Closed-loop randomized kinodynamic path planning for an autonomous underwater vehicle     

《Applied Ocean Research》2019

A randomized kinodynamic path planning algorithm based on the incremental sampling-based method is proposed here as the state-of-the-art in this field applicable in an autonomous underwater vehicle. Designing a feasible path for this vehicle from an initial position and velocity to a target position and velocity in three-dimensional spaces by considering the kinematic constraints such as obstacles avoidance and dynamic constraints such as hard bounds and non-holonomic characteristic of AUV are the main motivation of this research. For this purpose, a closed-loop rapidly-exploring random tree (CL-RRT) algorithm is presented. This CL-RRT consists of three tightly coupled components: a RRT algorithm, three fuzzy proportional-derivative controllers for heading and diving control and a six degree-of-freedom nonlinear AUV model. The branches of CL-RRT are expanded in the configuration space by considering the kinodynamic constraints of AUV. The feasibility of each branch and random offspring vertex in the CL-RRT is checked against the mentioned constraints of AUV. Next, if the planned branch is feasible by the AUV, then the control signals and related vertex are recorded through the path planner to design the final path. This proposed algorithm is implemented on a single board computer (SBC) through the xPC Target and then four test-cases are designed in 3D space. The results of the processor-in-the-loop tests are compared by the conventional RRT and indicate that the proposed CL-RRT not only in a rapid manner plans an initial path, but also the planned path is feasible by the AUV.  相似文献   

A novel spatial index using spatial analyses and hierarchical fuzzy expert system for obtaining green TOD: a case study in Tehran city     

Hamid Motieyan  Mohammad Saadi Mesgari 《国际地球制图》2019,34(1):1-22

Sustainable development is a vital and challenging factor for managing urban growth smartly. This factor contains three main components, namely economic growth, ecological protection and social justice. Green Transit-Oriented Development (GTOD) is a consummate planning approach in line with those components. Implementation of GTOD in an urban area is underpinned by its quantification. Therefore, a quantitative spatial index based on several indicators related to TOD and Green urbanism concepts should be developed. In this study, Geo-spatial Information Science and hierarchical fuzzy inference system (HFIS) were employed to calculate the indicators and aggregate them, respectively. In order to showcase the feasibility of the proposed method, it was implemented in a case study area in the City of Tehran, Iran. The result of this method is an integrated spatial GTOD index, which measures the neighbourhoods’ GTOD levels. These measurements specify weaknesses and strengths of neighbourhoods’ factors. Therefore, this index helps decision-makers to plan neighbourhoods based on land use and public transit views. Additionally, the HFIS method helps decision-makers to consider criteria and indicators with their inherent uncertainties and aggregate them with much fewer rules. For evaluating the results, the developed GTOD index was assessed with municipal action planning and attraction maps. According to the outcomes of the assessment, it is concluded that the proposed method is adequately robust and efficient for smart and sustainable urban planning.  相似文献   

A simplified approach to design fuzzy logic controller for an underwater vehicle   总被引：1，自引：0，他引：1  

K. Ishaque  S.S. Abdullah  S.M. Ayob  Z. Salam 《Ocean Engineering》2011,38(1):271-284

Fuzzy logic controller (FLC) performance is greatly dependent on its inference rules. In most cases, the more rules being applied to an FLC, the accuracy of the control action is enhanced. Nevertheless, a large set of rules requires more computation time. As a result, an FLC implementation requires fast and high performance processors. This paper describes a simplified control scheme to design a fuzzy logic controller (FLC) for an underwater vehicle namely, deep submergence rescue vehicle (DSRV). The proposed method, known as the single input fuzzy logic controller (SIFLC), reduces the conventional two-input FLC (CFLC) to a single input FLC. The SIFLC offers significant reduction in rule inferences and simplifies the tuning process of control parameters. The performance of the proposed controller is validated via simulation by using the marine systems simulator (MSS) on the Matlab/Simulink^® platform. During simulation, the DSRV is subjected to ocean wave disturbances. The results indicate that the SIFLC, Mamdani and Sugeno type CFLC give identical response to the same input sets. However, an SIFLC requires very minimum tuning effort and its execution time is in the orders of two magnitudes less than CFLC.  相似文献   

日照茶树种植区典型茶园的土壤肥力状况评价   总被引：1，自引：0，他引：1       下载免费PDF全文

王茂香  张祖陆  王学  张伦  代杰瑞 《山东国土资源》2011,27(7):29-33

通过野外采样和室内测定,以日照茶树种植区3个典型茶园为研究对象,每个茶园分别取鸠坑、黄山群体、福鼎大白各3个品种,最终取得9种茶样生长地的土样,研究分析土样的pH,有机质,全N,P,K,有效N,P,K等指标的土壤养分含量状况,并以此为评价指标,运用模糊综合评判法,对3个茶园的土壤肥力质量进行了综合评价。结果表明,茶园肥力综合水平为北垛春>碧波山庄>北叶青;茶园土壤总体上,pH值较适中,有机质含量很缺乏,全N含量偏低,全P含量中等,全K含量较高,有效N含量很缺乏,有效P含量非常丰富,有效K含量中等,并据此提出了关于该地区3个典型茶园今后合理施肥的一些建议。  相似文献   

Managing expert-information uncertainties for assessing collapse susceptibility of abandoned underground structures     

Aude Nachbaur  Jérémy Rohmer 《Engineering Geology》2011,(3):166

Assessing the collapse susceptibility of abandoned cavities at a regional scale is associated with large uncertainties that are mainly related to the very nature of the phenomena, but also to the difficulty in collecting exhaustive information at such a scale on often “forgotten” structures. In this context, the expert's role is essential, because he is able to synthesize the information resulting from the inventory and from the commonly imprecise, if not vague, criteria on the basis of his experience and his knowledge of the geological, historical, economic regional context.In this article, we propose mathematical tools for representing and processing this information in order to give flexibility to this step and manage the uncertainty inherent in the expert's information. The first tool, based on the weight of evidence theory, is for managing the uncertainty due to the heterogeneous spatial distribution of the data, whereas the second tool, based on the fuzzy set theory, is for managing the imprecision and incompleteness of available data, which hinder the definition of the class boundaries of the quantitative decision criteria. Based on an appropriate representation of the uncertainty sources (related to the input data and to the expert diagnostic), we then propose a methodology that integrates the uncertainty in the final output of the collapse susceptibility assessment and provides a confidence indicator useful within the decision-making process. The proposed methodology is applied to the Arras territory in the North of France, where abandoned chalk pits (dating back to the Roman ages) and war saps located in the vicinity of the First World War front lines (i.e. covered trenches), raise both difficulties for urban planning.  相似文献   

中外烈度表“人的感觉”和“器物的反应”对比研究   总被引：2，自引：0，他引：2  

夏坤  张令心  刘洁平 《地震工程与工程振动》2011,31(5):21-29

随着震害经验的积累以及人们对地震认识的深化,不断修改烈度标准,使烈度评定更加客观与科学是地震工程界一直所追求的.人的感觉和器物的反应都是评定一次地震时相应烈度的宏观标志,是烈度表的重要组成部分.鉴于此,本文简要介绍了中国历代地震烈度表(《新的中国地震烈度表》、《中国地震烈度表(1980)》、《中国地震烈度表( 1999...  相似文献   

A study of supervised classification accuracy in fuzzy topological methods     

Wenzhong Shi  Kimfung Liu  Hua Zhang 《International Journal of Applied Earth Observation and Geoinformation》2011

The multiple classifier system (MCS) is an effective automatic classification method, useful in connection with remote sensing analysis techniques. Combining MSC with induced fuzzy topology enables a decomposition of image classes. This fuzzy topological MCS then provides a new and improved approach to classification. The basic classification methods discussed in this paper include maximum likelihood classification (MLC), minimum distance classification (MIND) and Mahalanobis distance classification (MAH).  相似文献   

带孔洞面域间的拓扑关系的组合推理   总被引：1，自引：1，他引：0  

刘波  李大军  邹时林  阮见 《测绘学报》2011,40(2):262-267

空间对象间拓扑关系是GIS中空间要素间最基本也是最重要的关系之一,是进行空间查询和分析的基础,因而空间对象间拓扑关系一直是研究的热点之一。目前,对拓扑关系模型的研究主要集中在简单对象间拓扑关系方面,而对于带空洞的复杂面域间的空间拓扑关系的研究则相对较少,因而对它的进一步研究具有较重要的理论意义。本文在文献[11]的基础上,根据点集拓扑学理论,对带孔面域进行了定义。通过分析简单对象间拓扑关系的演变过程,提出一种能描述带一个孔的面域间的空间拓扑关系的方法,并用该方法详细推导了带一个孔的面域间有意义的拓扑关系。通过实验验证,证明该方法在理论上是可行的,对提高GIS对现实世界的建模和分析能力可提供一定的理论依据。  相似文献   

线实体候选匹配集的优化方法研究     

胡天硕  毛政元 《测绘科学》2011,36(2):132-135

地图数据合并是地理空间数据集成的基本途径,同名实体匹配是其中的重点与难点。本文根据线实体的形状将其分为简单线实体与复杂线实体,提出针对前者以线实体端点与中点为发生元生成的Voronoi图所得到的邻近对应关系为依据、针对后者以基于线实体缓冲区重叠度构造的相似性测度指标为依据优化候选匹配集的思路,并设计与实现了相关算法。实证研究表明,该算法能够适应不同比例尺与不同时相的城市道路网地图数据同名实体匹配。  相似文献   

复合面状对象拓扑关系的表达模型     

陈占龙  冯齐奇  吴信才 《测绘学报》2015,44(4):438-444

为表达复合面状对象间的细节拓扑关系,对经典9-交集模型进行了改进,给出两种基于分解思想的9-交集模型,其中分解成简单区域的9-交集模型方法相对简单,但表现形式繁琐;分解成点集的9-交集模型的表现形式符合经典9-交集模型,但计算较为复杂。通过示例比较了两种扩展9-交集模型及经典9-交集模型的表达能力。结果表明,两种扩展交集模型均能准确地表达出复合面状对象各子部分之间的拓扑关系的细节,扩充了9-交集模型的表达能力。  相似文献