常匹配导航进行了模拟试算,结果表明在现有的技术条件下,重力辅助匹配导航能够胜任水下航行的工作任务,保证长航时的水下定位精度。     

基于GNSS方位辅助惯性导航系统的水下地形精密测量技术

多波束测深技术是目前水下地形测量的主要技术手段,测量平台的瞬时姿态及方位是影响多波束测深系统最终成果准确度的重要因素。GNSS方位辅助惯性导航系统,作为目前应用较为广泛的方位、姿态、及位置综合测量系统,不仅能够提供高精度位置信息,同时也能提供测量平台的瞬时姿态及方位数据,而且因为具有GNSS方位辅助测量,使得最终方位测量结果比传统方位测量精度大大提高,这对于多波束最终测量成果精度提高具有重要意义。文中从GNSS方位辅助惯性导航系统原理及技术优势出发,结合Trimble RTX后处理技术,从姿态测量、方位测量及辅助高程测量方面分析了在多波束水下地形测量中的应用,并以实际测量成果来展现其在水下地形精密测量技术方面的优势,结果显示,定位精度可以达到优于2 cm级别,方位精度可以优于0.01°(依赖于双GNSS天线之间的基线长度),该技术对水下地形测量准确度提升作用显著。     

河道导航和测量系统的设计与实现

在分析河道测量导航技术现状和应用背景的基础上,讨论了河道导航与测量系统的设计原则、设计方案和运作流程,对某些设计细节作了较为详尽的介绍,对某些关键问题提出了相应的解决方法。     

一种用于水下无人航行器的局部避碰路径规划方法研究

研究水下无人航行器(UUV)的局部自动避碰路径规划,对人工势场法和速度障碍法进行改进, 提出一种在三维空间重新分配斥力的方法,联合应用人工势场法和速度障碍法,建立人工模拟势场求得合力, 通过合力的方向指引水下无人航行器航行,完成对动态静态障碍物的避让。仿真结果表明：该方法能有效在动静态混合环境下完成避碰,且平滑处理后的路径更符合水下无人航行器实际航行避碰操纵控制要求。     

Visually Augmented Navigation for Autonomous Underwater Vehicles

As autonomous underwater vehicles (AUVs) are becoming routinely used in an exploratory context for ocean science, the goal of visually augmented navigation (VAN) is to improve the near-seafloor navigation precision of such vehicles without imposing the burden of having to deploy additional infrastructure. This is in contrast to traditional acoustic long baseline navigation techniques, which require the deployment, calibration, and eventual recovery of a transponder network. To achieve this goal, VAN is formulated within a vision-based simultaneous localization and mapping (SLAM) framework that exploits the systems-level complementary aspects of a camera and strap-down sensor suite. The result is an environmentally based navigation technique robust to the peculiarities of low-overlap underwater imagery. The method employs a view-based representation where camera-derived relative-pose measurements provide spatial constraints, which enforce trajectory consistency and also serve as a mechanism for loop closure, allowing for error growth to be independent of time for revisited imagery. This article outlines the multisensor VAN framework and demonstrates it to have compelling advantages over a purely vision-only approach by: 1) improving the robustness of low-overlap underwater image registration; 2) setting the free gauge scale; and 3) allowing for a disconnected camera-constraint topology.      

Simulation of an Inertial Acoustic Navigation System With Range Aiding for an Autonomous Underwater Vehicle

This paper presents an integrated navigation system for underwater vehicles to improve the performance of a conventional inertial acoustic navigation system by introducing range measurement. The integrated navigation system is based on a strapdown inertial navigation system (SDINS) accompanying range sensor, Doppler velocity log (DVL), magnetic compass, and depth sensor. Two measurement models of the range sensor are derived and augmented to the inertial acoustic navigation system, respectively. A multirate extended Kalman filter (EKF) is adopted to propagate the error covariance with the inertial sensors, where the filter updates the measurement errors and the error covariance and corrects the system states when the external measurements are available. This paper demonstrates the improvement on the robustness and convergence of the integrated navigation system with range aiding (RA). This paper used experimental data obtained from a rotating arm test with a fish model to simulate the navigational performance. Strong points of the navigation system are the elimination of initial position errors and the robustness on the dropout of acoustic signals. The convergence speed and conditions of the initial error removal are examined with Monte Carlo simulation. In addition, numerical simulations are conducted with the six-degrees-of-freedom (6-DOF) equations of motion of an autonomous underwater vehicle (AUV) in a boustrophedon survey mode to illustrate the effectiveness of the integrated navigation system.     

水下导航定位技术研究进展

由于海水介质对电磁波的强吸收屏蔽效应影响,水下潜航器的隐蔽航行使得对其进行水下导航定位成为一个难点和热点研究方向。现有水下导航与定位技术以惯性导航传统自主导航技术为主体,围绕修正惯性导航产生的累积误差问题,发展形成了航位推算导航、地球物理匹配导航技术、水声导航技术等多种辅助导航技术。系统地介绍了这些水下导航技术及其组合方式的基本原理、主要特点及研究进展,并对未来水下导航技术发展趋势和应用进行了展望。     

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。     

探讨超疏水技术在水下航行器上的应用

超疏水技术通过在材料表面涂覆憎水的低浸润性涂层,导致水滴在其表面无法滑动铺展而保持球形滚动状,提升材料抗腐蚀、防污自清洁能力。 由于特殊的浸润特性,超疏水材料在水下航行器上的研究得到越来越多的关注。 超疏水技术有效地解决困扰水下航行器发展的瓶颈问题,降低航行阻力,噪音和提升防污抗腐蚀能力。 着重介绍超疏水技术在水下航行器减阻、防污抗腐蚀和降噪领域的应用现状。     

In Situ Alignment Calibration of Attitude and Doppler Sensors for Precision Underwater Vehicle Navigation: Theory and Experiment

This paper reports the development and experimental evaluation of two in situ least squares techniques for estimating the alignment matrix of Doppler sonars commonly used for precision navigation of oceanographic submersibles. Most previously reported methods addressed the problem of single degree-of-freedom heading alignment using bottom-lock Doppler sonar data and global positioning system (GPS) navigation data. This paper reports and evaluates two techniques for three degree-of-freedom calibration of attitude and Doppler sonar sensors using sensor data available to vehicles at full ocean depth. The first technique provides a general linear least squares estimate of the alignment matrix. The second technique results in a least squares alignment matrix estimate constrained to the group of rotation matrices. The performance of these estimates is evaluated with a laboratory remotely operated vehicle (ROV) and a field-deployed autonomous underwater vehicle (AUV). Experimental results are reported which demonstrate that Doppler navigation employing the reported alignment calibration techniques significantly improves navigation precision. The experiments show that the latter technique provides calibration estimates that improve Doppler navigation precision not only on the calibration data set itself, but also provide improved precision over a wide variety of vehicle trajectories other than the calibration data set.     

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。     

AUV自主导航航位推算算法的分析研究

地球形状的不规则性,各种导航传感器本身的误差,以及仪器的安装偏差等,使得AUV(自治水下机器人)在进行远距离自主航行时,自主导航的精度大大下降。针对以上问题及实际工程需要,论文对AUV自主导航的航位推算算法做了进一步研究并加以改进,以提高其自主导航精度。最后,利用2004年中国科学院沈阳自动化所水下机器人研究中心进行AUV湖试所获得的数据,对文中提出的算法进行了验证。结果表明,AUV的自主导航精度得到大大提高,可以用于修正原来的自主导航算法。