基于射频识别技术的考勤系统

目录摘要·········································································I目录·········································································II第一章RFID的介绍····························································11.1RFID技术特点·····························································21.2RFID系统的组成···························································31.3电子标签的内部结构························································41.3.1阅读器································································41.3.2天线···································································51.3.3中间件·································································61.4RFID系统工作原理························································71.5RFID与其他自动识别技术···················································81.5.1条形码技术······························································81.5.2磁卡识别技术····························································81.5.3生物识别技术····························································91.5.4RFID区别与其他自动识别技术的特点·······································91.6RFID的应用现状···························································10第二章需求分析······························································112.1系统开发目标·····························································112.2系统总体规划·····························································112.2.1用户特点·······························································112.2.2系统功能·······························································122.2.3系统UML建模···························································142.3可行性分析·······························································162.3.1技术可行性·····························································163.3.2经济可行性·····························································17第三章基于RFID的考勤系统设计的系统框图·····································183.1数据流程图·······························································193.1.1用户登录模块···························································213.1.2信息管理功能···························································223.1.3射频卡分配功能························································233.1.4员工出勤情况记录功能···················································243.1.5查询功能·······························································253.1.6数据库管理功能·························································253.2数据库概念设计···························································28第四章系统实施······························································304.1系统应用实例·····························································304.1.1考勤数据管理模块·······················································304.4.2排班管理模块···························································304.4.3加班请假管理模块·······················································31第五章总结··································································31摘要本文研究和设计了一种基于射频识别（RFID）技术的考勤系统。此系统是利用RFID技术随着计算机技术与网络技术的迅猛发展，考勤管理系统不断向着集成化、智能化网络化与分布式的方向发展。在各个企业中，企业员工的考勤工作不仅工作量大，而且时效性强。过去，企业多采用手工记录或打卡记录的方式进行管理，效率和透明度较差，并且也容易出错；随着射频识别技术的发展和企业信息化建设的进行，使用射频识别技术管理企业考勤工作也成为大势所趋，它为企业的考勤工作节约了第一章RFID的介绍1.1RFID技术特点RFID是RadioFrequencyIdentification的缩写，即射频识别，俗称电子标签。它是用无线射频方式进行非接触双向通信,以达到识别目的并交换数据的一项新技术。它主要与当今数字化商务相适应,可以实现自动识别和远程监控及管理。其通信距离范围可从几厘米到几十米,而且依据读写方式不同,可以输入几千字节的数字信息,具有极高的保密性]。FRID技术的环境适应性强，可全天候、无接触地完成自动识别、跟踪和管理功能,且穿透能力和抗干扰能力强。RFID技术可识别高速运动物体，并可同时识别多个标签，操作快捷方便。因此，RFID技术已在世界各地得到广泛应用，如工业自动化、商业自动化、交通运输控制管理等众多领域。1.2RFID系统的组成最基本的RFID系统由电子标签、读写器（阅读器）、天线三部分组成。而一个完整的RFID系统还需要管理软件。RFID的基本组成部分：RFID标签俗称电子标签，也称为应答器（Tag，Transponder,Responder）。电子标签是指由IC芯片和无线通信天线组成的超微型的小标签，其内置的射频天线用于和读写器进行通信。根据工作方式可分为主动式（有源）和被动式（无源）两大类。当RFID标签进入读写器的作用区域，就可以根据电感耦合原理（近场作用范围内）或电磁反向散射耦合原理（远场作用范围内）在标签天线两端产生感应电势差，并在标签芯片通路中形成微弱电流，如果这个电流强度超过一个阈值，就将激活RFID标签芯片电路工作，从而对标签芯片中的存储器进行读/写操作，微控制器还可以进一步加入诸如密码或防碰撞算法等复杂功能。RFID标签芯片的内部结构主要包括射频前端、模拟前端、数字基带处理单元和EEPROM存储单元四部分。电子标签内部结构如图所示.1.3电子标签的内部结构1.3.1阅读器阅读器也称读写器、询问器（Reader，Interrogator），是对RFID标签进行读/写操作的设备，主要包括射频模块和数字信号处理单元两部分。读写器的频率决定了RFID系统工作的频段，，其功率决定了射频识别的有效距离。读写器是RFID系统中最重要的基础设施。一方面，RFID标签返回的微弱电磁信号通过天线进入读写器的射频模块中转换为数字信号，再经过读写器的数字信号处理单元对其进行必要的加工整形，最后从中解调出返回的信息，完成对RFID标签的识别或读/写操作；另一方面，上层中间件及应用软件与读写器进行交互，实现操作指令的执行和数据汇总上传。在上传数据时，读写器会对RFID标签原子事件进行去重过滤或简单的条件过滤，将其加工为读写器事件后再上传，以减少与中间件及应用软件之间数据交换的流量，因此在很多读写器中还集成了微处理器和嵌入式系统，实现一部分中间件的功能，如信号状态控制、奇偶位错误校验与修正等。读写器内部结构如图所示.1.3.2天线天线（Antenna）是RFID标签和读写器之间实现射频信号空间传播和建立无线通讯连接的设备。RFID系统中包括两类天线，一类是RFID标签上的天线，由于它已经和RFID标签集成为一体，因此不再单独讨论，另一类是读写器天线，既可以内置于读写器中，也可以通过同轴电缆与读写器的射频输出端口相连。目前的天线产品多采用收发分离技术来实现发射和接收功能的集成。天线在RFID系统中的重要性往往被人们所忽视，在实际应用中，天线设计参数是影响RFID系统识别范围的主要因素。1.3.3中间件中间件（Middleware）是一种面向消息的、可以接受应用软件端发出的请求、对指定的一个或者多个读写器发起操作并接收、处理后向应用软件返回结果数据的特殊化软件。中间件在RFID应用中除了可以屏蔽底层硬件带来的多种业务场景、硬件接口、适用标准造成的可靠性和稳定性问题，还可以为上层应用软件提供多层、分布式、异构的信息环境下业务信息和管理信息的协同。中间件的内存数据库还可以根据一个或多个读写器的读写器事件进行过滤、聚合和计算，抽象出对应用软件有意义的业务逻辑信息构成业务事件，以满足来自多个客户端的检索、发布/订阅和控制请求。1.4RFID系统工作原理由读写器通过发射天线发送特定频率的射频信号，当电子标签进入发射天线有效工作区域是产生感应电流，从而获得能量被激活，使电子标签将自身编码信息通过内置射频天线发送出去：读写器的接受天线接收到从标签（射频卡）发送过来的调制信号，经天线调节器传送到读写器信号处理模块，经解调和解码后将有效信息送至后台主机系统进行相关处理：主机系统根据逻辑运算判断该卡的合法性，识别该标签的身份，针对不同的设定做