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1、<p><b> 附件 外文翻譯</b></p><p> Optic fiber-based dynamic pressure sensor for WIM system </p><p> Shenfang Yuana, , , Fahard Ansarib, Xiaohui Liua and Yang Zhaob</p><p
2、> aThe Aeronautical Key Laboratory for Smart Materials and Structures, Nanjing University of Aeronautics and Astronautics, 29 YuDao Street, Nanjing 210016, China</p><p> bDepartment of Civil and Materia
3、ls Engineering, University of Illinois at Chicago, Illinois, IL 60607, USA</p><p> Received 16 August 2004; </p><p> accepted 10 November 2004. </p><p> Available onl
4、ine 15 December 2004. </p><p><b> Abstract</b></p><p> An optic fiber-based dynamic pressure sensor is described here to measure weight-in-motion of vehicles. In the research repor
5、ted herein, a Michelson interferometer with specially designed hardware and software were developed and experimentally subjected to dynamic compressive loads of different magnitudes, and loading rates. Experiments showed
6、 that both output fringe number and fringe period could be used to indicate the dynamic load. A calibration technique has been put forward to calibrate the</p><p> Keywords: Optic fiber sensor; Dynamic pres
7、sure; Weight-in-motion; Hardware and software</p><p> Article Outline</p><p> 1. Introduction </p><p> 2. The sensor design </p><p> 2.1. Sensor setup </p>&
8、lt;p> 2.2. Sensor principle</p><p> 3. Experimental procedures and results </p><p> 3.1. Experimental setup </p><p> 3.2. Experimental data </p><p> 3.3. Repeat
9、ability of the sensor </p><p> 3.4. Calibration of the sensor </p><p> 3.4.1. Calibration of the static weight </p><p> 3.4.2. Calibration of the dynamic weight</p><p&
10、gt; 4. Conclusion </p><p> References </p><p><b> Vitae</b></p><p> 1. Introduction</p><p> The need to weigh vehicles in motion, applied especially to
11、 traffic control, has grown substantially in the past decades. Several techniques for weighting vehicles in-motion are now used including piezoelectric cables, capacitive mats, hydraulic and bending-plate load cells [1].
12、 Hydraulic and bending-plate load cells offer high accuracy (1–5%) and dynamic range, yet suffer from high installation costs and size constraints. The piezoelectric and capacitive mat techniques are substantially lower
13、i</p><p> Based on the effect of polarization coupling between two orthogonally polarized eigenmodes of polarization-maintaining fiber, Ansari et al. report on using highly birefringence polarization-mainta
14、ining (HiBi) fiber for dynamic measurement of pressure with practical ramifications to the determination of weigh-in-motion of trucks [3]. Navarrete and Bernabeu report a multiple fiber-optic interferometer consisting of
15、 a Mach-Zehnder interferometer configuration with one of its arms replaced by anothe</p><p> The present work describes the development of a dynamic pressure sensor based on the Michelson interferometer, wh
16、ich has simple structure, is cost effective and can potentially offer the high accuracy required for many applications. Special hardware and system software based on Labview WINDOWS/CVI are designed to implement the sens
17、or functions, such as eliminating environmental noise, self-triggering of the test procedure and the fringe number and fringe period simultaneous count. Responses of t</p><p> 2. The sensor design</p>
18、<p> 2.1. Sensor setup</p><p> Fig. 1 illustrates schematically the proposed dynamic pressure sensor system. Single-mode optical fiber is used as a sensing element to form a Michelson interferometer
19、. The optoelectronics components of the interferometer consist of a laser operating at wavelength of 1550 nm, a laser isolator and a photodiode. The sensor is made of communication grade optical fiber (Corning SMF28
20、). The output signal from the detector-amplifier is first fed to a special hardware circuits including a two-order hig</p><p> Fig. 1. Dynamic fiber optic pressure sensor setup.</p><p> V
21、iew Within Article</p><p> 2.2. Sensor principle</p><p> One arm of the Michelson interferometer is subjected to a distributing dynamic load Ld(t). The generalized stress–optic relationship be
22、tween the optical path change Δl and the strain induced over the gauge length can be derived as Eq. (1) [6]:</p><p><b> (1)</b></p><p><b> and</b></p><p>&
23、lt;b> (2)</b></p><p> where P11 and P12 are the Pockels constant; l the length(gauge length) of the optical fiber within the pressure field; tx, ty and tz correspond to the mechanical and geometri
24、cal property of the optical fiber and the host material-epoxy. </p><p> By measuring the deformation of the fiber, the strain in the host material can be measured. The strain is linearly proportional to the
25、 external applied pressure p. Consider α as a constant of proportionality between the pressure and the change in length of the fiber Δl, then</p><p><b> (3)</b></p><p><b> an
26、d</b></p><p><b> (4)</b></p><p> Thus, the output fringe number of the Michelson interferometer is</p><p><b> (5)</b></p><p> where Nf
27、 is the output fringe number; λ the wavelength of the laser light. </p><p> The fringe period can be deduced by Eq. (6):</p><p><b> (6)</b></p><p> where Tf is the fr
28、inge period; t the loading time, approximately equal to the duration time of the optic fiber fringe. </p><p> 3. Experimental procedures and results</p><p> 3.1. Experimental setup</p>
29、<p> The experimental setup is shown in Fig. 2. A steel chamber is designed to contain the optical fiber. The optic fiber is sandwiched between two 1 cm thick stiff rubber pads and glued to one of the two piec
30、es. Rubber pads are necessary for the protection of fiber from damage. The cross-sectional area of the loading surface for the steel chamber is 247.1 mm × 24 mm. The gauge length of the optical f
31、iber pressure sensor is 247.1 mm. A closed-loop materials testing system (MTS) is used for the applic</p><p> Fig. 2. Experimental setup.</p><p> View Within Article</p><p
32、> Fig. 3 shows a typical loading profile and fringe output of the interferometer during the duration of the applied ramp function load. As can be seen, the number of fringes at left corner of Fig. 3 is so great that
33、it is hard to distinguish each fringe. Thus, another figure on the right is used. The figure is the enlargement of the circled area to show clearly the fringes. Because of the polarization effect, the amplitudes of fring
34、es slightly vary. But will not influence the fringe count and peri</p><p> Fig. 3. Typical loading procedure and fiber optic sensor output waveform.</p><p> View Within Article</p>
35、<p> 3.2. Experimental data</p><p> Fig. 4 shows the experimental results of the fringe number and fringe period readouts of the sensor output under different loads. Lines with different signs repres
36、ent relations between the sensor's outputs and the maximum amplitudes of the load under different loading rates.</p><p> Fig. 4. The experimental results: the fringe numbers and fringe periods vs.
37、loads.</p><p> View Within Article</p><p> The fringe number has a linear relationship with the static load, while the fringe period has a non-linear one. Note that, the relationship differs u
38、nder different loading rates, since with increasing loading rate, the same maximum amplitude load will turn out to a bigger dynamic load, which causes the increase in fringe number and the decrease in fringe period. Thou
39、gh both the fringe number and the fringe period are sensitive to the dynamic load, their sensitive ranges are different. The sensit</p><p> Considering Eqs. (5) and (6), the functions between loads and frin
40、ge number and fringe period can be approached as Eqs. (7) and (8), respectively:</p><p><b> (7)</b></p><p> Ls=ksn1Nf+ksn2</p><p><b> (8)</b></p>&
41、lt;p> where ksn1, ksn2, kst1 and kst2 are the parameters approached. </p><p> 3.3. Repeatability of the sensor</p><p> Three experimental results under the same loading conditions are comp
42、ared in Fig. 5 demonstrating that the dynamic fiber optic pressure sensor has good repeatability.</p><p> Fig. 5. Illustration of the repeatability of the optic fiber sensor.</p><p> View
43、 Within Article</p><p> 3.4. Calibration of the sensor</p><p> According to the fringe number and period of the optic fiber sensor output, the dynamic load and static load of the vehicle passe
44、d can be obtained from the calibration process.</p><p> 3.4.1. Calibration of the static weight</p><p> The function approach method was adopted to calibrate the static weight measured. It sho
45、uld be mentioned that the load duration time t should also be gained by the sensor system in order to get the static weight. Usually it is easy to get. The following steps are taken to calibrate the static weight: </p
46、><p> Step 1: Using the function approach method to approach the measured data when the sensor experienced the different static applied load with the same loading rate. Linear function and power function are a
47、dopted for the fringe number data and fringe period data. The approached results are shown in Table 1. </p><p><b> Table 1. </b></p><p> Step 1 approached results</p><p&
48、gt; Full-size table</p><p> View Within Article</p><p> Step 2: Go on using six-order polynomial function to approach the ksn1 = f1(t), ksn2 = f2(t), kst1 = f3(t
49、) and kst2 = f4(t), here the fn(t) are the fitted polynomial functions.</p><p> Step 3: Using ksn1 = f1(t), ksn2 = f2(t), kst1 = f3(t) and kst2 = f4(t) obta
50、ined from step 2 together with Eqs. (7) and (8) to calibrate the fringe number and fringe period measured to static load.</p><p> Due to the limitation of paper length, only the calibration results when t
51、160;= 1 and 4 s are described. In Fig. 6, compared with the real applied static load, the precision of the researched sensor is 5% higher using fringe number readout and 15% higher using fringe period readout.&
52、lt;/p><p> Fig. 6. Static load calibration results.</p><p> View Within Article</p><p> 3.4.2. Calibration of the dynamic weight</p><p> As shown in Eq. (5), the
53、fringe number has a linear relation with the dynamic load. This relationship can be described as</p><p><b> (9)</b></p><p> Ld=kdn1Nf+kdn2</p><p> where kdn1 and kdn2
54、 are the parameters approached. </p><p> The dynamic weight calibration has been developed based on the following assumption. When the loading speed is very slow, the dynamic weight the sensor subjected to
55、can be assumed to be the same as the static weight applied with the slow loading speed. In the experiments, when loading time is 6 s, the largest dynamic load the sensor subjected to is considered to be equal to the
56、 largest static load applied. So the proportionality constants kdf1 and kdf2 between the fringe number and the dynamic l</p><p><b> (10)</b></p><p> kdf1=ksf1|t=6=0.028</p>
57、<p><b> (11)</b></p><p> kdf2=ksf2|t=6=?10.81</p><p> Therefore, the dynamic loads can be calculated using Eq. (9), shown in Fig. 7. Fig. 7 shows that the same largest static
58、 loads under different loading rates produce different dynamic loads. The higher the loading rate is, the bigger the dynamic load is. </p><p> Fig. 7. Dynamic load calibrated results using fringe numbe
59、r readout.</p><p> View Within Article</p><p> To the fringe period readout, since the parameters Ksp1 and Ksp2 are not constants when sensor experiences different dynamic loads, it cannot be
60、calibrated using the above mentioned method.</p><p> 4. Conclusion</p><p> A dynamic optic fiber pressure sensor based on the Michelson interferometer is introduced. This sensor reported here
61、has the advantages of simplicity and low cost. Experiments show that both output fringe number and fringe period can be used to indicate the load. A calibration technology is developed to calibrate the sensor. Both the d
62、ynamic weight and static weight of the passing vehicle can be obtained. The findings resulted from these studies have developed an understanding for the behavior o</p><p><b> 譯文</b></p>&
63、lt;p> WIM系統(tǒng)中以光纖為基礎的動態(tài)壓力傳感裝置</p><p> 沉方元,F(xiàn)ahard Ansarib,劉小慧和楊昭</p><p> 航空重點實驗室,智能材料與結(jié)構(gòu),南京航空航天大學29有道街,南京210016,中國</p><p> 土木與材料工程學院,芝加哥伊利諾伊大學部,伊利諾伊州和IL 60607,美國</p><
64、p> 2004年8月16日收到;</p><p> 2004年11月10日接受。</p><p> 2004年12月15日在線。</p><p><b> 摘要:</b></p><p> 在這里描述一種光纖為基礎的動態(tài)壓力傳感裝置來測量車輛荷載的方法。在研究報告中,是專門設計的邁克爾遜干涉儀的硬件和所設
65、計的軟件遭受不同程度的動態(tài)壓縮載荷和裝載率的實驗。實驗結(jié)果表明,輸出文件數(shù)據(jù)和圖像均可以用來表示動態(tài)負載。于是校準傳感器的校準技術(shù)被提了出來,可以得到無論是動態(tài)的荷載和通過車輛的靜態(tài)荷載。該調(diào)查結(jié)果顯示,在這些研究開發(fā)的干涉下的動態(tài)壓縮應力狀態(tài)傳感器的作用是了解基本的在光纖應用的方案—光纖傳感器監(jiān)測車車輛荷載。</p><p> 關鍵詞:光纖傳感器,動態(tài)壓力,動荷載,硬件和軟件</p><
66、p><b> 文章概要</b></p><p><b> 1.介紹</b></p><p><b> 2.傳感器的設計</b></p><p> 2.1.傳感器安裝</p><p> 2.2.傳感器的工作原理</p><p>
67、 3.程序?qū)嶒灪徒Y(jié)果</p><p><b> 3.1.實驗裝置</b></p><p><b> 3.2.實驗數(shù)據(jù)</b></p><p><b> 3.3.重復試驗</b></p><p> 3.4.傳感器的校準</p><p>
68、 3.4.1.標定的靜態(tài)荷載</p><p> 3.4.2.標定的動荷載 </p><p><b> 4.結(jié)論</b></p><p><b> 1介紹</b></p><p> 過去的幾十年中需要權(quán)衡運動荷載,特別是在交通控制中,已經(jīng)大幅增加。車輛的動荷載幾個技術(shù)現(xiàn)在已經(jīng)應用于包括壓
69、電電纜,電容墊,液壓和彎曲載荷細胞[1]的使用。液壓和彎板稱重傳感器會提高準確度(1-5%)和其動態(tài)范圍,但是因其高安裝成本和規(guī)模的限制而無法廣泛應用。壓電和電容墊技術(shù)會使成本大幅降低,但卻不太準確(5-15%),在速度低于二十公里每小時[2]和[3]的無法正常工作。為了提供降低安裝和維護成本的方法,以光纖為基礎的WIM系統(tǒng)動態(tài)壓力傳感裝置現(xiàn)正開發(fā)的改進,未來可能取代目前使用的裝置。</p><p> 安薩里等
70、人基于光纖偏振,做出了偏振耦合的兩個正交偏振效應的模態(tài)參數(shù)。做出了對壓力動態(tài)測量的高雙折射偏振(HiBi)與運動貨車軸重動荷載的實際后果對比的報告[3]。納瓦雷特和伯納烏報告是對多光纖干涉儀的馬赫曾德爾干涉儀結(jié)構(gòu)組成用另一馬赫曾德爾干涉儀取代作為研究內(nèi)容[4]。科森蒂諾和格羅斯曼開發(fā)利用的是動態(tài)傳感器微彎理論容重在運動中的結(jié)果[5]。</p><p> 本節(jié)描述了一個基于邁克爾遜干涉儀的動態(tài)壓力傳感器的研制,它
71、具有結(jié)構(gòu)簡單,成本低,可提供高精度等許多潛在優(yōu)點。它具有基于Labview Windows / CVI開發(fā)的特殊的硬件和系統(tǒng)軟件,旨在實現(xiàn)消除環(huán)境噪聲的影響,例如,自我引發(fā)的測試程序和條紋數(shù)及附帶期間同時計數(shù)傳感器的功能。傳感器的動態(tài)響應進行研究時,受到了不同程度的負荷率和動態(tài)壓縮載荷的影響。并有研究校準傳感器數(shù)據(jù)標定方法。</p><p> 2 傳感器的設計 2.1傳感器安裝 圖 1說明了擬定的動態(tài)壓力傳
72、感器系統(tǒng)。單模光纖是用來作為傳感元件以構(gòu)成一個邁克爾遜干涉儀。該干涉儀的光電組件包括一個長度在1550納米的激光隔離器和一個光電二極管激光波長。該傳感器是由光纖通信級(康寧SMF28)。從檢測器,放大器的輸出信號是先輸入到一個特殊的硬件電路,包括一個2階高通濾波器,一個零點檢測電路和觸發(fā)器電路。硬件電路的設計實施下列功能:(1)自我診斷的車輛到達時間自行觸發(fā)測量過程;(2)提供消除低頻干擾的功能,如溫度的影響而使該元素的變化緩慢,;(3
73、)提供減少噪音的功能,頻率波段類似的邁克爾遜干涉儀的輸出有用的信息。其中的一個可能的噪聲源是接近路過車輛的線。自邁克爾遜干涉儀的輸出是在壓力下邊緣可以作為高頻比較受溫度變化,激光二極管的性能和低頻率的變化和其它環(huán)境影響,一個2階高通濾波器所造成的噪音信號通過的消除這些低頻成分。一個零點檢測電路的設計更改計算機中的數(shù)據(jù)采集系統(tǒng)反正弦表邊緣,以脈沖信號進行計數(shù)的條紋數(shù)和測量的邊緣時期。自觸發(fā)功能是通過施密特電路,施密特電路的閾值電壓設置根據(jù)
74、實驗來區(qū)分在測試環(huán)境造成的微小振動引起的真正的條紋信</p><p> 圖 1光纖壓力傳感器的動態(tài)設置</p><p> 3 實驗程序和結(jié)果 3.1 實驗裝置 實驗裝置如圖2所示。一個鋼室的設計研究包含光纖。該光纖是夾在兩個1厘米厚的硬橡膠墊和粘在兩個硬橡膠墊件之一上。橡膠墊是為保護光纖不受損壞。該室的裝載鋼材表面的橫截面面積為247.1毫米× 24毫米。該光纖壓力傳感
75、器測量長度為247.1毫米。一個封閉的回路材料的測試系統(tǒng)(MTS)是用于壓力的加載。在不同加載速率和加載程度下的活荷載是動態(tài)負載模擬加載的,荷載是由道路車輛造成的。</p><p><b> 圖2實驗裝置。</b></p><p> View Within Article</p><p> 圖3顯示了應用在斜坡函數(shù)加載的時間,是由常用的
76、裝載配置儀器及附帶的干涉儀的輸出。可以看出在邊緣的左上角的數(shù)字。圖3是太大以至于很難區(qū)分每個邊緣的數(shù)字。因此,數(shù)字有另一個用途,這個數(shù)字是該圈的地方擴大,顯示清晰的邊緣的數(shù)字。由于極化效應,條紋的振幅略有不同。但不會影響計數(shù)和時間,因此,在本文忽視。在實驗中,負荷的壓力在7.5兆帕時增量會多達30 MPa,相應的最大壓力水平從44.5KN增大為最大的178KN。裝載時間是從1開始從第1至6秒遞增。</p><p>
77、; 圖3典型的裝載程序和光纖傳感器的輸出波形。</p><p> View Within Article</p><p> 3.2。實驗數(shù)據(jù)圖4顯示的條紋數(shù)的實驗結(jié)果和不同負荷下的傳感器輸出讀數(shù)的時期。不同的標志線代表不同加載速率之間的傳感器的輸出和負載的最大振幅的關系。</p><p> 圖4實驗結(jié)果:邊緣的數(shù)字和荷載。</p><
78、;p> View Within Article</p><p> 附加的數(shù)字,與靜載荷的線性關系,而邊緣地方有一個非直線的。請注意,這種關系隨著不同加載速率不同,因為相同的最高振幅負荷將變成一個更大的動態(tài)負載,這將導致在條紋數(shù)的增加和邊緣減少。雖然雙方的條紋數(shù)及附加時期敏感的動態(tài)負載,其敏感范圍是不同的,加載時靈敏度是在整個測試范圍不變。當荷載低,動態(tài)荷載小的變化可能無法識別的條紋數(shù)。另一方面,該時期的
79、邊緣敏感負荷不是一個常數(shù)。當荷載降低,動態(tài)負載小的變化對應的邊緣時期大的變化。這兩個參數(shù)可以一起使用提供了更精確的荷載指標進行測試。</p><p> 考慮均衡器(5)及(6),與壓力的條紋數(shù)及附加時期的功能都可以接近的均衡器(7)及(8),分別為:</p><p><b> (7)</b></p><p> Ls=ksn1Nf+ksn2
80、</p><p><b> (8)</b></p><p> 其中參數(shù)ksn1,ksn2,kst1和kst2接近,參數(shù)ksn1,ksn2,kst1和kst2接近。</p><p> 3.3 重復性的傳感器圖5是三個相同加載條件下的實驗結(jié)果進行了比較,動態(tài)展示光纖壓力傳感器具有良好的重復性。</p><p> 圖
81、5光纖傳感器的重復性</p><p> View Within Article</p><p> 3.4。該傳感器的校準根據(jù)條紋數(shù)和光纖傳感器的輸出期間,可從動態(tài)車輛載荷和靜載荷傳遞的過程中校準。</p><p> 3.4.1靜態(tài)重量校準測量該函數(shù)逼近法是采用靜態(tài)重量校準測量。應該一提的是負載持續(xù)時間t也應獲得的傳感器系統(tǒng),以獲得靜態(tài)重量。通常很容易得到
82、的。采取以下步</p><p> 第1步:使用函數(shù)方法測量數(shù)據(jù)時,經(jīng)歷了不同的傳感器適用于具有相同的靜態(tài)負荷率時。線性函數(shù)和冪函數(shù)采用的條紋數(shù)數(shù)據(jù)及附加期間的數(shù)據(jù)。在接觸的結(jié)果列于表1。表1 第1步接近結(jié)果</p><p> Full-size table</p><p> View Within Article</p><p>
83、 第2步:繼續(xù)使用6階多項式函數(shù)接近ksn1 = F1類(噸),ksn2 = f2類(噸),kst1 =三級方程式(t)和kst2 = F4類(噸),這里的新的重量(噸)是擬合多項式函數(shù)。第3步:使用ksn1 = F1類(噸),ksn2 = f2類(噸),kst1 =三級方程式(t)和kst2 = F4類(噸)均衡器,從步驟2一起獲得(7)及(8)校準條紋數(shù)及附帶期間測得靜載荷。由于紙張的長度的限制,只有當T =校準結(jié)果1和4秒在圖
84、6中描述。與實際應用靜載荷相比,該研究傳感器精度比使用條紋數(shù)讀出提高5%,比使用附帶期間讀數(shù)高15%。</p><p> 圖。 6。靜負荷測量結(jié)果。</p><p> View Within Article</p><p> 3.4.2權(quán)重的動態(tài)測量式(5)所示,條紋數(shù)已與動態(tài)負載呈線性關系。這種關系可以說是</p><p><
85、;b> (9)</b></p><p> Ld=kdn1Nf+kdn2</p><p> 其中參數(shù)kdn1和kdn2接近。</p><p> 動態(tài)校準權(quán)重的開發(fā)是基于以下的假設。當加載速度很慢,動態(tài)重量傳感器受到可以認為是與加載速度慢的靜態(tài)重量相同。在實驗中,當加載時間為6秒,最大的動態(tài)負載傳感器被認為是平等的最大靜載荷應用。因此,相稱常數(shù)
86、kdf1和kdf2之間的條紋數(shù)和動態(tài)負載可以用噸來計算,即數(shù)據(jù)</p><p><b> (10)</b></p><p> kdf1=ksf1|t=6=0.028</p><p><b> (11)</b></p><p> kdf2=ksf2|t=6=?10.81</p>
87、<p> 因此,可以用計算式(9)動態(tài)加載。,如圖7所示。圖7顯示,根據(jù)不同的負荷率相同的最大靜載荷產(chǎn)生不同的動態(tài)負載。較高的負荷率,更大的動態(tài)負載。</p><p> 圖7動態(tài)負載校準結(jié)果使用條紋數(shù)讀數(shù)。</p><p> 要讀出邊緣時期以外的數(shù)據(jù),參數(shù)Ksp1和Ksp2不是常數(shù)時,以不同的動態(tài)負載傳感器的經(jīng)驗,它不能被使用上述方法校準。</p><p
88、><b> 4結(jié)論</b></p><p> 這里報告在使用一個光纖壓力傳感器的基礎上,介紹了邁克爾遜干涉儀。該傳感器具有簡單和成本低等優(yōu)點。實驗結(jié)果表明,兩個輸出條紋數(shù)及附加期可用于指示荷載。通過校正技術(shù)來開發(fā)校準傳感器。無論是動態(tài)的車輛荷載,和靜態(tài)荷載可以得到。根據(jù)上述這些研究,國家制定了動態(tài)壓縮干涉下的應力傳感器,這一類傳感器可以應用到監(jiān)測車在行駛中車輛的重量。</p&
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