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关键词： 山地果园   单轨运输机   控制系统   射频识别   远距离通信  

摘要： 我国果树的种植规模在世界前列。但是，南方常绿果园主要种植在丘陵山区，果品和农资物料的运输作业目前仍主要以人力为主，工作效率低、劳动强度大，人力成本逐年增大。单轨运输机具有安装结构简单、轨道铺设灵活、转弯半径小等特点，是山地果园机械化生产运输的重要方式。针对山地果园地势起伏多变，树冠密闭且遮挡严重等作业环境因素导致操作人员难以实时操控单轨运输机进行精准作业的问题，本文设计了单轨运输机作业状态感知与通信控制系统，通过综合应用射频识别技术（RFID）和远距离通信技术（LoRa）实现对运输机的运行状态精准感知和作业模式可靠控制，进而提升果园运输装备的安全性和精确性。　　单轨运输机作业状态感知与通信控制系统以STM32单片机为核心控制器，主要包括高频RFID测速定位模块和LoRa通信控制模块两部分。其中，高频RFID测速定位模块应用双阅读器读取基准定位标签组的时间差，基于混合测速定位方法实时计算运输机的在轨作业状态;LoRa通信控制模块负责将状态信息远程传输至上位机，并通过接收上位机控制信号实现对运输机作业的远程可靠操控。本文依次对系统的核心控制板和各个硬件模块，以及移动端和PC端上位机监测控制软件进行了设计，实现了硬件、软件相结合的单轨运输机作业控制系统。　　本文搭建了单轨运输机作业测试平台，并依次开展了运输机定位、通信等试验。单轨运输机定位试验结果表明，高频RFID测速定位在基准定位标签间距为车长（D=3.42m）时，其对单轨运输机定位误差≤6.17cm;与大疆Air2无人机GNSS定位相比，定位误差降低了72.93cm。单轨运输机通信试验结果表明，与ZigBee无线通信相比，LoRa无线通信具有更可靠的通信性能;当配置LoRa模块空中速率为2.4kbps、发射功率为30dBm时，在果园环境下点对点可靠通信距离不小于600m。基于作业测试平台的试验结果验证了本文设计的系统能够实现对单轨运输机作业状态的精准感知与实时控制，具有较好的可行性和精准性，研究工作为果园运输装备的高效智能控制提供了技术积累。

关键词： Antennas   MIMO communication   Ultra wideband antennas   Antenna radiation patterns   Gain   Reflector antennas   Transmitting antennas   UWB   MIMO   isolation   RFID   ECC  

摘要： An 8-element Multiple Input Multiple Output (MIMO) antenna is implemented for Chipless-RFID Tags (CRT) that function in the Ultra-Wideband (UWB) frequency range. The single UWB antenna contains a rectangular radiator in which two ellipses are cut from the two lower corners. Also, two circles are etched from the upper corners of the ground. This antenna is designed by placing eight antenna elements at 45 degrees direction (clockwise and anticlockwise) and a thin line-shaped decoupling structure is used to enhance isolation at lower frequencies. Also, a T-shaped structure is used to enhance the notched band characteristics. The working frequency of the antenna is from 3.5 GHz to 10.5 GHz with WiMAX and WLAN notched bands using U-slot and Split Ring Resonator (SSR) metamaterial, respectively. The antenna obtains a peak gain of 5 dB (single element). This antenna has radiation efficiency from 76.4% to 92.7%. This antenna design will inspire the designers of chipless RFID (CRFID) to produce low-cost tags.

关键词： Resonant frequency   Resonators   Iterative methods   Radiofrequency identification   Tuning   Encoding   Time-frequency analysis   Frequency response   SIgnal detection   Frequency response   radiofrequency identification   resonator   robustness   signal detection  

摘要： Earlier studies have improved the data capacity of frequency-coded chipless radiofrequency identification (RFID) to 100 bits, but these high-density tags may suffer from two limitations, including the design complexity for billions of tags and an additional procedure for measuring clutter. In this paper, a calibration-free chipless RFID system with 20.7-bit capacity is proposed;moreover, the design of the 1.68 million tags is highly efficient, preventing individual and iterative optimization for such large numbers of configurations. These distinct features are obtained by integrating the signal processing of reader and the resonance synthesis of tags. The signal processing employs short-time Fourier transform (STFT) and enhanced filtering to achieve calibration-free detection. The resonance synthesis features minimized numbers of geometric parameters, reduced mutual coupling between resonators, and response surface models for the resonant frequency to realize noniterative optimization. The proposed system is validated by three approaches. First, residual plots indicate that the range of residuals is confined to the average bandwidth of frequency slots. Second, 36 IDs are sampled and automatically transformed into chipless tags. The measured reliability of four bands is as high as 100%, 95.0%, 98.3%, and 93.9%, respectively. Finally, the parameterization of signal processing is validated by time-frequency analysis and reliability.

关键词： 智能门禁系统   人脸识别   反向射频   同向追踪  

摘要： 提出了基于RFID的通信方法，通过在连接平面上垂直部署大规模被动标签，用于智能感知访问控制事件，本文利用计算机视觉和智能门禁感知模块解决了不同环境中系统识别精度的问题更能充分研究访问控制事件与接收到的射频信号之间的相关性。为了降低环境的干扰，文章利用大矩阵对标签进行部署；同时，为了消除不同方向对智能系统感知识别产生的较大影响，采用同向转换模块使系统的识别精度得以提高。最后，为了评估RFID在真实环境中的性能，文章建立了能提取时空特征的深度学习模型，便于智能门禁系统能更精确的识别控制，实验结果表明智能门禁系统能够实现最佳的感知识别。

关键词： Radiofrequency identification   Radio frequency   Three-dimensional displays   Radar tracking   Sensors   Data models   Training   3D human pose tracking   few-shot fine-tuning   generalization   meta-learning   RFID sensing  

摘要： With the development of Radio-Frequency (RF) sensing techniques, RF based 3D human pose estimation has attracted increasing interest recently. Unlike video camera based techniques, RF sensing has the unique strength of preserving user privacy. However, due to the complex wireless channels indoors, a well-trained RF sensing system is usually hard to generalize to new environments. In this paper, we propose an environment adaptive solution for Radio-Frequency Identification (RFID) based 3D human skeleton tracking systems. We first analyze the challenges in environment adaptation for RFID based sensing systems. Following the analysis, we then propose a meta-learning approach for RFID-based 3D human pose tracking, termed Meta-Pose. The system is implemented with off-the-shelf RFID devices and can well adapt to new environments with few-shot fine-tuning, thus greatly simplifying the deployment of the trained system. We conduct extensive experiments in different indoor scenarios to validate the high adaptability and accuracy of the Meta-Pose system.

关键词： STM32   控制系统   生猪饲喂   RFID   最小二乘法  

摘要： 近年来,我国养殖业得到快速发展,生猪养殖方式逐渐从传统养殖转变为智慧数字养殖。生猪饲喂作为生猪养殖的关键一环,其装置的精准性受到国内外研究人员的广泛关注,且随着从事生猪养殖人员的减少,养殖设备的自动化、精准化、智能化变的更加重要。本文研究设计了一款基于STM32的生猪流食自动饲喂装置控制系统,主要包括以下研究内容:(1)根据猪舍特定环境和设计需要,确定了饲喂装置的总体设计参数,按照设计要求进行硬件选型,选择合适的核心处理器、电动球阀、光偶隔离开关、电动推杆、存储模块等,将各个模块与电路板进行整合,完成生猪饲喂装置控制系统的硬件部分设计。(2)核心选用STM32F103ZET6微处理器,辅以电动球阀、称重模块、RFID识别模块、电动推杆等完成精准下料设计,搭建基于阿里云的控制系统,通过无线模块完成装置数据上传、下发。饲养员可以在PC端和手机端对装置进行控制和监视,能够实时查看生猪采食信息,根据生成的生猪饲喂曲线,制定个性化饲喂方式,做到精准饲喂。(3)在Matlab软件上利用最小二乘法对下料时间与下料量进行函数拟合,对电动球阀开启时间内下料量、电动球阀完全开启时间内下料量、电动球阀关闭时间内下料量分段处理,将拟合后的函数进行程序编写,作为系统控制下料量函数。(4)选用Altium Designer20绘图软件对数据采集电路、下发控制电路、RFID耳标识别电路等电路进行设计,绘制PCB电路板,对装置中高频震荡电路采用包地处理防止对信号电路产生影响,保证系统的数据采集和云端控制的稳定性。在完成系统整体设计后,分别对系统下料精准性、RFID识别距离等进行试验,分析了系统的下料精准性和RFID的识别距离,优化下料量和下料时间的拟合函数。当系统在测试实验中满足生猪精准饲喂要求时,将装置在实际环境中进行了安装试用,结果表明:该下料系统的精准度较高,能够保证下料误差在7%之内,满足生猪精准饲喂要求;同时系统的可靠性较高,运行稳定,具有良好的应用前景。

关键词： 射频识别   虚拟无线电   RTX   实时性   读写器  

摘要： 软件无线电旨在满足通信系统应用的多样性。而早期的软件无线电仍然依靠ASIC、DSP、FPGA或者ARM等专业硬件平台来处理基带信号,不可避免地存在专业要求高、灵活性差、应用面狭窄等问题。但随着多核CPU的发展与集成电路的不断进步,虚拟无线电的强重构性和应用灵活的特点使软件无线电得以进入更加软件化的虚拟无线电时代。 本文首先分析了软件无线电的不足,结合RFID技术,经过对比得出基于Windows操作系统的虚拟无线电比基于Linux操作系统的虚拟无线电具有交互界面良好、应用程序丰富等更优越的特点,但其实时性不足,难以符合现代通信协议标准最低要求的短板成为制约基于Windows系统的虚拟无线电发展与应用的最大因素。针对此,本文采用了一套增强Windows操作系统实时性的技术——RTX。RTX在工业控制与测试中使用很广,本文通过Windows与RTX的结合,设计了一种基于RTX中断的双向通信系统虚拟无线电通用实现方案并给出了系统中主从设备发送与接收流程和相关处理方法。系统使用中断的方式实现硬件板卡与多核处理器间的时钟同步,从而提升整个通信系统的实时性和CPU使用效率。 整个读写器方案在系统仿真上,首先对ISO/IEC18000-6C协议做了相关的介绍,对标签识别层、指令、物理层以及物理链路作了概述和研究分析。其次,编写了链路的相关算法。在Matlab仿真平台上进行了上下行链路仿真,并验证了系统相关功能,通过分析对比,在不失真的前提下选择系统链路最佳参数和最优算法。 在系统实现方面,本文所搭建的基于RTX的RFID读写器系统平台,结合虚拟无线电技术,首先,在设计上,对软件实现做了相关研究和介绍,如在PC端用RTX验证实时性可以满足通信协议的要求、驱动程序设计和在标签识别层和基带信号处理上关键算法的设计与实现。在硬件上,对DMA、FPGA、射频前端等模块做了详细的设计与分析。其次,利用Matlab平台对上下行链路误帧率、长短前导同步性能、下采样倍数和单双路接受性能进行仿真,对比结果,逐步探索,确定出最佳的参数设置。最后在设计的平台上进行收发通路验证,确定测试的中心频率为902MHZ,通过比较接收端和发送端基带信号验证硬件系统性能。在硬件系统确定且保证性能的情况下进行最后的协议一致性测试。测试包括信号生成、测量、反馈等整个交互流程的完整功能测试,代表着对Tag的身份认证完成,验证了整个系统的可行性。

关键词： Badges   Cloners   Cyber security   Radio frequency identification   RFID   Software defined radio  

摘要： This thesis proposes a way of detecting when radio frequency identification (RFID) badge credentials are being captured through the use of software defined radio (SDR). A method for using SDR to detect when badge cloning technologies are in use on the premises is presented, tested, and analyzed. This thesis presents an overview of the problem with badge systems and a background literature review. Next, the proposed method of detection and its workings are presented. Then, the strategy for evaluating the methods performance. This is discussed by discussion and evaluation of the results. Finally, the thesis concludes with a discussion of the method’s potential benefits and proposed future work.

关键词： Strain   Capacitive sensors   RFID tags   Sensor phenomena and characterization   Microstrip antennas   Broadband antennas   Semiconductor device measurement   Chipless radio frequency identification (RFID)   data enhancement   microstrip notch circuit   multiparameter information fusion   strain sensing  

摘要： According to the current development situation, the application of chipless radio frequency identification (RFID) sensors in structural health monitoring has the disadvantages of difficult detection, poor effect, and single design function, limiting the further development of this technology. Therefore, a new type of RFID strain sensor that realizes the compact structure and separated function of miniaturized chipless RFID coded tags is proposed. The integrated disk monopole antennas make wireless measurement possible. Through the single-parameter strain simulation analysis, six characteristic parameters with good linearity are determined. The time sequences data enhancement algorithm and the background noise data enhancement algorithm are used to expand the training dataset. Then, the BP neural network is utilized for data fusion, and the training error finally converges to 0.0005. A comparison experiment between wired and wireless is designed, and the wireless experiment is optimized through wired experimentation. The results of wireless measurement experiments show that, combined with multiparameter information fusion technology, the average error between the proposed sensor and the actual strain is 6.04%, and the minimum error is 0.25%. The multiparameter fusion monitoring method of the strain sensor corrects the error of single-parameter measurement, and its accuracy and robustness are improved.