摘要
21世纪是信息化时代,测试控制技术与通信技术、计算机技术一起构成了信息产业的三大支柱。近年来,由于测试技术在机械工业中的飞速发展和广泛应用,我国的许多高等院校和职业技术培训机构均开设了机械工程测试技术教学的课程,是机械专业学生必修的一门主干技术基础课。
课程主要介绍了机械工程、工业自动化等工程领域中常见物理量如压力、应变、温度、噪声等传感器的测量原理、测试方法以及信号分析的方法。与其他专业课相比,这门课程具有以下特点:信号处理知识不仅理论性强、公式推导复杂;而且要求思维从时域向着频域转变;传感器的应用和测试过程抽象。只有通过大量直观的实验操作,才能达到最佳的学习效果[1]。这就使机械工程测试实验系统的设计开发成为教学急需解决的问题。针对这门课程的特点,采用虚拟仪器技术开发出基于LabVIEW平台的集虚拟仿真与机械测试为一体的综合实验系统。改变了传统的实验教学模式,采用循序渐进的方式,将实验内容划分为信号仿真实验、综合性实验、探究性实验三个部分。本论文从如下几个部分进行阐述:首先,从性能、价格、可重复操作性等方面将虚拟仪器平台与传统的机械测试设备做了对比,然后分析了课程的内容,并结合学生的特点及培养要求,设计规划实验系统的内容。
其次,针对每个实验部分,开发出具有相应功能的实验软件。具体如下:仿真实验室,针对书本中涉及的信号处理知识,确定虚拟实验室的实验内容。并针对各个知识点分别编写了程序实现其功能,最后,经过web网络发布程序。综合实验,针对机械测试中常用的机械量确定实验内容。硬件方面,选择相应的传感器、采集卡。软件方面,选择LabVIEW软件,编制数据采集及数据显示程序。探究性实验,搭建实验平台。利用现有的实验台(包括电机和转子等)、传感器、信号调理模块和数据采集卡等,用于模拟旋转机械的各种状态。结合转子实验台模拟的故障,建立了一个完成的旋转机械故障诊断实验系统,通过该实验系统可以采集到转子运行的各种数据,并分析和显示数据。
开发出的基于LabVIEW的教学实验系统与机械测试技术课程紧密联系,信号仿真实验室涉及信号时频域分析、滤波器设计、采样等实验。紧贴书本,帮助广大学生理解和消化信号处理基础知识。同时,综合性实验和探究性实验与工程应用相结合。在教学实践中,该系统能起到良好的辅助教学作用更有利于学生掌握传感器、信号处理知识和测试系统的知识;并利于学生实践创新能力的培养。
The 21st century is an era of information. Testing and control technology, communication technology and computer technology constitute the three pillars of the information industry together. In recent years, since the testing technology has a rapid development and wide application in machinery industry, engineering testing technology as a course was added in many colleges.
The course introduces the testing methods and signal analysis methods of common physical principles in mechanical engineering, industrial automation or other engineering fields, such as pressure, strain, temperature, noise and other principles. The course is not only strong theoretical, complicated formula, but mode of thinking will be changed from the time domain to the frequency domain, and the process of specific application is abstract. Only through a lot of intuitive experimental operation can achieve the best learning results. This makes design and developed mechanical engineering testing laboratory become an urgent problem. In response to this feature, we developed a mechanical testing system which based on LabVIEW platform. We use progressive teaching methods instant traditional teaching methods. The content of experiment is divided into three parts; there are basic experiment, comprehensive experiment and exploratory experiment. Helping students deepen their understanding of the book, and improve skills and practical ability in the course of the experiment. This paper describes several parts from the following:
First, compared virtual instrument with traditional mechanical test system on the performance, price, operational and other aspects, and then analyzes the content of curriculum, planning the content of experimental systems.
Second, Simulation Laboratory: determine the contents of the virtual laboratory experiments which related to the signal processing knowledge in books. And program for each knowledge point to achieve its function. Finally, publishing the program through web. Comprehensive Experiment: determine the amount of experimental content which are commonly used for mechanical testing machine. The hardware side, select the appropriate sensors, the acquisition card. The software side, select the LabVIEW software, program data collection and data preparation procedures. Exploratory experiments: Build the experimental platform. Use the existing test bed (including the motor and the rotor etc), sensors, signal conditioning modules and data acquisition card and so on, to simulate various states of rotating machinery. Built a completely fault diagnosis experimental system of rotating machinery. Through the experimental system, many data form the running rotor, can be collected, analyzed and displayed.
The experimental system based on LabVIEW is combined with mechanical testing techniques teaching courses closely. The signal Simulation Laboratory is the basis experiments based on book, involving the time-frequency domain analysis, filter design, sampling and other experiments, close to the books and helping students understanding and digest the majority of basic theoretical knowledge of signal processing and digestion. Meanwhile, comprehensive experiments and exploratory experiments are combined with engineering applications. In teaching practice, the system can play a good role in supporting education. More conducive to students to master the sensors, signal processing knowledge and test knowledge of the system, and help students’practice and innovation ability.
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