吳亞壘,祁力鈞,張 豪,程湞湞,劉婠婠,謝德盛,Elizabeth Musiu
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基于嵌入式互聯(lián)網(wǎng)的遠(yuǎn)程智能噴霧控制系統(tǒng)設(shè)計(jì)
吳亞壘1,祁力鈞1※,張 豪1,程湞湞1,劉婠婠1,謝德盛2,Elizabeth Musiu1
(1. 中國農(nóng)業(yè)大學(xué)工學(xué)院,北京 100083;2. 深圳市隆瑞科技有限公司,廣州 518108)
為提高設(shè)施農(nóng)業(yè)植保作業(yè)智能管控能力,該文提出一種基于STM32F101和STM32F103嵌入式技術(shù),結(jié)合4G互聯(lián)網(wǎng)、局域WIFI通信技術(shù)及超聲波靶標(biāo)檢測算法,能夠便捷地對設(shè)施作業(yè)裝備遠(yuǎn)程視頻與控制的方案,達(dá)到人機(jī)分離與精準(zhǔn)施藥的目的。該系統(tǒng)在Eclipse和Keil-uvision4開發(fā)環(huán)境下采用Socket和多線程技術(shù)實(shí)現(xiàn)雙向通信,以TCP通訊協(xié)議為媒介,Android端和客戶端通過互聯(lián)網(wǎng)或無線網(wǎng)卡轉(zhuǎn)接移動路由實(shí)現(xiàn)遠(yuǎn)程智能噴霧控制。試驗(yàn)結(jié)果表明:1)Android端能夠在LAN或Internet中實(shí)現(xiàn)智能噴霧裝備的近遠(yuǎn)程控制,軟件界面回傳狀態(tài)無卡頓、延時發(fā)生,能夠準(zhǔn)確發(fā)射控制指令,實(shí)現(xiàn)了對靶標(biāo)間歇性施藥管控;2)系統(tǒng)建立的雙向心跳包能夠在通信故障情況下迫使噴霧裝備處于休眠狀態(tài),經(jīng)測試,心跳包設(shè)定時間與噴霧裝備休眠響應(yīng)時間平均相對誤差不超過5.50%;3)采用視頻幀對冠層中線定位,借助超聲檢測算法確定風(fēng)送距離參數(shù)且建立冠層體積模型。試驗(yàn)發(fā)現(xiàn),冠層密度對體積測量結(jié)果有顯著影響,但總體測量準(zhǔn)確度可達(dá)94.67%。該研究對其他農(nóng)機(jī)裝備的智能化管控研究有參考意義。
噴霧;控制;設(shè)計(jì);STM32嵌入技術(shù);無線網(wǎng)絡(luò)通信技術(shù);超聲波檢測算法
近年來,隨著中國農(nóng)業(yè)產(chǎn)業(yè)結(jié)構(gòu)的不斷優(yōu)化調(diào)整,設(shè)施農(nóng)業(yè)種植面積和產(chǎn)量穩(wěn)步提升[1]。中國已成為世界上設(shè)施栽培面積最大的國家,預(yù)計(jì)2030年中國設(shè)施栽培面積可望增至1 70萬hm2。在設(shè)施農(nóng)業(yè)快速發(fā)展的同時,其施藥設(shè)備和技術(shù)卻滯于瓶頸期[2],防治過程中不僅農(nóng)藥利用率低,且易導(dǎo)致施藥人員中毒等一系列問題[3]。隨著機(jī)械化與智能化的發(fā)展,將遠(yuǎn)程控制[4]與農(nóng)藥噴施技術(shù)[5-6]相結(jié)合對確保人員安全、降低勞動強(qiáng)度、克服青壯勞動力短缺及其精確靶標(biāo)施藥等[7-8]具有重要的實(shí)際意義。
國內(nèi)外學(xué)者已經(jīng)在林木果園[9-11]、田間植株[12-13]、和設(shè)施園藝[14-16]上開展了遠(yuǎn)程控制和精確靶標(biāo)施藥研究。姜紅花等[17]將植保機(jī)械與電子控制技術(shù)及物聯(lián)網(wǎng)技術(shù)相結(jié)合,設(shè)計(jì)了高通過性履帶自走式果園自動對靶風(fēng)送噴霧機(jī)。徐波等[18]基于Android平臺的平板電腦,對林木進(jìn)行測試,能在Wi-Fi環(huán)境下實(shí)現(xiàn)噴霧啟停控制、參數(shù)設(shè)置等功能。劉雪美等[19]針對大田植株行距、株距較大的作物對行施藥的農(nóng)藝要求,設(shè)計(jì)了噴桿噴霧精確對靶施藥系統(tǒng)。Gázquez等[20-22]研究設(shè)計(jì)了設(shè)施園藝智能施藥機(jī)器人系統(tǒng),在預(yù)定軌道上行走,按設(shè)定噴藥量進(jìn)行噴霧作業(yè),且自動控制施藥時間,自動施藥避免操作者與農(nóng)藥過度接觸帶來的危害[3]。祁力鈞等[23]在袁雪等[24]基礎(chǔ)上利用GPRS通信和控制技術(shù)初步實(shí)現(xiàn)了對設(shè)施群內(nèi)彌霧機(jī)遠(yuǎn)程控制和操作。總的來說,針對遠(yuǎn)程控制與精準(zhǔn)施藥技術(shù)研究還相對較少,技術(shù)還不成熟,系統(tǒng)亟需完備[25]。
本文基于嵌入式開發(fā)和4G互聯(lián)網(wǎng)技術(shù),旨在設(shè)計(jì)“互聯(lián)網(wǎng)+”設(shè)施智能遠(yuǎn)程控制系統(tǒng),并對該系統(tǒng)在北京(中國農(nóng)業(yè)大學(xué)植保實(shí)驗(yàn)室)和深圳(深圳市隆瑞科技有限公司)之間進(jìn)行了通信測試與試驗(yàn)驗(yàn)證。該系統(tǒng)以超聲波傳感器為載體,采用檢測算法確定風(fēng)送距離參數(shù)和建立冠層體積方程,從而根據(jù)作物需求,在特定環(huán)境下確定噴施量與噴施距離,提高農(nóng)藥噴霧施用效率。
本文研制了一種基于可視化人機(jī)交互模式的遠(yuǎn)程遙控作業(yè)車,整車結(jié)構(gòu)緊湊,可遙控實(shí)現(xiàn)其在矮化果園和設(shè)施溫室等狹窄場所機(jī)動靈活作業(yè),具有響應(yīng)迅速,動作執(zhí)行可靠的優(yōu)點(diǎn)。該遠(yuǎn)程施藥控制系統(tǒng)基于C/S架構(gòu),施藥系統(tǒng)軟件由Android端、4G互聯(lián)網(wǎng)無線網(wǎng)絡(luò)和噴霧裝備客戶端組成。該系統(tǒng)設(shè)計(jì)的創(chuàng)新思想是將華為4G全網(wǎng)通無線網(wǎng)卡與內(nèi)嵌花生殼服務(wù)的蒲公英路由器耦合在一起,擺脫了固定寬帶網(wǎng)絡(luò)受地域限制弊端,同時達(dá)到內(nèi)網(wǎng)穿透的目的。用戶能夠借助LAN或Internet實(shí)現(xiàn)智能噴霧裝備的近遠(yuǎn)程控制,圖1為遠(yuǎn)程施藥控制系統(tǒng)原理圖。
圖1 遠(yuǎn)程施藥控制系統(tǒng)原理圖
遠(yuǎn)程施藥控制系統(tǒng)客戶端主要由行走平臺和施藥系統(tǒng)組成,如圖2所示。
1.軌道 2.行走電機(jī) 3.避障傳感器 4.左右搖擺機(jī)殼 5.攝像機(jī) 6.超聲波模塊 7.按鍵板與WI-FI模塊 8.上下?lián)u擺噴頭
行走平臺在軌道上由大功率無刷電機(jī)驅(qū)動,平臺前后各裝有紅外傳感器檢測前后方有無障礙物并作出避障動作,此平臺一機(jī)多用,可用于果蔬運(yùn)輸。施藥系統(tǒng)包括檢測裝置與噴霧執(zhí)行裝置:檢測裝置主要包括攝像機(jī)與超聲波模塊,攝像機(jī)負(fù)責(zé)返回視頻幀信息,當(dāng)視頻幀中檢測裝置運(yùn)行至冠層中心線位置處,行走電機(jī)停止;每個超聲波傳感器進(jìn)行掃描,借助超聲波檢測算法對測試冠層體積進(jìn)行反演和風(fēng)送距離參數(shù)確定,初步確定噴施量與噴施距離,繼而實(shí)現(xiàn)對單位面積上沉積量改變。噴霧執(zhí)行裝置通過自適應(yīng)風(fēng)機(jī)風(fēng)速調(diào)整,改變風(fēng)機(jī)輸送距離,同時通過齒輪的嚙合運(yùn)動實(shí)現(xiàn)上下?lián)u擺,在風(fēng)力的擾動下對枝葉進(jìn)行翻轉(zhuǎn),實(shí)現(xiàn)作物的上下端和葉背、葉面霧滴均勻沉積。該噴霧裝備主要技術(shù)參數(shù)如表1所示。
表1 噴霧裝備的技術(shù)參數(shù)
系統(tǒng)APP開發(fā)基于TCP/IP協(xié)議,采用Socket和多線程技術(shù),在Eclipse集成開發(fā)環(huán)境下采用java語言設(shè)計(jì)完成,生成APK文件,運(yùn)行平臺為OPPO R11。
2.1.1 Android端遠(yuǎn)程通信優(yōu)化
本文遠(yuǎn)程控制基本原理是“端口映射”+“動態(tài)域名”。端口映射使得外網(wǎng)對于路由器(蒲公英路由器X5型)上一個特定端口的訪問會被路由器轉(zhuǎn)到一個指定的客戶端IP(本文IP為192.168.1.107),此時路由器起到“橋”功能,使外網(wǎng)和噴霧裝備上面的WI-FI模塊(物理地址為94:BA:56:00:C9:01)聯(lián)通,鑒于路由器上的外網(wǎng)訪問IP不斷被更新,有且通過花生殼動態(tài)域名設(shè)置解析IP地址,本文動態(tài)訪問域名為20220787by.iask.in,可實(shí)現(xiàn)局域網(wǎng)轉(zhuǎn)外網(wǎng)功能,從而操作人員可以通過外網(wǎng)控制噴霧裝備。
2.1.2 Android端系統(tǒng)IP數(shù)據(jù)包優(yōu)化
通信協(xié)議中單字符通信方式干擾較大,本文Android端與噴霧裝備端數(shù)據(jù)交換采用IP包形式[26]傳送控制指令,包頭和包尾均為0XFF,解包機(jī)制可以對數(shù)據(jù)包精確接收及終止。IP包的數(shù)據(jù)交換格式規(guī)定為:{包頭,類型位,命令位,數(shù)據(jù)位,包尾},如:{FF,溫濕度顯示,溫濕度接收,溫濕度值,F(xiàn)F}和{FF,風(fēng)速設(shè)定,風(fēng)速發(fā)送,風(fēng)速值,F(xiàn)F},IP數(shù)據(jù)包分別采用Input Stream類和Output Stream類從流中讀取與輸出數(shù)據(jù)包,同時實(shí)例化socket Writer對象,以Byte打包方式將數(shù)據(jù)包發(fā)送到路由器,路由器借助花生殼服務(wù)端口映射把數(shù)據(jù)包轉(zhuǎn)發(fā)給客戶端串口。發(fā)送至STM32單片機(jī)的數(shù)據(jù)包利用解包機(jī)制將該包解開,并控制模塊執(zhí)行相關(guān)操作,最后采用flush和close方法分別刷空輸出流及關(guān)閉流以釋放資源。
邱占芝等[27]對數(shù)據(jù)包接收情況進(jìn)行了試驗(yàn)驗(yàn)證,當(dāng)試驗(yàn)環(huán)境空曠情況下,數(shù)據(jù)包被噴霧裝備接收端穩(wěn)定接收,但是當(dāng)環(huán)境復(fù)雜(障礙物遮擋等情況),數(shù)據(jù)包有可能被屏蔽或遮擋,無法被接收端接收。對此,在程序中定義應(yīng)答和計(jì)時變量,如timer.schedule(new MyTask(), 1000, 150),當(dāng)手機(jī)端未接收到應(yīng)答情況下,每隔150 ms循環(huán)發(fā)射該控制命令,直到接收應(yīng)答停止。
本文在搭載遠(yuǎn)程通信的基礎(chǔ)上,通過視頻幀對果樹中心線進(jìn)行簡單定位,為后續(xù)果樹冠層體積測量提供輔助算法??紤]到試驗(yàn)過程中算法工效及分割難度,本算法截取底部1/8圖像。在eclipse開發(fā)環(huán)境中架構(gòu)opencv鏈接庫,首先對該圖像進(jìn)行Ostu法二值化,算出最優(yōu)閾值T后可根據(jù)式(1)將圖像分成樹干和背景2個部分。其次根據(jù)式(2)、(3)求解樹干左右兩側(cè)行像素累加平均值,然后對其平均值作比,如果比值為1,完成此次視頻幀定位。
式中為二值化圖像灰度數(shù)值,T為自適應(yīng)最優(yōu)閾值;=1為背景(白色),=0為樹干(黑色)。
式中(,)為第行第列的像素值;left為第行樹干左側(cè)的像素值;right為第行樹干右側(cè)的像素值;left為第行樹干左側(cè)的寬度;right為第行樹干右側(cè)的寬度;為圖像寬度;為圖像高度;為樹干左側(cè)像素平均值與右側(cè)像素平均值的比。
簡潔易用是本文Android端系統(tǒng)界面設(shè)計(jì)理念。作業(yè)界面包括工作參數(shù)顯示、指令輸入和消息提示,分別用于顯示和設(shè)置噴霧設(shè)備的噴霧參數(shù)及反饋狀態(tài)信息;該系統(tǒng)界面可獲取設(shè)施內(nèi)實(shí)時數(shù)據(jù)并采用數(shù)據(jù)可視化技術(shù)[17],監(jiān)測溫濕度實(shí)時數(shù)據(jù)參量變化,若不滿足噴霧環(huán)境溫濕度則終止此次作業(yè),同時視頻插件嵌套到控制界面,多線程實(shí)時監(jiān)測作物體積參數(shù)及噴霧裝備在線工作狀態(tài)等情況[28];同時考慮到Android端系統(tǒng)視頻幀監(jiān)測算法對于背景復(fù)雜的現(xiàn)場有局限性,為保證噴霧質(zhì)量,通過代碼在界面生成淺藍(lán)色標(biāo)記線,輔助視頻幀進(jìn)行中線定位。各個Activity直接用Intent函數(shù)進(jìn)行轉(zhuǎn)換,主要UI界面設(shè)計(jì)如圖3所示。
圖3 UI界面設(shè)計(jì)
Fig.3 UI interface design
本文嵌入式硬件電路以STM32主芯片為核心,主要分為按鍵板(圖4a)和控制板(圖4b)電路,按鍵板與控制板采用RS-485通信協(xié)議接口,可實(shí)現(xiàn)多點(diǎn)通信且RS-485接口具有良好抗噪干擾性,長距離傳輸?shù)葍?yōu)點(diǎn)[29]。按鍵板較控制板芯片多12個引腳,主要用于連接超聲波傳感器和溫濕度引腳;該按鍵板主要發(fā)送和回傳指令,通過矩陣鍵盤掃描,串口中斷等完成對控制板信號發(fā)送,通過WIFI模塊完成數(shù)據(jù)包指令的回傳,包括溫濕度、電壓、風(fēng)速及超聲波檢測算法等數(shù)值??刂瓢迳厦姘娫唇祲?、電機(jī)驅(qū)動、避障限位、流量及風(fēng)速設(shè)定等功能模塊。電源降壓模塊分別給電機(jī)驅(qū)動部分和控制部分供電。傳感器模塊主要是避障和限位模塊進(jìn)行信號反饋,間接調(diào)控電機(jī)驅(qū)動模塊啟停。
1.USB轉(zhuǎn)WIFI模塊 2.測距1信號線 3.測距2信號線 4.測距3信號線 5.測距4信號線 6.通信信號線 7.STM32F103單片機(jī) 8.程序燒錄串口 9.溫濕度信號線 10.RS485信號線
1.USB to WIFI module 2.Ranging 1 signal line 3.Ranging 2 signal line 4.Ranging 3 signal line 5.Ranging 4 signal line 6.Communication signal line 7.STM32F103 MCU 8. Program burning serial port 9. Temperature and humidity signal line 10. RS485 signal line
a. 噴霧裝備系統(tǒng)按鍵板PCB設(shè)計(jì)
a. Spray equipment system key board PCB design
1.電源線 2.RS485通訊線 3.STM32F101單片機(jī) 4.程序燒錄串口 5.上下?lián)u擺信號線 6.風(fēng)機(jī)信號線 7.左右搖擺信號線 8.避障信號線 9.限位信號線 10.行走信號線 11.測距5信號線 12.水泵信號線 13.測距6信號線
1.Power cable 2.RS485 communication cable 3.STM32F101 MCU 4.Program burning serial port 5.Up and down swing signal line 6.Fan signal line 7.Left and right swing signal line 8.Obstacle avoidance signal line 9.Limit signal line 10.Travel signal line 11.Ranging 5 signal line 12.Pump signal line 13.Ranging 6 signal line
b. 噴霧裝備系統(tǒng)控制板PCB設(shè)計(jì)
b. Spray equipment system control board PCB design
圖4 噴霧裝備系統(tǒng)硬件電路設(shè)計(jì)
Fig.4 Spray equipment system hardware circuit design
3.2.1 軟件心跳包對故障的響應(yīng)優(yōu)化設(shè)計(jì)
軟件系統(tǒng)故障發(fā)生較頻繁,如手機(jī)APP異常關(guān)閉,網(wǎng)絡(luò)連接故障,噴霧裝備驟停等事故。為此,大部分采用TCP自身心跳包機(jī)制[30],如SO_KEEPALIVE函數(shù),默認(rèn)120 min心跳頻率,僅用于?;睿珶o法判斷噴霧裝備的斷電、故障、網(wǎng)線及邏輯層等斷線事故,對于噴霧裝備的作業(yè)安全存在隱患。其次,send或者receive也可判定掉線,但在長連接下,有可能長時間都沒有數(shù)據(jù)往來,中間節(jié)點(diǎn)故障難以預(yù)測,僅用于維持長連接,保活。本文自行優(yōu)化心跳包可以對故障及時處理,提升作業(yè)安全水平。心跳檢測步驟如圖5所示:1)Android和噴霧裝備客戶端每隔5 s發(fā)送一次無效的IP數(shù)據(jù)包給服務(wù)器,且發(fā)包時各啟動一個超時定時器timeAPP-;2)兩端接收到檢測包,應(yīng)該回復(fù)應(yīng)答指令;3)如果雙方均收到應(yīng)答包,線路連接正常,超時定時器被reset;4)如果雙方的超時定時器超時,沒有響應(yīng)應(yīng)答,表明故障發(fā)生,雙方作業(yè)終止,并實(shí)時在Android界面提示連接故障等反饋信息,通知施藥人員處理。
圖5 心跳包檢測機(jī)制原理圖
3.2.2 超聲檢測風(fēng)送距離參數(shù)確定
本文依托超聲波傳感器測量噴頭到冠層的送風(fēng)距離,根據(jù)氣流場攜帶霧滴能力特性的能力對軟件部分進(jìn)行設(shè)計(jì)。根據(jù)牛頓第二運(yùn)動定律
式中F為噴頭軸線方向受力,N;air為空氣作用力,N;為霧滴質(zhì)量,kg;a為霧滴加速度,m/s2。當(dāng)a趨于0,氣流不再有向前的驅(qū)動力,當(dāng)氣流速度趨于2 m/s[31],根據(jù)行業(yè)標(biāo)準(zhǔn)定義為氣流的輸送距離,此段位移定義為風(fēng)送距離[32],便于調(diào)整設(shè)定對應(yīng)的出風(fēng)口風(fēng)速參數(shù)。
3.2.3 超聲檢測冠層體積系統(tǒng)設(shè)計(jì)
人工測量方法采用Wheaton和Albrigo冠層體積測量法[33]??偨Y(jié)前人研究基礎(chǔ)上,本文設(shè)計(jì)了“圓柱體積求和法”用于測量冠層體積。超聲波傳感器等間距安裝在桅桿上,各傳感器離地面的高度及傳感器間距都可根據(jù)實(shí)際對象進(jìn)行調(diào)節(jié),所謂圓柱體積求和法是將果樹冠層看成是個圓柱組成,其體積即為個圓柱體積之和(為超聲波傳感器數(shù)目),通過公式(5)可計(jì)算出果樹冠層體積,其測量原理如圖6所示。
注:Dn第n個超聲波傳感器探測到的傳感器與果樹冠層的距離,m;Dc為超聲波傳感器與果樹中心線(作物行中心線)之間的距離,m;Ds為超聲波傳感器之間的間距,m。
式中V為果樹冠層體積,m3。
傳感器1和測量結(jié)果不一定是最低與最高冠層處的半徑,即以下和以上冠層體積將可能會被漏算或多算,但對于冠層來說,漏算和多算的體積在本研究作中忽略處理。本文選取6個超聲波傳感器,等間距25 cm裝配,此外在視頻幀輔助作用下進(jìn)行冠層模型中心線定位,得到檢測距離,利用本文設(shè)計(jì)的“圓柱體積求和法”計(jì)算果樹冠層體積,測量結(jié)束,初步得到施藥量,后續(xù)在檢測距離的基礎(chǔ)上實(shí)時確定風(fēng)速。
為了驗(yàn)證IP數(shù)據(jù)包能夠?qū)崿F(xiàn)通信,將圖4a中的程序燒錄信號線JTMS,JTCK,GND與ULink2相連接,上電操作,在keil-vision4界面開啟在線調(diào)試功能;開啟噴霧裝備,等待啟動燈常亮,手機(jī)端點(diǎn)擊按鈕指令,在軟件界面watch窗口中,可以實(shí)時查看變量,觀察電腦端IP數(shù)據(jù)的接收狀態(tài),圖7a中接收到的通信協(xié)議為噴頭轉(zhuǎn)動控制指令,圖7b中接收到的通信協(xié)議為風(fēng)機(jī)速度控制指令,結(jié)果表明,Android發(fā)送的控制指令能被噴霧裝備準(zhǔn)確接收。
為了驗(yàn)證Android和噴霧裝備能夠?qū)崿F(xiàn)局域網(wǎng)和遠(yuǎn)程互聯(lián)網(wǎng)通信,利用“Ping”命令可以檢查網(wǎng)絡(luò)是否連通,測試網(wǎng)絡(luò)時延,可很好地判定網(wǎng)絡(luò)故障。“Ping”是Windows下用戶使用的發(fā)送ICMP回送請求的命令,在Unix和Linux下也有這個命令;ping也屬于一個通信協(xié)議,其應(yīng)用格式為:Ping空格IP地址。在中國農(nóng)業(yè)大學(xué)植保機(jī)械實(shí)驗(yàn)室和深圳市隆瑞科技有限公司分別進(jìn)行通信驗(yàn)證。在默認(rèn)情況下,僅發(fā)送4個數(shù)據(jù)包,通過這個命令自定義發(fā)送個數(shù),有助于衡量網(wǎng)絡(luò)速度,如圖7c和7d分別為局域網(wǎng)和遠(yuǎn)程互聯(lián)網(wǎng)內(nèi)Ping 指令結(jié)果。本文發(fā)送12個數(shù)據(jù)包,分別ping -n 12 192.168.1.107和ping -n 12 20220787by.iask.in,并未出現(xiàn)丟包問題且平均時間分別為5和79 ms,能實(shí)現(xiàn)雙向通信。
圖7 IP數(shù)據(jù)包與遠(yuǎn)程通信測試結(jié)果
為驗(yàn)證心跳包機(jī)制的穩(wěn)定性和可控性,采用PC396秒表對Android端和裝備客戶端整個通信系統(tǒng)進(jìn)行響應(yīng)時間試驗(yàn)測試。心跳包的發(fā)射頻率不能過高,易造成數(shù)據(jù)阻塞,同時由表1知,噴霧裝備行進(jìn)速度過快時要求響應(yīng)時間較短,防止因速度過快而造成的響應(yīng)距離延長,其次不同時間段網(wǎng)絡(luò)負(fù)載情況有差異?;谝陨涎芯浚?guī)定不同的時斷開始試驗(yàn),設(shè)定不同的心跳包故障檢測時間,在雙向通信正常的情況下分別進(jìn)行響應(yīng)時間的測試。試驗(yàn)中異常關(guān)閉Android端軟件,開始記錄噴霧裝備到結(jié)束運(yùn)動的時間,系統(tǒng)響應(yīng)時間試驗(yàn)結(jié)果如表2所示。
表2 系統(tǒng)響應(yīng)時間試驗(yàn)結(jié)果
注:1,2,3,4分別為08:00,12:00,16:00,20:00時間段測試系統(tǒng)響應(yīng)時間;為一天內(nèi)4個時間段系統(tǒng)平均響應(yīng)時間;相對誤差=|平均響應(yīng)時間-心跳包故障檢測時間|/心跳包故障檢測時間×100%。
Note:1,2,3and4are the system response time of 8 o'clock, 12 o'clock, 16 o'clock, and 20 o'clock, respectively;is the average system response time of 4 time periods in a day; relative error = | Average response time-Heartbeat packet failure detection time|/heartbeat packet failure detection time×100%.
試驗(yàn)測試后發(fā)現(xiàn),系統(tǒng)的心跳包機(jī)制運(yùn)行穩(wěn)定,可保障噴霧裝備與施藥作業(yè)安全,系統(tǒng)的響應(yīng)時間平均相對誤差不超過5.50%,滿足實(shí)際作業(yè)故障處理要求;在一天內(nèi)的不同作業(yè)時斷,網(wǎng)絡(luò)延遲程度不一,主要是傍晚以后,系統(tǒng)響應(yīng)時間增長,可能的原因是該時斷下網(wǎng)絡(luò)負(fù)載加大造成的;由表2又知,系統(tǒng)平均響應(yīng)時間誤差隨心跳包發(fā)射時間延長變化不大,表明系統(tǒng)的響應(yīng)速度較快。
在中國農(nóng)業(yè)大學(xué)植保機(jī)械實(shí)驗(yàn)室4 m×3 m區(qū)域內(nèi)試驗(yàn)測試,如圖8所示。
圖8 試驗(yàn)區(qū)示意圖
建立直角坐標(biāo)系,區(qū)域布置在第一象限,坐標(biāo)點(diǎn)標(biāo)記(一個單位長度為1 m),矮化果樹坐標(biāo)點(diǎn)(2,2.4),噴霧機(jī)在作業(yè)時由坐標(biāo)點(diǎn)(0,0)作業(yè)至(4,0)結(jié)束。試驗(yàn)中,本文選取矮化仿真榕樹冠層模型作為研究對象,榕樹冠層模型枝干數(shù)目為5,可進(jìn)行枝干拆解,按照枝干拆解個數(shù)0、1、2用于表征冠層模型的稠密程度,共分為濃密、較密和稀疏3類。將放置好的模型繞坐標(biāo)點(diǎn)(2,2.4)處等角度旋轉(zhuǎn),每60°旋轉(zhuǎn)1次,共旋轉(zhuǎn)6次,分別按照該操作將3類模型先后進(jìn)行試驗(yàn)測試。試驗(yàn)結(jié)果如圖9所示,試驗(yàn)現(xiàn)場如圖10所示。
圖9 不同疏密冠層手動與檢測算法自動測量對比
圖10 遠(yuǎn)程噴霧控制系統(tǒng)圖
為評估系統(tǒng)測量法和手動測量法對于冠層體積的檢測效果,將不同靶標(biāo)擺放角度處的系統(tǒng)測量值和手動實(shí)測值進(jìn)行比較(圖9),分析采樣點(diǎn)冠層體積偏差程度和測量準(zhǔn)確度[34],式(6)、(7)分別表述采樣點(diǎn)中最大相對測量誤差max和平均相對誤差ave。
冠層體積超聲算法檢測試驗(yàn)表明:冠層的稠密程度對冠層檢測系統(tǒng)的準(zhǔn)確度影響較大,當(dāng)冠層為濃密時,6種擺放角度下所測結(jié)果與手動測量結(jié)果平均誤差不超過5.33%,最大相對誤差僅為6.40%,且各測試結(jié)果沒有明顯的差異性;當(dāng)冠層稠密程度為較密時,6種擺放角度下所測結(jié)果與手動測量結(jié)果平均誤差不超過10.74%,且各測試結(jié)果有明顯的波動,這與冠層不同擺放位置的孔隙度有關(guān)系;當(dāng)冠層稠密程度為稀疏時,6種擺放角度下所測結(jié)果與手動測量結(jié)果最大相對誤差達(dá)到50.57%,且各測試結(jié)果差異性顯著,可能是冠層過于稀疏造成超聲波信號丟失。可見冠層濃密程度明顯影響系統(tǒng)測量準(zhǔn)確度,還需要試驗(yàn)中不斷積累經(jīng)驗(yàn)。視頻幀如果拍攝到稀疏情況,不宜用本系統(tǒng)進(jìn)行冠層體積測量,反之樹葉濃密適合用本系統(tǒng)進(jìn)行冠層體積測量,測量準(zhǔn)確度高達(dá)94.67%。
1)本文遠(yuǎn)程智能噴霧控制系統(tǒng)能夠?qū)崿F(xiàn)局域網(wǎng)和遠(yuǎn)程互聯(lián)網(wǎng)通信,利用“Ping”命令檢查網(wǎng)絡(luò)對IP數(shù)據(jù)包的響應(yīng)情況,并未出現(xiàn)丟包問題且平均響應(yīng)時間分別為5和79 ms,能實(shí)現(xiàn)雙向穩(wěn)定通信。
2)經(jīng)過試驗(yàn),系統(tǒng)的心跳包機(jī)制運(yùn)行穩(wěn)定,可保障噴霧裝備與施藥作業(yè)安全,且響應(yīng)時間平均相對誤差不超過5.50%,滿足實(shí)際作業(yè)故障處理要求;同時噴霧裝備行進(jìn)速度過快時要求響應(yīng)時間較短,防止因速度過快而造成的響應(yīng)距離延長;該裝備系統(tǒng)不宜傍晚作業(yè),系統(tǒng)的響應(yīng)時間較長。
3)冠層稠密程度對冠層體積測量系統(tǒng)測量結(jié)果有顯著影響。稀疏情況下冠層體積手動測量值與自動測量值間有顯著差異;較密情況下次之;濃密情況下冠層體積手動測量值與自動測量值間無顯著差異,適宜用本文冠層體積測量系統(tǒng),最大相對誤差僅為6.40%,且測量準(zhǔn)確度高達(dá)94.67%;該方案便于改善噴施量與噴施距離,且冠層覆蓋率和分布均一性將得到明顯改善。
4)該遠(yuǎn)程控制與優(yōu)化施藥系統(tǒng)可實(shí)現(xiàn)人機(jī)分離與精準(zhǔn)施藥。通過試驗(yàn)可知,針對機(jī)身故障的檢測及處理具有較高的可靠性,同時對于傳統(tǒng)生產(chǎn)模式的改造及智能農(nóng)機(jī)的推廣具有潛在的應(yīng)用價值。本文后續(xù)將進(jìn)行冠層定心,實(shí)現(xiàn)精確對靶噴霧方面的研究。
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Design and experiment of remote intelligent spray control system based on embedded internet
Wu Yalei1, Qi Lijun1※, Zhang Hao1, Cheng Zhenzhen1, Liu Wanwan1, Xie Desheng2, Elizabeth Musiu1
(1.100083,; 2.518108,)
In view of the current weak status of intelligent management and control systems for facility of agriculture and dwarfed orchards, high labor intensity and complicated spraying environment, this article proposed an embedded technology, which took STM32F101 and STM32F103 as the core and basis, combined with 4G Internet and ultrasonic target detection algorithm, and was able to remotely control agricultural machinery to achieve the purpose of human-machine separation and precise application of pesticides. The system used Socket and multi-thread technology to implement two-way communication under the Eclipse and Keil-uvision4 development environment. With TCP communication protocol as the medium, the Android and client transferred remote routing through the Internet or wireless network card to achieve remote intelligent spray control. The test results show that: 1) Android can implement near-remote control of smart spray equipment in the LAN or Internet. The software interface returns that no stagnant state or delay occurs and it can accurately transmit control commands and achieve intermittent application of the target. 2) The bidirectional heartbeat package established by the system can force the spray equipment to be dormant in the event of communication failure. After testing, the error rate of the heartbeat packet set-up time and the spray equipment dormancy response time does not exceed 5.50%. 3) Use the video frame to locate the canopy middle line, and use the ultrasonic detection algorithm to determine the wind-distance parameters and establish the canopy volume model. Through experiments, it is found that the degree of canopy denseness has a significant impact on the measured results of the canopy volume measurement system. The text measurement system should be used in dense canopy conditions, and the measurement accuracy is as high as 94.67%. 4) The remote smart spray control system in this article can realize local network and long-distance internet communication. Use “Ping” command to check the network response to IP data packets. There is no packet loss problem and the average response time is 5 and 79 ms, respectively. 5) The degree of canopy density has a significant effect on the measurement of the canopy volume measurement system. There is a significant difference between the manual and automatic measurements of the canopy volume in sparse conditions. On the contrary, there is no significant difference between the manual and automatic measurements of the canopy volume in the dense conditions, which is suitable for measuring the canopy volume in this article. In the system, the maximum relative error is only 6.4%, and the canopy coverage and distribution uniformity will be significantly improved. 6) A remote control and optimized application system available for complete Internet-based spray equipment is designed. The system can realize human-machine separation and precise application of pesticides. Through tests, it can be seen that the detection and processing of the fuselage faults has high reliability. At the same time, it has potential application value for the transformation of traditional production modes and the promotion of smart agricultural machinery. The study can also provide reference for the automation and intellectualization of other agricultural machinery equipment.
spraying; control; design; STM32 embedded technology; wireless network communication technology; ultrasonic detection algorithm
10.11975/j.issn.1002-6819.2018.20.004
TP212.9; S491
A
1002-6819(2018)-20-0028-08
2018-05-01
2018-08-01
科技部國家重點(diǎn)研發(fā)計(jì)劃項(xiàng)目“現(xiàn)代果園智能化精細(xì)生產(chǎn)管理技術(shù)裝備研發(fā)”(2017YFD0701400);科技部國家重點(diǎn)研發(fā)計(jì)劃項(xiàng)目“地面與航空高工效施藥技術(shù)及智能化裝備)2016YFD0200700)”。
吳亞壘,博士生,研究方向?yàn)橹饕獜氖轮脖C(jī)械研究。Email:kevin_wuyalei@cau.edu.cn
祁力鈞,博士,教授,研究方向?yàn)閺氖轮脖C(jī)械研究。Email:qilijun@cau.edu.cn
吳亞壘,祁力鈞,張 豪,程湞湞,劉婠婠,謝德盛,Elizabeth Musiu. 基于嵌入式互聯(lián)網(wǎng)的遠(yuǎn)程智能噴霧控制系統(tǒng)設(shè)計(jì)[J]. 農(nóng)業(yè)工程學(xué)報(bào),2018,34(20):28-35. doi:10.11975/j.issn.1002-6819.2018.20.004 http://www.tcsae.org
Wu Yalei, Qi Lijun, Zhang Hao, Cheng Zhenzhen, Liu Wanwan, Xie Desheng, Elizabeth Musiu. Design and experiment of remote intelligent spray control system based on embedded internet[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2018, 34(20): 28-35. (in Chinese with English abstract) doi:10.11975/j.issn.1002-6819.2018.20.004 http://www.tcsae.org