【作者】 陈丽君；

【导师】 童刚；

【作者基本信息】 青岛科技大学 ， 控制理论与控制工程， 2008， 硕士

【摘要】 粘度是流体的重要物理性质之一,是食品业、油漆业、聚合涂层业、石油工业及其它工业的一个重要的标准特征。测量流体的粘度在工业生产和基础学科研究中都非常有意义。但是国内生产的在线粘度计在功能、精度和稳定性上都不尽如人意,而国外生产的粘度计虽然性能优越,但其昂贵的价格让人望而却步。因此,对于流体粘度在线测量方法的研究至关重要。本文将可编程序控制器、组态软件与工业控制计算机相结合,开发设计了流体粘度在线测量系统,其主要任务是提高测量精度,降低测量成本,实现在线测量。本文从理论基础,硬件构成及软件设计等方面详细地论述了流体粘度在线测量系统设计的基本原理和总体方案。提出了将软测量技术应用于粘度在线测量,首先解决了传统粘度测量设备应用于在线测量性能差的问题;其次大大地降低了粘度测量的成本;最后,由于软测量模型的参数易于更改,维护保养非常方便。为保证模型的精确性,采用统计判别法和滤波的方法对数据进行预处理,并在模型估测值偏差超限时及时校正模型。针对系统实时性的要求,利用可编程控制器与上位机进行串口通信,并设计数据采集程序,同时实现模拟量数据滤波及A/D转换功能。为便于工作人员实时监控注聚液粘度,采用MCGS组态软件设计上位机监控画面,将整个监控软件分成四个功能模块,使系统变得可视化、系统化。应用DDE技术实现了组态软件与MATLAB之间的通信,有效地解决了组态软件处理数据功能薄弱的问题;同时利用SQL技术将数据从组态软件中转存入Access数据库,解决了大量采集数据的存储问题,为日后读取和管理提供了方便。更多还原

【Abstract】 Viscosity is one of the most important physical properties of liquid, and also is an important standard character in the industry of foodstuff, oil paint, polymerization coating, petroleum and other industry. It is very significative to measure liquid viscosity in industrial production and basic study. The domestic on-line viscometer is not satisfying all in function, precision and stability, while the viscometer overseas has good capability, but also is very expensive. Therefore, research on on-line measuring of liquid viscosity is quit important.We combined PLC, Configure software and industrial control computer to develop an on-line measuring system of liquid viscosity, main tasks of which are enhancing measuring precision, reducing measuring cost and realizing measuring on-line.In this paper, we detailedly discuss the fundament and whole scheme of on-line measuring of liquid viscosity from basic theory, hardware composing and software designing. Applying soft-sensing technology to measure viscosity is advanced, and it has three main merits. Firstly, the problem of traditional viscosity measuring instruments perform badly when they are used to measure on-line is solved, secondly, measuring cost is reduced consumedly, finally, maintenance is convenient for the parameters of model are easy to be modified. In order to ensure the accuracy of the model, we apply the statistic discriminance and method of filter to do data pretreatment, and modify the model in time when the model output error beyond limits.To the request of real-time measuring, the communication between PLC and PC is established, and we design data acquisition programmatic which the analog data filter and A/D conversion is realized. Convenient for monitoring liquid viscosity, we design monitoring interface with MCGS and divide it into four function modules, which makes the whole system visual and systematize.Communication between MCGS and MATLAB was realized through DDE technology, and the unsubstantial function of data processing of MCGS is solved availably. Meanwhile, we storage large numbers of collecting data in Access database with SQL technology convenient for reading and management.更多还原