趙立新，張?jiān)鲚x，王成義，薦世春，劉 童，崔東云，丁筱玲

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基于變距光電傳感器的小麥精播施肥一體機(jī)監(jiān)測(cè)系統(tǒng)設(shè)計(jì)

趙立新1，張?jiān)鲚x1，王成義2，薦世春3，劉 童1，崔東云1，丁筱玲1※

（1. 山東農(nóng)業(yè)大學(xué)機(jī)械與電子工程學(xué)院，泰安 271018； 2. 山東農(nóng)業(yè)大學(xué)信息科學(xué)與工程學(xué)院，泰安 271018； 3. 山東省農(nóng)業(yè)機(jī)械科學(xué)研究院，濟(jì)南 250100）

為實(shí)現(xiàn)小麥精播施肥過(guò)程的實(shí)時(shí)監(jiān)測(cè)，確保播種作業(yè)質(zhì)量，該文設(shè)計(jì)了一種基于變距光電傳感器的小麥精播施肥一體機(jī)監(jiān)測(cè)系統(tǒng)。該監(jiān)測(cè)系統(tǒng)以STM32單片機(jī)硬件系統(tǒng)為下位機(jī)，通過(guò)反射式光電傳感器和旋轉(zhuǎn)編碼器分別獲取種肥流動(dòng)與種肥軸轉(zhuǎn)動(dòng)信息，判斷精播機(jī)運(yùn)行狀態(tài)，并通過(guò)Modbus通訊協(xié)議將信息傳輸至MCGS觸摸屏上位機(jī)人機(jī)交互界面實(shí)時(shí)顯示。下位機(jī)排種監(jiān)測(cè)電路仿真測(cè)試結(jié)果表明，放大電路對(duì)種管光電傳感器檢測(cè)距離的改變值為4～7 mm；上下位機(jī)通訊測(cè)試結(jié)果表明，數(shù)據(jù)傳輸內(nèi)容準(zhǔn)確率為100%；監(jiān)測(cè)系統(tǒng)樣機(jī)試驗(yàn)測(cè)試結(jié)果表明，故障報(bào)警準(zhǔn)確率≥92.5%，種肥缺失、堵塞、泄漏響應(yīng)時(shí)間分別≤0.2、≤0.3、≤0.3 s。該監(jiān)測(cè)系統(tǒng)實(shí)現(xiàn)了對(duì)小麥精播施肥機(jī)作業(yè)的實(shí)時(shí)高精度監(jiān)測(cè)，有助于提高小麥精播機(jī)作業(yè)質(zhì)量。

監(jiān)測(cè)；設(shè)計(jì)；傳感器；精播施肥機(jī)；變距；MCGS觸摸屏

0 引 言

精密播種已成為現(xiàn)代播種技術(shù)的主要發(fā)展方向[1]，播種機(jī)作業(yè)質(zhì)量會(huì)直接影響小麥的生長(zhǎng)和產(chǎn)量。面對(duì)復(fù)雜的田間墑情、機(jī)器震動(dòng)、嘈雜噪聲等不利因素以及種肥管的全封閉環(huán)境，僅采用視聽方式難以實(shí)時(shí)了解播種機(jī)的運(yùn)行狀態(tài)，當(dāng)出現(xiàn)種肥管堵塞或種肥缺失等問(wèn)題時(shí)會(huì)造成大面積缺苗斷垅的狀況從而導(dǎo)致減產(chǎn)[2-5]，同時(shí)機(jī)具在地頭轉(zhuǎn)向過(guò)程中會(huì)因種肥掉落而造成浪費(fèi)。因此研制與精播機(jī)配套的監(jiān)測(cè)系統(tǒng)具有重要的生產(chǎn)意義和經(jīng)濟(jì)效益。

目前，國(guó)外對(duì)精播機(jī)監(jiān)測(cè)系統(tǒng)進(jìn)行了較多研究，美國(guó)Precision Planting公司設(shè)計(jì)的基于光電傳感器的MeterMAx試驗(yàn)臺(tái)功能齊全，可迅速準(zhǔn)確地檢測(cè)播種故障以及播種參數(shù)，但該產(chǎn)品在國(guó)內(nèi)使用時(shí)需配備專屬電源[6-7]，該公司研制的WaveVision監(jiān)測(cè)器解決了排種過(guò)程中多粒種子同時(shí)通過(guò)導(dǎo)種管無(wú)法區(qū)分的問(wèn)題，提高了排種性能監(jiān)測(cè)的可靠性及準(zhǔn)確性[8]。Karayel等[9]設(shè)計(jì)的高速攝像系統(tǒng)實(shí)現(xiàn)了對(duì)小麥和大豆布種粒距與落種速度的檢測(cè)，但該系統(tǒng)圖像的處理過(guò)程無(wú)法做到在線監(jiān)測(cè)。Navid等[10]在Karayel的研究基礎(chǔ)之上增加圖像數(shù)量并結(jié)合MATLAB處理數(shù)據(jù)的方法獲取更加準(zhǔn)確的監(jiān)測(cè)結(jié)果。美國(guó)John Deere公司基于光電傳感器研發(fā)的SeedStar系列監(jiān)測(cè)儀將播種監(jiān)測(cè)推向?qū)嵱没?，該公司的第二代產(chǎn)品還可實(shí)時(shí)進(jìn)行播種參數(shù)設(shè)置[11-12]。國(guó)內(nèi)對(duì)精播機(jī)監(jiān)測(cè)系統(tǒng)的研究起步較晚，但成果顯著[13]，張繼成等[14-15]設(shè)計(jì)了一種基于光敏電阻的監(jiān)測(cè)裝置能夠?qū)崿F(xiàn)大型精密播種施肥機(jī)在播種施肥作業(yè)過(guò)程中對(duì)每個(gè)作業(yè)單體的實(shí)時(shí)監(jiān)測(cè)；Lu等[16-20]基于對(duì)射式紅外檢測(cè)方法設(shè)計(jì)的播種質(zhì)量監(jiān)測(cè)系統(tǒng)可對(duì)播種過(guò)程出現(xiàn)的故障情況發(fā)出聲光報(bào)警信號(hào)；丁幼春等[21-24]利用光纖傳感器法、聚偏氟乙烯（PVDF）壓電薄膜法以及時(shí)間間隔法分別對(duì)油菜等小粒徑排種器的排種性能監(jiān)測(cè)進(jìn)行了研究；周利明等[25-26]基于電容器電容隨板間介質(zhì)變化原理開發(fā)的電容式傳感器可對(duì)小麥、玉米的排種性能進(jìn)行在線監(jiān)測(cè)；陳進(jìn)等[27-28]運(yùn)用高速攝像系統(tǒng)對(duì)精密排種器的種子排種過(guò)程進(jìn)行圖像采集進(jìn)而處理得到排種器性能的方法；胡少興等[29]提出了基于神經(jīng)網(wǎng)絡(luò)的種子位置智能檢測(cè)方法，該方法可全面監(jiān)測(cè)種子的運(yùn)動(dòng)情況。

實(shí)際應(yīng)用中，圖像處理法雖可高精度監(jiān)測(cè)落種過(guò)程，但設(shè)備昂貴、數(shù)據(jù)量大，難以實(shí)現(xiàn)實(shí)時(shí)監(jiān)測(cè)；電容法和壓電感應(yīng)法面對(duì)機(jī)具震動(dòng)以及復(fù)雜的田間墑情難以保證精度；光電感應(yīng)法成本低廉、便于維護(hù)，但傳統(tǒng)的對(duì)射式光電傳感器安裝對(duì)精度要求較高，易受機(jī)具震動(dòng)影響。實(shí)驗(yàn)室前期設(shè)計(jì)研究了電控寬幅小麥精播施肥機(jī)，達(dá)到了均勻播種的目的[30]。本研究在此基礎(chǔ)上設(shè)計(jì)了基于變距光電傳感器的小麥精播施肥一體機(jī)監(jiān)測(cè)系統(tǒng)，該系統(tǒng)以反射式光電管為監(jiān)測(cè)傳感器，通過(guò)單片機(jī)控制傳感器根據(jù)需要改變檢測(cè)距離，結(jié)合通過(guò)MODBUS傳輸協(xié)議接收主控系統(tǒng)利用旋轉(zhuǎn)編碼器測(cè)取的種肥軸轉(zhuǎn)速，同時(shí)監(jiān)測(cè)排種施肥狀況，安裝方便、運(yùn)行穩(wěn)定，實(shí)現(xiàn)了免耕精播施肥機(jī)在作業(yè)過(guò)程中對(duì)排種、排肥器單體的實(shí)時(shí)監(jiān)測(cè)。

1 系統(tǒng)結(jié)構(gòu)與工作原理

1.1 監(jiān)測(cè)系統(tǒng)結(jié)構(gòu)方案

監(jiān)測(cè)系統(tǒng)的結(jié)構(gòu)分為下位機(jī)STM32F103硬件電路與上位機(jī)觸摸屏人機(jī)交流界面2部分。下位機(jī)硬件電路由OH-1021光電傳感器（日本ALEPH公司生產(chǎn)，檢測(cè)距離2～30 mm）、信號(hào)整形放大電路、編碼器轉(zhuǎn)速采集模塊、通訊模塊、中央處理器及外圍電路組成。上位機(jī)人機(jī)交流部分采用MCGS觸摸屏，觸摸屏放置于駕駛室內(nèi)便于駕駛員及時(shí)觀察機(jī)具運(yùn)行狀況。系統(tǒng)結(jié)構(gòu)如圖1所示。

圖1 小麥精播施肥一體機(jī)監(jiān)測(cè)系統(tǒng)結(jié)構(gòu)示意圖

1.2 監(jiān)測(cè)原理

圖2為傳感器安裝及工作過(guò)程示意圖。監(jiān)測(cè)系統(tǒng)排種管與排肥管均采用PVC-U管，該管壁厚2 mm，外徑28 mm，該管內(nèi)壁光滑，對(duì)流體阻力小，透光性強(qiáng)，不會(huì)因?yàn)閮?nèi)壁堆積少量的灰塵而影響紅外光線的透過(guò)性。排種與排肥監(jiān)測(cè)傳感器均采用OH-1021反射式光電傳感器，可通過(guò)改變傳感器供電電壓來(lái)改變探測(cè)距離，傳感器的檢測(cè)距離與供電電壓成正相關(guān)，如圖3所示。當(dāng)有物體阻擋紅外光線時(shí)，傳感器輸出低電平；無(wú)物體阻擋紅外光線時(shí)，傳感器則輸出高電平。

排種管中小麥顆粒處于充滿狀態(tài)，小麥顆粒經(jīng)排種管流入排種器（如圖4a所示）。設(shè)定排種傳感器的初始檢測(cè)距離為5 mm，即管壁厚度（2 mm）與單粒小麥短徑（3 mm）的總和。正常工作時(shí)，顆粒流動(dòng)經(jīng)過(guò)光電傳感器監(jiān)測(cè)位置時(shí)反射紅外光線，傳感器輸出經(jīng)歷高電平-低電平-高電平的變化過(guò)程。

紅外光線照射于種管壁上2個(gè)顆粒之間的空隙時(shí)，故障類型無(wú)法區(qū)分。通過(guò)單片機(jī)控制IO口輸出電平控制三極管的導(dǎo)通，改變傳感器檢測(cè)距離。當(dāng)單片機(jī)輸出高電平時(shí)，三極管導(dǎo)通，傳感器電壓提升，檢測(cè)距離增加，進(jìn)而了解種管種子存量情況，確定故障類型。

肥料從排肥器排出后落入排肥管（如圖4b所示），肥料顆粒運(yùn)動(dòng)至光電傳感器監(jiān)測(cè)位置時(shí)反射紅外光線，傳感器輸出經(jīng)歷高電平-低電平-高電平的變化過(guò)程，單片機(jī)監(jiān)測(cè)傳感器的輸出狀態(tài)。具體故障判斷類型如表1所示。

圖2 傳感器安裝及工作過(guò)程示意圖

圖3 傳感器檢測(cè)距離與供電電壓關(guān)系

圖4 傳感器監(jiān)測(cè)示意圖

表1 故障監(jiān)測(cè)判斷

注：堵種：排種器故障造成堵轉(zhuǎn)；缺種：種箱中麥種缺失；漏種：因毛刷磨損造成的種子泄漏。堵肥：排肥器故障造成堵轉(zhuǎn)；缺肥：肥箱肥料缺失；漏肥：因排肥器毛刷磨損造成的肥料泄漏。

Note: Blocking wheat: Lock-rotor in case of seeding device fault; Lack wheat: lack of seeds in seed box; Leaking wheat: leaking of wheat in case of brush worn. blocking fertilizer: Lock-rotor in case of fertilizing device fault; lacking fertilizer: lack of fertilizer in fertilizer box; leaking fertilizer: leaking of fertilizer in case of brush worn.

主控系統(tǒng)采用1 000線歐姆龍旋轉(zhuǎn)編碼器采集排種軸轉(zhuǎn)速和排肥軸轉(zhuǎn)速。系統(tǒng)驅(qū)動(dòng)直流電機(jī)屬于感性負(fù)載，轉(zhuǎn)速突變的可能性較小，為最大程度降低監(jiān)測(cè)滯后性對(duì)監(jiān)測(cè)系統(tǒng)程序故障判斷過(guò)程造成的影響，主控系統(tǒng)以100 Hz頻率向監(jiān)控系統(tǒng)發(fā)送種肥軸轉(zhuǎn)速。

2 下位機(jī)監(jiān)測(cè)系統(tǒng)電路設(shè)計(jì)

監(jiān)測(cè)系統(tǒng)硬件電路包括排種檢測(cè)變距電路、排肥監(jiān)測(cè)硬件電路、STM32F103微處理器最小系統(tǒng)和TTL轉(zhuǎn)485通訊模塊。排種故障監(jiān)測(cè)電路的放大器件選取9013NPN三極管，三極管基極連接單片機(jī)I/O口。傳感器監(jiān)測(cè)供電部分對(duì)于三極管放大電路屬于有源負(fù)載。單片機(jī)輸出低電平時(shí)，傳感器電壓和檢測(cè)距離均初始設(shè)置；單片機(jī)輸出高電平時(shí)，三極管處于放大狀態(tài)，負(fù)載電壓提升，檢測(cè)距離增加；單片機(jī)再次輸出低電平時(shí)，負(fù)載電壓與監(jiān)測(cè)距離再次回到初始狀態(tài)。排種監(jiān)測(cè)電路如圖5a所示。

排肥監(jiān)測(cè)電路包括信號(hào)采集部分和電壓比較放大電路，如圖5b所示。為避免傳感器輸出電平與單片機(jī)輸入引腳電平不匹配，本研究采用日本Sonteen公司的LM339芯片對(duì)傳感器的輸出信號(hào)進(jìn)行整形濾波，單片機(jī)采集比較器的輸出信號(hào)從而獲取排肥管中肥料下落情況。

圖5 下位機(jī)電路原理圖

3 系統(tǒng)軟件設(shè)計(jì)

該監(jiān)控系統(tǒng)的軟件由下位機(jī)監(jiān)測(cè)處理程序和上位機(jī)程序組成。下位機(jī)監(jiān)測(cè)處理程序采用C語(yǔ)言編寫，易于移植，可讀性強(qiáng)；上位機(jī)程序采用圖形化界面，用于顯示播種機(jī)排種和排肥的工作狀況。

3.1 下位機(jī)排種、排肥監(jiān)測(cè)流程

下位機(jī)監(jiān)測(cè)處理程序采用時(shí)間間隔任務(wù)循環(huán)程序設(shè)計(jì)方法，以TIM2作為基準(zhǔn)時(shí)間劃分任務(wù)時(shí)間片段，循環(huán)執(zhí)行數(shù)據(jù)采集和數(shù)據(jù)通信等任務(wù)。

排種管光電傳感器安裝于排種器上方，當(dāng)紅外光線照射在緊貼管壁的2個(gè)小麥顆?？障稌r(shí)，無(wú)法準(zhǔn)確判定故障類型，此時(shí)啟動(dòng)變距任務(wù)函數(shù)改變傳感器檢測(cè)距離，檢測(cè)排種管小麥顆粒數(shù)量，若有小麥?zhǔn)Ｓ鄤t傳感器輸出為低電平，此時(shí)排種管出現(xiàn)堵種故障；若無(wú)小麥?zhǔn)Ｓ鄤t傳感器輸出為高電平，此時(shí)為缺種故障。排種檢測(cè)處理算法流程如圖6a所示。

排肥光電傳感器安裝于排肥器下方，根據(jù)數(shù)據(jù)采集函數(shù)和排肥軸轉(zhuǎn)速判定排肥器的運(yùn)行狀態(tài)，排肥故障監(jiān)測(cè)流程如圖6b所示。

注：VS為排種軸轉(zhuǎn)速，r·min-1；VF為排肥軸轉(zhuǎn)速，r·min-1。

3.2 上位機(jī)觸摸屏報(bào)警界面設(shè)計(jì)

上位機(jī)觸摸屏人機(jī)交流界面的功能是幫助駕駛員實(shí)時(shí)了解播種施肥過(guò)程的種肥狀態(tài)信息，及時(shí)處理故障問(wèn)題。

上位機(jī)的后臺(tái)數(shù)據(jù)更新采用循環(huán)策略中的ReadP（批量讀?。┟钜?00 Hz頻率向下位機(jī)發(fā)送機(jī)具運(yùn)行狀態(tài)請(qǐng)求，界面腳本程序以500 Hz頻率刷新來(lái)自下位機(jī)的應(yīng)答信號(hào)，保證下位機(jī)的數(shù)據(jù)能實(shí)時(shí)顯示在上位機(jī)報(bào)警界面。

本研究中樣機(jī)設(shè)計(jì)中排種器與排肥器各有8個(gè)，在報(bào)警界面中分別用8個(gè)指示燈代表各排種器和排肥器的工作狀態(tài)，每個(gè)指示燈下方均有3個(gè)動(dòng)畫標(biāo)簽代表不同的故障類型（堵種，缺種，漏種；堵肥，缺肥，漏肥）。當(dāng)指示燈顯示綠色時(shí)代表機(jī)具工作正常，當(dāng)指示燈顯示紅色時(shí)代表有故障發(fā)生，同時(shí)具體故障類型顯示于指示燈下方。

4 排種監(jiān)測(cè)電路仿真

為確定電路設(shè)計(jì)中2個(gè)電位器的最佳比例值，在試驗(yàn)之前進(jìn)行了電路仿真。

利用Multisim電路仿真軟件建立下位機(jī)電路模型，如圖7所示。開關(guān)S1初始狀態(tài)下連接GND（ground，大地）（即IO輸出低電平），電位器A的比例值為0，三極管處于截止?fàn)顟B(tài)。調(diào)節(jié)電位器B的值，負(fù)載電壓即為變距前的傳感器電壓，結(jié)果表明負(fù)載電壓與電位器B的比例值呈正相關(guān)。根據(jù)傳感器供電電壓與檢測(cè)距離關(guān)系得知，當(dāng)傳感器檢測(cè)距離為5 mm時(shí)，負(fù)載端電壓為2.646 V（如圖3點(diǎn)所示），此時(shí)電位器B的比例值為92%（如圖8a所示）。

注：2N2222A代表實(shí)際電路的9013NPN三極管；開關(guān)S1模擬單片機(jī)輸出電平狀態(tài)；XMM1、XMM2與XMM3為電壓表；Key=A和Key=B分別表示通過(guò)鍵盤A和B調(diào)整電位器比例值。

調(diào)節(jié)電位器A的比例值，分別記錄不同比例值時(shí)開關(guān)1連接3.3 V電源和GND（I/O輸出高低電平）時(shí)的負(fù)載電壓，電位器A比例值與負(fù)載電壓關(guān)系如圖8b所示，由圖8b可知電位器A的比例值為84%時(shí)負(fù)載壓差最大，此時(shí)可最大程度改變探測(cè)距離。

注：V1為開關(guān)S1連接至3.3 V電源時(shí)負(fù)載電壓；V2為開關(guān)S1連接至GND(Ground)時(shí)負(fù)載電壓；V3為V1與V2的電壓差值；V4為開關(guān)S1連接至3.3 V電源時(shí)負(fù)載電壓；V5為開關(guān)S1連接至GND時(shí)負(fù)載電壓；V6為V4與V5的電壓差值；L1為開關(guān)S1連接至3.3V電源時(shí)傳感器檢測(cè)距離；L2為開關(guān)S1連接至GND時(shí)傳感器檢測(cè)距離；L3為L(zhǎng)1與L2的距離差值。

設(shè)定電位器A的比例值為84%，微調(diào)電位器B的比例值，對(duì)比開關(guān)S1分別連接GND與3.3V電源時(shí)的負(fù)載電壓。仿真結(jié)果如圖8c所示，電壓差值為0.413～0.646 V，可使光電傳感器檢測(cè)距離增加4～7 mm（如圖8d所示，即圖3中點(diǎn)到點(diǎn)的變化），此壓差的變化足以解決紅外光線位于管壁上2個(gè)顆粒之間的空隙時(shí)，無(wú)法判定故障的問(wèn)題。

5 田間試驗(yàn)與結(jié)果分析

為檢測(cè)精播施肥一體機(jī)監(jiān)測(cè)系統(tǒng)的技術(shù)指標(biāo)與可靠性，在課題組前期研制的寬幅小麥免耕精播施肥一體機(jī)的基礎(chǔ)上，安裝了基于變距光電傳感器的監(jiān)測(cè)系統(tǒng)。于2016年10月在山東大華機(jī)械有限公司試驗(yàn)田內(nèi)進(jìn)行監(jiān)測(cè)系統(tǒng)的檢測(cè)試驗(yàn)。試驗(yàn)所用小麥品種為“濟(jì)麥17”，其含水率為11.8%；肥料選取齊商化肥廠生產(chǎn)的控釋摻混肥料。圖9為試驗(yàn)現(xiàn)場(chǎng)。

圖9 試驗(yàn)現(xiàn)場(chǎng)

1）種肥缺失監(jiān)測(cè)試驗(yàn)

在種肥箱內(nèi)分別放置0.5 kg麥種與5 kg復(fù)合肥料，啟動(dòng)播種機(jī)進(jìn)行播種施肥試驗(yàn)，當(dāng)出現(xiàn)種肥缺失時(shí)，人為添加同等質(zhì)量種肥顆粒，持續(xù)播種。拖拉機(jī)帶動(dòng)機(jī)具以不同速度向前行進(jìn)，使用毫秒計(jì)時(shí)器記錄各排種器和排肥器種肥實(shí)際缺失到系統(tǒng)種肥缺失報(bào)警的時(shí)間間隔，并統(tǒng)計(jì)報(bào)警次數(shù)，測(cè)試重復(fù)5次。

2）種肥堵塞監(jiān)測(cè)試驗(yàn)

種肥堵塞監(jiān)測(cè)試驗(yàn)采用塑料袋堵塞落種口和落肥口的方式進(jìn)行。啟動(dòng)播種機(jī)進(jìn)行播種試驗(yàn)，使用毫秒計(jì)時(shí)器記錄各排種器和排肥器種肥實(shí)際堵塞到系統(tǒng)種肥堵塞報(bào)警的時(shí)間間隔，并統(tǒng)計(jì)報(bào)警次數(shù)，機(jī)具以不同速度進(jìn)行測(cè)試，試驗(yàn)重復(fù)5次。

3）種肥泄漏監(jiān)測(cè)試驗(yàn)

種肥泄漏監(jiān)測(cè)試驗(yàn)采用人為制造種肥泄漏故障的方式進(jìn)行，將種肥管與排種器和排肥器分離，模擬種肥泄漏灑落過(guò)程。啟動(dòng)監(jiān)測(cè)系統(tǒng)，使用毫秒計(jì)時(shí)器記錄各排種器和排肥器種肥實(shí)際泄漏到系統(tǒng)泄漏報(bào)警的時(shí)間間隔，并統(tǒng)計(jì)報(bào)警次數(shù)，模擬不同種肥泄漏流速，試驗(yàn)重復(fù)5次。

試驗(yàn)結(jié)果如表2所示，由試驗(yàn)數(shù)據(jù)得知，種肥缺失報(bào)警監(jiān)測(cè)準(zhǔn)確率均≥95%，響應(yīng)時(shí)間均≤0.2 s；監(jiān)測(cè)系統(tǒng)種肥堵塞監(jiān)測(cè)準(zhǔn)確率均≥95%，響應(yīng)時(shí)間均≤0.3 s；監(jiān)測(cè)系統(tǒng)種肥泄漏監(jiān)測(cè)準(zhǔn)確率均≥92.5%，響應(yīng)時(shí)間均≤0.3 s，系統(tǒng)能夠迅速準(zhǔn)確的對(duì)各種運(yùn)行故障進(jìn)行報(bào)警。

注：監(jiān)測(cè)精度=系統(tǒng)檢測(cè)次數(shù)/人工統(tǒng)計(jì)次數(shù)×100%，即系統(tǒng)監(jiān)測(cè)準(zhǔn)確率。

Note: Check =Check by system/Check by artificial ×100%, that is, the system check accuracy.

6 結(jié)論與討論

1）該研究設(shè)計(jì)了一種基于變距光電傳感器的小麥精播施肥一體機(jī)監(jiān)測(cè)系統(tǒng)，該系統(tǒng)下位機(jī)采用反射式光電傳感器和旋轉(zhuǎn)編碼器分別獲取種肥流動(dòng)與種肥軸轉(zhuǎn)動(dòng)信息，判斷精播機(jī)運(yùn)行狀態(tài)（正常、堵塞、缺失和泄漏），并通過(guò)Modbus通訊協(xié)議將狀態(tài)信息傳輸至人機(jī)界面顯示，實(shí)現(xiàn)精播施肥一體機(jī)作業(yè)過(guò)程的實(shí)時(shí)監(jiān)測(cè)。

2）運(yùn)用Multisim對(duì)監(jiān)控系統(tǒng)排種監(jiān)測(cè)電路進(jìn)行仿真與試驗(yàn)測(cè)試，結(jié)果表明：放大電路對(duì)排種管光電傳感器檢測(cè)距離的改變值為4～7 mm，該距離能有效調(diào)整傳感器檢測(cè)距離。

3）對(duì)監(jiān)控系統(tǒng)進(jìn)行樣機(jī)故障模擬測(cè)試，結(jié)果表明：系統(tǒng)報(bào)警響應(yīng)準(zhǔn)確，故障監(jiān)測(cè)準(zhǔn)確率≥92.5%；報(bào)警響應(yīng)速度快，種肥缺失、堵塞、泄漏響應(yīng)時(shí)間分別≤0.2、≤0.3、≤0.3 s。

田間試驗(yàn)過(guò)程中，偶爾會(huì)出現(xiàn)漏種（漏肥）的誤報(bào)、響應(yīng)延遲等現(xiàn)象，分析原因：1）外界環(huán)境噪聲干擾了數(shù)據(jù)的傳輸；2）機(jī)器振動(dòng)影響了反射式光電傳感器的固定位置。因此后續(xù)工作主要為研究噪聲干擾濾除算法、設(shè)計(jì)具有防震功能的傳感器固定裝置進(jìn)而提高系統(tǒng)監(jiān)測(cè)準(zhǔn)確率。

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Design of monitoring system for wheat precision seeding-fertilizing machine based on variable distance photoelectric sensor

Zhao Lixin1, Zhang Zenghui1, Wang Chengyi2, Jian Shichun3, Liu Tong1, Cui Dongyun1, Ding Xiaoling1※

(1.,271018,; 2.,271018,; 3.,250100,)

Precision seeding has become the main developing direction of the modern seeding technology, and the quality of seeding machine’s operation will directly affect the growth and yield of wheat. Facing complex field moisture, machine vibration, noise and other unfavorable factors as well as the fully closed environment of seeds’ tubes and fertilizer’s tubes, only using audio-visual method is difficult to know the running status of seeder in real time. When the seeds’ tubes and fertilizer’s tubes are plugged or the seeds and fertilizer are lacked, it will cause the question of seedling absence in large areas, and result in yield reduction. Therefore, researching and developing the monitoring system of seeding-fertilizing machine has important significance and benefits both in producing and economy. In the early research stage of the laboratory, an electronically controlled wide wheat fertilization precision seeder was designed to achieve wide precision seeding. In order to realize the real-time monitoring of the process of wheat precision seeding-fertilizing machine and ensure the operation quality, a monitoring system with variable distance photoelectric sensor, which can realize the function of wheat precision seeding-fertilizing machine, was designed based on the previous research. The monitoring system takes the STM32 MCU (micro control unit) hardware detection system as the lower computer, and transmits the information by Modbus communication protocol to man-machine interface of MCGS (Monitor and Control Generated System) touch screen displaying real-time operation status. The lower computer uses a reflective photocell as a monitoring sensor, and determines the malfunction type by combining the information of seeds’ and fertilizer’s flow and shaft rotation measured by master system’s rotary encoder and transferred by Modbus communication. The monitoring sensors of wheat and fertilizer were adopt OH-1021 reflective photoelectric sensor which transmitting terminal and receiving terminal distributed on the same side. When there are particles blocking infrared light, the sensors output low level; when there are no particles, the sensors output high level. The sensor output experiences a high-low-high level change process when the infrared light is reflected while the particles flow through the photoelectric sensor. It is easier to determine the operating status of the fertilizing according to the fertilizer shaft speed and the output of fertilizer sensor data collected by MCU, since the fertilizing sensor was installed under the row fertilizer device. But the seed tube with sensor was installed above the seeding device, in which the wheat particles were full and flowing slowly. The initial detection distance of the seed sensor is set as 5 mm, which is the sum of the short diameter (3 mm) of single wheat particle and the tube thickness (2 mm). In normal operation, the wheat particles reflect the infrared light when flowing through the position of seed sensor, and the sensor output experiences a high-low-high level change process. The MCU determines the operating status of the seeding according to the sensor output and seed shaft speed. During the monitoring of seeding, the type of malfunction cannot be distinguished when the infrared light is located on the gap between 2 particles on the wall of the seed tube. The MCU controls the conduction of the triode via changing the IO (Input /Output) port output by activating the variable pitch task function, and thereby controls the detection distance of the sensor. When the output of the MCU is high, the triode is turned on, then voltage of the sensor is increased, resulting in the increase of detection distance, and thereforethe type of malfunctions is determined by further understanding on the seed-reserve in the seed tube. The circuit simulation test results of the lower computer’s seeds’ tube show that the detection distance of the photoelectric sensor of the seeds’ tube is changed by 4-7 mm under the amplifier circuit; monitoring system prototype test results show that the accuracy of fault alarm at least reaches 92.5%, and the response time of lacking seeds and fertilization, blockage and leakage is less than or equal to 0.2, 0.3 and 0.3 s, respectively. The monitoring system realizes high-precision real-time monitoring of wheat seeding and it can improve the quality of wheat seeding.

monitoring; design; sensor; precision seeding-fertilizing machine; variable distance; MCGS touch screen

趙立新，張?jiān)鲚x，王成義，薦世春，劉 童，崔東云，丁筱玲. 基于變距光電傳感器的小麥精播施肥一體機(jī)監(jiān)測(cè)系統(tǒng)設(shè)計(jì)[J]. 農(nóng)業(yè)工程學(xué)報(bào)，2018，34(13)：27－34.doi：10.11975/j.issn.1002-6819.2018.13.004 http://www.tcsae.org

Zhao Lixin, Zhang Zenghui, Wang Chengyi, Jian Shichun, Liu Tong, Cui Dongyun, Ding Xiaoling. Design of monitoring system for wheat precision seeding-fertilizing machine based on variable distance photoelectric sensor[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2018, 34(13): 27－34. (in Chinese with English abstract) doi：10.11975/j.issn.1002-6819.2018.13.004 http://www.tcsae.org

2017-12-12

2018-04-04

山東省農(nóng)機(jī)裝備研發(fā)創(chuàng)新計(jì)劃項(xiàng)目（2015YZ103）；山東省農(nóng)業(yè)重大應(yīng)用技術(shù)創(chuàng)新項(xiàng)目（SNZY31955）；山東農(nóng)業(yè)大學(xué)現(xiàn)代農(nóng)業(yè)智能化裝備研發(fā)項(xiàng)目（SDAU24131）

趙立新，副教授，主要從事傳感器技術(shù)、機(jī)電裝備智能化設(shè)計(jì)、機(jī)電一體化技術(shù)等教學(xué)研究工作。Email：xlding103@163.com

丁筱玲，教授，研究生導(dǎo)師，主要從事模式識(shí)別與智能控制、自動(dòng)化儀器儀表與裝置、自動(dòng)控制等方面的教學(xué)科研工作。 Email：xld@sdau.edu.cn

10.11975/j.issn.1002-6819.2018.13.004

S223.2+4

A

1002-6819(2018)-13-0027-08