Visibility-Based Planning of Sensor Control Strategies

We consider the problem of planning sensor control strategies that enable a sensor to be automatically configured for robot tasks. In this paper we present robust and efficient algorithms for computing the regions from which a sensor has unobstructed or partially obstructed views of a target in a goal. We apply these algorithms to the Error Detection and Recovery problem of recognizing whether a goal or failure region has been achieved. Based on these methods and strategies for visually cued camera control, we have built a robot surveillance system in which one mobile robot navigates to a viewing position from which it has an unobstructed view of a goal region, and then uses visual recognition to detect when a specific target has entered the region. Received November 11, 1996; revised January 12, 1998.     

一种遥测系统实时传感器网络体系结构

分析了遥测系统组网的实现方法和存在问题，针对遥测系统的业务量模式提出了一种实时Ad Hoc传感器网络体系结构，包括新的最终期限优先级调度和距离-拥塞路由协议，仿真结果显示该体系结构比先来先服务的调度算法与DSR路由协议的组合明显减少了端对端最终期限不符合率。     

Optimal Camera Placement for Automated Surveillance Tasks

Camera placement has an enormous impact on the performance of vision systems, but the best placement to maximize performance depends on the purpose of the system. As a result, this paper focuses largely on the problem of task-specific camera placement. We propose a new camera placement method that optimizes views to provide the highest resolution images of objects and motions in the scene that are critical for the performance of some specified task (e.g. motion recognition, visual metrology, part identification, etc.). A general analytical formulation of the observation problem is developed in terms of motion statistics of a scene and resolution of observed actions resulting in an aggregate observability measure. The goal of this system is to optimize across multiple cameras the aggregate observability of the set of actions performed in a defined area. The method considers dynamic and unpredictable environments, where the subject of interest changes in time. It does not attempt to measure or reconstruct surfaces or objects, and does not use an internal model of the subjects for reference. As a result, this method differs significantly in its core formulation from camera placement solutions applied to problems such as inspection, reconstruction or the Art Gallery class of problems. We present tests of the system’s optimized camera placement solutions using real-world data in both indoor and outdoor situations and robot-based experimentation using an all terrain robot vehicle-Jr robot in an indoor setting.     

A Complexity-Level Analysis of the Sensor Planning Task for Object Search

Object search is the task of searching for a given 3 D object in a given 3 D environment by a controllable camera. Sensor planning for object search refers to the task of how to select the sensing parameters of the camera so as to bring the target into the field of view of the camera and to make the image of the target to be easily recognized by the available recognition algorithms. In this paper, we study the task of sensor planning for object search from the theoretical point of view. We formulate the task and point out many of its important properties. We then analyze this task from the complexity level and prove that this task is NP-Complete.     

Cross-layer Enhancement to Multi-hop Routing in Sensor Networks： an Empirical Study

Lossy link is one of the unique characteristics in random-deployed sensor networks. We envision that robustness and reliability of routing cannot be ensured purely in network layer. Our idea is to enhance the performance of routing protocol by cross-layer interaction. We modified mint protocol, a routing protocol in TinyOS and proposed an enhanced version of mint called PA-mint. A transmission power control interface is added to network layer in PA-mint. When routing performance of the current network is not satisfied, PA-mint monotonically increases the transmission power via the interface we added. PA-mint is able to connect orphan nodes and robust to node mobility or key nodes failure. In the case that automatic request retransmission is employed, the number of retransmissions can be reduced by PA-mint. Results from experiments show that PA-mint increases the reliability and robustness of routing protocol by cross-layer interaction.     

A Robust Method for the Concurrent Motion Planning of Multi-Manipulators Systems

In this article a robust and simple procedure for the on-line concurrent motion planning of multi-manipulators is presented. The approach is based on solving for each manipulator a linear system of equations taking into account a vector for motion planning, and an original scheme for the appropriate perturbation of the pseudoinverse matrix. This method can pursue simultaneously both motion coordination and singularities prevention in real time in a sensor based environment. These properties make it suitable for fully autonomous or telerobotic systems operations.     

Localized Techniques for Broadcasting in Wireless Sensor Networks

In this paper we tackle the problem of designing simple, localized, low energy consuming, reliable protocols for one-to-all communication in large scale wireless sensor networks. Our first proposed technique, called the Irrigator protocol, relies on the idea to first build a sparse overlay network, and then flood over it. The overlay network is set up by means of a simple, distributed, localized probabilistic protocol and spans all the sensor nodes with high probability. Based on the algorithmic ideas of the Irrigator protocol we then develop a second protocol, dubbed Fireworks, with similar performance that does not require any overlay network to be set up in advance. Asymptotic analytical results are provided which assess the reliability of the Irrigator and Fireworks techniques. The theoretical analysis of the proposed protocols is complemented and validated by a (simulation based) comparative performance evaluation that assesses several advantages of our new protocols with respect to gossiping and simple flooding. Differently from previous studies, we analyze and demonstrate the performance of our protocols for two different node distributions: The typical uniform distribution and a newly defined “hill” distribution, here introduced to capture some of the important and more realistic aspects of node deployment in heterogeneous terrain. Simulation results show that the proposed schemes achieve very good trade-offs between low overhead, low energy consumption and high reliability. In particular, the Irrigator and Fireworks protocols are more reliable than gossiping, and significantly reduce the number of links along which a message is sent over both flooding and gossiping.     

Sensor placement for fault isolation in linear differential-algebraic systems

An algorithm is proposed for computing which sensor additions make a diagnosis requirement specification regarding fault detectability and isolability attainable for a given linear differential-algebraic model. Restrictions on possible sensor locations can be given, and if the diagnosis specification is not attainable with any available sensor addition, the algorithm provides the solutions that maximize specification fulfillment. Previous approaches with similar objectives have been based on the model structure only. Since the proposed algorithm utilizes the analytical expressions, it can handle models where structural approaches fail.     

面向无线传感器网络节点定位的移动锚节点路径规划

节点定位是无线传感器网络技术研究的一个基本问题,大多数无线传感器网络的应用和中间件技术都需要节点的位置信息.目前比较实用的定位方法是利用一些移动锚节点(如安装有GPS)根据有效的规划路径移动,通过发送包含其自身坐标的信息来定位其他节点,该方法不过多地增加无线传感器网络成本,还可以获得较高的定位精度.在该方法中,移动锚节点的路径规划问题是需要解决的基本问题.主要研究移动锚节点的路径规划问题,把图论引入到无线传感器网络节点定位系统.把无线传感器网络看成一个连通的节点无向图,路径规划问题转化为图的生成树及遍历问题,提出了宽度优先和回溯式贪婪算法.仿真实验和真实系统实验结果表明,该方法能够很好地适应无线传感器网络节点随机分布的节点定位,可以取得较高的定位精度.     

基于二次Bezier曲线的无线传感网避障路径规划研究

用固定Sink节点进行无线传感网内数据采集的传统方式会导致热点区域(hot spot)问题,而采用移动Sink节点进行数据采集可以克服这个问题,从而达到均衡网络能量分布与延长网络生命周期的效果.本文针对类车型机器人作为无线传感网中移动数据汇聚节点的应用场景,提出了一种基于Bezier连续曲线的移动Sink节点避障路径规划算法.本文构建了连续分段Bezier曲线为巡航轨迹,采用人工势场中的斥力场理论实现对多个障碍物的智能躲避,动态调节二次Bezier曲线的内部控制点位置,将障碍物排斥在二次Bezier曲线之外.仿真结果验证本文提出的算法可以实现移动Sink节点规划路径的避障功能,同时Bezier曲线规划算法简单,计算量较小.     

An Architecture for Planning in Embedded Systems

This work is focused on an architecture for systems which act inside an unpredictable world (embedded systems). Several systems dealing with the above issue have been proposed so far. We classify them by means of their architectures and algorithms, obtaining, for example, classical, deferred and reactive planning. From the systems developed up to now, we can point out some of the features that embedded systems must have. Namely, each system must have a flexible architecture, so it can deal with different problems. Each system must allow different basic activities, i.e., actuators and sensors controlling, plan formation and execution, and so on. Each system must have a flexible failure handling mechanism , since no action is guaranteed to succeed. In this paper, we propose a system called MRG which addresses the above features. Its architecture has several modules which can be combined in different ways depending on the problem. A module performs a basic activity. The system is able to detect and to react to failures. The architecture allows MRG a parallel activation of modules and a quick reaction to external events. The control of the architecture is reached by means of a planning language which has a small set of powerful control structures. MRG has been experimented in a complex large-scale application.     

Sensor Placement for Sensing Coverage and Data Precision in Wireless Sensor Networks

We present a novel paradigm of sensor placement concerning data precision and estimation. Multiple abstract sensors are used to measure a quantity of a moving target in the scenario of a wireless sensor network. These sensors can cooperate with each other to obtain a precise estimate of the quantity in a real-time manner. We consider a problem on planning a minimum-cost scheme of sensor placement with desired data precision and resource consumption. Measured data is modeled as a Gaussian random variable with a changeable variance. A gird model is used to approximate the problem. We solve the problem with a heuristic algorithm using branch-and-bound method and tabu search. Our experiments demonstrate that the algorithm is correct in a certain tolerance, and it is also efficient and scalable.     

传感网络在水电边坡变形优化检测中应用仿真

在水电边坡变形的检测过程中,需要根据坡变幅度,布置传感节点,传递相关数据,由于坡变幅度一般都伴随不规则起伏,造成传感器节点传递的信号无法形成线性特征,传统的检测方法为了克服非线性变化,需要在大起伏区域布置多个节点,以保证检测的准确性,一旦水电边坡规模大,地质条件较为复杂,将会导致检测节点过多,降低了检测效率。为解决上述问题,提出采用坡变估计模型的水电边坡变形优化传感器检测方法。构建传感网络水电边坡变形检测模型,分别对大坡变区域进行模型的坡变参数预估、参数精估、检验模型适应性、模型修正和模型预报,根据上述模型进行模型最优化评测,实现传感网络在水电边坡变形优化检测。实验结果表明,利用改进算法进行水电边坡变形优化检测,可以减小检测误差、提高检测的准确性,提高检测效率。     

支持新节点加入的传感器网络密钥分配协议

密钥分配协议对于无线传感器网络安全起着基础性作用.如何降低节点的密钥存储损耗,并且支持新节点与原有节点的通信密钥的建立,成为传感器网络密钥分配协议的主要难题.基于E-G协议的基础上,采用了划分网络的方式来降低节点的密钥存储损耗,并在此基础上提出了一种利用秘密共享的方式来实现新加入节点与网络中原有节点的密钥建立方法.还利用C ,对节点的密钥存储和全网连通度进行了仿真,最后对节点的存储损耗,通信代价和抗攻击能力进行了分析.     

A General Framework for Assembly Planning: The Motion Space Approach

Assembly planning is the problem of finding a sequence of motions to assemble a product from its parts. We present a general framework for finding assembly motions based on the concept of motion space . Assembly motions are parameterized such that each point in motion space represents a mating motion that is independent of the moving part set. For each motion we derive blocking relations that explicitly state which parts collide with other parts; each subassembly (rigid subset of parts) that does not collide with the rest of the assembly can easily be derived from the blocking relations. Motion space is partitioned into an arrangement of cells such that the blocking relations are fixed within each cell. We apply the approach to assembly motions of several useful types, including one-step translations, multistep translations, and infinitesimal rigid motions. Several efficiency improvements are described, as well as methods to include additional assembly constraints into the framework. The resulting algorithms have been implemented and tested extensively on complex assemblies. We conclude by describing some remaining open problems. Received November 15, 1996; revised January 15, 1998.     

A General Framework for Expressing Preferences in Causal Reasoning and Planning

We consider the problem of representing arbitrary preferencesin causal reasoning and planning systems. In planning, a preferencemay be seen as a goal or constraint that is desirable, but notnecessary, to satisfy. To begin, we define a very general querylanguage for histories, or interleaved sequences of world statesand actions. Based on this, we specify a second language inwhich preferences are defined. A single preference defines abinary relation on histories, indicating that one history ispreferred to the other. From this, one can define global preferenceorderings on the set of histories, the maximal elements of whichare the preferred histories. The approach is very general andflexible; thus it constitutes a ‘base’ languagein terms of which higher-level preferences may be defined. Tothis end, we investigate two fundamental types of preferencesthat we call choice and temporal preferences. We consider concretestrategies for these types of preferences and encode them interms of our framework. We suggest how to express aggregatesin the approach, allowing, e.g. the expression of a preferencefor histories with lowest total action costs. Last, our approachcan be used to express other approaches and so serves as a commonframework in which such approaches can be expressed and compared.We illustrate this by indicating how an approach due to Sonand Pontelli can be encoded in our approach, as well as thelanguage PDDL3.     

造纸过程纸张定量传感器故障诊断方法研究

本文介绍一种作者提出的容错型纸张定量传感器的原理及性能，给出了应用卡尔曼滤波器的传感器故障诊断算法，与容错型纸张定量传感器结合，实现了对传感器部分部件故障的容错，从而提高了传感器的可靠性。仿真实验结果表明，文中所给的故障诊断方法能及时准确探明和隔离出传感器故障。     

面向弹道规划的网络化反导空间威胁建模研究

针对现有弹道规划中的威胁源建模方法不能有效地体现网络化反导体系的作战特点问题,采用网络化反导体系的效能指数来衡量某型超音速战术导弹在突防过程中面临的空间威胁程度.给出了网络化反导防御体系条件下,导弹的威胁指标体系,建立了基于综合指数法的威胁度计算模型.最后,对威胁度模型进行了实例计算,并根据计算结果生成了威胁态势图,从而验证了模型的有效性.     

Production and Maintenance Planning for Electricity Generators: Modeling and Application to Indian Power Systems

This paper describes the development of an optimization model to perform the fuel supply, electricity generation, generator maintenance, and inter-regional transmission planning for the Northern Regional Electricity Board (NREB) of India. A review of the existing planning process of NREB revealed several areas of potential improvement. In the past, NREB did not use optimization and/or probabilistic methods in their planning. Their decision-making on maintenance, generation and fuel allocation was being performed in a sequential and 'fragmented' fashion, ignoring the possibility of interaction between the generation, transmission, and fuel supply subsystems. The deterministic treatment of outages of generators, and the planning criterion of spreading demand shortfall uniformly across the regions, were other areas of potential improvement. An integrated model, using linear programming together with a heuristic, has been developed to perform joint decision-making on fuel supply, maintenance, generation, and transmission. Monte Carlo simulation is used to incorporate the random outages of generators. The model has been prototyped using GAMS language together with a spreadsheet interface, and implemented for the NREB system. Substantial reduction in system costs is envisaged based on the results of a case study. The model is expected to aid the complex decision-making process of NREB planning engineers in several important ways.