Improving the accuracy of ultrasound-based localisation systems

We present an improvement to ultrasound-based indoor location systems like Cricket (Priyantha et al. The Cricket location-support system, 2000). By encoding and modulating the ultrasound pulses, we are able to achieve greater accuracy in distance measurements. Besides improving the distance measurements, we improve the position update rate by synchronising the active beacons. We also propose a method that could further improve the update rate by superimposing encoded ultrasound pulses. Further, an experimental evaluation of our improvements is presented.     

WSN下一种基于时间序列分析的跟踪方法

针对Cricket室内定位系统在没有获得足够的距离信息时无法对移动目标进行准确定位的问题,提出了一种基于时间序列分析ARMA模型的方法。在距离信息不足时根据移动目标历史位置信息构造ARMA模型,得到预测位置,再根据预测位置结合距离信息进行目标定位。实验结果表明,在传感器网络中,该方法在移动目标跟踪上是可行和有效的。     

室内Cricket无线传感器网络定位方法的改进

在无中心构架的Cricket无线传感器网络室内定位系统中,呈线性关系的参与定位的3个参考节点坐标会使三边测量法失效,从而导致系统进行大量的冗余计算甚至崩溃。采用参考节点坐标的最小距离决策和二次迭代法,使得系统在三边测量法失效的前提下仍能正常运行。通过实验证明这种改进方案提高了系统的稳定性和效率。     

基于Cricket传感器网络室内定位系统的设计与实现

在高精度传感器网络室内定位系统中,基于到达时间差的定位系统得到了越来越普遍的研究。以Cricket传感器为载体,根据射频和超声波信号的传输特性以及信标布局的特点设计了一种改进的通信机制,不但提高了传感器网络通信质量的而且也降低了传感器节点的能量消耗。并提出了一种与传感器工作机制相关且误差限制在1 cm以内的计算距离的方法;最后根据信标节点与接收器之间的几何关系,实现了满足室内环境下接收器移动性需要的位置计算算法。     

Robot phonotaxis in the wild: a biologically inspired approach to outdoor sound localization

Cricket phonotaxis (sound localization behavior) was implemented on an autonomous outdoor robot platform inspired by cockroach locomotion. This required the integration of a novel robot morphology (Whegs) with a biologically based auditory processing circuit and neural control system, as well as interfacing this to a new tracking device and software architecture for running robot experiments. In repeated tests, the robot is shown to be capable of tracking towards a simulated male cricket song over natural terrain. Range fractionation and gain control were added to the auditory control circuit in order to deal with the substantial change in amplitude of the signal as the robot approached the outdoor sound stimulus. We also discuss issues related to acoustic interference from motor noise, the need for a motor feedback mechanism to better regulate the drive signal and plans for future work incorporating additional sensory systems on this platform.     

Legality of bowling actions in cricket

An ergonomic methodology has been designed and developed to evaluate the legality of bowling actions in cricket. This paper describes the methodology and a case study related to an international cricket player with an unorthodox bowling action. Objective measurements were used to evaluate the action. An electrogoniometer and a force-sensing resistor (FSR) were used for this purpose. The electrogoniometer measured the elbow angles in the sagittal plane, while the FSR indicated the instant of ball release to assess the presence of any elbow 'straightening' directly preceding delivery. The FSR was attached to a finger depending on the type of ball delivered. Angles and forces were sampled at 500 Hz and stored in a data logger. The information collected was downloaded on to a computer for further analyses. The angle information preceding ball release is a clear indicator of arm 'straightening' during bowling. The methodology has high reliability and accuracy in the evaluation of the legitimacy of bowling actions as defined by the International Cricket Council laws.     

Technical Note - Legality of bowling actions in cricket

An ergonomic methodology has been designed and developed to evaluate the legality of bowling actions in cricket. This paper describes the methodology and a case study related to an international cricket player with an unorthodox bowling action. Objective measurements were used to evaluate the action. An electrogoniometer and a force-sensing resistor (FSR) were used for this purpose. The electrogoniometer measured the elbow angles in the sagittal plane, while the FSR indicated the instant of ball release to assess the presence of any elbow ‘straightening’ directly preceding delivery. The FSR was attached to a finger depending on the type of ball delivered. Angles and forces were sampled at 500 Hz and stored in a data logger. The information collected was downloaded on to a computer for further analyses. The angle information preceding ball release is a clear indicator of arm ‘straightening’ during bowling. The methodology has high reliability and accuracy in the evaluation of the legitimacy of bowling actions as defined by the International Cricket Council laws.     

Cricket behaviour-based evolutionary computation technique in solving engineering optimization problems

Meta-heuristicalgorithms are widely used in various areas such as engineering, statistics, industrial, image processing, artificial intelligence etc. In this study, the Cricket algorithm which is a novel nature-inspired meta-heuristic algorithm approach which can be used for the solution of some global engineering optimization problems was introduced. This novel approach is a meta-heuristic method that arose from the inspiration of the behaviour of crickets in the nature. It has a structure for the use in the solution of various problems. In the development stage of the algorithm, the good aspects of the Bat, Particle Swarm Optimization and Firefly were experimented for being applied to this algorithm. In addition to this, because of the fact that these insects intercommunicate through sound, the physical principles of sound propagation in the nature were practiced in the algorithm. Thanks to this, the compliance of the algorithm to real life tried to be provided. This new developed approach was applied on the familiar global engineering problems and the obtained results were compared with the results of the algorithm applied to these problems.     

A-Eye: Automating the role of the third umpire in the game of cricket

Cricket is a sport that involves two teams, say Team A and Team B, and two field umpires. Initially, Team A bats to score some runs, while Team B balls. Then, Team A balls and Team B bats to overcome the score of Team A. If this happens, then Team B wins. Otherwise, Team A wins. The balling team can dismiss a batsman from scoring through a Run-Out, i.e., the batsman fails to enter an area before three stumps are dislodged in that area. In this case, a third umpire makes the ‘Run-Out/Not-Out’ decision through video technology. This process can consume around one minute which disrupts the pace of the game. In this paper, we propose and validate a novel technology called A-Eye, which automates the role of the third umpire. By applying A-Eye to a set of autonomously-filmed Run-Out videos, we show that it is efficient as compared to the third umpire, and almost as accurate. Also, it can be used to estimate a rating for the field umpires. These results have been recognized internationally, and have convinced our local cricket council to employ A-Eye within a professional cricket tournament.     

An OWA‐Based Model for Talent Enhancement in Cricket

Cricket being an extremely competitive game; players are always under pressure to perform and improve continuously. Talent enhancement in cricket is conventionally achieved through practice under coach's supervision and analysis using costly assistive technology. Although this approach is workable, but it is constrained due to nonavailability of quality coaches, equipment, and in many cases the limited domain knowledge of the coaching staff. This constraint is significant for a country like India where 55,000 matches and 1,210,000 players play cricket daily. The literature review did not reveal any algorithm/model/framework focused on the issue of talent enhancement. In this paper, we present an alternate/supporting approach based on comparison of the players’ overall talent class viz‐a‐viz the corresponding performances of the player against the 28 aspects of talent from cricketing perspective. The Ordered Weighted Averaging Aggregation (OWA) operator was used to aggregate the opinion of experts for assessment of talent classes in cricket. The normative data obtained for a cricket enthusiast was then compared using normalized adequacy coefficient with aggregated opinions of experts. This resulted in identification of the talent class of the cricketer. Subsequently, the weaknesses were identified by comparing the outcomes of the identified parametric tests for this cricket enthusiast with the value corresponding to his/her talent class. The algorithm was validated using two‐sided t test. A case showing implementation of algorithm is also explained.     

基于P2P覆盖树网络的流媒体传输技术优化研究

PeerCast是一个基于P2P网络的流媒体传输系统,各节点被组织成树状来进行数据的分发.但没有一个有效的机制来维护树的平衡和保证所选取的父节点是最佳的节点.在此基础上,对该系统进行优化,在媒体数据包上加一个字节用来标识当前节点与根节点的距离,并对节点间响应消息进行优化.实验结果表明,这些优化措施能够有效的维护树的平衡和降底数据传输时延.     

基于嵌入式技术的开关寿命测试仪的设计

为了对开关的寿命进行快速准确地测试,设计了开关寿命测试仪。设计过程如下:首先设计了测试仪的硬件,该硬件使用LPC2138CPU芯片采集开关触头对应的开关量,并与TG12864液晶模块接口输出提示信息;其次设计了判断开关好坏算法和识别坏触头算法;最后根据算法给出了测试仪软件的流程图。应用表明,用这种设计方法实现的测试仪工作可靠、容易使用,适合在开关生产行业推广应用。     

坑道水核磁共振探测激发磁场计算与测试方法研究

提出一种测量激发场垂直于地磁场分量的测量方法：应用固定线圈电磁感应法测量激发场,应用磁通门传感器测量地磁场,通过矢量运算求解激发场垂直于地磁场的分量。制作了激发场测量装置,通过对比激发场的径向分量和轴向分量的理论计算值和实测值,验证测量装置有效性。分析固定点处激发场垂直于地磁场的分量受线圈布设方向的影响,推导出固定点处激发场垂直于地磁场的分量取最大值时线圈布设角度求解方法,为实际探测线圈布设方向提供理论指导。     

电容式倾角传感器在底盘悬挂系统中的应用

以P89V51RD2FN单片机为控制核心,采用电容式倾角传感器实时测量车辆底盘的倾斜角,并用光电传感器检测车辆最终运动姿态和车速。光电传感器和倾角传感器将实时测量信号馈送至单片机,并采用增量式PID控制算法确保车辆能够达到平衡。利用CANBUS 2.0将数据传输至车载电脑来达到智能化车姿控制。实验结果表明:系统响应时间快,精度高,性能稳定。     

不确定性研讨信息的结构化与融合方法

基于流形正则化框架提出一种分类算法(MLD-RLSC),以解决高维文档分类问题。该算法通过构建训练样本的最近邻图来估计数据空间的几何结构并将其作为流形正则化项,结合多变量线性回归获得高维文档的低维流形结构,并采用k近邻分类器对低维流形进行分类,得到针对多类问题的分类器。该算法能够充分利用训练样本的类别信息来帮助学习以提取有效特征。通过在Reuters-21578数据集上的实验,证明该算法的分类性能和运行速度比传统分类器有较大的提高。     

基于文本分类TFIDF方法的改进与应用

TFIDF是文档特征权值表示常用方法。该方法简单易行，但低估了在一个类中频繁出现的词条，该词条是能够代表这个类的文本特征的，应该赋予其较高的权重。通过修改TFIDF中IDF的表达式，来增加那些在一个类中频繁出现的词条的权重，用改进的TFIDF选择特征词条、用遗传算法训练分类器来验证其有效性。该方法优于其它算法，实验表明了改进的策略是可行的。     

Structuring formal specifications—a lesson relearned

Specifications written in the formal specification language Z often make use of a form of decomposition that is novel to programmers. A published Z specification is rewritten using the form of decomposition familiar to programmers. Whenever decomposition is used, there must be some strategy for deciding what is to go in one component and what is to go in another. At the highest level, the strategy underlying the rewritten specification is the well-known strategy of separating user interface issues from deeper system functionality issues. The effectiveness of the strategy is put to a simple test by showing how a modification to the interface can be supported by a modification to only part of the specification. The conclusions drawn are that care over decomposition is important in specifications, just as it is in programs, and that lessons learned from programming about effective decomposition strategies can be applicable at the specification level, too. In particular, the lesson relearned is that it is important to separate information about a system's functionality from information about how this functionality is presented to users.     

离轴式拖车移动机器人的任意路径跟踪控制

离轴式拖车移动机器人属于非完整系统,当车头线速度随时间变化且过零变号时,难以用一个控制器实现系统对期望路径的跟踪.本文研究离轴式拖车移动机器人系统的任意路径跟踪问题.首先由系统和虚拟小车的运动学方程得到误差状态模型,线性化后用坐标变换将其化为标准型,然后基于Lyapunov方法构造出一种跟踪控制律.只要车头的运动线速度有界且不趋于零,其导数有界,则所设计的控制律就可以保证系统跟踪任意的期望路径,且跟踪误差最终一致有界,最终界的大小与期望路径的曲率变化率成比例.当期望路径的曲率变化率为零或趋于零时,所设计的控制律可以保证拖车移动机器人指数收敛到期望路径.仿真结果证实了控制律的有效性.     

光纤Bragg光栅损伤检测系统

损伤会导致结构局部刚度的下降,结果使损伤部位邻域的应变场分布发生显著变化。光纤Bragg光栅（FBG）传感器具有很高的灵敏度并能组成传感网络,适合于检测应变场的变化。通过应变场的变化也可以对失效螺钉进行定位。分布在结构表面的FBG传感器检测的应变数据组成向量,其单位向量定义为“模式”,该模式与载荷大小无关,与加载点位置有关,因此,能用于描述应变场。如果损伤前后模式的相关系数小于1,则加载点附件的螺钉可以判定为损伤。该方法在机翼盒段螺钉失效检测实验得到应用。     

基于使用剖面的软件可靠性测试用例生成方法

为了获得软件的可靠性指标,需要设计操作剖面来仿真用户实际使用软件的情况,并基于操作剖面来进行可靠性测试.传统的基于操作剖面的可靠性测试方法难以适用于航天软件,为了解决此问题,描述了一种具有层次化网络体系结构特征的使用剖面的形式化定义,阐述了构造这种使用剖面的系统化方法,给出了根据使用剖面生成用于软件可靠性测试操作序列的算法,以及基于操作序列生成可靠性测试用例的方法.提出的方法经过实验验证表明是可行的.