Use of coded infrared light for mobile robot localization

This paper presents mobile robot localization using coded infrared light as artificial landmark. Different from RFID, coded infrared light has highly deterministic characteristics. It is implemented with IR LEDs and phototransistors. By putting several IR LEDs on the ceiling, the floor is divided into several sectors and each sector is set to have a unique identification. Coded infrared light tells which sector the robot is in, but the size of the uncertainty is still too large if the sector size is large, which usually occurs. Dead-reckoning provides the estimated robot configuration, but the error becomes accumulated as the robot travels. This paper presents an algorithm that combines both the encoder and the coded infrared light information so that the size of the uncertainty becomes smaller. It also introduces a framework that can be used with other types of artificial landmarks. The characteristics of the developed coded infrared light and the proposed algorithm are verified from experiments.     

风险评估技术在我国的应用进展

基于风险的检验（RBI）技术是在追求特种设备安全性与经济性相统一的基础上建立起来的一种优化检验方案的方法,自2003年开始逐渐在我国得到应用和推广。综述了RBI技术在我国的应用进展,介绍了RBI技术的原理及其在石油化工、电力、船舶行业和海上石油平台系统中的实施情况,重点对该技术在我国应用时遇到的问题,特别是相应软件的国产化问题、国家法规的支持等进行了详细探讨,指出了RBI技术在我国仍存在的空白点和应用前景。     

Embedded System for Construction Asset Tracking Combining Radio and Ultrasound Signals

Today’s sensor technology provides the increased opportunities for automation and improvement in data acquisition and construction processes. However, many current field practices at construction sites still rely on manual processes for asset tracking and information handling. Previous technologies, such as radio frequency identification and global positioning systems, do not provide a solution to automated asset tracking because of their limitations in terms of applicability and performance in a typical construction environment. This paper introduces a new development of an embedded sensor system for construction asset tracking by combining radio and ultrasound signals. We present the detailed hardware and software architecture and have implemented outdoor experiments to examine the accuracy and performance of the designed system. The results obtained showed the accurate distance and position estimation with enhanced networking flexibility. The findings and lessons learned from this research demonstrate the potential for future practical deployment of similar systems in many civil engineering applications.     

Improved Damage Localization and Quantification Using Subset Selection

Because a structure’s modal parameters (natural frequencies and mode shapes) are affected by structural damage, finite- element model updating techniques are often applied to locate and quantify structural damage. However, the dynamic behavior of a structure can only be observed in a narrow knowledge space, which usually causes nonuniqueness and ill-posedness in the damage detection problem formulation. Thus, advanced optimization techniques are a necessary tool for solving such a complex inverse problem. Furthermore, a preselection process of the most significant damage parameters is helpful to improve the efficiency of the damage detection procedure. A new approach, which combines a parameter subset selection process with the application of damage functions is proposed herein to accomplish this task. Starting with a simple 1D beam, this paper first demonstrates several essential concepts related to the proposed model updating approach. A more advanced example considering a 2D model is then considered. To determine the capabilities of this approach for more complex structures, a trust region-based optimization method is adopted to solve the corresponding nonlinear minimization problem. The objective is to provide an improved robust solution to this challenging problem.     

On nucleation and propagation of PLC bands in an Al–3Mg alloy

The processes of nucleation and propagation of Portevin–LeChatelier deformation bands during tensile deformation of the alloy AA5754 have been investigated by a special optical technique for local strain measurements, combining both a line-scan and a CMOS camera to record the changes of surface strain, applying digital image correlation. Examples for bands of types A and B are observed and discussed with respect to the micro-mechanisms of their nucleation and propagation, emphasizing local stress concentrations in addition to the well-known effects of dynamic strain aging and dislocation interactions for explaining the PLC behavior. Finally the nucleation and propagation of PLC bands are simulated by computations based on a simple constitutive model.     

ONE UNIVERSITY ONE VILLAGE PROGRAM: PROMOTING ENDOGENOUS DEVELOPMENT IN RURAL AREAS THROUGH LOCAL PRACTICE

This interview is centered on the practice of earth architecture in rural West China, starting from introducing the post-earthquake reconstruction project in Guangming Village, Yunnan Province, as an outstanding example of the practice of the “One University, One Village” Rural Sustainable Development Assistance Program. Li Wan, the interviewee, explains the differences of design consideration and the difficulties in practicing earth architecture throughout China, while giving her prospect on its future application. Through a further introduction on the operation and project procedure of the Program by Wan and her team, the interviewee addresses that architects should take their responsibilities on solving social issues, with a hope that, through their site-based efforts, the Program could provide a global paradigm to similar earth architecture practices in other regions, rousing designers’ awareness of localization.     

绝对定位机制下目标位置估计辅助的群机器人搜索

基于扩展微粒群算法模型控制群机器人协同搜索目标时,成员机器人在社会经验和自身认知,主要是社会经验引导下逐步向目标趋近.由于社会经验仅从成员机器人的认知中“选举”产生,未形式化地融合多个机器人的经验,因此文中从群机器人通信子系统在本质上属于无线传感器网络的事实出发,引入集体决策机制,改进社会经验的生成模式.用无线传感器网络中的测距定位方法来估计目标位置,并将估计值作为社会经验引入现有模型.仿真结果表明,当群体规模够大时,采用文中社会经验生成模式可使协同搜索速度得到提高.     

基于无线传感网的海洋监测节点定位算法

针对应用于海洋监测的无线传感器网络,提出了一种基于蒙特卡罗算法的节点定位算法。该算法根据海洋中洋流在某一时间段内线性运动的特性,通过引入符合海水运动规律的角度来提高节点在位置预测阶段的精度;并根据节点感知压力的大小来确定预测坐标的置信度,以对预测坐标进行修正,进而得到最终的预测结果。仿真结果表明,该算法比传统的定位方法在不同的锚节点密度、节点密度、节点运动速度和时间等条件下都表现出更好的性能。     

基于视觉FastSLAM的移动机器人自主探索方法*

针对室内环境下机器人的移动和定位需要,提出基于视觉FastSLAM的移动机器人自主探索方法.该方法综合考虑信息增益和路径距离,基于边界选取探索位置并规划路径,最大化机器人的自主探索效率,确保探索任务的完整实现.在FastSLAM 2.0的基础上,利用视觉作为观测手段,有效融合全景扫描和地标跟踪方法,提高数据观测效率,并且引入地标视觉特征增强数据关联估计,完成定位和地图绘制.实验表明,文中方法能正确选取最优探索位置并合理规划路径,完成探索任务,并且定位精度和地图绘制精度较高,鲁棒性较好.     

基于最优信标节点的无线传感器网络质心定位算法

针对无线传感器网络(WSN)质心定位(CL)算法精度不高的问题,提出了一种基于最优信标节点的质心定位(OBCL)算法.OBCL算法采用了4个移动信标节点,首先,对移动信标节点的路径进行规划;然后,未知节点根据集合偏移度(SDD)从候选信标节点集合中选出最优信标节点来进行位置估计;其次,为了解决信标节点不足导致无法定位的问题,引入角色转变机制,未知节点在完成定位之后成为准信标节点来进行辅助定位;最后,为了保证网络中所有节点能够完成定位,在完成初次定位之后,需要进行重定位过程.仿真实验结果表明,与CL、基于加权的质心定位(WCL)、利用接收信号强度加权的质心定位(RR-WCL)这3种算法相比,OBCL算法的平均定位误差分别降低了67.7%、39.2%、24.4%.由于OBCL算法只需要4个移动信标节点就能达到较好的定位效果,因此适合应用于对网络成本低、定位精度要求高的场景.