Huang Xiaofei， Shen Rongwei

（Tianjing University of Technology and Education， Tianjin 300222， China）

Design of signal acquisition system for engine electronic control system based on LabVIEW

Huang Xiaofei， Shen Rongwei

（Tianjing University of Technology and Education， Tianjin 300222， China）

With the rapid development of the automobile industry， the number of domestic cars is increasing， corresponding requirements to the automobile repair plant is also getting higher and higher. According to the relevant information， it shows that judging the car troubles in the automobile repair plant still relys on manual testing. And machine intelligent detection is relatively backward compared with western developed countries. The main reason is that the testing equipment in market is now expensive， the general repair plant can not afford. So it is necessary to develop a set of the equipment with lower price and reliable performance to meet the market demand， and the virtual instrument is the best choice. This paper introduces the structure， function and characteristics of the signal acquisition system software of the engine management system designed by LabVIEW. And the contrast verifcation is carried out， which proves that the system is reliable and stable.

data acquisition； LabVIEW； virtual instrument

In the operation process of the automobile engine management system， the condition monitoring， performance analysis and fault diagnosis of the signal under various conditions can not be separated from the signal acquisition and analysis. Now equipments and instruments popular with the domestic market of special testing and high analysis precision testing are mainly foreign developed， and some of our equipment， such as developed by Bosch Bosch FSA740， it is expensive and the operation is complex. And most of the domestic analytical instruments are the function of a single digital or analog instrumentation. With the rapid development of electronic technology and the wide application of PC technology， virtual instrument technology is also widely used in the detection and analysis of equipment. Compared with the traditional test equipment， the virtual instrument has the advantages of simple operation， graphical interface， user's own choice，good price， and so on. Therefore， combined with the current market demand and research needs， the author made use of advanced virtual instrument technology， in the LabVIEW environment， developed a variety of signal detection and sampling of visual data processing.

1　Introduction of LabVIEW

LabVIEW（Laboratory Virtual Instrument Engineering） is a graphical programming language by the United States NI introduced， the program is produced in block diagram form， easy to use， especially for hardware and software engineers， technical staff training test， pipeline technology staff and applications can be able grasp the operation methods and apply it to practice in a very short time. LabVIEW integrates hardware GPIB， PCI，RS-232 and RS-485 protocol and data acquisition card communication， it has built all the features to facilitate the application of TCP / IP， ActiveX software standard library functions［1］. Graphical programming language，also known as "G" language， which is very convenient programmers to develop software， mainly to replace the fowchart program code， you can shorten the development cycle and high efficiency also greatly simplifies the complexity of the code［2］. This is a powerful and fexible software.

2　Development of signal acquisition system in LabVIEW environment

Electronic engine control scheme of the sensor signal acquisition system is to test and study the acquisition engine sensor signal， PCLD - 8710 wiring board is accepted by the virtual instrument to collect the digital quantity， and then connects to PCI - 1712 data acquisition card through the data bus， according to LabVIEW program， to collect signal data for analysis， calculation and processing， and the realization of the analysis on data display and the sensor signal acquisition achieved graphical display.

2.1Hardware design of acquisition system

2.1.1Type of detection sensor

Taking Lavida sedan engine as an example， the sensor mainly includes throttle gate position sensor， intake pressure sensor， intake air temperature sensor， coolant temperature sensor， knock sensor， oxygen sensor， crankshaft position sensor， cam shaft position sensor， boost pressure sensor，pedal position sensors and airfow sensor.

2.1.2Data acquisition card selection

On the basis of the actual sensor signal acquisition parameter requirements and cost control in a number of thinking， this paper adopts the PCI-1712 Advantech products. The main features of PCI-1712 data acquisition card are as follows：

（1）The board itself A/D memory FIFO buffer 1K and D/A output of the FIFO buffer 32K.

（2）1MHz sampling rate， 12 bit A/D converter and the adoption of PCI data bus transmission［3］.

（3）16 way single ended or 8 way differential analog input （AI0—AI15）， or combination method input.

Automatic calibration of analog input and output. The input gain of each channel can be programmed， etc.

2.1.3conditioning circuit

Signal conditioning the main role is to amplify the weak signal to transform into standard signal to meet the insertion type collecting device of analog voltage input range； blocking the signal of computer and sensor to protect the test signal without interference by the common mode voltage； in the test signal flter out unwanted signals.

2.1.4Selection of PC machine

This system uses the existing Lenovo desktop， can meet the requirements of the experiment.

2.2Software design of acquisition system

2.2.1Software structure

The application program mainly realizes the function：collection parameter setting， data acquisition， signal realtime display and signal storage four function modules.

2.2.2Signal acquisition module

Analog input， analog output， timer， and digital input/ output are the main functions of LabVIEW data acquisition. And analog input mode is one of the most commonly used way. A data acquisition process， the analog signal is mainly through the data acquisition card multiway switch， A/D conversion chip and data cache of a number of components will be a single channel analog signal converted into digital signals， and storage in the data cache， and computer through the LabVIEW VI code control data acquisition card of a few parts of the operation. Computer and data acquisition is the mutual information conversion， communication and control through the PCI bus. The module of real-time acquisition of sensor signals is utilized to realize the data acquisition card.

2.2.3Parameter setting module

This part mainly carries on the disposition to the data acquisition system's many kinds of parameters. Including the sampling rate， sampling channel selection， sampling time and the number of samples. In order to simplify the complex frame， the local variable configuration parameters to the follow-up， and maintain a consistent and synchronization.

2.2.4Signal display module

Good human-computer interaction interface makes the operation of the instrument is very simple. Data collected in the form of one-dimensional array of input to the Split DArray. which is converted to two-dimensional array after the index array， according to the conditions before the structure of the index values are given out the corresponding sub array. And then input to create the waveform as the Y value of the waveform， through the creation of the array in the waveform chart display.

3　Example application

To further demonstrate the function of the system， to the corresponding test， the test mainly as follows： through the data bus of PCI interface to Ni the data acquisition card is introduced into a computer， for Santana engine sensor signals data acquisition， then the number according to channel 1 are connected， and in the total die corresponding to the input to collect data. In system software interface displays test data.It fnally puts the signals and traditional oscilloscope display is connected， to compare the results of the two， the error in the range of 1%， at the same time， the software interface wave effect smooth and intuitive， and conventional oscillograph display effect are similar. It is proved that the system is easy to maintain and extend， and it has wide application value in the process of laboratory virtual research.

4　Concluding remarks

In this paper， based on LabVIEW， a graphical programming language， the completion of the electronic control engine sensor signal acquisition system confguration and the system completed the sampling signal of sensor and display are verified by the system which is stable and reliable. Compared with the traditional data acquisition instrument， the one based on virtual instrument LabVIEW has the advantages of low cost， easy maintenance， simple operation and short development cycle.

［Reference］

［1］BOQIANG S， DEYONG Z， CHANG L， et al. Practical course of LabVIEW6.1 programming technology［M］. Beijing：China Railway Publishing house， 2002.

［2］XINHUA W. Application of virtual instrument in data acquisition［J］. Pingxiang College， 2011（6）：33-35.

［3］HANG M Y. The basic principle of virtual instrument and its application［J］. Computer Optical Disc Software and Application， 2011（9）：37.

基于LabVIEW的发动机管理系统信号采集系统设计

黄晓飞，申荣卫
（天津职业技术师范大学，天津300222）

随着汽车工业的迅速发展，家用轿车的数量也越来越多，相应对汽车修理厂的要求也越来越高。而据有关资料表明，现在汽车修理厂判断汽车故障依然是靠人工方法。而机器智能检测相对西方发达国家比较滞后。主要原因就是现在市场上的检测设备比较昂贵，一般修理厂负担不起。所以需要开发一款价格低廉并具备可靠性能的设备来适应市场的需求，而虚拟仪器是.最好的选择。文章介绍了利用LabVIEW设计出的发动机管理系统信号采集系统软件的结构、功能、特点，并进行了对比验证，证明了该系统是可靠、稳定的。

数据采集；LabVIEW；虚拟仪器

introduction：Huang Xiaofei （1988— ）， male， Tingjing， graduate student； research direction： automotive electronic control technology.