機(jī)電外文文獻(xiàn)翻譯--采用Atmel 89S51微控制器的風(fēng)速風(fēng)向測(cè)量系統(tǒng)【中文4420字】【PDF+中文WORD】
機(jī)電外文文獻(xiàn)翻譯--采用Atmel 89S51微控制器的風(fēng)速風(fēng)向測(cè)量系統(tǒng)【中文4420字】【PDF+中文WORD】,中文4420字,PDF+中文WORD,機(jī)電外文文獻(xiàn)翻譯,采用Atmel,89S51微控制器的風(fēng)速風(fēng)向測(cè)量系統(tǒng)【中文4420字】【PDF+中文WORD】,機(jī)電,外文,文獻(xiàn),翻譯,采用,Atmel,89
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采用Atmel 89S51微控制器的風(fēng)速風(fēng)向測(cè)量系統(tǒng)
Eunice Sophia K T 物理系
Sri Krishnadevaraya大學(xué)，Anantapuramu -515003，A.P.，印度
電子郵件：eunice.sophia@gmail.com
Raghavendra Rao Kanchi
SK大學(xué)工程與技術(shù)學(xué)院物理系主任，VLSI與嵌入式系統(tǒng)實(shí)驗(yàn)室教授，
Anantapuramu - 515003，A.P.印度
電子郵件：kanchiraghavendrarao@gmail.com
摘要 - 本文介紹了圍繞8051系列微控制器之一構(gòu)建的簡(jiǎn)單儀器設(shè)計(jì)，用于測(cè)量瞬時(shí)風(fēng)速和風(fēng)向。 這個(gè)系統(tǒng)包括一個(gè)改進(jìn)，但價(jià)廉的杯式風(fēng)速計(jì)：戴維斯儀器6410感測(cè)上述兩個(gè)風(fēng)的參數(shù)。 處理系統(tǒng)的準(zhǔn)確性在系統(tǒng)與風(fēng)傳感器接口之前被估計(jì)。 該軟件采用C語(yǔ)言開(kāi)發(fā)，數(shù)據(jù)每三秒鐘在16x2液晶顯示屏上顯示。 然后將收集的數(shù)據(jù)繪制成圓形直方圖進(jìn)行分析。 所設(shè)計(jì)的系統(tǒng)由于其有效測(cè)量的原因而具有進(jìn)一步發(fā)展和應(yīng)用的潛力，這與標(biāo)準(zhǔn)讀數(shù)相關(guān)。
關(guān)鍵詞-AT89S51;風(fēng)速計(jì);LCD; 指南針點(diǎn); 摩擦系數(shù);
1、簡(jiǎn)介
即使技術(shù)日新月異，器件變得更加智能化，8051微控制器及其衍生產(chǎn)品仍然有望在各種應(yīng)用領(lǐng)域找到應(yīng)用。 目前的工作是關(guān)于測(cè)量?jī)蓚€(gè)主要的氣象變量[1]，即在氣象學(xué)，風(fēng)資源評(píng)估研究，空中和水上航行，采礦和農(nóng)業(yè)等許多應(yīng)用中重要的風(fēng)速和風(fēng)向。
根據(jù)2011年3月的統(tǒng)計(jì)數(shù)據(jù)，印度僅安裝了29％的風(fēng)力發(fā)電總潛力，其中32％單獨(dú)用于技術(shù)上[2]。 由于政府的目標(biāo)是到2022年將風(fēng)力發(fā)電量提高到60GW，顯然印度更加專注于利用可再生能源發(fā)電用于清潔能源技術(shù)。 因此，該研究提出了可能提供潛在風(fēng)資源評(píng)估的設(shè)計(jì)。
風(fēng)一般是通過(guò)其標(biāo)量組件進(jìn)行測(cè)量和分析的; 與風(fēng)向標(biāo)或風(fēng)向標(biāo)的風(fēng)速計(jì)和風(fēng)向的風(fēng)速。 對(duì)流層空氣循環(huán)系統(tǒng)的年度性質(zhì)，同時(shí)影響著一個(gè)地點(diǎn)的風(fēng)速和風(fēng)向[3]。 由于其線性和準(zhǔn)確性，通常使用杯型和螺旋槳型旋轉(zhuǎn)式風(fēng)速計(jì)進(jìn)行風(fēng)速測(cè)量。 雖然所采取的測(cè)量通常是平均風(fēng)資料，但瞬時(shí)風(fēng)測(cè)量也很重要。 瞬時(shí)風(fēng)速和方向數(shù)據(jù)有助于分析渦輪機(jī)和塔架的建造，而平均風(fēng)速數(shù)據(jù)預(yù)測(cè)風(fēng)力發(fā)電[4]。 由于功率與風(fēng)速的立方功率成正比，因此風(fēng)速測(cè)量的微小差異會(huì)大大影響發(fā)電量[5]。 所以準(zhǔn)確的風(fēng)速測(cè)量有助于計(jì)算安裝風(fēng)力渦輪機(jī)的良好可行性研究。
在用于將旋轉(zhuǎn)速率轉(zhuǎn)換為用于記錄風(fēng)速的適當(dāng)電信號(hào)的不同機(jī)制[1]中，其中四種常用于使用直流發(fā)電機(jī)，交流發(fā)電機(jī)，電接觸器和中斷光束的換能器。
2、文獻(xiàn)調(diào)查
以前與風(fēng)速計(jì)和葉片接口進(jìn)行風(fēng)速和風(fēng)向測(cè)量的工作考慮如下：
Ivan Simeonov等[6]開(kāi)發(fā)了一種短期天氣預(yù)報(bào)嵌入式系統(tǒng)，其中風(fēng)速傳感器給出方波脈沖，每升高1公里就需要修正風(fēng)速讀數(shù)。
Michael Cosgrove等人[7]設(shè)計(jì)了一個(gè)超低成本的測(cè)風(fēng)儀，用于風(fēng)力發(fā)電的可行性調(diào)查。 在這種情況下，雖然磁簧開(kāi)關(guān)在杯子的每次旋轉(zhuǎn)時(shí)產(chǎn)生一個(gè)單一開(kāi)關(guān)閉合的脈沖，但是開(kāi)發(fā)了去抖動(dòng)的算法。
Haci Can和Vedat M. Karsh [8]從事數(shù)據(jù)記錄器的開(kāi)發(fā)工作，使用基于8051的微控制器來(lái)測(cè)量風(fēng)速和風(fēng)向，也看到了對(duì)信號(hào)調(diào)理電路的需求。
Yahya S.H. Khraisat [9]在開(kāi)發(fā)低成本的自動(dòng)化系統(tǒng)的工作中，不斷測(cè)量直流發(fā)電機(jī)類型的端口電壓的天氣參數(shù)，在與微控制器接口之前，需要進(jìn)行信號(hào)調(diào)理。
Fouad Sh. Tahir等人[10]設(shè)計(jì)了一個(gè)基于個(gè)人電腦的數(shù)據(jù)采集系統(tǒng)來(lái)測(cè)量溫度，風(fēng)速和方向參數(shù)。即使當(dāng)風(fēng)速傳感器為杯子的一次旋轉(zhuǎn)而產(chǎn)生一個(gè)開(kāi)關(guān)閉合周期時(shí)，在用于計(jì)算風(fēng)速輸出的電路中增加了DAC。
David Wekesa等[11]利用Atmel Atmega 32微控制器開(kāi)發(fā)了一種自動(dòng)化，低成本的風(fēng)速和方向數(shù)據(jù)記錄系統(tǒng)，該系統(tǒng)采用基于光電子的系統(tǒng)，可提供更高的每轉(zhuǎn)脈沖數(shù)，即6至44 [12]。
Mehedi Al Emram等[13]也開(kāi)發(fā)了基于光電子學(xué)的風(fēng)速和風(fēng)向測(cè)量系統(tǒng)。對(duì)于風(fēng)速計(jì)的風(fēng)杯的單次旋轉(zhuǎn)產(chǎn)生多于一個(gè)的脈沖需要信號(hào)調(diào)節(jié)電路。
從上述考慮的工作中，產(chǎn)生正弦波的換能器需要額外的信號(hào)調(diào)節(jié)電路或具有去跳動(dòng)電路的方波。 但是這個(gè)系統(tǒng)不需要信號(hào)調(diào)節(jié)，即使沒(méi)有任何去跳動(dòng)電路或去跳動(dòng)算法或者使用DAC，傳感器也很容易連接。通過(guò)使用摩擦系數(shù)從較低的高度推斷風(fēng)速的值來(lái)進(jìn)行高度的修正。
3、硬件
A. 硬件描述
硬件主要由AT89S51單片機(jī)，風(fēng)速傳感器或風(fēng)速計(jì)和LCD組成。
AT89S51是一款高性能的低成本微控制器。 它是一個(gè)具有4K字節(jié)在系統(tǒng)可編程閃存的8位微控制器。片上閃存使程序存儲(chǔ)器可以在系統(tǒng)內(nèi)或通過(guò)傳統(tǒng)的非易失性存儲(chǔ)器編程器重新編程。AT89S51的其他顯著特點(diǎn)是：128字節(jié)的RAM，32條I / O線和2個(gè)16位定時(shí)器/計(jì)數(shù)器[14]。
所使用的風(fēng)速計(jì)[15]具有對(duì)稱地保持在豎直軸上的3個(gè)半球形杯。這種機(jī)械式風(fēng)速計(jì)的設(shè)計(jì)在旋轉(zhuǎn)過(guò)程中施加均勻的扭矩。 它是一種電氣接觸式的無(wú)源傳感器，可以計(jì)算一段時(shí)間內(nèi)的吹氣量。 當(dāng)磁簧開(kāi)關(guān)接觸到磁鐵的影響時(shí)，設(shè)備不通電但發(fā)出脈沖。 簧片開(kāi)關(guān)的安裝使得每次旋轉(zhuǎn)杯子時(shí)都會(huì)產(chǎn)生一次閉合。 傳感器包括密封軸承，使用壽命長(zhǎng)，能夠抵御颶風(fēng)的強(qiáng)風(fēng)，雖然對(duì)起動(dòng)閾值低的微風(fēng)敏感。 傳感器的規(guī)格說(shuō)明范圍和精度在風(fēng)洞試驗(yàn)中得到驗(yàn)證。 杯子的材料重量輕，多功能和生態(tài)高效，其運(yùn)行范圍從小于1英里/小時(shí)到200英里/小時(shí)（英里）。杯子的旋轉(zhuǎn)速度與吹風(fēng)成正比。
與風(fēng)速計(jì)相連的風(fēng)向標(biāo)是靈活的，響應(yīng)速度快，指向風(fēng)向。 葉片裝有一個(gè)20k電位器。 在葉片的方向相應(yīng)的電壓被識(shí)別并且方向被相應(yīng)地顯示在LCD上。 雨刮器到終端的阻力與方位角完全一致。 方向與氣象風(fēng)向一致。 指向北方的葉片從0度開(kāi)始，在羅盤上順時(shí)針?lè)较蛞苿?dòng)16點(diǎn)。
表一.羅盤指示
指南針指向
等級(jí)
N
348.75 – 11.25
NNE
11.25 – 33.75
NE
33.75 – 56.25
ENE
56.25 – 78.75
E
78.75 – 101.25
ESE
101.25 – 123.75
SE
123.75 – 146.25
SSE
146.25 – 168.75
S
168.75 – 191.25
SSW
191.25 – 213.75
SW
213.75 – 236.25
WSW
236.25 – 258.75
W
258.75 – 281.25
WNW
281.25 – 303.75
NW
303.75 – 326.25
NNW
326.25 – 348.75
B. 硬件設(shè)計(jì)
該設(shè)計(jì)采用傳感器單元，隨后是處理單元和顯示單元。
圖1.系統(tǒng)的設(shè)計(jì)
處理單元由一個(gè)ADC和AT89S51單片機(jī)以及5V電源電路組成。 顯示單元有一個(gè)LCD，每3秒更新一次風(fēng)速和風(fēng)向信息。
通過(guò)使用來(lái)自函數(shù)發(fā)生器的與風(fēng)傳感器（即TTL兼容的方波）相似的輸出來(lái)估算所設(shè)計(jì)的硬件的風(fēng)速計(jì)算精度。 結(jié)果顯示在下表中。
表二. 頻率輸入與顯示輸出的比較
給定的頻率 (Hz)
計(jì)算值為2.25秒
LCD讀取2.25 秒
3
6.75
7
5
11.25
11
10
22.5
23
20
45
45
30
67.5
67
40
90
89
65
146.25
145
78
175.5
174
85
191.25
190
98
220.5
219
100
225
224
106
238.5
237
上面比較的結(jié)果表明處理單元的輸出與給定的頻率很好地相關(guān)。
傳感器發(fā)出的速度脈沖直接與微控制器連接，無(wú)需信號(hào)調(diào)節(jié)。 電路中使用的上拉電阻可確保單片機(jī)檢測(cè)到的信號(hào)始終為高電平，除非傳感器將其拉低。 該機(jī)制包括在2.25秒的采樣周期內(nèi)對(duì)脈沖進(jìn)行計(jì)數(shù)，這與風(fēng)速和風(fēng)向測(cè)量的推薦采樣平均次數(shù)1-5秒相一致[1]。
傳感器輸出的風(fēng)向通過(guò)8位單通道ADC 0804與控制器連接。 微控制器被編程為根據(jù)ADC的值發(fā)出適當(dāng)?shù)姆较颉?
功能電路圖如下：
圖2.電路框圖
電路的照片如下所示。
圖3.電路板上。
風(fēng)速計(jì)被固定在一個(gè)2英尺的桿上，放在一個(gè)3層的建筑物上，用于露天測(cè)量。 傳感器布置在空氣自由流動(dòng)的地方，但由于基礎(chǔ)設(shè)施的限制，不能滿足特定的要求，如固定在7英尺以上。 然而，在東北方向的一個(gè)不可避免的混凝土阻礙。 下圖顯示了傳感器的所有側(cè)面。
圖4.放置在露天讀數(shù)的風(fēng)速計(jì)。
4、軟件
該軟件是使用KeilμVision5集成開(kāi)發(fā)環(huán)境（IDE）以C語(yǔ)言開(kāi)發(fā)的[16]。通過(guò)USB供電的傳統(tǒng)8051存儲(chǔ)器編程器將軟件的十六進(jìn)制文件加載到微控制器上。 該軟件的流程圖如下：
圖5.風(fēng)速和方向測(cè)量算法
五、結(jié)果與討論
速度的風(fēng)速測(cè)量以英尺/分鐘的方向記錄，液晶顯示器上羅盤方向的縮寫。
傳感器對(duì)瞬間天氣狀況的反應(yīng)似乎是靈活和準(zhǔn)確的。 風(fēng)向指向風(fēng)向，風(fēng)向很好地適應(yīng)了風(fēng)向的任何微小變化。 杯式風(fēng)速計(jì)根據(jù)風(fēng)向移動(dòng)。 觀察是在一天中的三個(gè)半小時(shí)內(nèi)進(jìn)行的。 每2分鐘記錄的讀數(shù)平均為半個(gè)小時(shí)，并與印度斯里蘭卡克里希納德瓦拉亞大學(xué)（SKU）建立的氣溶膠和大氣研究實(shí)驗(yàn)室（AARL）實(shí)驗(yàn)室的聲速測(cè)量讀數(shù)的標(biāo)準(zhǔn)值進(jìn)行比較。 10米高的標(biāo)準(zhǔn)讀數(shù)和16米高的觀測(cè)值列表如下：
表三. 標(biāo)準(zhǔn)和風(fēng)速和方向的觀測(cè)值
Hr
標(biāo)準(zhǔn)WS10m（m / s）
觀測(cè)WS16m（m / s）
標(biāo)準(zhǔn)WDir 10m
觀測(cè)WDir16m（指南針點(diǎn)）
16.5
1.5267
1.69875
68.5148 (ENE)
ENE
17.0
1.8173
2.01168
76.0462 (ENE)
ENE
17.5
1.8193
2.06756
92.9933 (E)
E
下圖顯示了使用Oriana 4軟件繪制的風(fēng)玫瑰圖：
圖6. 16:00至16:30，ENE的風(fēng)向平均值
圖7. 16:30至17:00期間ENE的風(fēng)向平均值
圖8. 17:00至17:30 E期間的風(fēng)向平均值
結(jié)果的幾點(diǎn)是：
·在16小時(shí)到16小時(shí)30分鐘的半小時(shí)內(nèi)，大部分時(shí)間的風(fēng)很大，占總數(shù)的50％，而東北偏東。
·在16：30-17：00的時(shí)間段內(nèi)，沿東 - 東北方向觀測(cè)到更高的風(fēng)速，從東方吹來(lái)高頻風(fēng)，甚至接下來(lái)的半小時(shí)。
·由于大部分時(shí)間偏東風(fēng)，西北側(cè)的障礙物對(duì)觀測(cè)影響很小，風(fēng)向讀數(shù)與標(biāo)準(zhǔn)讀數(shù)恰好一致。
·在16米處觀測(cè)到的風(fēng)速高于預(yù)期的10米處的風(fēng)速。
·死區(qū)誤差從0o到5o，從355o到360o。 但后期的錯(cuò)誤被編程淘汰了。
將10米高的風(fēng)速標(biāo)準(zhǔn)值外推到觀測(cè)值相關(guān)的高度16米。 為了外推，使用了Hellmann提出的冪律[17]。 方程是：
v / v0 =（H / H0）α（1）
其中v是高度H處的速度，v0是高度H0處的速度（通常被稱為10米高度），α是摩爾系數(shù)或Hellmann指數(shù)或風(fēng)切變系數(shù)[18]。 這個(gè)系數(shù)是一個(gè)地點(diǎn)特定地形的函數(shù)，這個(gè)參數(shù)可以隨著一天中的小時(shí)，一年的時(shí)間以及大氣條件如空氣密度而變化。 下面的表格[17]涉及各種景觀的摩擦系數(shù)α。
表四. 不同景觀的摩擦系數(shù)表
地面類型
摩擦系數(shù)（α）
湖泊，海洋和光滑的硬地
0.10
草原（地面）
0.15
高大的作物，樹(shù)籬和灌木
0.20
森林茂密的土地
0.25
有一些樹(shù)木和灌木的小鎮(zhèn)
0.30
高層建筑物的城市地區(qū)
0.40
通過(guò)重寫（1）計(jì)算摩擦系數(shù)α
α=（ln（v）-ln（v0））/（ln（H）-ln（H0））（2）
根據(jù)2016年4月1日15時(shí)至15時(shí)15分的標(biāo)準(zhǔn)風(fēng)資料，18米高的風(fēng)速（v）為1.4704m / s，10米高的風(fēng)速（v0）為1.39m / s。 從（2），這些值的摩擦系數(shù)是0.1。 但觀測(cè)是在同一天從16Hr到17Hr 30min，當(dāng)溫度下降，摩擦系數(shù)增加的時(shí)候進(jìn)行。 因此，接下來(lái)的兩個(gè)摩擦系數(shù)即0.15和0.20被考慮用于從10m到16m的高度推斷標(biāo)準(zhǔn)讀數(shù)。
結(jié)果列表如下。
表五.外推的標(biāo)準(zhǔn)值和觀測(cè)的風(fēng)速圖
S.No
時(shí)間(Hrs)
WS(m/s)
α=0.15
WS(m/s)
α=0.20
觀察 WS (m/s)
1
16.5
1.6382
1.6771
1.69875
2
17
1.9499
1.9964
2.01168
3
17.5
1.9521
1.9986
2.06756
α等于0.15和0.20的摩擦系數(shù)的外推標(biāo)準(zhǔn)風(fēng)速讀數(shù)與觀測(cè)到的風(fēng)速值強(qiáng)相關(guān)。 相關(guān)系數(shù)分別為0.99091和0.99089。
從圖4可以看出，大部分時(shí)間的東風(fēng)沒(méi)有任何明顯的障礙物。此外，觀測(cè)到的風(fēng)速值稍高一些，可以用來(lái)解釋丘陵，建筑物等發(fā)生的風(fēng)速加速。風(fēng)會(huì)遇到阻塞[17]。
然而，電力管理對(duì)風(fēng)力資料的長(zhǎng)期觀測(cè)使用相對(duì)較短。
6.結(jié)論
利用AT89S51微控制器和Davis風(fēng)速儀6410開(kāi)發(fā)的系統(tǒng)測(cè)量實(shí)時(shí)風(fēng)速和風(fēng)向顯示的結(jié)果相當(dāng)準(zhǔn)確，這得到了當(dāng)天同一時(shí)間SKU大氣研究實(shí)驗(yàn)室的標(biāo)準(zhǔn)值的證實(shí)。所獲得的強(qiáng)相關(guān)系數(shù)表明該系統(tǒng)是可靠的。
參考
[1]美國(guó)環(huán)境保護(hù)局（EPA）。 “監(jiān)管建模應(yīng)用氣象監(jiān)測(cè)指南”，2000年2月。EPA-454 / R-99-005。
[2] http://www.infraline.com/reportdetails/112/Wind-Power-Outlook-in-
印度2015.htm
[3] http://green-power.com.pl/en/home/wiatr-i-jego-pomiar-w-energetyce- wiatrowej /
[4] http://www.homepower.com/articles/wind-power/design- installation / understanding-wind-speed
[5] http://www.wwindea.org/technology/ch01/en/1_4.html
[6] I. Simeonov，H. Kilifarev，R. Llarionov，“短期天氣預(yù)報(bào)嵌入式系統(tǒng)”，計(jì)算機(jī)系統(tǒng)和技術(shù)國(guó)際會(huì)議論文集（CompSysTech'06），2006年。
[7] M. Cosgrove，B. Rhodes，J. Scott，“風(fēng)力發(fā)電可行性調(diào)查的超低成本測(cè)井風(fēng)速儀”，研究門，2007年1月。
[8] H. Can，V. M. Karsh，“利用基于8051的微控制器進(jìn)行多點(diǎn)風(fēng)速和方向測(cè)量和數(shù)據(jù)記錄”，美國(guó)科學(xué)雜志，157：2482-2488,2007。
[9] Yahya S. H. Khraisat，“在約旦設(shè)計(jì)無(wú)線氣象站”，加拿大科學(xué)和教育中心，第一卷。 2012年1月5日，1日。
[10] F. S. Tahir，A. M. Salman，J. K. Mohammed，W. K. Ahmed，“風(fēng)速，方向和溫度測(cè)量的數(shù)據(jù)采集系統(tǒng)”，Journal of Engineering， 18，沒(méi)有。 11，第1229-1236頁(yè)，2012年11月。
[11] D.W Wekesa，J.N. Kamau，J.N. Mutuku，“用于風(fēng)速和方向測(cè)量的校準(zhǔn)數(shù)據(jù)記錄儀表系統(tǒng)”，工程創(chuàng)新基礎(chǔ)研究期刊， 1（3），第53-57頁(yè)，2013年6月。
[12] S. Pindado，J. Cubas，F(xiàn). Sorribes-Palmer，“風(fēng)杯測(cè)風(fēng)儀，風(fēng)能產(chǎn)業(yè)的基本氣象儀器。在IDR / UPM研究所進(jìn)行研究“，Sensors， 2014年8月14日，第21428-21452頁(yè)。
[13] http://documents.mx/documents/a-microcontroller-based-system-for- determining-instantaneous-wind-speed-and.html
[14] AT89S51 Datasheet.pdf。
[15]戴維斯風(fēng)速儀6410 Datasheet.pdf。
[16] http://www.keil.com/c51/pk51kit.asp
F.Banuelos-Ruedas，C.A. Camacho，S. Rios-Marcuello。 “在一個(gè)地區(qū)的風(fēng)能資源評(píng)估中使用的方法”?？捎茫簑ww.intechopen.com
[18] Firas A. Hadi，“診斷風(fēng)速外推的最佳方法”，國(guó)際電氣，電子和儀器工程高級(jí)研究雜志。第一卷.2015年10月
Wind Speed and Direction Measurement System Using Atmel 89S51 Microcontroller Eunice Sophia K T Department of Physics,Sri Krishnadevaraya University,Anantapuramu-515003,A.P.,India.Email: Raghavendra Rao Kanchi Professor,VLSI&Embedded System Laboratory,Department of Physics and Principal,College of Engineering and Technology,SK University,Anantapuramu 515003,A.P.,India.Email: AbstractThis paper presents a simple instrumentation design built around one of the 8051 family microcontroller to measure instantaneous wind speed and wind direction.This system includes an improved,yet an inexpensive cup anemometer:Davis Instruments 6410 to sense the above said two wind parameters.The accuracy of the processing system is estimated prior to the interfacing the system with the wind sensor.The software is developed in C language and the data is displayed on 16x2 LCD for every three seconds.The collected data is then plotted in circular histogram for analysis.The system designed has the potential to be further developed and be used for in applications for the reason of its effective measurement which correlated well with the standard readings.KeywordsAT89S51;Anemometer;LCD;Compass points;Friction coefficient;I.INTRODUCTION Even as the technology improves day by day and the devices get smarter,8051 microcontroller and its derivatives still hold the promise of being a sufficient one in finding applications in various application fields.The present work concerns the measurement of two of the primary meteorological variables 1 namely wind speed and direction which is important in many applications like meteorology,wind resource assessment studies,air and water navigation,mining and agriculture.As per the statistics on March 2011,only 29%of the total gross potential for wind power development was installed in India of which 32%alone is technically usable 2.Since the government targets for to enhance the wind power production to 60GW by 2022,its clear that India is more focused to produce electricity using renewable sources towards clean energy technology.The study therefore presents a design which could possibly provide a potential to be used in wind resource assessments.Wind is commonly measured and analyzed with its scalar components separately;wind speed with anemometer and wind direction with wind vane or weather vane.The annual nature of the system of air circulation in the troposphere,affects both the wind speed and direction at a location 3.Due to their linearity and accuracy,rotational anemometers of cup and propeller type are commonly used for wind speed measurements.Though the measurements taken are usually of mean wind data,instantaneous wind measurement is also important.Instantaneous wind speed and direction data assist in analyzing the build of the turbine and tower whereas the mean wind speed data predicts wind power generation 4.Minor differences in the wind speed measurement affects the power generation greatly since the power is proportional to the cube power of the wind speed 5.So accurate wind speed measurements helps in calculating good feasibility studies for installing wind turbines.Among the different mechanisms 1 used to convert the rate of rotations to an appropriate electrical signal for recording the wind speed,four of them are commonly used which employ transducers of type DC generator,AC generator,the electrical contact and the interrupted light beam.II.LITERATURE SURVEY Previous works relating to interfacing the cup anemometer and the vane for the wind speed and direction measurement are considered as follows:Ivan Simeonov et al 6 developed an embedded system for short-term weather forecast in which the wind speed transducer gave square wave pulses whose wind speed readings needed correction for every 1 kilometer increase in altitude.Michael Cosgrove et al 7 designed an ultra-low cost logging anemometer intended for feasibility surveys of wind power generation.In this case,although the magnetic reed switch produced one pulse for single switch closure per revolution of the cups,an algorithm for debouncing was developed.Haci Can and Vedat M.Karsh 8 work in the development of a data logger using 8051 based microcontroller to measure wind speed and direction,also saw the need for signal conditioning circuitry.Yahya S.H.Khraisat 9 in his work of developing a low-cost automated system that continuously measured weather parameters the terminal voltage from DC generator type,saw the need of signal conditioning before interfacing with the microcontroller.Fouad Sh.Tahir et al 10 designed a data acquisition system based on personal computer to measure temperature,wind speed and direction parameters.Even when the wind speed transducer produced one switch closure cycle for a single rotation of the cups,a DAC was added in the circuitry for the calculation of wind speed output.David Wekesa et al 11 developed an automated,low-cost system of wind speed and direction data logger using Atmel Atmega 32 microcontroller which used optoelectronics-based system that give higher pulse rates per revolution i.e.6 to 44 12.Mehedi Al Emram et al 13 also developed a system for measuring wind speed and direction based on optoelectronics.The production of more than one pulse for a single revolution of the wind cups of the anemometer needed signal conditioning circuitry.From the above works taken into consideration,the transducers that produce the sinusoidal wave needed an additional circuit for signal conditioning or a square wave with a de bounce circuit.But this system doesnt need signal conditioning and the sensor is easily interfaced even without any de bounce circuit or de bounce algorithm or use of a DAC.The correction in the altitude is carried out by extrapolating the values of wind speed from a lower height using friction coefficient.III.HARDWARE A.Description of the Hardware The hardware primarily consists of the AT89S51 microcontroller,wind sensor or anemometer and LCD.AT89S51 is a high performing low-cost microcontroller.It is an 8-bit microcontroller with 4K bytes of In-system programmable flash memory.The on-chip flash enables the program memory to be reprogrammed either in-system or by conventional nonvolatile memory programmer.The other salient features of AT89S51 are:128 bytes of RAM,32 I/O lines and two 16bit timers/counters 14.The anemometer 15 used has a 3 hemispherical cups symmetrically held on to the vertical shaft.This design of mechanical type anemometer exerts uniform torque during revolutions.It is a passive transducer of electrical contact type that calculates the amount of air blowing in an interval of time.The device is not powered but sends out a pulse when the reed switch makes a contact on influence of the magnet.The reed switch is mounted so that it makes a single closure per revolution of the cups.The sensor includes sealed bearings for long life and can stand up to hurricane force winds although being sensitive to a light breeze with low starting threshold.Specifications of the sensor state that the range and accuracy were verified in the wind tunnel tests.The material of the cups is of light weight,versatile and eco-efficient with its operating range from less than 1 mph to over 200 miles per hour(mph).The rate of rotation of the cups is proportional to the wind blow.The weather vane that comes attached with the anemometer is flexible and has quick response to align itself pointing to the direction in which the wind blows.The vane is fitted inside with a 20k potentiometer.The vanes direction corresponding voltage is recognized and direction is displayed accordingly on the LCD.The resistance from the wiper to the terminal is completely linear with azimuth.The directions are in accordance with the meteorological wind direction.The vane pointing north starts with 0 degrees and moves clockwise through 16 points on compass rose.TABLE I.COMPASS DIRECTIONS Compass points Degree N 348.75 11.25 NNE 11.25 33.75 NE 33.75 56.25 ENE 56.25 78.75 E 78.75 101.25 ESE 101.25 123.75 SE 123.75 146.25 SSE 146.25 168.75 S 168.75 191.25 SSW 191.25 213.75 SW 213.75 236.25 WSW 236.25 258.75 W 258.75 281.25 WNW 281.25 303.75 NW 303.75 326.25 NNW 326.25 348.75 B.Hardware design The design employs the sensor unit followed by the processing unit and the display unit.Fig.1.Design of the system The processing unit consists of an ADC and AT89S51 microcontroller along with the 5V power supply circuit.The display unit has a LCD that updates the wind speed and direction information every 3 seconds.The hardware designed was estimated for wind speed calculation accuracy by using a similar output as of the wind sensor i.e.a TTL compatible square wave,from a function generator.The results are shown in the table below.TABLE II.COMPARISON OF FREQUENCY INPUT AND DISPLAYED OUTPUT Frequency given(Hz)Calculated value for 2.25 sec LCD read for 2.25 sec 3 6.75 7 5 11.25 11 10 22.5 23 20 45 45 30 67.5 67 40 90 89 65 146.25 145 78 175.5 174 85 191.25 190 98 220.5 219 100 225 224 106 238.5 237 The results compared above shows that the output from the processing unit relates well with the frequency given.The speed pulse sent by the sensor was directly interfaced with the microcontroller without the need for signal conditioning.A pull-up resistor used in the circuit ensures the signal detected by the microcontroller is always high except when the sensor pulls it low.The mechanism includes counting the pulses in a sampling period of 2.25seconds which is in accordance with the recommended sampling averaging times of 1-5 seconds for wind speed and wind direction measurements 1.The wind direction output from the sensor is connected to the controller through ADC 0804 which is a 8-bit and single channeled.The microcontroller is programmed to send out the appropriate direction according to the value at ADC.The functional circuit diagram is as follows:Fig.2.Block diagram of the circuit The photograph of the circuit is shown below.Fig.3.Circuit on board.The anemometer was fixed to a 2 foot pole and placed atop a 3-storey building for the open air measurements.The sensor was arranged at a location where there is free flow of air but could not meet the specific requirements like fixing it above 7 feet due to infrastructural constraints.However,there was an unavoidable concrete obstruction to the northeastern side of the placement.The picture below shows all the sides of the sensor.Fig.4.Anemometer placed for open air readings.IV.SOFTWARE The software was developed in C language using Keil Vision5 Integrated Development Environment(IDE)16.The hex file of the software was loaded on to the microcontroller by USB powered conventional 8051 memory programmer.The flowchart of the software is as follows:Fig.5.Wind speed and direction measurement algorithm.V.RESULTS AND DISCUSSIONS Wind measurement of speed is recorded in mph and direction by the abbreviation of the compass direction on LCD.The sensors response to the instant weather conditions appear to be flexible and accurate.The vane heeded well to any slight change in the wind direction by pointing itself into the direction of the wind.The cup anemometer moved in accordance with the wind flow.The observations were taken for three half-an-hours during the day.The readings noted for every 2 minutes were averaged to half an hour and compared with the standard values of the sonic anemometer readings from the Aerosol and Atmospheric Research Laboratory(AARL)lab set up by ISRO at Sri Krishnadevaraya University(SKU).The standard readings at 10m height as well as the observed values at 16m height are tabulated below:TABLE III.STANDARD AND OBSERVED VALUES OF WIND SPEED AND DIRECTION Hr Standard WS10m(m/s)Observed WS16m(m/s)Standard WDir10m Observed WDir16m(Compass points)16.5 1.5267 1.69875 68.5148(ENE)ENE 17.0 1.8173 2.01168 76.0462(ENE)ENE 17.5 1.8193 2.06756 92.9933(E)E Wind Rose graphs plotted using Oriana 4 software are shown below:Fig.6.Wind direction resultant mean at ENE for 16:00 to 16:30.Fig.7.Wind direction resultant mean at ENE during 16:30 to 17:00.Start Include suitable header files Define ports Initialize LCD Set Timer 1 to count 8-bit value Start counting pulses for the sampling period and stop the counter Display the wind run on LCD Read the wind direction digital output from ADC Select the wind direction according to the analog voltage and display on LCD Do it for ever Fig.8.Wind direction resultant mean at E during 17:00 to 17:30 A few points of the results are:?Easterly wind blew for most of the time during the half an hour between 16hr to 16hr 30 min forming 50%of the total while the resultant mean is towards East-North east.?During the 16:30 to 17:00 time period,higher wind speeds were observed along East-Northeast and East direction with high frequency wind blowing from the East even for next half an hour.?The obstruction on north-western side impacted little on the observations due to easterly wind blowing for most of the time and the wind direction readings coincided exactly with that of the standard readings.?The wind speeds as observed at 16m are higher as expected with the wind speed measured at 10m.?The dead band error is present from 0o to 5o and from 355o to 360o.But the latter part of the error was eliminated by programming.The standard values of wind speed at height of 10m are extrapolated to the height of 16m at which the observed values relate.For extrapolation the power law 17 proposed by Hellmann is used.The equation is v/v0 =(H/H0)(1)Where v is the the speed at height H,v0 is the speed at height H0(frequently referred to as a 10-meter height)and is the friction coefficient or Hellmann exponent or wind shear coefficient 18.This coefficient is a function of the particular topography at a site,and this parameter can vary by the hour of the day,time of the year and with atmospheric conditions such as air density.The table 17 shown below relates the friction coefficient for a variety of landscapes.TABLE IV.FRICTION COEFFICIENT TABLE FOR DIFFERENT LANDSCAPES.Landscape type Friction coefficient()Lakes,ocean and smooth hard ground 0.10 Grasslands(ground level)0.15 Tall crops,hedges and shrubs 0.20 Heavily forested land 0.25 Small town with some trees and shrubs 0.30 City areas with high rise buildings 0.40 The friction coefficient is calculated by rewriting(1),as =(ln(v)ln(v0)/(ln(H)ln(H0)(2)According to the standard wind data from 15Hrs to 15.5Hrs on 1st April,2016 the wind speed(v)at 18m height is 1.4704m/s and at 10m height,the wind speed(v0)is 1.39m/s.From(2),the friction coefficient for these values is 0.1.But the observations were taken on the same day from 16Hr to 17Hr 30min which was toward evening when the temperature fall and the friction coefficient increase.So the next two friction coefficients i.e.0.15 and 0.20 were taken into consideration for extrapolating the standard reading from 10m to 16m height.The results are tabulated as below.TABLE V.EXTRAPOLATED STANDARD VALUES AND OBSERVED WIND SPEED READINGS S.No Time of the day(Hrs)WS(m/s)=0.15 WS(m/s)=0.20 Observed WS(m/s)1 16.5 1.6382 1.6771 1.69875 2 17 1.9499 1.9964 2.01168 3 17.5 1.9521 1.9986 2.06756 The extrapolated standard wind speed readings for both the friction coefficients of equal to 0.15 and 0.20 strongly correlated with the observed values of wind speed.The correlation coefficients are 0.99091 and 0.99089 respectively.The easterly wind blowing for most of the time did not have any apparent obstructions as can be seen from Fig.4.Moreover,a little higher observed wind speed values can be accounted for the wind speed acceleration that occurs over hills,buildings etc(when the wind encounters an obstruction)17.The power management however is relatively short for the use of long term observations of wind data.VI.CONCLUSION The system developed using AT89S51 microcontroller and Davis Anemometer 6410 to measure real-time wind speed and wind direction showed fairly accurate results which were corroborated by the standard values from the Aerosol and Atmospheric Research Laboratory at SKU,taken during the same hours on the same day.The strong correlation coefficients obtained showed that the system can be a reliable one.References 1 USA Environmental Protection Agency(EPA).“Meteorological Monitoring Guidance for Regulatory Modeling Applications”,February 2000.EPA-454/R-99-005.2 http:/ 3 http:/green-.pl/en/home/wiatr-i-jego-pomiar-w-energetyce-wiatrowej/4 http:/ 5 http:/www.wwindea.org/technology/ch01/en/1_4.html 6 I.Simeonov,H.Kilifarev,R.Llarionov,“Embedded system for short-term weather forecasting”,Proceedings of International Conference on Computer Systems and Technologies(CompSysTech06),2006.7 M.Cosgrove,B.Rhodes,J.Scott,“Ultra-low-cost Logging Anemometer for Wind Power Generation Feasibility Surveys”,Research Gate,January 2007.8 H.Can,V.M.Karsh,“Multipoint Wind speed and direction measurement and data logging by using 8051-based microcontroller”,American Journal of Science,157:2482-2488,2007.9 Yahya S.H.Khraisat,“Design a Wireless Meteorological Station in Jordan”,Canadian Center of Science and Education,vol.5,no.1,January 2012.10 F.S.Tahir,A.M.Salman,J.K.Mohammed,W.K.Ahmed,“Data Acquisition System for Wind Speed,Direction and Temperature Measurements”,Journal of Engineering,vol.18,no.11,pp.1229-1236,November 2012.11 D.W Wekesa,J.N.Kamau,J.N.Mutuku,“Calibrated data logging instrumentation system for wind speed and direction measurements”,Basic Research Journal of Engineering Innovation,vol.1(3),pp.53-57,June 2013.12 S.Pindado,J.Cubas,F.Sorribes-Palmer,“The Cup Anemometer,a Fundamental Meteorological Instrument for the Wind Energy Industry.Research at the IDR/UPM Institute”,Sensors,vol.14,pp.21428-21452,August 2014.13 http:/documents.mx/documents/a-microcontroller-based-system-for-determining-instantaneous-wind-speed-and.html 14 AT89S51 Datasheet.pdf.15 Davis Anemometer 6410 Datasheet.pdf.16 http:/ 17 F.Banuelos-Ruedas,C.A.Camacho,S.Rios-Marcuello.“Methodologies used in its impact in the Wind Energy Resource Assessment in a Region”.Available: 18 Firas A.Hadi,“Diagnosis of the Best Method for Wind Speed Extrapolation”,International Journal of Advanced Research in Electrical,Electronics and Instrumentation Engineering.vol.4,no.10,October 2015.
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