NNFFC-adaptive output feedback trajectory tracking control for a surface ship at high speed     

Li-Jun Zhang  Xue Qi 《Ocean Engineering》2011,38(13):1430-1438

An adaptive output feedback controller based on neural network feedback-feedforward compensator (NNFFC) which drives a surface ship at high speed to track a desired trajectory is designed. The tracking problem of the surface ship at low speed has been widely investigated. However, the coupling interactions among the forces from each degree of freedom (DOF) have not been considered in general. Furthermore, the influence of the hydrodynamic damping is also simplified into a linear form or neglected. On the contrary, coupling interactions and the nonlinear characteristics of the hydrodynamic damping can never be neglected in high speed maneuvering situation. For these reasons, the influence of the nonlinear hydrodynamic damping on the tracking precision is considered in this paper. Since the hydrodynamic coefficients of the surface ship at high speed are very difficult to be accurately estimated as a prior, it will be compensated by NNFFC as an unknown part of the tracking dynamics system. The stability analysis will be given by the Lyapunov theory. It indicates that the proposed control scheme can guarantee that all the signals in the closed-loop system are uniformly ultimately bounded (UUB), and numerical simulations can illustrate the excellent tracking performance of the surface ship at high speed under the proposed control scheme.  相似文献   

Robust coordinated motion control of an underwater vehicle-manipulator system with minimizing restoring moments     

Jonghui Han  Jonghoon Park 《Ocean Engineering》2011,38(10):1197-1206

For autonomous manipulation in water, an underwater vehicle-manipulator system (UVMS) should be able to generate trajectori9es for the vehicle and manipulators and track the planned trajectories accurately. In this paper, for trajectory generation, we suggest a performance index for redundancy resolution. This index is designed to minimize the restoring moments of the UVMS during manipulation, and it is optimized without impeding the performance of a given task. As a result, the restoring moments of the UVMS are decreased, and control efforts are also reduced. For tracking control of the UVMS, a nonlinear H_∞ optimal control with disturbance observer is proposed. This control is robust against parameter uncertainties, external disturbances, and actuator nonlinearities. Numerical simulations are presented to demonstrate the performance of the proposed coordinated motion control of the UVMS. The results show that control inputs for tracking are reduced, and the UVMS can successfully track generated trajectories.  相似文献   

2008年黄海绿潮路径的数值模拟   总被引：2，自引：0，他引：2  

郑向阳  邢前国  李丽  施平 《海洋科学》2011,35(7):82-87

利用FVCOM模式拉格朗日粒子跟踪模块模拟了2008年5月到7月黄海绿潮漂移路径,根据遥感图像选取粒子跟踪的初始位置和初始时刻,模式中加入M2,S2,K1,01四个主要分潮和Quickscat每日风场资料作为驱动,模拟的粒子运动的主要路径和到达青岛近岸的时间与遥感图像对比都比较吻合。该结论进一步验证了前人关于青岛绿潮来...  相似文献   

Simulated eddy induced vertical velocities in a Gulf of Alaska model     

Shannon H. Nudds  Jennifer A. Shore 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(11):1060-1068

Mesoscale eddies can distribute nutrients, heat and fresh water into the Gulf of Alaska (GOA) from the coastal margins. While many studies have investigated the physical characteristics of GOA eddies, their effects on passive-dispersive particles have not been previously simulated to investigate eddy induced upwelling. A climatologically forced Parallel Ocean Program simulation of the north Pacific Ocean with an online particle tracking scheme was used to simulate passive-dispersive particles in the Gulf of Alaska. In-eddy vertical Lagrangian velocities of the particles were calculated both inside and outside the eddies and showed upwelling rates are generally greater inside the eddies where the vertical velocities of the particles ranged from 0.2 to 0.7 m/day.  相似文献   

基于灰度匹配的序列影像的目标跟踪研究与实现          下载免费PDF全文

张春茂  闫凤林  宋学征 《海洋测绘》2011,31(3):37-39

利用匹配算法对视频帧进行处理可以实现对特定目标的跟踪.通过在Matlab平台上利用基于灰度的匹配算法实现简单背景下的单目标跟踪,来说明目标跟踪的基本过程,并且对在Matlab平台上实现目标跟踪所遇到的坐标系转换、运算速度以及适用范围等问题进行了分析讨论.  相似文献   

基于频率差异的多次波识别     

潘军  王修田 《中国海洋大学学报(自然科学版)》2011,(Z1):146-150

从简化的海洋地震勘探的基本模型出发,根据一次波和多次波的传播所经介质品质因子的不同,通过理论分析和数值实验证明了随着传播时间的增加,一次波的主频可明显低于同一时间段的海水鸣震主频;提出了将多次波的传播时间和相应主频结合起来判别多次波的"时间-频率识别模式"。实际资料的处理实验表明:与传统的"时间识别模式"相比,基于"时间-频率识别模式"的多次波衰减,可在压制多次波的同时较好地保持有效信号的基本特征。  相似文献   

遥感影像局部兴趣目标的可逆信息隐藏算法          下载免费PDF全文

王兰  刘宇  韩强雷  吴彬  徐明世 《海洋测绘》2011,31(5):48-51

提出了一种适用于遥感影像局部兴趣目标授权使用的可逆信息隐藏算法.提取遥感影像上的局部兴趣目标作为待隐藏的信息,并在原始图像上对该目标进行变形处理,然后利用可逆整数线性变换实现待隐藏信息的调制嵌入,授权用户能够完全无损重建原始遥感影像.算法为盲算法,具有较大的嵌入容量,含隐藏信息图像的峰值信噪比较高,并且可以有效抵抗剪切...  相似文献   

非零偏移距声地层剖面多次波的时距分析及压制示例     

王鹏伟  王修田 《中国海洋大学学报(自然科学版)》2011,(Z1):324-330,340

基于对符合二维观测的模型中非零偏移距全程多次波时距关系的理论分析可知:无论地下反射界面为水平的还是倾斜的,非零偏移距的全程n次多次波的旅行时总是小于相应一次波旅行时的n倍,但非零偏移距与零偏移距全程多次波的时距差异,随偏移距的增大而增大,而随探测深度的增大而减小。基于该理论分析结论,对在零偏移距假设下计算的多次波旅行时先行调整,使其与非零偏移距的多次波旅行时相对应后再进行压制处理,可获得更高质量的声地层剖面。  相似文献   

黄海绿潮应急溯源数值模拟初步研究   总被引：2，自引：0，他引：2  

吴玲娟  曹丛华  黄娟  曹雅静  高松  白涛 《海洋科学集刊》2011,50(6):44-47

基于三维全动力POM 海洋模式, 根据2008 年6 月1 日海监飞机监测绿潮所在位置, 采用拉格朗日粒子追踪法反向积分, 追溯绿潮来源。数值模拟结果显示, 回溯至5 月中旬, 绿潮主要来源于黄海南部江苏连云港和盐城近海海域。黄海绿潮溯源数值模拟, 为政府相关部门了解绿潮的源头, 并采取相应的措施提供依据, 进而为保护生态环境、防灾减灾做贡献。  相似文献   

目标跟踪中参考模型的自动初始化方法     

程明智  高俊祥 《成都信息工程学院学报》2011,26(3):318-322

目标跟踪中参考模型的初始化大多需要手动完成,现有的自动初始化方法也存在明显缺陷,针对这些问题提出了一种自动、精确初始化参考模型的方法。首先采用连通组分标记算法对目标进行计数,并计算每个目标的位置;然后根据回转半径张量法求出包含目标的最小外接矩形;最后从最小外接矩形的参数出发用蒙特卡洛算法求出参考模型的估计。实验结果表明在不同的场景下算法均能准确完成参考模型的初始化,计算出的模型能够体现目标的视觉特征。  相似文献