AGV视觉导航中Kalman滤波最优控制器的设计

为解决电子地图辅助视觉导航AGV的控制精度问题,将AGV中基于视觉的位置信号离散化后得到AGV中心轴的偏距和偏角.作为滤波器的输入信号,用U-D分解的Kalman滤波可以有效地消除在AGV导航中存在的白噪声.其中在时域中采用递推算法为最优控制输入稳定的状态量,并保证数值的稳定性,使系统的鲁棒性好;再经过状态反馈最优控制系统得到最优的控制输出.结果表明,用此方法设计的控制器稳定性强,抗干扰能力强,AGV在该控制器的作用下,转弯半径为5 m时,方向偏差在±0.5.内变化,侧向偏差控制在±4 mm之内.该控制器适应于工业环境中强电气噪声的环境,对直线和曲线路径有很好的跟踪效果,用于自动导向车辆等智能运输设备,符合工业应用的要求.     

离散线性随机系统输入—输出关系的数学描述

研究离散线性随机系统输入-输出间的关系,证明了任何线性随机系统输出方差与其输入无关.因此在任何意义下由方差极小化而得最优控制是不可能的,且已证明,输出与其集点间的期望差依赖于控制信号的选择,得到了最小偏差控制器,考虑了与线性随机系统输入-输出关系有关的所谓完全i-步输出可达性这一重要概念,并给出了以输入-输出随机差分方程所描述的多变量随机系统的完全i-步输出可达性的充要条件,并可由此得到输出可达性的简易检验方法.     

基于RFID阵列的无轨AGV系统的研究与设计

为改进有轨自动导航小车(AGV)的不足,研究一种基于RFID阵列的无轨AGV系统。该系统包括RFID阵列地板、无线通信网络、上位机、运行场地地图、小车运行控制系统;AGV安装若干RFID读卡器,运行在RFID阵列地板上,运行时通过读取地板下RFID电子标签的ID号,并通过无线通信网络发送到上位机;上位机构建和存储RFID阵列地板地图,上机位将接收到的ID号与存储的地图进行对照,计算出小车当前的位置的运行姿态,依据预设的运行路径生成AGV当前的控制指令并通过无线网络发送小车,控制小车的运行。系统通过利用RFID与地图实现定位,上位机生成控制指令的方式,实现AGV无轨运行。验证测试结果表明,AGV在预设运行路径上行驶,平均定位精度5cm,实用性好,稳定性高。     

基于遗传算法的平面车库车辆路径规划

随着物流系统自动化、智能化水平的提高,AGV在物流系统的应用越来越普遍。AGV的导航是AGV的核心技术,而路径规划是AGV导航的重要环节之一。本文应用遗传算法求解单个AGV的路径规划问题,最后给出该算法实现的路径规划仿真和实验结果,实验结果证实了该方法的有效性。     

一种用于小型敏捷仓库的AGV视觉导航方法研究

随着物流行业的发展,物流自动化仓库正在朝着多用户、多品种和高度灵活性的柔性自动化仓库发展,传统AGV(automatic guided vehicle)难以满足物流仓库的新需求。针对实际需求,基于色差阈值分割的方法对AGV的导航路径偏差进行提取并融合,采用"预瞄闭环控制"的思想设计路径跟踪控制器,实现了机器人高精度的路径跟踪。最后,在搭建的模拟仓库中,对设计AGV的导航性能进行了全面测试,实验结果表明,该视觉导航AGV导航灵活,精度高,运行平稳,可以满足柔性仓储的需求。     

基于模糊神经网络的AGV避障路径研究

通过对AGV运动学模型进行分析,针对AGV在未知环境中的避障问题,将模糊控制与神经网络相结合,形成模糊神经网络控制器,对AGV行驶环境进行分析,将障碍物信息输入控制器,从控制器输出数据中找出避障最佳路径,利用模糊神经网络自学习和自适应能力,提高AGV避障的成功率。     

一款AGV磁导航传感器的设计

在工业自动化的发展过程中,AGV（自动导引车辆）广泛投入使用,目前应用较广泛的导航方式之一是磁条导航,它具有对环境要求低、安装简单、易维护、成本低等优点。设计了一款AGV磁导航传感器,该传感器以ARM Cortex-M3为核心、RS232C线驱动和磁导航模拟前端设计硬件实验平台,实时采集磁导航信号,采集到的信号通过对数-双曲正切函数的鲁棒自适应滤波算法,减小AGV行驶过程中的偏差,在C/OS Ⅲ微型操作系统进行任务循环调度,通过人机交互界面观测传感器实时状态,对AGV的运行轨迹进行修正。根据实验数据和仿真结果表明：使用该磁导航传感器的AGV行驶偏差较小,车身更加平稳。     

对角式舵轮分布的AGV路径纠偏控制研究

针对对角式舵轮分布的自动导航车 (Automated Guided Vehicle，AGV )的路径纠偏，提出了一种模糊控制+滑模控制的控制方法。首先，对对角式舵轮分布的AGV进行数学描述，对其运动学、动力学分析建模；其次根据运动学模型，以车体位置、角度偏差为输入量，车体转向角度为输出量，设计模糊运动控制器作为外环控制器，然后根据其非线性动力学模型设计滑模控制器作为内环控制器；最后通过MATLAB环境下的Simulink仿真研究，表明所制定的控制策略有效，保证了对角式舵轮分布的AGV的快速且稳定的路径纠偏。     

基于ANFIS的电动赛车加速驱动控制的优化

为提高赛车在中低速下的加速能力,针对传统模糊控制依赖操作人员的经验、控制精度较低等缺点,提出一种基于自适应神经模糊推理系统的电动赛车加速驱动控制优化方法。该方法以当前加速踏板开度对应的最高车速为驾驶员期望车速,以驾驶员期望车速与实际车速的偏差及其变化率为输入变量,以加速踏板修正系数为输出变量,将加速踏板修正系数与当前加速踏板开度相乘得到修正后的加速踏板开度。Matlab/Simulink仿真与实车测试结果表明:在对加速踏板采用相同的操作控制下,优化后的驱动控制方法增加了赛车加速踏板的开度;在加速结束时刻,赛车车速的仿真值较优化前提高209%,实测值较优化前提高174%。     

多AGV群控调度的蚁群算法研究

本文对多AGV群控调度中的单车导航定位及其行走路径进行了研究,并分析了蚁群算法在调度中的可行性。为缩短自动导引车调度系统的研发周期、降低研发成本,寻求能适应不同环境的通用调度策略以及增强对实际调度任务和故障的鲁棒性。在多自动导引车群控调度中使用蚁群算法,建立了调度系统的数学模型,并通过MATLAB仿真验证了此方法的可行性,得到了最优的导航路径及调度方案。     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.