外文翻譯-基于gps的動物跟蹤系統(tǒng)

1、<p>　　基于GPS的動物跟蹤系統(tǒng)</p><p><b>　　摘要：</b></p><p>　　野外感知系統(tǒng)是一種用于監(jiān)測沼澤鹿行為和遷徙模式的無線傳感網(wǎng)。該系統(tǒng)將收集微氣候以及動物的位置信息，并將這些信息以數(shù)據(jù)流的方式使用點(diǎn)對點(diǎn)網(wǎng)絡(luò)傳達(dá)到基站?；臼褂镁W(wǎng)關(guān)，將收集到的所有數(shù)據(jù)上傳到互聯(lián)網(wǎng)上的一個數(shù)據(jù)庫和用基于可視化軟件的瀏覽器將這些信息描繪出來。每一

2、個點(diǎn)將顯示五個信息，即：位置（用GPS），溫度，濕度，前進(jìn)方向和環(huán)境亮度。此外，該節(jié)點(diǎn)將有一個實(shí)時時鐘同步網(wǎng)絡(luò)和保持時間信息。一個外部數(shù)據(jù)閃存空間將會用于記錄從傳感器和網(wǎng)絡(luò)節(jié)點(diǎn)上獲取的數(shù)據(jù)。無線電收發(fā)機(jī)通過點(diǎn)對點(diǎn)的通信協(xié)議將數(shù)據(jù)傳送到基站。一個太陽能接受系統(tǒng)為電池提供節(jié)點(diǎn)能量，用于延長節(jié)點(diǎn)的壽命。這個系統(tǒng)將會被做成項圈的形式，這樣能比較容易的套在動物的脖子上。</p><p>　　關(guān)鍵詞：GPS跟蹤；野外感知系統(tǒng)

3、；無線傳感網(wǎng)，野生動物跟蹤，微型氣候感知器</p><p><b>　　I.前言</b></p><p>　　無線傳感器網(wǎng)絡(luò)(WSN)總是使用從分布式自治節(jié)點(diǎn)空間獲得的感知。把微型傳感器、微控制器、無線電收發(fā)機(jī)和一種帶有電源,低功耗和廉價的傳感器節(jié)點(diǎn)(我們將簡單地稱之為節(jié)點(diǎn))結(jié)合可以用于監(jiān)視物理或環(huán)境的條件,如不同位置上的溫度、聲音、振動、壓力、運(yùn)動等。對于正在移動的

4、節(jié)點(diǎn)這個任務(wù)將變得更具挑戰(zhàn)性。工程所要進(jìn)一步研究的問題是如何使節(jié)點(diǎn)的電力供應(yīng)足夠維持到最后一年。這篇文章的重點(diǎn)就是如何通過對數(shù)據(jù)的處理，改善無限傳感網(wǎng)的設(shè)計來突破無限 傳感網(wǎng)在能量方面的束縛。</p><p>　　過去已經(jīng)見過各種各樣的無線傳感器網(wǎng)絡(luò)應(yīng)用于棲息地監(jiān)控、地震檢測,環(huán)境監(jiān)測、健康系統(tǒng)監(jiān)統(tǒng)等,這些領(lǐng)域很少會遇到移動節(jié)點(diǎn),動態(tài)網(wǎng)絡(luò)拓?fù)?通信失敗,電力供應(yīng)有限,惡劣的環(huán)境條件變化等情況。</p>

5、<p>　　為了從對野生動物監(jiān)測中尋到解決問題的方法和了解動物與其周圍環(huán)境的復(fù)雜的關(guān)系,科學(xué)家必須親自到現(xiàn)場去收集所需要的數(shù)據(jù)。在某些情況下將無線電發(fā)射機(jī)安置動物身上能讓研究變得更加容易,但是圖像的大部分仍然不能被標(biāo)記出來，因為缺少有效的數(shù)據(jù)收集。有許多理由去解釋為什么頻繁的到現(xiàn)場去做調(diào)查是困難和不明智的。首先,研究物種時要做到完全避免人類干擾幾乎是不可能的。人類頻繁的訪問或打擾已潛移默化中對物種產(chǎn)生了影響 [1]。其次,

6、在晚上追蹤活動的動物與其說是做實(shí)驗或做研究還不如說是冒險。最后, 如果不使用專用的低成本傳感器網(wǎng)絡(luò)設(shè)備。它不僅費(fèi)時而且需要花費(fèi)大量的資金來跟蹤動物遷移以及其飲食習(xí)慣。</p><p>　　因此就需要一個自動化的系統(tǒng),帶有擁有眾多網(wǎng)絡(luò)傳感器節(jié)點(diǎn)的自然空間能夠長時間的收集數(shù)據(jù)(即使在夜間)、如果沒有這樣的系統(tǒng)，靠人工檢測，則研究范圍和結(jié)論的準(zhǔn)確率則非常有限。它還能夠在不對生態(tài)造成干擾的情況下收集數(shù)據(jù)和相比傳統(tǒng)研究方式

7、來說，它是一種更為經(jīng)濟(jì)方法來進(jìn)行長期的研究。一些監(jiān)控野生動物運(yùn)動和習(xí)性的先進(jìn)理念曾做過嘗試，如斑馬網(wǎng)絡(luò)[2]和偉大的鴨子島實(shí)驗[1]。通過以上經(jīng)驗的學(xué)習(xí)，我們可以知道生物感知網(wǎng)絡(luò)的構(gòu)建也是出于同樣的出發(fā)點(diǎn)。它是擁有更低能耗,更大的范圍、更加多樣的環(huán)境感知特性和更健壯數(shù)據(jù)備份的系統(tǒng)。</p><p>　　野外感知系統(tǒng)是一個用于監(jiān)控沼鹿(澤鹿)行為和遷移模式的無線傳感器網(wǎng)絡(luò)系統(tǒng)。該系統(tǒng)對于那些中型或大型的物種同樣適用

8、。這個系統(tǒng)中配有GPS、無線收發(fā)器和其他各種傳感器、硬件為支持野生動物監(jiān)控的需要而設(shè)計的。捕獲的數(shù)據(jù)可以提供給野生動物研究人員讓他們完成研究和學(xué)習(xí)的目。它將有助于他們理解瀕危物種的需求,以及這些物種與周圍的環(huán)境關(guān)系。本文在節(jié)點(diǎn)，基地，網(wǎng)絡(luò)的水平上探討了野外感知系統(tǒng)的硬件和軟件設(shè)計的體系結(jié)構(gòu)。特別是它把設(shè)計和測試系統(tǒng)時遇到的問題也體現(xiàn)了出來。</p><p>　　II.基于GPS的動物跟蹤系統(tǒng)</p>

9、<p>　　生物傳感網(wǎng)是一種試圖讓研究人員了解更多有關(guān)沼鹿的生活習(xí)性的途徑。輸入的該系統(tǒng)的設(shè)計要有哪些功能由野生動物研究人員輸入。這個系統(tǒng)計劃將帶有傳感器的輕質(zhì)項圈安放在動物的脖子上。這個項圈會從附近動物中收集到科學(xué)研究所需要的數(shù)。將收集到的有用數(shù)據(jù)數(shù)據(jù)發(fā)送到其他節(jié)點(diǎn)或基站, (基站越來越偏好的情況下兩者都是可用)。</p><p>　　這個系統(tǒng)的主要的功能是使用GPS跟蹤動物的遷徙運(yùn)動。要獲取的數(shù)據(jù)

10、除了位置信息,還包括動物的生活習(xí)性和它的周圍環(huán)境參數(shù)。也可以說成是一項對動物的活動的研究。動物的生活模式需要被記錄下來。自從監(jiān)測區(qū)域變大后,獲得的數(shù)據(jù)需要不斷的從一個節(jié)點(diǎn)傳到另一個節(jié)點(diǎn)依據(jù)直到它轉(zhuǎn)移到一個基站。最后系統(tǒng)需要運(yùn)行持續(xù)至少12個月,因此電源設(shè)計和使用需要優(yōu)化</p><p>　　位置記錄: 在監(jiān)測動物的遷移模式時，GPS需呀能夠精準(zhǔn)的定位。研究人員指定的位置每3個小時能發(fā)生三次GPS位置信息就足以繪畫

11、出這個動物的近一年的運(yùn)動軌跡</p><p>　　周圍環(huán)境:由于在過去的一年里沼鹿的遷徙受地面植被的覆蓋率的影響,所以研究人員還需要監(jiān)控動物的居住和覓食環(huán)境。用于測量溫度、濕度,和光線以及動物活動的傳感器也同時安裝在了系統(tǒng)里。</p><p>　　數(shù)據(jù)傳輸和恢復(fù): 分散的數(shù)據(jù)只有在被傳播到基站(s)的情況下才能被科學(xué)家收集起來用于分析。因為沼鹿的活動范圍相當(dāng)?shù)拇?，所以不可能在它們的整個活動

12、地區(qū)安裝眾多基站。為了解決這個問題,我們需要通過移動網(wǎng)絡(luò),采用點(diǎn)對點(diǎn)通信方式是試</p><p>　　圖在無線卡插槽上傳輸數(shù)據(jù)[2]。為了彌補(bǔ)時間上的延遲,節(jié)點(diǎn)上安裝了一個較大的外部flash用來容納數(shù)據(jù)在節(jié)點(diǎn)上的生成時間以及傳輸過程中獲取的時間。3.1節(jié)討論更詳細(xì)的討論了數(shù)據(jù)的交流問題。</p><p>　　能量獲取:每一個檢測點(diǎn)都必須工作最少一年,用于追蹤遷移路徑,避免人為干預(yù)。他們與

13、其他節(jié)點(diǎn)唯一的連接是通過無線鏈接或基站。而且,由于在節(jié)點(diǎn)的重量上有一個限制,就不能提供一個巨大的電源供應(yīng)。因此,節(jié)點(diǎn)需要輕量級電力備份系統(tǒng)。鑒于這種動物大部分在露天的環(huán)境下活動,所以可以通過太陽能來給系統(tǒng)提供電力供應(yīng)。只要認(rèn)真落實(shí)能源采集，補(bǔ)充的管理政策,能源的需求容易得到滿足。能源的提供將會在3.3節(jié)更詳細(xì)地討論</p><p><b>　　III．系統(tǒng)概述</b></p>

14、<p>　　大體上生物傳感網(wǎng)系統(tǒng)分為如圖1所示的幾個部分,即硬件、相關(guān)系統(tǒng)軟件和驅(qū)動器,中間設(shè)備服務(wù)器連接數(shù)據(jù)記錄和web主機(jī)服務(wù)設(shè)備最后基于瀏覽器的可視化軟件。</p><p>　　圖1 生物傳感網(wǎng)系統(tǒng)概述</p><p><b>　　1)硬件架構(gòu)</b></p><p>　　完整的傳感器節(jié)點(diǎn)連同電池充電系統(tǒng)的是以一個項圈的形式呈

15、現(xiàn)的，它被套在了沼鹿的脖子上。生物傳感網(wǎng)節(jié)點(diǎn)的硬件系統(tǒng)的體系結(jié)構(gòu)如圖2所示。</p><p><b>　　圖2 硬件設(shè)計框架</b></p><p>　　為了滿足在準(zhǔn)確性、能量、電壓兼容性和成本方面的考慮[6]，每個組件都在原來的基礎(chǔ)上經(jīng)過了精心挑選。這個組件由如下的一個單個節(jié)點(diǎn)組成:</p><p>　　微控制器——ATMega1281V[7

16、],128 k字節(jié)程序內(nèi)存,是核心處理單元的設(shè)計。它有4 k字節(jié)的eepm和8 k字節(jié)的存儲器。有兩個可獨(dú)立使用的串口。</p><p>　　GPS和無線電收發(fā)機(jī)的通信與核心處理單元同步。這使我們能夠消除軟件章節(jié)3.2節(jié)描述的多路復(fù)用的開銷。當(dāng)連續(xù)通信是，內(nèi)部諧振器是不夠準(zhǔn)確，這時需要在外部加上一個1.83728 MHz的晶振。(限制波特誤差百分之零[7])。</p><p>　　實(shí)時時鐘

17、——DS3231[8]——為了能夠使所有的節(jié)點(diǎn)在同一個時間啟動以達(dá)到同步。外部RTC必須準(zhǔn)確將這些節(jié)點(diǎn)同步。它還產(chǎn)生周期性的中斷來將微控制器從“斷電”睡眠模式中喚醒。高度的準(zhǔn)確性,集成的溫度測量使設(shè)備的晶體振蕩器(TCXO)、I2C接口在不同的波特率工作時仍能適合這一應(yīng)用。系統(tǒng)中在時間上的任何不匹配(在兩個交互節(jié)點(diǎn))將會花費(fèi)大量的電力在網(wǎng)絡(luò)的同步上。由于運(yùn)行環(huán)境的不同，RTC在不同的節(jié)點(diǎn)上運(yùn)行是有偏差的。為了維護(hù)節(jié)點(diǎn)與節(jié)點(diǎn)之間通信的準(zhǔn)確

18、性,RTC與GPS設(shè)備每五天實(shí)現(xiàn)一次同步,保持1秒內(nèi)的時鐘偏差。</p><p>　　GPS -拉森IQ GPS接收機(jī)與天線[9],它有封裝小、處于工作模式的時候能耗低(89兆瓦為3.3 v)。為了達(dá)到較高的精度,它使用十二處理渠道來跟蹤GPS衛(wèi)星信號。拉森IQ GPS支持NMEA協(xié)議的GPRMC通信形式。這一通信協(xié)議包涵了所有需要的內(nèi)容，即日期、緯度、經(jīng)度和時間。它與單片機(jī)通信頻率為4800個bps。自其讀數(shù)開

19、始， GPS每3小時會自動轉(zhuǎn)換開/關(guān)模式。為了利用GPS的“熱啟動”功能,我們使用一個電池備份機(jī)制。</p><p>　　無線電收發(fā)機(jī)——XBee-Pro[10]——這個數(shù)碼網(wǎng)絡(luò)關(guān)鍵</p><p>　　通信模式是基于IEEE 802.15.4 ZigBee /標(biāo)準(zhǔn)。它運(yùn)行在2.4 ghz ISM波段(只有在印度免費(fèi)提供),通信距離超過一公里。然而和900 MHz相比，傳輸距離相同是，這個

20、頻率導(dǎo)致更高的能源消耗,我們得使用更高的數(shù)據(jù)頻率和更小型而緊湊的天線。</p><p>　　低成本、低功耗和易用性也是其優(yōu)勢。它還提供了五個睡眠模式來滿足不同應(yīng)用場合的需求。當(dāng)它僅是一個供電系統(tǒng)而不使用其時間功能時，我們用最低功率的睡眠模式。幾毫秒的延遲對于系統(tǒng)來說是允許存在的。</p><p>　　內(nèi)存——愛特梅爾公司AT45DB16B數(shù)據(jù)flash[11]，我們需要一個大的內(nèi)存存儲空間

21、來彌補(bǔ)基站與節(jié)點(diǎn)之間通信的延遲。對于我們的無線傳感器網(wǎng)絡(luò),一個節(jié)點(diǎn)需要收集的數(shù)據(jù)來自同行,這要求更高內(nèi)存容量。AT45DB16B擁有SPI接口正好符合了這一要求?；赨CBs環(huán)球文件系統(tǒng)[13]的可操作的內(nèi)部開發(fā)文件系統(tǒng)[12], 的使用,這使得存儲系統(tǒng)簡單和高效。</p><p>　　附加的傳感器,為了收集沼鹿周圍環(huán)境的參數(shù)，從大鴨島上的經(jīng)驗試驗[1]中得知我們需要在節(jié)點(diǎn)上安裝數(shù)字傳感器。濕度傳感器有內(nèi)置的加熱

22、器用于蒸發(fā)吸收水。Sensirion SHT11的[14]傳感器是一個數(shù)字溫度和濕度傳感器(分辨率:0.01°C和0.05% RH)的組合。這傳感器是被一個蓋帽(IP67標(biāo)準(zhǔn))遮著，使其感知環(huán)境的同時達(dá)到保護(hù)它的作用。我們使用一個TAOS的TSL2561t[15]這是一款高靈敏度的數(shù)字光傳感器。 為了監(jiān)控動物的活動我們使用了飛思卡爾半導(dǎo)體 的MMA6270QT[16]模擬加速度計。這些擁有位置信息的數(shù)據(jù)為更加深入的了解沼鹿的遷

23、移模式及與氣候的變化。</p><p>　　節(jié)點(diǎn)的設(shè)計采用大量的減少噪音的技術(shù)。為了降低ADC的噪聲，一個LC濾波器（L =10MH和C=0.1μF的）已被添加到的ADC引腳的微控制器。此外，為了減少噪音[6]，AVCC被連接到主電源供應(yīng)系統(tǒng)且沒有任何扇區(qū)出線。整個PCB敷銅用以使噪聲保持在最低水平，同時還消散節(jié)點(diǎn)產(chǎn)生的熱。如圖3所示。節(jié)點(diǎn)的大小為5×6平方厘米，僅重34gms。包括電源（LIION電池

24、與太陽能充電機(jī)制）體系的總重量為，不含項圈小于300gms（使用4鋰離子電池重148克）。</p><p>　　圖3 （a）頂視圖 （b）底視圖</p><p><b>　　2）軟件架構(gòu)</b></p><p>　　設(shè)計主要解決的是問題是能源，wildCENSE軟件工具的有效的調(diào)度和事件同步。節(jié)點(diǎn)大部分時間都保持在休眠/無效模式。以一個產(chǎn)生周期

25、性中斷的實(shí)時時鐘（RTC）為基礎(chǔ)，從的傳感器和GPS上收集所需的數(shù)據(jù)。準(zhǔn)確性的RTC有助于實(shí)現(xiàn)節(jié)點(diǎn)到節(jié)點(diǎn)，或節(jié)點(diǎn)與基地之間信息的同步。 GPS每3小時發(fā)送一次數(shù)據(jù)，并安設(shè)定好的每十分鐘喚醒相應(yīng)的傳感器。無線收發(fā)機(jī)， GPS和外接存儲器都有獨(dú)立的端口，即USART0，USART1，SPI，我們都能同時使用它們。當(dāng)GPS處于開機(jī)狀態(tài)，并在修理的過程， 如果附近有節(jié)點(diǎn)/基站則可以無線電進(jìn)行數(shù)據(jù)的傳輸。當(dāng)前讀/寫數(shù)據(jù)段的指針存儲在微控制器的EE

26、PROM。這的優(yōu)點(diǎn)是在重新啟動的情況下，（如看門狗復(fù)位），數(shù)據(jù)段指針可以從EEPROM中重新獲取，</p><p>　　一旦發(fā)現(xiàn)了節(jié)點(diǎn)/基站，所以得節(jié)點(diǎn)會在相同的時間開啟和并同時進(jìn)行數(shù)據(jù)交換。成功轉(zhuǎn)移到所述基站的數(shù)據(jù)是將會從節(jié)點(diǎn)中刪除。微控制器和無線收發(fā)信機(jī)之間的通訊波特率被設(shè)置為57600，雖然這個無線電收發(fā)機(jī)也支115200的波特率。我們的測試結(jié)果表明， 在較低的波特率（57600）數(shù)據(jù)有更好的可靠性，因此使

27、用了這以波特率。</p><p><b>　　3）系統(tǒng)能源管理</b></p><p>　　WSN的能源需求是設(shè)計時要考慮的最最關(guān)鍵的要素。當(dāng)權(quán)衡節(jié)點(diǎn)的重和??它的能量所需時，野生動物監(jiān)測方案變得更具挑戰(zhàn)性。在本節(jié)中，我們將在軟件和硬件水平上討論我們的能源管理技術(shù)，和野外感知體系。圖4中所示的是一個節(jié)點(diǎn)能源消耗的比例圖。能量的具體消費(fèi)計算在本節(jié)C部分。</p&g

28、t;<p>　　圖4 野外感知系統(tǒng)節(jié)點(diǎn)的功耗必比例圖</p><p>　　A.硬件級別的能源管理 理想的檢測節(jié)點(diǎn)包涵一定數(shù)量的傳感器沿與其他外圍設(shè)備，如RTC，外部閃存和無線電收發(fā)信機(jī)。為這樣復(fù)雜的系統(tǒng)設(shè)計一個簡單的電源供應(yīng)器是一個巨大的挑戰(zhàn)。所有組件和傳感器都經(jīng)過精心挑選，都是低功耗以及幾乎相同的輸入電壓范圍3.3V。該系統(tǒng)是由一個可再充電的鋰離子電池供電，它可以安全地電壓范圍為2.7

29、 V至4.2 V。太陽能發(fā)電被附加上去以便進(jìn)一步增強(qiáng)節(jié)點(diǎn)的壽命。此外，未用引腳和數(shù)字輸入緩沖器分別被配置成輸出引腳和禁用，最大限度地減少他們的能源泄漏。使用一個共同的電壓（3.3V）的決定不僅是為了節(jié)點(diǎn)電壓設(shè)計的簡單，同時也能夠節(jié)省那些浪費(fèi)在不同的電壓調(diào)節(jié)上的能量。為了最大限度的利用電池的能量，一個DC / DC轉(zhuǎn)換器，德州儀器（TI）[17]的一款降壓升壓器TPS63001被使用。它可提供恒定的輸出電壓3.3V的最大輸出電流1.8A;

30、轉(zhuǎn)換效率高達(dá)96％。</p><p>　　B.軟件級別的能源管理</p><p>　　當(dāng)節(jié)點(diǎn)處于非活動狀態(tài)時，野外感知系統(tǒng)采用微控制器的“關(guān)機(jī)”睡眠模式，從而節(jié)省了大量的能源。另一種方法是使用雙時鐘方案，而不是睡眠模式，但是使用外部實(shí)時定時器時鐘的同時，我們?nèi)阅軌蛲ㄟ^它自身的掉電模式功能節(jié)省能源。這個斷電模式的特點(diǎn)是把所有的一切都關(guān)機(jī)，并且通常包括時鐘源[7]，在3.3V的電壓下消耗的電流

31、小于10uA的“看門狗”。掉電檢測器是在睡眠模式狀態(tài)狀態(tài)下[18]唯一工作的模擬量模塊。但是，因為自從該模塊在我們的設(shè)計中不需要以后，我們已經(jīng)把它永久關(guān)閉，確保進(jìn)一步降低 “斷電”睡眠模式的供電。在處理和讀取傳感器時需要較小的延時，這個時候另一個節(jié)省功耗的模式，“省電”睡眠模式將被使用。</p><p>　　隨著微控制器，其他外圍設(shè)備也提出休眠模式，以最大限度地減少能源的使用。當(dāng)節(jié)點(diǎn)是在睡眠模式時GPS被關(guān)閉。這

32、是通過電源開關(guān)TPS2092[19]來實(shí)現(xiàn)的，。應(yīng)用程序不是每時每刻的使用使我們有機(jī)會讓無線收發(fā)器處在最低功耗模式下，這一模式的功耗不到其他模式1/5。</p><p>　　C.節(jié)點(diǎn)壽命估算表1說明了節(jié)點(diǎn)上的各個組件的電力需求。以下假設(shè)是基于每個節(jié)點(diǎn)的組件能工作最低一年：?節(jié)點(diǎn)每3小時進(jìn)行測量。?假設(shè)，大部分的時候，沼鹿活動在露天的環(huán)境里，可得到一個明確的GPS位置信息。?每隔一小時，節(jié)點(diǎn)通過RTC同步

33、試圖與其他節(jié)點(diǎn)/基地進(jìn)行聯(lián)系，。</p><p>　　?只有70％的鋰離子電池的能量已經(jīng)假定可用[20]。?最后，我們假設(shè)一個節(jié)點(diǎn)，每天會從其他節(jié)點(diǎn)收到最多7頁數(shù)據(jù)并想其他節(jié)點(diǎn)發(fā)送一頁的轉(zhuǎn)換數(shù)據(jù)。在一個月的時間里，該節(jié)點(diǎn)把它的所以數(shù)據(jù)都傳輸給基站。 按上述的假設(shè)和使用所述的硬件，每個節(jié)點(diǎn)每天需要13.5mAh能量或7040mAh一年。為了滿足上述要求，鋰離子電池包8Ah的容量是足夠的。太陽能充電可進(jìn)一步

34、延長節(jié)點(diǎn)的工作時間。在表1中，我們將用“TX”代表發(fā)送模式，“RX” 代表接收模式和“PD”代表斷電模式。 “組件在不同模式下的平均電流（以毫秒安培）的要求在第4欄給出。第5列“T”給所采取的傳感器及其它外設(shè)單次讀出的典型時間（單位為秒）。最后一列，即“C”是在不同的模式下各個組件每天的電流需求（mAh）。</p><p><b>　　表1 節(jié)點(diǎn)壽命估計</b></p><

35、;p><b>　　IV 總結(jié)</b></p><p>　　本文提出了一種用于監(jiān)測野生動物的無線傳感網(wǎng)操作原型。 野外感應(yīng)是一種緊湊，準(zhǔn)確，高效節(jié)能的感應(yīng)。除了高效節(jié)能，它還提供詳細(xì)的位置信息且擁有非常高的精度。 軟件協(xié)議和硬件實(shí)現(xiàn)都經(jīng)過精心設(shè)計，以實(shí)現(xiàn)優(yōu)化系統(tǒng)能源的要求。雖然GPS和無線電收發(fā)器等單元要消耗相當(dāng)大的能源，但是利用太陽能充電機(jī)制，節(jié)點(diǎn)壽命將大為提高。</p>

36、<p><b>　　英文原文：</b></p><p>　　wildCENSE: GPS based Animal Tracking System</p><p>　　Abstract—wildCENSE is a Wireless Sensor Network (WSN) system which attempts to monitor the beh

37、aviour and migration patterns of Barasingha (Swamp Deer). The system would collect the micro-climatic as well as positional information of the animal and communicate it to a base station through flooding of data using pe

38、er-to-peer network. The base station, using a gateway, upload all the collected data to a database server on Internet and portray the information using browser based visualization softwa</p><p>　　the synchro

39、nization of the network and to keep timing information. An external data flash memory would be used to record the data collected from sensors and other peer nodes. A radio transceiver would transmit the data to the base

40、station by using a peer to peer communication protocol. A solar energy harvesting system for recharging node’s power supply batteries is being added to prolong the lifetime of nodes. The system would be integrated in the

41、 form of a collar that can be easily fitted on th</p><p>　　Keywords- GPS Tracking; wildCENSE; micro-climate sensing; Wireless Sensor Networks; wildlife tracking </p><p>　　I. INTRODUCTION </p&

42、gt;<p>　　Wireless sensor networks (WSN) invariably employ sensing from spatially distributed autonomous nodes. With a little jugglery of sensors, micro-controllers, radio transceiver and an energy source, low-powe

43、r and inexpensive sensor nodes (we’ll simply call them nodes) can be made to cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion etc. at different locations

44、. The task becomes more challenging when the nodes are mobile. To further qu</p><p>　　The recent past has seen a wide variety of WSN applications namely Habitat monitoring, Seismic Detection, Environmental m

45、onitoring, Health monitoring systems etc., of which mobile nodes, dynamic network topology, communication failure, limited power supply, harsh environmental conditions are few of the varied challenges. </p><p&

46、gt;　　To address the issues in wildlife monitoring and to understand the complex relationship of animals with their surrounding, scientists had to collect the required data manually by visiting the site. In some cases the

47、 search was made easier by tagging the animal with radio transmitters to relocate them easily, but yet the seemingly bigger part of the picture remained un-addressed: the efficient data collection. There are numerous rea

48、sons why it is difficult and not advisable to visit the site freq</p><p>　　An automated system would thus be desired, equipping natural spaces with numerous networked sensor nodes to enable long-term data co

49、llection at times (even at night), scales and resolution which are very difficult if not impossible, to achieve by manual monitoring. It also allows collecting data without disturbing the ecology and yet represents a sub

50、stantially more economical method for conducting long-term studies than traditional one. Significant proofs of concepts and previous attempts to mon</p><p>　　wildCENSE is a WSN system which attempts to monit

51、or the behavior and migration patterns of Barasingha (Swamp Deer). System being designed can be suitable for many more species of medium to large size. Equipped with a GPS, Radio transceiver and various other sensors, th

52、e hardware is designed to support the needs of wildlife monitoring. The captured data can be provided to the wildlife researchers for their research and study purposes. It will be helpful to them to understand the needs

53、of the enda</p><p>　　The paper fundamentally discusses the hardware and software design architecture of the wildCENSE system at the node, base and network levels. In particular, it embodies the issues and co

54、nstraints, which were met during the design and testing of the system. </p><p>　　II. GPS BASED ANIMAL TRACKING SYSTEM </p><p>　　The Barasingha is native to India and Nepal. Once it populated thr

55、oughout the basins of the Indus, Ganges and Brahmaputra rivers, as well as parts of central India reaching out till the river Godavari. But in past few decades its population has declined significantly listing them as en

56、dangered species by IUCN from 1984 to 1996 and as vulnerable since 1996 [4]. Wildlife researchers while surveying Jhilmil Tall (Uttaranchal) area came across some 30 heads of the Barasingha on February 3, 2005 [5].</p

57、><p>　　The prime requirement is to track the migratory movement of the animal which is done using a Global Positioning System (GPS). Besides the location, the animal's habitat and its ambient environment pa

58、rameters are of interest. Also a study of the animal’s activities viz. the grazing patterns of the animal needs to be recorded. Since the area under surveillance is large, the acquired data needs to be propagated on a no

59、de to node basis until it is transferred to a base station. Lastly the system nee</p><p>　　Positional Logs: The GPS reading needs to be accurate and precise, in view with the migration pattern of the animal.

60、 As researchers specify, a location reading every 3 hours would be enough to draw a close enough movement track of the animal over a year. </p><p>　　Ambient Environment: With the animal covering a lot of gro

61、und during its migration over the year, the researchers also need to monitor the environment in which the animal dwells and grazes. Sensors for measuring the temperature, humidity, and light as well as animal activity ar

62、e embodied in the system. </p><p>　　Data Transmission and Recovery: To collect the dispersed data for analysis by the researchers, it needs to be transmitted to the base station(s). Since the Barasingha has

63、a fairly large movement track it is not possible to equip the entire region with numerous base stations. To address this issue, the data needs to be moved through the network, employing node to node communications as was

64、 attempted in Zebranet[2]. In order to compensate for high latency, the node has a large external flash to ac</p><p>　　Energy harvesting: The nodes need to be alive for a minimum of a year, tracking the migr

65、ation path, avoiding any human intervention. Their only contact is the wireless link with other nodes or the base station as the case may be. Also, since there is a limitation on the weight of the node, a bulky power sup

66、ply is forbidden. Hence, the node needs to have lightweight power back up system. Given that the animal will mostly be in large fields under open skies, the required power supply could be equi</p><p>　　III.

67、System Overview </p><p>　　Broadly the wildCENSE system is divided as in Figure 1, namely the hardware, related system software and drivers, middleware servers with data logging and web hosting services and f

68、inally the browser based visualization software. </p><p>　　1) Hardware Architecture </p><p>　　The complete sensor node along with the battery recharging system is in the form of a collar to be w

69、orn by the animal. Hardware system architecture of wildCENSE node is as depicted in Figure 2. The design issues as discussed in Section 2 have been carefully met. </p><p>　　Each component has been carefully

70、selected based on earlier prototypes to meet accuracy, power, voltage compatibility and cost considerations [6]. The components that make up a single node are as follows:</p><p>　　Micro-controller – ATMega12

71、81V [7], with 128K bytes program memory, is the core processing unit of our design. It has 4K bytes of EEPROM and 8K bytes of SRAM. The availability of 2 USART ports enables independent </p><p>　　Figure 1. w

72、ildCENSE System Overview</p><p>　　communication of GPS and Radio transceiver with the core processing unit simultaneously. This allows us to remove the multiplexing overhead as described in the software sect

73、ion 3.2. The internal resonator is not accurate enough for serial communication, so an external crystal of 1.83728 MHz is used. (limiting baud error to zero percent [7]). </p><p>　　Real Time Clock - DS3231 [

74、8] - For node discovery, all the nodes need to wake up at the same time requiring them to be synchronized. External RTC is required to accurately synchronize these nodes. It also generates periodic interrupts to wake up

75、the micro-controller from its “Power Down” sleep mode. Features like extreme accuracy, integrated temperature compensated crystal oscillator (TCXO), I2C interfacing at different baud rates make the device ideal for this

76、application. Any mismatch in the t</p><p>　　GPS – Lassen iQ GPS Receiver with antenna [9] – It has a small footprint, low energy consumption (89mW at 3.3V) in active mode. To achieve high accuracy, it uses t

77、welve processing channels to track the GPS satellite signals. Lassen iQ GPS supports the required NMEA protocol with GPRMC message format, which contains all the required information namely date, latitude, longitude and

78、time. It serially communicates with the microcontroller at 4800 bps. Our GPS is used in On/Off mode since readings ar</p><p>　　Radio Transceiver – XBee-Pro [10] -This Digi-Key communication module is based o

79、n ZigBee/IEEE 802.15.4 standard. It operates at 2.4GHz (only freely available ISM band in India), providing a range of more than a kilometer. While using this frequency results in higher power consumption for same range

80、compared to 900 MHz, we gain in terms of much higher data rate and smaller compact antenna. </p><p>　　Low cost, low power and ease of use are among the other advantages. It also provides five sleep modes to

81、meet various needs of different applications. We use lowest power sleep mode as it is not a time but power critical system. Delay of few milliseconds of wake up are well within the system’s tolerance</p><p>

82、　　Figure 2. wildCENSE Hardware setup depicting various components, their interfacing and power supply. </p><p>　　Memory – ATMEL AT45DB16B Data flash [11] A high memory storage is required to complement the l

83、ong latency of communication between the base and the node. For our WSN, a node needs to collect data from its peers, asking for a higher memory capacity. AT45DB16B, with SPI interfacing looks quite promising for the sce

84、nario. An operational in-house developed file system [12], based on UCBs Matchbox file system [13], is being used, which makes the storage system simple and efficient. </p><p>　　Additional sensors - To colle

85、ct the ambient environment parameters of the animal, the node mostly incorporates digital sensors, as from the experiences of Great Duck Island Experiment [1]. The humidity sensor has an inbuilt heater to evaporate absor

86、bed water. Among the set of sensors are the Sensirion’s SHT11 [14] which is a digital temperature and humidity sensor (Resolution: 0.01°C and 0.05% RH). This sensor is shielded by a cap (IP67 standard) which lets it

87、 sense the environment but at the sa</p><p>　　The node has been designed employing numerous noise reduction techniques. To reduce the ADC noise, a LC filter (L=10mH and C=0.1uF) has been added to the ADC pin

88、s of the micro-controller. Also, the AVCC is connected to the main power supply without any in between fan out lines, to reduce noise [6]. The whole PCB has copper pouring to keep the noise at a minimum level as also to

89、dissipate any heat generated by the node. Figure 3 depict the node. The size of the node is 5 x 6cm2, weighing only 34g</p><p>　　(a) (b) </p><p>　　Figure 3. wildC

90、ENSE node, (a)top view (b)bottom view </p><p>　　2)Software Architecture </p><p>　　Addressing the main design constraint, the energy; wildCENSE software implements effective scheduling and synchr

91、onizing of events. The node is kept in sleep/inactive mode for most of the time. Desired data is collected from sensors and GPS on the basis of periodic interrupts generated by a real time clock (RTC). The accuracy of th

92、e RTC helps the node in synchronization during node to node interactions as also with the base. GPS samples are taken every 3 hours and the wake up of respective sensor</p><p>　　All of the nodes wake up at t

93、he same time and the data exchange process is initiated, once the node/base discovery is done. Data transferred to the base station is successively deleted from the nodes. The communication baud rate between the micro-co

94、ntroller and radio transceiver is set to be 57600, though a higher baud rate of 115200 is supported by this radio transceiver. Our test results show better data reliability at the lower baud (57600) and hence the trade-o

95、ff. </p><p>　　3)System Energy Management </p><p>　　WSN energy requirements are by far the most critical and important design considerations. In case of wildlife monitoring the scenario becomes m

96、ore challenging, where a trade-off is needed between the weight of the node and its energy requirement. In this section we discuss our techniques for energy management, at the software level and the hardware level as wel

97、l for wildCENSE. An instance of the node’s power consumption is shown in Figure 4. The details of energy consumption calculation are give</p><p>　　A. Hardware Level Energy Management </p><p>　　T

98、he desired node is populated by number of sensors along with other peripheral including RTC, external flash memory and radio transceiver. Designing a simple power supply for such complex system was a challenge. All compo

99、nents and sensors were carefully selected to have low energy profile and almost similar input supply range with 3.3V as the common voltage. The system is powered by a re-chargeable Li-ion battery, which can safely have v