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关键词： 射频识别   室内定位   地下停车场   近邻标签   参考标签  

摘要： 随着时代的进步,国内汽车保有量持续增长,导致停车位越来越紧张。为满足人们生活需要,地下停车场也越建越多。然而,由于其复杂结构、以及车主对路线不熟悉,导致许多车主都面临着“停车难、寻车难”等一系列问题,这些问题严重影响了地下停车场的使用率和体验感。同时,由于GPS、北斗等信号在地下停车场中易被干扰或丢失,无法满足人们对定位精度的需要,所以迫切需要一种高精度室内定位方法来定位车辆。RFID技术凭其低成本、高精度等优点成为室内定位技术中的热门技术。本文主要针对基于RFID的地下停车场定位技术进行研究,其主要工作内容如下:1)针对在参考标签网格化部署场景下的静态定位问题,提出一种基于观测源加权的三边定位改进算法(Trilateral Localization Algorithm based on Observation Source Weighting,TLOW);该算法在三边定位算法和三边质心加权定位算法对待测标签进行粗定位的基础上,引入观测源RFID阅读器,通过观测源对粗定位结果进行距离检测,并与观测源自身到待测标签的距离进行校验,赋予粗定位结果相应的差值可信度权值进行精确定位。通过实验证明,TLOW算法同三边定位算法相比定位精度提升26.18%,系统稳定性提升38.45%。2)针对在参考标签稀疏且不规则部署场景下的静态定位问题,提出了一种基于RFID虚拟标签的改进算法(Location Algorithm based on Virtual Tag,LAVT);LAVT算法是一种基于LANDMARC算法的定位技术,它通过采用外心的方式插入虚拟标签,逐步缩小待测标签近邻区域的面积,使得近邻标签更靠近待测标签,从而提高定位精度;此外,LAVT算法提出采用二阶Lagrange插值方法估计虚拟标签的RSSI。仿真实验证明,LAVT算法的定位精度较LANDMARC提升了19.03%。3)针对待测目标移动场景下的动态定位问题,提出一种基于角度的移动轨迹定位算法(Algorithm of Moving Trajectory Tracking and Location Based on Angle,MTTA);该算法在角度定位算法的基础上,提出一种参考标签与天线阵列组合的优化布局方式;并采用卡尔曼滤波对待测区域中标签信号过滤,根据RSSI差值的方法得出动态近邻标签,进而通过与该动态近邻标签相关联的天线,对移动车辆测量角度,最后测出移动车辆的轨迹。仿真实验证明,MTTA算法对移动车辆的定位精度相对EKF＿WSN和EKF＿WSL算法分别提升了68.08%,42.26%。通过实验证明本文所提三种算法在不同应用环境下都能够有效提升RFID定位系统的定位精度,在地下停车场中具有较好的适用性。

关键词： 无人仓库   RFID定位   任务分配   路径规划   冲突消解  

摘要： 随着物流行业的不断发展和快递业务量的持续增长,传统的仓储物流方式已经不能满足日益增长的订单量和消费者对物流速度和准确性的要求;与此同时,机器人等自动化技术和物联网的发展使得物流企业可以实现仓储物流的自动化和无人化,在此背景下无人仓库应运而生。本文以无人仓库为背景,针对机器人拣货过程中货物定位、任务分配和路径规划等问题进行研究,具体研究内容包括: 首先,分析无人仓库的特点和需求,研究了适用于无人仓库的机器人拣货模式和拣货流程,进而给出了机器人拣货系统的构成和场景布局。 其次,基于RFID技术实现了货物的定位。研究了传统的LANDMARC定位系统和算法,建立三维模型,在MATLAB平台进行定位仿真,分析了算法参数对定位精度的影响;提出了基于RSSI值优化的LANDMARC定位方法,针对RSSI值在定位中起到的关键作用,使用了卡尔曼滤波算法对RSSI值进行优化处理,通过MATLAB仿真结果对比,验证了优化后的LANDAMARC定位算法定位精度更高。 第三,在货物位置定位的基础上,对拣货机器人进行拣货任务分配的研究。针对多机器人拣货任务分配问题,建立多机器人拣货任务分配的数学模型,明确了总拣货距离最小的目标函数;在求解计算时,针对传统粒子群算法容易陷入局部最优等问题,引入了遗传算法的交叉和变异思想,设计新的变异算子,使得粒子能够在整个空间进行搜索;在MATLAB平台上进行仿真对比,结果表明本文提出的粒子群-遗传算法相较于传统的粒子群算法和遗传算法,具有更好的寻优效果。 第四,在拣货任务分配的基础上,对机器人拣货路径规划问题进行研究。针对单个机器人路径规划问题的求解计算中,对传统的A*算法进行改进,在A*算法的代价函数中添加了转弯代价的同时,为启发函数增加了动态调节的权重,以减少规划路径的转弯次数并提高搜索效率,并在MATLAB平台通过不同规模的案例仿真验证了改进算法的有效性;针对多机器路径规划中可能出现的冲突问题,使用了时间窗模型,利用机器人的时间窗重叠情况判断冲突,结合机器人的优先级,对机器人进行路径重规划,通过仿真验证了冲突消解策略的有效性。 最后,针对无人仓库多机器人拣货案例,使用本文提出的方法在MATLAB平台进行仿真应用,结果显示本文的研究方法可以有效地实现在机器人拣货时的货物定位、拣货任务的合理分配,以及拣货机器人的路径规划。

关键词： Backscatter   chipless tag   code density   electromagnetic devices   frequency domain   passive RFID tags   radar cross-section (RCS)   radio frequency identification (RFID)  

摘要： In this article, a compact chipless RFID tag with a small size and high data density is proposed. The tag consists of nested octagonal loops arranged in a concentric configuration. Each two neighboring resonating elements are decentrally coupled by two connector lines at obverse sides. The small size of the tag is achieved through embedding multiple octagonal elements in a nested arrangement, which share the same side, and through connecting the neighboring elements. The tag configuration is designed and optimized to improve the resonating modes with respect to the number of resonating elements. The number of generated resonating modes (N) is mathematically obtained by N=2n-1, such (n) is the resonating elements number. An 11-bits data capacity is presented in the proposed tag within a physical dimension of 10 x 10 mm(2), resulting high data density of 11 b/cm(2). The proposed tag is realized on Rogers RT/Duroid 5880 substrate having substrate height h=0.508 mm, relative permittivity epsilon(r) = 2.2, and loss tangent d = 0.0009. The proposed tag is designed and simulated using CST Studio Suite (R). The tag's performance is initially evaluated through simulation and analyzed for effectiveness. The tag is then fabricated and measured, and the results are compared to ensure agreement between simulation and measurement. The tag advantages are compact size, high data density, and improved resonating modes. The operating frequency range of the proposed tag is 7.5 GHz-15 GHz.

关键词： Internet of things  

摘要： The wired communication between the fixed reader and database in traditional RFID systems is considered a safe channel. However, the mobile reader and the database communicate wirelessly in mobile RFID systems, so the channel is no longer safe and reliable. Therefore, the traditional RFID authentication protocol cannot be applied to mobile RFID systems. An ultra-lightweight mobile-wireless bidirectional authentication protocol MAP-SKBO based on a shared private key and bitwise operation, is proposed to solve this problem. MAP-SKBO is based on the bitwise operation mechanism, which adopts ultra-lightweight bit replacement and self-combined cross-bit operation to encrypt the transmitted information and uses random numbers to maintain the transmission information’s freshness and the shared information private key. During the communication process, the tag, the reader, and the database authenticate each other to resist sabotage by an attacker. Security analysis shows that MAP-SKBO can achieve tasks such as the dynamic update of the shared private key and desynchronization-attack resistance. The formal mathematical reasoning of MAP-SKBO by GNY logic proves the correctness of MAP-SKBO. A performance analysis indicates that MAP-SKBO has low computational complexity and is suitable for low-cost mobile RFID systems. © 2022,International Journal of Network Security. All Rights Reserved.

关键词： RFIDs   ASK modulator   CMOS   Current reuse VCO   Injection locking  

摘要： 射频识别(Radio Frequency Identification,RFID)是当今一种无处不在的技术,其众多应用造福于世界各地的人类生活。不同应用的RFID对电路架构的要求不一样,例如高数据速率的RFID标签和读写器。传统的无源超高频(Ultra-high frequency,UHF)读写器一般工作在900MHz和2.4GHz频段,采用无源反向散射技术进行设计。本文提出了一种低功耗、高数据速率的ASK调制器电路,用于工作在10.5 GHz和24 GHz频段的RFID标签。调制器的设计基于有源电路并利用VCO来产生载波。本文首先设计了采用电流复用型压控振荡器(VCO)设计有源低功率和高数据速率ASK调制器,该调制器可以被用于自供电的RFID标签中。与传统的交叉耦合VCO相比,电流复用型VCO具有较低的功耗和相位噪声。该调制器基于GF130nm CMOS工艺,工作频率为10.5 GHz,其直流功耗为864 μW,供电电压为1.2V,平均电流为720μA,能够以40Mbps的速率进行通信。由于交叉耦合PMOS-NMOS晶体管对的堆叠串联结构,电流复用型VCO相比于基于NMOS-NMOS或PMOS-PMOS的传统交叉耦合对型VCO,仅消耗一半的平均电流和更少的功率。为了预测本调制器在最差PVT场景下的性能,基于蒙特卡罗法对工艺角的影响进行了仿真,仿真版图面积为0.5 × 0.5 mm2。其次设计了一种基于动态体偏置技术的低功率低相噪电流复用型VCO,从而实现用于RFID标签的ASK调制器。本文使用深N阱NMOS晶体管代替普通的NMOS晶体管用于交叉耦合对的设计,用于施加偏置信号,深N阱隔离衬底并避免了通过衬底的电流路径。该设计使用了这样一种规则,即如果NMOS晶体管的衬底端口处于比其源极端口更高的电势区中,晶体管的阈值电压会降低,反之亦然。该技术与注入锁定技术和电流复用技术同时使用外,降低了调制器的功耗。该电路整体功耗为790 μW,电源电压为1.1 V,该振荡器在偏移频率为1 MHz的相位噪声为-106dBc/Hz。该调制器可以产生20 Mbps的ASK调幅信号。最后本文设计了一种工作在24 GHz ISM波段具有超低功耗的ASK调制器,该调制器采用了基于交叉耦合VCO的LC偏置网络。该偏置网络实现了两个目标:首先,它给交叉耦合网络中的晶体管提供阈值电压,而与电源电压无关。这可以对流过VCO电路的电流进行的控制,并达到最小的功耗。第二,充当阻抗变换电路,与使用GF 130 nm CMOS工艺设计的传统差分型VCO相比,可以产生更高的谐振频率。该ASK调制器的版图尺寸为0.46 × 0.7 mm2。在版图后仿真结果中,直流供电电压为300 mV时得到了 490 μW的功耗。以上设计可作为反向散射技术的信号源源,为低功耗RFID调制器的设计提供了解决方案。本论文采用不同的电流复用技术对传统的VCO进行了改进,实现了电源效率的提升。此外,短距离无线通信技术在现代的挑战和机遇需要不同频段的电路设计方案,使RFID标签具有自供电功能,以提高其可用性。

关键词： RFID   读写器天线   近场   三维均匀   可扩展  

摘要： RFID是一种通过电磁波自动采集物品信息的技术,其非接触性、快速高效识别的特点在信息化时代得到了广泛的应用。在智能书架、药品管理等许多应用场景中,读写器天线需要近距离读取物品信息,此时传统的远场RFID系统已不再适用。为了解决这一问题,学者们提出近场RFID系统,在该系统中读写器天线在近场区域内有均匀的场分布,区域外场强迅速衰减。对于电耦合读写器天线来说,近场区内电场三维分量均匀分布可以保证任意方向的标签不会出现漏读现象,同时通过调整天线单元结构数量实现不同的场均匀分布范围来满足不用应用场景需求是一个大的挑战。本文从该角度出发,设计电场三维分量均匀且具有可扩展特性的近场读写器天线。首先,提出一款多层结构可重构的读写器天线。该天线通过两层微带线结构的分时工作,在可控区域内实现电场三维分量的均匀分布。对微带线结构不同辐射单元数目下电场分量的仿真证实了该天线的可扩展性。仿真结果显示该天线远场最大增益为-5.6dBi,测试结果显示其在0.85-0.96GHz带宽内反射系数小于-l0dB,标签100%读取率的读取体积为240mm×200mm×150mm。其次,提出一款垂直于天线表面电场均匀度改善的多层结构可重构读写器天线。该天线通过四条呈中心对称分布的弯折微带线来改善上一款天线垂直于天线表面的电场均匀度。其同样可以通过调整微带结构辐射单元数目实现不同场景下读取范围需求。仿真结果显示该天线远场最大增益为-8.6dBi,垂直于天线表面的电场场强最大波动幅度大约为改进前天线的1/6倍。测试结果显示该天线在0.83-0.93GHz带宽内反射系数小于-10dB,标签100%读取率的读取体积为360mm×400mm ×200mm,平行于天线表面的读取范围为改进前天线的3倍,读取高度比改进前天线高50mm。最后,提出一款基于PIN二极管可重构的读写器天线。该天线在微带结构上加载了 8个PIN二极管,通过直流偏置电路控制二极管的工作状态实现电场三维分量的均匀分布。该天线结构同样具有可扩展特性。仿真结果显示该天线远场最大增益为-5dBi,测试结果显示其在0.92-0.93GHz带宽内反射系数小于-10dB,标签100%读取率的读取体积为840mm×840mm×250mm,平行于天线表面的读取范围是前面所提出天线的4.9倍,读取高度比前面所提出天线高50mm。

关键词： Radiofrequency identification   Sensors   Market research   Food industry   Bibliometrics   Industries   Temperature measurement   Edible   food   green   NFC   radiofrequency identification   smart packaging  

摘要： The emerging fourth industrial revolution is revolutionizing the food industry, which has historically been plagued by food waste and contamination. Several Internet-of-Things (IoT) technologies have been proposed for optimizing processes and reducing costs while improving health conditions and safety in food consumption. Among them, radiofrequency identification (RFID) has been considered from the beginning a key instrument, especially in food logistics and management. Many contributions and case studies from academia and industry demonstrated the strategic role and the impact on existing and future paradigms of food. The literature analysis in the present work suggests a growing interest in RFID to implement optimization procedures for food management and control. This review describes RFID employment in three pillars of the Fourth Generation of the Food Industry (FI4.0): Logistics, Sensing, and Green RFID. The logistics one comprises the most mature applications for RFID, such as cold-chain monitoring or product tracking. Food sensing, instead, is currently the most attractive research area for both industry and academia, so researchers are focusing their attention on detecting physical and chemical parameters through direct and indirect sensing approaches. Furthermore, the ever-increasing amount of electronic waste motivated the research community to provide sustainable tags to establish Green RFID devices. According to this literature review, RFID can foster the fourth industrial revolution in food, especially considering the emerging synergy with artificial intelligence and biodegradable/resorbable materials.

关键词： Crack detection   UHF RFID   ML   mining structural health monitoring (SHM)   moving conveyor belt  

摘要： The mining conveyor belt is an imperative component of the mine industry which serves the crucial role of transporting materials. Predicament such as conveyor belt cracks has to be avoided, because any potential cause of conveyor belt failure constitutes risk of fatalities and significant economic implications. Hence, a new crack detection method is developed which can duly alert prior to any inception of failure. The research incorporates an interdigital capacitor (IC) based Ultra High Frequency (UHF) radio frequency identification (RFID) tag as sensor and Machine Learning (ML) to monitor the formation of cracks. This is done by collecting data from the UHF sensor when it is placed on a conveyor belt. Two states of the conveyor belt are investigated - stationary and a travelling belt moving at speeds between 1-5 m/s. For the case of motion, it is successfully replicated with the help of an electrical treadmill. By using ML integration, the outcomes will be more effective in tracking crack features. The model is tested with different types of inputs, followed by classification based on experimental data. This method results in a very accurate determination of cracks, crack orientation and width. The experimental model is 97.2% accurate in identifying the presence of cracks and 93.9% accurate in detecting their orientation;it can also determine half a millimetre-wide crack width with 97% of accuracy. This detection system is extremely accurate, even when there is movement. The achieved detection rate of 99.4% depicts the effectiveness of the model performance by successfully combating the interferences caused by motion. This research is intended to be a stepping stone towards an efficient remote health monitoring (HM) system suitable for the smart future.