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关键词： RFID   Arduino   ID   access control   car parking   tag  

摘要： This article intends to present the construction and operation of a scale model of a car parking whose access control system is based on RFID (Radio Frequency Identification). Centred around the control access system and the functioning of RFID components, this paper does not go into detail about other aspects of car parking and seeks to simplify them as much as possible. RFID (radio frequency identification) is a type of wireless communication that includes the use of electromagnetic or electrostatic coupling in the radio frequency portion of the electromagnetic spectrum to uniquely identify an object, animal or person. We believe that understanding the access control system can later help an authorized person to implement it in any real parking system, the differences being given by the number of parking spaces, access/exit gates, complexity, layout, etc. The model is composed of an Arduino Nano 3.0 board and other Arduino components. These modules are controlled by a code written in Arduino IDE language. The proposed system aims to create an easy to use and easy to implement paid card car parking and featuring 4 parking spots with IR sensors and 2 gates, one gate for entrance and one gate for exit. Each gate has its own RFID control access plus one card/tag recharging simulated machine.

关键词： Antenna arrays   Radiofrequency identification   Spirals   Dipole antennas   Antenna measurements   Power dividers   Phased arrays   Antenna array   circular polarization   patternreconfigurable antenna   RFID read antenna  

摘要： A low-cost, pattern-reconfigurable, circularly polarized, high-gain, radio-frequency identification (RFID) reader antenna array is presented. It is a 2 x 2 array whose elements are based on an innovative Archimedean spiral design. A 4-way power divider feed network with switchable delay lines is designed that enables reconfiguring the radiation patterns of the array. Because of its high realized gain and nine reconfigurable states, the developed reader antenna can be applied in long-distance, wide-coverage RFID inventorying. The fabricated prototype, with dimensions 1.15 x 1.15 x 0.07 lambda(3)(L) at 920 MHz, achieves a measured axial-ratio (AR) fractional bandwidth of 4.6%, and a peak realized gain (RG) of 10.5 dBic (12 dBic without the feed network). The RG of its reconfigurable patterns is greater than 6 dBic within theta = 0(degrees)+/- 45(degrees) for all azimuth angles. It was also tested in an outdoor range as the reader antenna for a practical RFID system. The maximum read distance was 22.3 m.

关键词： Autonomous robot   retail robot   UHF-RFID robot   RFID rotating antenna   smart inventory   SLAM   tagged item traceability   tag localization  

摘要： This paper presents the development and testing of a robot designed for automated inventory and 3D localization of items in high-density shelving systems. To enhance accuracy in locating UHF-RFID tagged objects by using synthetic aperture-based methods, rotating antennas are installed on the robot. This allows more degrees of freedom in antenna trajectory, by reaching large synthetic apertures that may deliver high-performance localization. The robot can navigate complex environments by utilizing a depth camera and a visual odometry system, and it can effectively avoid obstacles with the help of a Laser Imaging Detection And Ranging system. Extensive testing is conducted in a realistic shop-like scenario where tagged products are placed on either wooden shelves or hung on metal racks. The robot navigation capabilities are verified together with its inventory and localization performance for different visibility conditions of the tagged items.

关键词： Ultra-high frequency   RFID electronic tags   front end circuit   true random number generator   Ultra-high frequency   RFID electronic tags   front end circuit   true random number generator  

摘要： Among various wireless communication methods, the ultra-high frequency (UHF) passive Radio Frequency Identification (RFID) electronic tags are widely used due to their ability to transfer information without internal power supply. In this study, a low-power UHF passive RFID tag front-end with a novel structure including a true random number generator is designed and fabricated in standard 180nm CMOS technology. The proposed front-end circuit includes an analog front-end, an RF front-end, and an impedance matching network. The received RF energy is impedance-matched to the analog front-end, generating a power supply voltage for the RF front-end. The RF front-end performs signal demodulation and generates a reference clock. A novel true random number generator (TRNG) is designed in the proposed RF front-end to achieve signal anti-collision functionality. The experimental results indicate that the total power consumption of the RFID tag front-end is 8.67 mu W, and the TRNG circuit can produce a series of random number with 85.5% of credibility, which effectively improves the randomness of the communication keys.

关键词： RFID   SRR   偶极子天线   机器学习   遗传算法   优化设计  

摘要： 射频识别(Radio Frequency Identification,RFID)作为物联网产业中的关键技术之一,是一种通过电磁波以非接触方式对目标信息进行自动识别的技术,其在诸多领域都具有广阔的应用前景。RFID标签天线是RFID系统的一个基本组成单元,因而标签的性能对RFID系统的整体性能有着显著的影响。为此,围绕实际工程应用需求,本文开展了宽带高增益RFID标签天线的研究与设计工作,主要的内容如下: 1.基于开环谐振器(Split Ring Resonator,SRR)的RFID天线设计。根据SRR结构谐振的产生机理,分析了 SRR内外环的半径和开口宽度等结构参数对天线性能的影响,并通过SRR内外环之间的相互耦合,在谐振点处实现了与偶极子天线类似的全向辐射特性。进而,设计了一款基于SRR的小型化RFID标签天线,仿真结果表明,该天线在中心谐振频率915MHz处具有110MHz的带宽,增益可达-1.3dB,且所具有的全向辐射特性能较好地满足诸多实际应用需求,但相较于偶极子天线,其增益并不占优势。 2.弯折型偶极子RFID标签天线的设计。以偶极子作为基础结构,采用弯折线技术来实现标签天线的小型化,分析了对于谐振频率和输入阻抗影响较大的结构参数。而后,通过分析和优化不同的耦合结构,实现了标签天线与标签芯片之间的良好阻抗匹配,并以此为基础设计了多款加载耦合结构的弯折型偶极子RFID标签天线。最后,选择综合性能最优的设计进行实物制作,该款弯折型偶极子标签天线中心频率同样为915MHz,带宽为90MHz,天线的增益可达2.3dB,尺寸仅为25×52×1.6mm3,辐射方向图具有良好的全向性,且对比文献中已报道的偶极子RFID天线,其在增益及尺寸方面都更有优势。由于加工误差的存在,最后实测得到的工作频点为910MHz,该频点处标签的最大增益为1.8dB,同时在全方向上都有着较好的阅读距离,最大阅读距离为11.5m。 3.基于机器学习的RFID标签天线设计方法研究。第一部分是正向设计,首先以对标签天线性能影响最大的结构参数(即天线末端展宽的宽度W和高度H)作为输入,天线的带宽作为输出,建立神经网络正向预测模型;然后,外接遗传优化算法(Genetic Algorithm,GA),将天线的带宽作为优化的目标函数,寻找其最大值;所得结果显示:通过基于机器学习模型的正向优化,可实现124MHz的工作带宽,并且与利用全波仿真软件的优化方法相比极大地节省了时间。第二部分是逆向设计,与正向设计方法不同,逆向设计是将期望的天线的带宽作为神经网络的输入,对应的天线结构参数W和H作为输出;这里通过将正向设计所得到的带宽作为期望输入,利用训练好的逆向设计网络给出对应天线的结构参数;仿真验证显示:逆向设计网络能够较为精确地预测出期望的天线结构,这初步验证了逆向设计的可行性。

关键词： 射频识别   信息收集   目标标签   时间高效  

摘要： 随着RFID技术的不断发展和应用规模的扩大,传统的信息收集协议已无法满足一些高实时性应用的需求。例如,在冷藏仓库管理系统中,需要实时读取带有传感器的标签所收集的数据。然而,仓库中的普通标签也有可能响应阅读器的指令,与带传感器标签发送的信号产生冲突,影响阅读器对带传感器标签信息的收集效率。因此,如何高效地收集目标标签的信息成为一个具有挑战性的问题。为了满足小规模单阅读器RFID系统和大规模多阅读器RFID系统对目标标签信息收集的需求,本文通过对PIC协议和BIC协议的改进,提出了两种目标标签信息收集协议,以提高目标标签信息的收集效率并适应不同规模应用的需求。主要内容如下: (1)针对现有单阅读器目标标签信息收集协议中,存在单比特分配向量的分配效率低和轮询非目标标签ID导致数据发送量大的问题,提出一种增强型基于完美哈希的信息收集协议(E-PIC)。在原有协议的分配阶段中,通过构造双比特分配向量,使阅读器每轮广播的分配向量都能为更多目标标签安排在收集阶段的响应顺序,防止收集目标标签信息时发生冲突,同时停用部分非目标标签,减少后续阶段的时间开销。在轮询阶段,阅读器首先找出未被最小完美哈希过滤器停用的非目标标签,通过广播相邻两个非目标标签所在时隙索引的差值,以及下一个时隙中目标标签的确认值,停用分配到该时隙的非目标标签。相较于发送非目标标签的96位ID,发送间隔与确认值所需要的时间更少。仿真结果显示,比起现有的PIC协议,所提出的方法能降低3%的执行时间。 (2)针对现有多阅读器目标标签信息收集协议中,由于无法快速确认阅读器本地标签ID而导致时隙利用率低的问题,或因收集少量非目标标签信息产生额外时间开销的问题,提出了一种基于本地标签应答的布隆-完美哈希信息收集协议(BPIC)。阅读器通过接收本地标签的应答信号,并根据信道内的载波情况,构造一个布隆过滤器,用于确定位于其信号范围内所有标签的ID,防止因频繁查询非本地标签而出现大量空时隙,提高时隙利用率。然后,通过E-PIC协议为所有本地标签中的目标标签安排唯一的响应顺序,并停用所有非目标标签,以提高本地目标标签信息的收集效率。仿真结果显示,相较于现有E-TIC与Loc P协议,所提出的方法能减少10%以上的执行时间。

关键词： Energy harvesting  

摘要： We propose a new dual-band passive RFID tag antenna design by combining a rectangular spiral coil and patch-meander-line dipole with an interconnected structure. This design enables operation in high-frequency (HF) and ultra-high-frequency (UHF) RFID systems, suitable for energy harvesting and tracking applications. The simulations by the CST full-wave software demonstrate conjugate impedance matching between the tag antenna and two RFID tag chips. At 13.56 MHz (HF), the tag antenna exhibits an inductive reactance of 422.79 Ω, while at 922.5 MHz (UHF), it presents an impedance of 9 41 + j174 96 Ω. The antenna generates a maximum magnetic field intensity of 0.5 A/m and omnidirectional electromagnetic fields with an antenna realized gain of -4.26 dBi at 922.5 MHz. We also analyze the impact of the tag antenna combination using numerical software. Furthermore, we fabricate a prototype tag antenna and validate its performance with RFID readers. The proposed tag antenna achieves the maximum read ranges of 11 cm and 6.9 m for the HF (13.56 MHz) and UHF (920-925 MHz) bands, respectively, accompanied by the energy harvesting of 1.48 volts at the HF band by the coupling magnetic field received by the HF antenna to the chip ST25DV04K at the output voltage pin. © 2024 Supakit Kawdungta et al.