外文翻译1

The Design of LDF Data Acquisition System Based on LabVIEW

Abstract

In the formation of liquid drops, different kinds of liquids may have different outer profiles; the change of volume and shape in the process of drop formation can indirectly reflect liqui d’s physical and chemical properties, such as surface tension and viscosity, etc. Real-time detection the size of drops in the forming process is on the basis of drop analysis technique. Previous researchers have studied that optic fiber and capacitance drop sensor fusion technology can indirectly gain drop’s form and the volume. This article is based on the optic fiber and capacitance drop sensor theory, designing the system based on the LabVIEW software to realize the LDF (Liquid Drop Fingerprint) data acquisition function. The experiment results show that the system can well realize the acquisition, compared with the traditional VC programming technology, this data acquisition system is high efficiency.

Keywords: LDF, Data Acquisition System, LabVIEW, Optic fiber-capacitance Liquid Sensor

1. Introduction

DAT (Drop Analysis Technology) means that under certain test system conditions, during the process of drops formation, it is needed to use various means to obtain the physical and chemical characteristic parameters of the measured liquid, to realize the liquid identification via qualitative and quantitative analysis(Song

Qing,2005).

From the above, it can be known that in the process of drop forming, it is very crucial to analyze its size and the outline which reflect the chemical and physical properties of the liquid. So how to test its size and outline is the focus of our research. Predecessors had made some theory research in this field, Dr Z.R.Qiu in Tianjin University mentioned the optic fiber and capacitance sensor fusion technology in his doctoral dissertation(Qiu Zurong,2000), demonstrating that through testing the drop capacitance sensor changing and light intensity we can indirectly measure the drop

size and outline. This article is built on the optical fiber-capacitance sensor fusion technology and its principle diagram is as shown in Figure 1.

Selection and/or peer-review under responsibility of Conference ESIAT2011 Organization Committee.

As shown in Figure 1, one signal is light, the light from the light source by input optical fiber importing into drop. The light is reflected and absorbed in the internal of drop, then derived by output optic fiber. It is changed into analog signals after being transferred through photoelectric model. This signal is sent to one channel of data acquisition card, according to the setting parameters acquisition card completing

acquisition and processing tasks. At last, the results are uploaded to the computer. The other signal is electrical signals, which is f orming between the head drop’s bottom with cone annular plate and circular plate. This change of capacitance indirectly reflects the drop’s size change. After frequency voltage transforming circuit, capacitance signal is converted into voltage signal, by subsequent DAQ processing circuit with algorithm processor, then results uploaded to the computer, realizing the computing, display and storing functions.

So, how to get optic fiber and capacitance sensor output voltage signal and

real-time displaying and storing are the experimental keys. The traditional data acquisition systems are designed according to data

acquisition characteristics, combining hardware circuit with VC programming to realize (Sun Xin,etal,2009). However, hardware circuit design with high speed data acquisition is complex, with so many disturbances, big noise, cumbersome software, much costing(Zhao Yibin,etal,2005). While LabVIEW is a language based on the graphic programming technology (Lin Jing,etal,2005), in data acquisition, it has prominent superiority, briefness and modifying conveniently, and changing

parameters by software easily. This paper is an application of LabVIEW in drops analysis of high-speed data acquisition.

2. Design of Hardware

During the forming of drops, optic fiber signal and capacitance signal changes in a small range, considering the magnification matching, channel numbers, AD transforming precision, etc. In the trial, we used type

PCI-9113A(https://www.360docs.net/doc/7012822031.html,) data acquisition board which is developed by ADlink Company, as shown in Figure 2. PCI-9113A has 32 bit PCI bus; plug and play; 32 one-port input channels or 16 differential input channels; on board with

low-pass filter used in signal disposal or attenuation; 2500Vrms segregation voltage; with 12 bit successive approximation type A/D converter; three optional programmable gain1, 10 and 100; sampling frequency can achieve 100KHz (single channel model); dual polarity input range:±5V, ±0.5 V, ±0.05 V, single polarity input range: 0 ~10V, 0 ~ 1V, 0 ~ 0.1 V; two trigger mode, software trigger and timer trigger; with the FIFO storage of 1,024 data on board; automatic scanning function with channel choosing; standard half long card structure, standard DB-37 hole type connector.

This data acquisition board’s perfor mance is basically accord with the requirement, price ratio is high.It can complete the experiment task well.

Combining the design with our research background, the change of the capacitance is about 0.5uF between drop in completely full state and completely fallen state, and parasitic capacitance itself 1uF.(Song Qing,2005). So the value of capacitance change comparing with stray capacitance value is very small. This makes the capacitance signal processing circuits more demanding. In order to derivate DB37 interface for convenient measuring, and also for actual situation and task, making the acquisition card to better achieve our function and goal, we design the data acquisition interface board, as shown in Figure2-(b). And according to the actual application, we select the mode of 2 channels one-port input model.And for the sake of the subsequent convenient debugging, in the design of circuit board, we put some test

points for key signals. The main structure parts of the interface board are DB37 interface, the power modules, filtering and amplification analog parts. Hardware part has been designed well and then we can

start software implementation.

a) PCI-9113A b) the Interface board

Figure 2 Data acquisition card and interface board

3. Data Acquisition based on LabVIEW

According to the actual need, the software is designed as shown in Figure 3. The whole process of data acquisition and processing is: first calling data acquisition program that showing data acquisition procedures will start next; Then, determining the corresponding parameters of optic fiber, capacitance signal acquisition program, such as the sampling rate, the channel, input methods one-port input or differential input, sampling points, etc. The setting of these several specific parameters should correspond to the hardware structure and the board which is been wired subsequently, etc. Backup acquisition program diagram is shown in Figure 4

Figure 3 Front panel diagram

Figure 4 Backstage diagram and program flow chart

In the process of data acquisition, according to the different type of interface card, buffer size, while buffer is full of data, it can real-time display through the waveform chart. In order to freely control optic fiber signal and capacitance signal displaying, we designed three button related with display, which is convenient for observation and analysis in the experimental process. After acquisition has been completed,we can choose freely whether to store it or empty it according to experimental effect. Preserving data button can store the optic fiber, capacitance data documents in electronic format file to the appointed place according to the pattern setting. Front panel diagram is showed in Figure 3.

4. Experimental Results

The data acquisition system about liquid drop is built according to principle diagram in Figure1. The LDF of the ethanol with concentration of 100% is as shown in Figure 5 based on LabVIEW acquisition system.

By measuring results, the system can well realize data acquisition function. It is capacitance signal of ethanol for 100% in Figure 5-(a). Capacitance signal is linear growth, which is consistent with theory analysis (Song Qing,2005). In turndown of drop, capacitance signal mutate which is tally with the actual situation. And in the measurement of liquid drops, the cyclical change matches the number of the drops, showing that our system can be well tracking signal changes and realizing data acquisition function.Figure 5-(b) is the ethanol optic fiber signal figure. Optical signal curve is smooth, presenting the good cyclical change trend, and is equivalent to capacitor signal cycle. Theoretical analysis and experimental results confirm each other, showing the correctness in theory and designing experiment. Figure 5-(c) is

optical optic fiber capacitance signal with two channels acquisition and both displaying. And comparing with separately collecting, the cycle is consistent, and signal with good repeatability.

Based on the graphic programming language, data acquisition function implementation is simple (Zhou ShaoLei,etal,2004). It is easy to operate and modify, making the researcher can concentrate more energy on system designing, reducing time on writing foundation of code. Especially in data acquisition, it shows big advantages, which is worth advocating and recommending.

a) Displaying capacitance signals b) Displaying optical signals

c) Displaying both optic fiber and capacitance signals

Figure 5 Data acquisition results

5. Conclusions

This experiment using data acquisition card based on LabVIEW software realized the optic fiber capacitance signal high-speed data acquisition function. Known from the experimental results, the scheme can be efficiently, quickly, low costly to realize high speed data acquisition function. And experimental results are congruent with the theoretical analysis, meeting the demand of precision, realizing the research goal. The scheme is worth advocating and promotion.

Reference

[1] Song Qing, Research of Liquid Identification Method based on the Liquid Drops Technology and LDF, [D], Tianjin:Tianjin University, 2005

[2] Qiu Zurong, Research of Drop Analysis Technology, [D], Tianjin: Tianjin University,2000

[3] Sun Xin, Yu Anping, the Vc++ In-depth Explanation, [M], Electronics Industry Press:2009,20-25

[4] Zhao Yibin, Zhou Yilin, the Data Acquisition System based on LabVIEW, [J], Journal of Qingdao University of Science and Technology, 2005, 10, 26 (5), 452-454

[5] Lin Jing, Lin Zhenyu, Zheng Furen etc, LabVIEW Virtual Instrument Designed from the Approaching to Master, [M],The People's Posts and Telecommunications Press: 2010 (7), 65-80

[6] https://www.360docs.net/doc/7012822031.html,/PD/cn/PD_detail.php?cKind=&pid=30&seq=&id=&sid

[7] Wei wei, Hu Wei, Wang Yongqing etc, Embedded Hardware System Interface Circuit Design, [M], Chemical Industry Press: 2010,280-300

[8] Zhou ShaoLei, Yang Xiuxia etc, Virtual Instrument Technology Analysis and Application, [M], Mechanical Industry Press:2004 (2), 50-76

The Design of LDF Data Acquisition System Based on LabVIEW

Abstract

In the formation of liquid drops, different kinds of liquids may have different outer profiles; the change of volume and shape in the process of drop formation can indirectly reflect liquid’s physical and chemical properties, such as surface tension and viscosity, etc. Real-time detection the size of drops in the forming process is on the basis of drop analysis technique. Previous researchers have studied that optic fiber and capacitance drop sensor fusion technology can indirectly gain drop’s form and the volume. This article is based on the optic fiber and capacitance drop sensor theory, designing the system based on the LabVIEW software to realize the LDF (Liquid Drop Fingerprint) data acquisition function. The experiment results show that the system can well realize the acquisition, compared with the traditional VC programming technology, this data acquisition system is high efficiency.

译文：

基于光纤电容液滴传感器的设计数据采集系统虚拟仪器

在液滴的形成，不同种类的液体可能有不同的外轮廓；在下降过程中形成的体积和形状的变化可以间接反映液体的物理化学性质，如表面张力、粘度等，实时检测在成形过程中液滴的大小，在液滴分析技术的基础上。以往的研究者们研究了光纤、电容液滴传感器融合技术可以间接的增益下降的形式和体积。本文是基于光纤、电容液滴传感器理论，基于LabVIEW软件实现过程的系统设计（液滴指纹）的数据采集功能。实验结果表明，该系统能很好地实现采集，与传统的编程技术相比，该数据采集系统效率高。