【作者】 孙梅娟；

【导师】 张涛；

【作者基本信息】 天津大学 ， 检测技术与自动化装置， 2005， 硕士

【摘要】 随着水资源的短缺,自来水的准确计量问题越来越受到重视。水表计量检定站在水表的准确计量检定方面发挥着非常重要的作用。目前水表检定站采用人工抄表、计算误差、处理数据,检定精度和效率低下,并且历史数据亦以纸质文件的形式保存,使得在检索过程中浪费了大量的时间,不能及时给用户和上级提供检定资料和各种数据的统计分析报表。因此,有必要研制一套具有较高自动化水平的水表检定装置和管理信息系统,使本市水表检定站各方面工作在同行业中达到领先水平。本系统就是为解决上述问题而研制的,主要内容如下:1、开发了一套管理信息系统。该管理信息系统涵盖了水表检定站所有的业务,包括检定业务管理、人事劳资管理、数据统计分析等八个子系统。系统采用结构化和面向对象相结合的方法,按照软件工程的设计步骤,进行了方案设计、需求分析、数据库设计、软件设计、编码等方面的工作,利用半动态的软件体系进行功能模块的提炼,将处理相似功能的代码封装起来,从而减少了代码量。2、进行了水表自动检定装置的研究。新研制的检定装置采用高精度的电磁流量计作为标准表,利用电动调节阀进行流量的控制,通过手持键盘录入水表读数,为水表检定工作由手工操作向计算机自动控制转化提供了设备条件。3、设计了一套计算机控制系统。充分利用工控机的硬件资源,配以相应的计数卡、D/A转换卡以及数字输出卡,运用软件编程驱动阀门工作,完成系统所需的采集和控制,采用一台工控机控制两条水表检定线,节省了一半的硬件开销。在软件的设计中,将有限状态机原理应用到高级软件编程中,实现了计算机异步控制,提高了工作效率。4、流量采用“开环+闭环”的控制策略,利用PID算法实现流量的闭环控制。同时,本文提出一种高压差下小流量的测量和控制策略,通过电动调节阀与自力阀的配合使用,增加了调节阀的调节范围和调节稳定性。5、作者在水表自动检定装置上做了大量的实验,结果表明该系统能够满足水表检定的要求。目前该系统已经通过验收并投入使用。更多还原

【Abstract】 With the lack of the water source, the accurate metering of tap water is more and more important. The Tap Water Meter Calibration Station plays an important role in the respect of accurate calibration. But its efficiency and calibration precision is low because of the manual work, like the value of water meter recording, the data processing, and error calculation, etc. Furthermore the history data is saved in paper so that too much time for index is wasted. Meanwhile the data and its statistic and analysis report can’t be provided for the superior and customers in time. Thus it is necessary to develop a new automatic calibration device and a management information system, which can help the station keeping ahead among the same field. The design system given in this dissertation mainly aims to solve these issues mentioned above. The main contents are as follows:(1) A management information system is developed. This system has touched almost all business management, eight subsystems in all, such as calibration business, human resource and labor, data statistic and analysis and so on. It is developed with the method of the combination of structural method and oriented object. According to the design steps of the software engineering, requirement analysis, software and database design, and code program are done. Meanwhile function modules can be abstracted using the semi-dynamic software programming system, which can encapsulate some codes with similar function and reduce the size of code.(2) The device of the calibration station is studied. The device uses two highly precise electromagnetic flow meters as the standard meter, and two motor regulated valves are equipped to control the flow. The recording value of the water meter is inputted to the computer by a hand keyboard. The device benefits the calibration work by changing manual operation to the computer auto-control.(3) A computer control system is designed here. PC equipped with I/O cards, including counter card, D/A card and digital output card drives the valve to work and samples data by programming. The system uses one computer to control two water meter calibration pipelines, which can economizes half cost of the hardware. The principle of the finite state machine is applied in the advanced software programming so that the two pipelines can run asynchronously and work efficiency is improved.更多还原