基于虛擬儀器的傳感器自動(dòng)測(cè)試系統(tǒng)設(shè)計(jì)與實(shí)現(xiàn)

1、·45·文章編號(hào):1007-757X(20105-0045-02基于虛擬儀器的傳感器自動(dòng)測(cè)試系統(tǒng)設(shè)計(jì)與實(shí)現(xiàn)李波,何黎明,王林摘 要:傳感器的檢測(cè)需要測(cè)試傳感器在不同工作環(huán)境下的性能,整個(gè)過(guò)程持續(xù)時(shí)間長(zhǎng),需要設(shè)定傳感器所處的環(huán)境溫度與壓力,并且每隔一段時(shí)間需要記錄傳感器當(dāng)前的參數(shù)值。在傳統(tǒng)的傳感器檢測(cè)系統(tǒng)中,這些操作都是人工完成的,效率比較低,隨著被測(cè)試的傳感器產(chǎn)品增加,人工的測(cè)試系統(tǒng)已經(jīng)無(wú)法滿足日益增長(zhǎng)的工作量需求。該文基于虛擬儀器技術(shù)設(shè)計(jì)了一套傳感器自動(dòng)測(cè)試系統(tǒng),提高了測(cè)試效率,實(shí)現(xiàn)了傳感器溫度性能的自動(dòng)測(cè)試系統(tǒng),明顯優(yōu)于傳統(tǒng)傳感器檢測(cè)系統(tǒng)。 關(guān)鍵詞:虛擬儀器;LabVI

2、EW ;傳感器檢測(cè) 中圖分類號(hào):TP274 文獻(xiàn)標(biāo)志碼:A0 引言 傳感器廣泛應(yīng)用于工業(yè)領(lǐng)域中,需要適應(yīng)各種工業(yè)環(huán)境,因此傳感器在環(huán)境的改變情況下性能的穩(wěn)定性就很重要,需要通過(guò)嚴(yán)格的測(cè)試才能投入使用。傳統(tǒng)測(cè)試系統(tǒng)中,把傳感器放置在溫度試驗(yàn)箱中,由人工監(jiān)測(cè)整個(gè)測(cè)試過(guò)程,包括調(diào)整試驗(yàn)箱溫度,設(shè)定溫度持續(xù)時(shí)間,定時(shí)記錄傳感器的性能參數(shù)等等,整個(gè)測(cè)試過(guò)程持續(xù)時(shí)間比較長(zhǎng)。隨著被測(cè)試的產(chǎn)品增加,傳統(tǒng)的依靠人工系統(tǒng)已經(jīng)不能滿足生產(chǎn)的要求。本文設(shè)計(jì)了基于PXI 總線技術(shù)和虛擬儀器平臺(tái)的傳感器測(cè)試系統(tǒng),采用了NI 的7位半高性能數(shù)據(jù)采集卡PXI-4071和矩陣開(kāi)關(guān)PXI-2503,實(shí)現(xiàn)了多個(gè)傳感器溫度性能的自動(dòng)

3、測(cè)試,改善了傳統(tǒng)測(cè)試系統(tǒng)中配置時(shí)間長(zhǎng)、效率低的問(wèn)題。1 傳感器溫度的性能測(cè)試傳感器溫度性能的測(cè)試,需要采集傳感器內(nèi)阻在不同溫度下的變化規(guī)律。為了方便測(cè)量,本文通過(guò)電橋電路把傳感器電阻的變化,轉(zhuǎn)換為電橋輸出電壓的變化。采集到電壓數(shù)據(jù)后,通過(guò)處理和計(jì)算得出溫度性能參數(shù)并給出測(cè)試結(jié)果。 1.1 傳感器測(cè)試的電橋電路 圖1 傳感器測(cè)試電橋電路圖其中,Rs 1,Rs 2,Rs 3是3個(gè)標(biāo)準(zhǔn)電阻,R 是傳感器的等效電阻,傳感器的電阻值隨著溫度變化電阻有波動(dòng)。假設(shè)電源供電電壓為Vs ,我們需要采集的信號(hào)為: 1(32o R Rs V VsRs Rs =×從上面公式可以知道Vo 的變化跟傳感器電阻值

4、R 的變化成正比的。1.2 傳感器隨溫度變化情況下的性能測(cè)試傳感器的工作環(huán)境是多變的,有時(shí)還需要在高溫下工作。因此需要傳感器長(zhǎng)時(shí)間保持工作的良好狀態(tài)需要做必要的測(cè)試,比如在長(zhǎng)時(shí)間溫度不變的工作環(huán)境下以及在溫度變化的情況中,同一溫度下性能的穩(wěn)定性等等。其中溫度滯后影響是最重要的評(píng)判要素之一。假設(shè)一個(gè)測(cè)試流程如下: 溫度滯后計(jì)算方法如下:其中,Vi (i =1,29為流程相應(yīng)的溫度點(diǎn)采集到的電壓信號(hào);V R 為量程壓力的輸出信號(hào),依量程可視為常量處理。一般取溫度滯后范圍為0.06%,如果溫度滯后值大于0.06%時(shí),判斷傳感器不合格。2 系統(tǒng)硬件的設(shè)計(jì)系統(tǒng)構(gòu)架如圖2所示。系統(tǒng)結(jié)構(gòu)主要分為基于PXI

5、總線的溫度與電壓數(shù)據(jù)采集部分和溫度環(huán)境模擬部分。作者簡(jiǎn)介:李波,男,上海交通大學(xué)自動(dòng)化系,在讀碩士研究生,從事工業(yè)自動(dòng)化研究,上海 200240;何黎明,男,上海交通大學(xué)自動(dòng)化系,博士,助理研究員,從事工業(yè)自動(dòng)化研究,上海 200240;王林,男,上海交通大學(xué)自動(dòng)化系,副教授,碩士生導(dǎo)師,從事工業(yè)控制技術(shù)、智能監(jiān)控系統(tǒng)應(yīng)用與研究,上海 200240·46 ·圖2 測(cè)試系統(tǒng)結(jié)構(gòu)框圖2.1 PXI 總線以及相關(guān)硬件設(shè)備的選擇PXI (PCI eXtensions for Instruments 是PCI 總線在儀器領(lǐng)域的擴(kuò)展。它是一種專門為數(shù)據(jù)采集以及自動(dòng)化打造的模塊化儀器平臺(tái)

6、,能滿足日益增加的對(duì)復(fù)雜儀器系統(tǒng)的需求的系統(tǒng)。PXI 系統(tǒng)由3個(gè)基本部分組成:機(jī)箱,系統(tǒng)控制器和外設(shè)模塊。機(jī)箱背板包含有定時(shí)和觸發(fā)總線,用于精確定時(shí)的星型觸發(fā)總線,讓高精度同步操作得以實(shí)現(xiàn)。通過(guò)MXI-3接口工具,PXI 系統(tǒng)可以直接被PC 或其他PXI 系統(tǒng)控制,這給虛擬儀器的開(kāi)發(fā)帶來(lái)了極大的方便。根據(jù)尺寸不同,機(jī)箱有4-18插槽不等,可以根據(jù)需要方便地增加外設(shè)模塊,實(shí)現(xiàn)系統(tǒng)的擴(kuò)展1。 2.2 傳感器測(cè)試環(huán)境的模擬考慮到傳感器檢測(cè)所需要的溫度和氣壓環(huán)境,并且其狀態(tài)可以通過(guò)程序控制,因此采用espec 快速溫度變化試驗(yàn)箱和DHI PPC3大氣壓力控制器,模擬傳感器檢測(cè)所需要的溫度和壓力環(huán)境。E

7、spec 快速溫度變化試驗(yàn)箱,是愛(ài)斯派克環(huán)境儀器公司的小型環(huán)境試驗(yàn)箱,可以通過(guò)RS485串口與工控機(jī)通訊,而且具有豐富的可編程指令系統(tǒng),可以通過(guò)程序控制試驗(yàn)箱的溫度以及試驗(yàn)箱溫度采集。類似地,DHI PPC3的指令對(duì)氣壓進(jìn)行控制與氣壓狀態(tài)的采集。 2.3 多傳感器測(cè)試數(shù)據(jù)的采集為了提高檢測(cè)效率,測(cè)試采用多個(gè)傳感器同時(shí)進(jìn)行測(cè)試?？紤]到有靜電和電磁干擾,我們把24個(gè)傳感器作為一組,放置在一個(gè)圓柱型金屬容器中,并給傳感器統(tǒng)一供電;考慮到容器里面和外面溫度變化速度的變化,因此有必要再在每個(gè)金屬容器中放置一個(gè)PT100,使得更準(zhǔn)確的獲取傳感器環(huán)境的溫度值。為了自動(dòng)采集多路傳感器的電壓信號(hào),我們基于NI

8、公司的18路插槽的PXI 系統(tǒng)平臺(tái),采用PXI-2503矩陣開(kāi)關(guān)以及PXI-4071數(shù)字萬(wàn)用表,PXI 系統(tǒng)控制器控制PXI-2503與PXI-4071,共同協(xié)作完成自動(dòng)采集。原理圖如。其中 PXI-2503是低壓多路復(fù)用器/矩陣?yán)^電器開(kāi)關(guān),最大工作頻率高達(dá)30KHz ,一共有48個(gè)接線端,并且可以根據(jù)需要選擇不同的繼電器切換模式,如24路兩線制,12路四線制等2。PXI-4071是高精度數(shù)字萬(wàn)用表,測(cè)量范圍廣,最高精度為7位半,電壓測(cè)量范圍±10 nV 到 1000 V ,電阻測(cè)量范圍10 µ到 5G 3。 圖3 PXI-2503和PXI-4071配合工作原理示意圖2.4

9、 環(huán)境溫度的采集環(huán)境溫度就是工裝內(nèi)部的溫度。工裝是指存放傳感器的容器,為了方便傳感器測(cè)試,傳感器是放置在工裝中的,工裝是一個(gè)閉合的金屬容器,可以防止靜電干擾,通過(guò)導(dǎo)線把測(cè)量信號(hào)引出至電壓測(cè)量設(shè)備。每個(gè)工裝中放置一個(gè)pt100,通過(guò)測(cè)量pt100的值來(lái)獲取工裝中的溫度值。溫度采用4線制測(cè)量方法。用4線制法通過(guò)導(dǎo)線把電阻接到PXI-2503,再通過(guò)PXI-4071測(cè)量,選擇4線制電阻測(cè)量方法獲得pt100的電阻值,再轉(zhuǎn)換為相應(yīng)的溫度值。原理分別如圖4和圖5所示。 圖4 四線法電阻測(cè)量電路 圖5 兩線法電阻測(cè)量電路圖中為電流源供電,RLead 為導(dǎo)線電阻,Rpt 為待測(cè)pt100電阻,V 是電壓表,

10、內(nèi)阻為Rv 。電流源電流大小為I ,電壓表讀數(shù)為U ,由電路分析知識(shí)可知:Rpt*Rv*IU=Rpt+Rv+2RLead 所以U Rpt*Rv'=I Rpt+Rv+2RLeadRpt =兩線制法測(cè)量得電阻值為U Rpt+2RLead*Rv '=I Rpt+Rv+2RLeadRpt =( 從上面的比較可以知道四線制法測(cè)量電阻更精確,實(shí)際中兩線法測(cè)量常溫下pt100溫度值為118,對(duì)應(yīng)溫度值為46.3,而四線法測(cè)量得電阻值為110,對(duì)應(yīng)的溫度為25,顯然對(duì)PT100電阻值采用四線制法測(cè)量是有必要的。3 軟件結(jié)構(gòu)(下轉(zhuǎn)第49頁(yè)5 系統(tǒng)的主要優(yōu)點(diǎn)該智能化資產(chǎn)管理系統(tǒng)采用了RFID、JS

11、P及J2EE等技術(shù),并與先進(jìn)的網(wǎng)絡(luò)通信技術(shù)相結(jié)合。與傳統(tǒng)的資產(chǎn)管理系統(tǒng)相比,該系統(tǒng)具有明顯的優(yōu)勢(shì)。它可以實(shí)現(xiàn)實(shí)時(shí)讀取, RFID電子標(biāo)簽實(shí)時(shí)發(fā)射資產(chǎn)信息,系統(tǒng)自動(dòng)讀取,無(wú)需人工現(xiàn)場(chǎng)清點(diǎn),提高了資產(chǎn)管理的效率和準(zhǔn)確性,節(jié)省了大量人工查看條碼的勞動(dòng)力成本;可以進(jìn)行遠(yuǎn)程控制,讀取的信息可以通過(guò)GPRS等方式實(shí)時(shí)傳送到后臺(tái)資產(chǎn)管理數(shù)據(jù)庫(kù),做到了現(xiàn)場(chǎng)資產(chǎn)情況與資產(chǎn)管理統(tǒng)計(jì)資料的一體化,保證了資產(chǎn)數(shù)據(jù)庫(kù)的實(shí)時(shí)和準(zhǔn)確;該系統(tǒng)運(yùn)行時(shí)高效精準(zhǔn),RFID 電子標(biāo)簽完全實(shí)現(xiàn)了資產(chǎn)管理的電子化和自動(dòng)化,避免了人工管理方式出現(xiàn)的錯(cuò)漏,并自動(dòng)對(duì)資產(chǎn)變更情況進(jìn)行追蹤。6 結(jié)論與JSP及J2EE等技術(shù)很好地結(jié)合在一起的RFI

12、D技術(shù)具有了更先進(jìn)的用武之地,它們共同構(gòu)建了智能化資產(chǎn)管理平臺(tái)。該平臺(tái)提供了一條解決龐雜的資產(chǎn)管理問(wèn)題的優(yōu)勢(shì)捷徑,它成功地解決了傳統(tǒng)的資產(chǎn)管理所面對(duì)的復(fù)雜繁瑣的問(wèn)題。隨著RFID技術(shù)在國(guó)內(nèi)的逐步成熟和推廣,相信未來(lái)這種基于RFID技術(shù)的智能化資產(chǎn)管理平臺(tái)將會(huì)越來(lái)越多的為更多的企業(yè)部門所應(yīng)用,從而進(jìn)一步推進(jìn)資產(chǎn)管理的規(guī)范化。參考文獻(xiàn)J,2005,(9:59-60.道貨運(yùn)J,2005,(12:18-19.界電信J,2006,(4:54-55.(收稿日期:2010-03-24程序流程圖整個(gè)測(cè)試系本文實(shí)現(xiàn)的多路傳感器溫度性能自動(dòng)測(cè)試系統(tǒng),以PXI-2503矩陣開(kāi)關(guān)和PXI-4071高精度數(shù)字萬(wàn)用表以溫

13、箱為硬件平臺(tái),LabVIEW的軟件開(kāi)發(fā)平臺(tái),進(jìn)行系統(tǒng)控制和數(shù)據(jù)采集,極大地改善了傳感器測(cè)試的效采用新型的自動(dòng)測(cè)試系統(tǒng)后,整個(gè)測(cè)試過(guò)程不需要人工的參與,節(jié)約了人力資源。李志武.基于PXI儀器儀表用戶National Instrument,NI PXI-2503userguaid,2006.National Instrument,NI PXI-4071_Specifications,2006.李海濤,趙勇.LabVIEW·49·process, part of the program code, experiment results are given in this pape

14、r and MATLAB as a tool is used to design for the program code.Key words: Pills Detection; Image Enhancement; Image Segmentation; Feature ExtractionRealization of Sensor Auto-Detective System Based on Virtual Instrument (45Li Bo, He Liming, Wang Lin (Shanghai Jiaotong University, Shanghai 200240, Chi

15、naAbstract: The detective of sensor depends on the performance under different working situation.It needs setting up the ambient temperature and pressure of environment and data acquisition every setting time.These things are all done manually in present testing system and it has not been meeting th

16、e growing needs of workload. An auto-detective system based on LavVIEW is introduced, which has realized the functional test of the sensor. The system accomplishes good effects, and can steadily improve the test efficiency.Key words: Virtual Instruments; LabVIEW; Sensor DetectedThe Intelligent Syste

17、m Of Asset Management Based On RFID Technology (47Xi Yunting, Hu Zhiping (College of Automotive Engineering, South China University of Technology, Guangzhou 510640, China Abstract: Asset management is very important to corporation; it becomes an inevitable part in modern corporation management. This

18、 paper introduces the basic concept and the operating principle of RFID technology, analyzes the advantages of application of RFID technology in asset management system. The technologies of composing asset management using RFID, JSP and J2EE are discussed in detail. So an effective approach to solve

19、 the problems of asset management is given based on this system.Key words: Asset Management; Tag; Intelligence; RFID; JSPDesign of Super Remote Sensing Image Database (50Pan Hongyan (School of Physics and Electronic, Information and Engineering, Wenzhou University, Wenzhou 325000, China Abstract: Ai

20、ming at complex TIF/TIFF format remote sensing super images, we designed and realized the miniature-extraction-based image database by using libtif function library by connecting Delphi and Interbase via firebird database engine. The contribution is as follows: linking the original image and miniatu

21、re through foreign key; dynamic display of the original images; module based architecture design increase the extensibility and reusability so as to facilitate the management; improved the image processing method of program by accelerate the speed by more than twenty times. The result turned out wel

22、l.Key words: Libtif; Fast Miniature-extraction; Remote Sensing Image; DatabaseStudy on Fuzzy PI Time-delay Compensation Algorithm of Networked Control System (53Qian Chunying, Zhou Zhijian (Department of Information Engineering, Wuxi Institute of Commerce, Wuxi 214063, ChinaAbstract: Using networked

23、 control system, a network-induced time-delay is generated, which causes advert effects on the closed-loop networked control system such as performance degradation and system destabilization. In this paper, contraposing the time-delay commonly existing in the remote control system, an intelligent fu

24、zzy logic compensator is introduced to design the traditional networked PI control system. One of the advantages of this fuzzy PI time-delay compensation algorithm is that it is not needed to completely redesign the existing PI controller, but simply modulates the PI controller action with the outpu

25、t of the intelligent fuzzy compensation. Using the fuzzy PI time-delay compensation to modulate the output of the PI controller. Simulation results of a networked controlled Brushless DC motor is used to illustrate the effectiveness and feasibility of the proposed fuzzy PI control scheme, and the us

26、e of the method makes the closed-loop system posses favorable dynamic and static performance and free from load disturbance.Key words: Networked Control System; Fuzzy PI Control; Time-delay CompensationLEARNERSS GARDENA Runtime Profile Method for Dynamic Binary Translation Using Hardware-Support Tec

27、hnique (56Yang Huibing, Guan Haibing, Liang Alei (Department of Computer Science, Shanghai JiaoTong University, Shanghai 200240, China Abstract: The traditional profiling strategy in dynamic binary translator is based on the basic block, the edge jump and the path tracing. In general, the method usi

28、ng software-only profiling typically incurs about 30% overhead of overall system. By hardware-support, dynamic optimization system can improve overall performance prominently. Moreover, the difficulty in HW/SW co-design is the communication overheads and partition between hardware and software. To t

29、he optimization process of DBT, This paper replaces the traditional software-only profiling by hardware-support profiling technique to reduce system overhead and to improve the overall performance of DBT system.It can obtain the better performance by reducing communication overhead to the minimum.Th

30、is article design and implement our idea on Dynamic Binary Translator, CrossBit.Key words: Dynamic Binary Translation; Profiling; Hardware-Software Co-designDesign and Implementation of Fire Brigade Data Backup System (59Ding Xiangguo (Shanghai Fire Brigade, Shanghai200051, ChinaAbstract: This paper

31、s analyzes present condition of data backup for shanghai fire brigade information system and requirements of data backup.Combined with advanced storage technology,fire brigade backup system framework is established,data backup sofeware is choiced,data backup strategy is presented. Key words: Fire Brigade; Information System; Data BackupResearch of Dat