外文翻譯---除草的四輪農(nóng)業(yè)機(jī)器車

1、<p>　　Agricultural Robotic Platform with Four Wheels Steering for Weed Detection</p><p>　　Thomas Bak; Hans Jakobsen</p><p>　　Department of Agricultural Engineering, Danish Institute of Agri

2、cultural Sciences, Schoottesvej. 17, DK-8700 Horsens, Denmark;e-mail of corresponding author: tb@control.auc.dk</p><p>　　(Received 10 January 2003; accepted in revised form 14 October 2003; Published online

3、23 December 2003)</p><p>　　A robotic platform for mapping of weed populations in fields was used to demonstrate intelligent concepts for autonomous vehicles in agriculture which may eventually result in a ne

4、w sustainable model for developed agriculture. The software implements a hybrid deliberate software architecture that allows a hierarchical decomposition of the operation. The lowest level implements a reactive feedback

5、control mechanism based on an extension of simple control for car-like vehicles to the four wheel ca</p><p>　　1. Introduction</p><p>　　Advances in mechanical design capabilities, sensing technol

6、ogies, electronics, and algorithms for planning and control have led to a possibility of realizing field operations based on autonomous robotic platforms The need for such systems is driven by increasing financial pressu

7、re on farmers combined with public concern about the environment and working conditions. Efficient deployment of autonomous robotic platforms in the field will allow care and management of crops in a very different way f

8、r</p><p>　　This paper presents an overview of the system and approach. Section 2 provides a system description. This includes a description of modular mechanical concepts well as the Techtronic implementatio

9、n of the system. Everything is tied together in hierarchical hybrid software architecture. In Section 3, the focus is on a specific mobility control strategy that extends simple controllers to 4WS. The result is a system

10、 that allows the vehicle to track a given path, while maintaining the front and rear</p><p>　　2. System description</p><p>　　The robotic platform described here is meant to demonstrate novel sen

11、sing capabilities (Sgaard &Olsen, 2000) and semi-autonomous operation of a robotic platform for agriculture. The immediate agronomic aim of the project is to demonstrate efficient measurement of spatial and temporal

12、crop and weed measurements. Given that the variability in weeds is measured and mapped, inputs can be varied according to a defined strategy providing environmental and economic benefits. Studies show that 50–80% of</

13、p><p>　　2.1. Robotic platform</p><p>　　The basis for the robotic platform is the mobility capability provided by the wheel module mechanism shown in Fig. 1. Each of the four identical wheel modules

14、 include a brushless electric motor for propulsion that provide direct drive without gearing. Motor, amplifier and microcontroller are all mounted in the wheel hub. Steering capability is achieved by a separate steering

15、motor mounted on top of the wheel module shaft to create a two-degree-of-freedom mechanism. The steering motor amplifier a</p><p>　　2.2. Platform electronics</p><p>　　This allows programs to be

16、built automatically and subsequently execute in near real-time on the platform computer. The solution supports transmission control protocol/internet protocol (TCP/IP) sockets for remote communication with the running co

17、de which allow monitoring and modification of parameters during development.</p><p>　　2.3. System architecture</p><p>　　The system architecture adopted is similar to the hybrid deliberate approa

18、ch (Arkin, 1990) that is now common in mobile robotics systems (Orebaack. & Christensen 2003). The three-layer architecture consists of: (1) a reactive feedback control mechanism that handles stabilization and tracki

19、ng, (2) a plan-execution mechanism that deals with e.g. trajectory generation and task decomposition, and (3) a mechanism for performing time-consuming deliberative computations and interaction with human opera</p>

20、<p>　　3 Mobility control</p><p>　　The motion of the robot can always be viewed as an instantaneous rotation around a time varying point called the instantaneous centre of rotation (ICR). Hence, at eac

21、h instant, the velocity vector of any point. Of the frame is orthogonal to the straight line joining this point and the ICR. </p><p>　　Controlling the vehicle position in the field implies controlling the tw

22、o-dimensional location of the ICR, which may be achieved by specifying the direction of travel of two points of the vehicle. To get experimental results with the 4WS system, a simple controller that controls two steering

23、 points was implemented, one at the front end and one at the rear of the vehicle. The 4WS is then utilized to minimize the distance to the desired path for both steering points independently as indicated in </p>

24、<p>　　This approach with two independent controllers allows us to switch between 2WS and 4WS without having to change the controller structure. As front and rear controllers are identical so without loss of generali

25、ty, the description here is focused on the front steering controller. Its control objective is to minimize the perpendicular distance to the path df. The sign of df indicates the side of the path on which the steering po

26、int is located. From df it calculates a commanded direction of the fron</p><p>　　where: h is a positive scalar converting the control signal to motor voltage.</p><p>　　This simple distribution a

27、ctually works very well in practice and in addition it also has an anti-spin effect. If a wheel slips, it will of course rotate a little faster as the EMF will grow to compensate for the missing torque, but the torque di

28、stribution among the wheels is not changed. A slipping wheel has a minor influence on the measured vehicle speed as it is based on the rotation speed of all wheels, but this can be solved by omitting a wheel if a slip de

29、tection indicates that it is slipp</p><p>　　作者：Thomas Bak; Hans Jakobsen</p><p><b>　　國籍：Danish</b></p><p>　　出處：Department of Agricultural Engineering, Danish Institute o

30、f Agricultural Sciences, Schoottesvej. 17, DK-8700 Horsens, Denmark;</p><p>　　除草的四輪農(nóng)業(yè)機(jī)器車</p><p>　　機(jī)器人平臺測繪雜草種群的領(lǐng)域是用來展示智能概念車輛，這最終將為高度發(fā)達(dá)的農(nóng)業(yè)引進(jìn)一種可持續(xù)的模式，現(xiàn)有的車輛適用于0.25米和0.5米行距的作物，這種車輛裝備了適用于行間向?qū)Ш退褜るs草的相機(jī)。

31、攜帶有四個特備的輪子的組合方法，允許轉(zhuǎn)向裝置和推進(jìn)力。這種結(jié)果被改進(jìn)了，允許機(jī)器在轉(zhuǎn)向時平行移動，是通過去耦合裝置來調(diào)節(jié)方向的。機(jī)器的控制是通過工具系統(tǒng)和基于控制的系統(tǒng)，這種軟件工具混合了成熟的建構(gòu)軟件，這種農(nóng)業(yè)軟件混合有機(jī)的操作。最低水準(zhǔn)是運用反饋系統(tǒng)，這種反饋系統(tǒng)基于汽車簡單控制的延伸，這種控制設(shè)計使得前后輪服從以設(shè)計的路徑，允許機(jī)器維持復(fù)雜的相關(guān)路徑，這種控制方法正在試驗中。</p><p><b&g

32、t;　　引言</b></p><p>　　在控制方面的機(jī)械設(shè)計能力，傳感技術(shù)，電子學(xué)和運算學(xué)的進(jìn)步已經(jīng)使得自動化的機(jī)器人操作的可能性。這種系統(tǒng)的需要正被逐漸增加的財政壓力，公眾對環(huán)境和工作條件的關(guān)注而驅(qū)動著。機(jī)器平臺和工具或許能精確的感覺到和控制到農(nóng)作物和他所處的環(huán)境從而使其比傳統(tǒng)的機(jī)器更有效。這能夠在提高精度和效率的同時降低對環(huán)境的反作用，這種結(jié)果對于高度發(fā)達(dá)的農(nóng)業(yè)是一種新的可持續(xù)模式，農(nóng)業(yè)機(jī)器向?qū)?/p>

33、已經(jīng)成為一種積極地研究領(lǐng)域好多年了，最初的商業(yè)導(dǎo)向系統(tǒng)已經(jīng)普及，拖拉機(jī)被提前預(yù)設(shè)的路徑控制，這種路徑是基于GPS系統(tǒng)。這些自動向?qū)C(jī)器解決了以上許多問題，但是在土壤，壓實，能源使用、排放物和精密等方面不是最好的解決方案。</p><p>　　把重心集中到能不斷操作和最小誤差的機(jī)器，能讓我們想到一系列的更小更特殊更精確更有效的機(jī)器。這種機(jī)器能夠以更低的頻率來工作更長的時間，同時比以往機(jī)器提供同樣甚至是更多的輸出。機(jī)

34、器在無人的情況下更長時間的操作時一項重大挑戰(zhàn)。最近在機(jī)械手工程的區(qū)域農(nóng)業(yè)者有很大的貢獻(xiàn)。</p><p>　　給在田里的雜草數(shù)量進(jìn)行草繪的機(jī)器人平臺在農(nóng)業(yè)里被用來示范自動車輛的智能觀念，這最終將為高度發(fā)達(dá)的農(nóng)業(yè)引進(jìn)一種可持續(xù)的模式，現(xiàn)有的車輛適用于0.25米和0.5米行距的作物，指導(dǎo)與農(nóng)作物相關(guān)的車輛線使用指導(dǎo)照相機(jī)提高工作率，減到最少的同時提供有價值的局限輸入對農(nóng)作物的傷害。四輪轉(zhuǎn)向（4WS）的引進(jìn)為這次研究提

35、供了一種更靈活的平臺，但改善的變動性也提供了一個數(shù)量更多的實際利益。四輪轉(zhuǎn)向系統(tǒng)允許車輛在轉(zhuǎn)向中平行的位移，從而調(diào)整位移取向。</p><p>　　鑒于有車輛的四個非線性性質(zhì)的獨立控制車輪的控制問題不是小事情，然而，那樣的控制系統(tǒng)在一種低速的情況下也能給出很好的結(jié)果。一種已經(jīng)成功被使用的方法就是在車輛的前頭安上比例控制器，這些結(jié)果解決了傳統(tǒng)的轎車般的車輛在兩個轉(zhuǎn)向車輪的問題，當(dāng)時四輪轉(zhuǎn)向的模糊控制被討論中。這里采

36、用的方法建立在兩輪轉(zhuǎn)向成功的試驗的基礎(chǔ)上的，同時引進(jìn)了一種簡單的4WS案例。</p><p><b>　　2. 系統(tǒng)描述</b></p><p>　　這里描述的機(jī)器人平臺。旨在展示新型傳感功能和一種農(nóng)業(yè)機(jī)器人半自動化操作。農(nóng)業(yè)經(jīng)濟(jì)項目的目的是控制有效的測量時間和控制的作物和雜草測量，考慮到雜草的測量方法和映射，輸入的不同，參照一個提供環(huán)境和經(jīng)濟(jì)效益的明確方法。研究表明

37、50%-80%的除草劑費用可以節(jié)省。</p><p><b>　　2.1 機(jī)器人平臺</b></p><p>　　機(jī)器人平臺的基礎(chǔ)是車輪模塊提供的流動性能力如圖1，每個特定功能的車輪模塊包括無刷電機(jī)提供無齒輪直接驅(qū)動推進(jìn)，電機(jī)，放大器和微控制器都安裝在輪轂上。</p><p>　　通過在車輪模塊安裝具有獨立轉(zhuǎn)向電機(jī)軸輪模塊來創(chuàng)建兩個自由度的機(jī)制

38、。轉(zhuǎn)向電機(jī)放大器和控制電子器安裝在方向盤馬達(dá)上，控制電子系統(tǒng)是基于商業(yè)農(nóng)業(yè)工作電腦和處理具體情況的控制系統(tǒng)。</p><p>　　車輪模塊有一個簡單的機(jī)械接口允許它可以安裝在幾乎任何車輛上，電器接口包括一個電源接口和一個控制器區(qū)域網(wǎng)絡(luò)（CAN）的總線接口控制模板如圖二。</p><p>　　該平臺是專門為農(nóng)業(yè)0.5米間隙作物的使用，具有良好的離地間隙，較小的車輪和0.25米行的駕駛區(qū)間。實

39、現(xiàn)由被動穩(wěn)定三點懸掛系統(tǒng)，確保所有車輪與地面接觸。該平臺為車輛提供細(xì)密的前面車廂電子系統(tǒng)，車廂后部的電池和可能的用戶界面。</p><p>　　2.2 平臺電子系統(tǒng)</p><p>　　通過提供控制平臺機(jī)電一體化系統(tǒng)，包括剛才所描述的機(jī)械概念和汽車電子控制系統(tǒng)來正確驅(qū)動機(jī)械子系統(tǒng)。電子架構(gòu)是圍繞平臺計算機(jī)（pc/104系統(tǒng)），如圖3所示。</p><p>　　該平臺

40、計算機(jī)軟件實現(xiàn)Linux操作系統(tǒng)，該發(fā)展是由MathWorks公司的支持實行車間。允許帶定制C代碼直接來源于仿真模型，這使得程序?qū)⒆詣咏⒑碗S后在近實時的平臺上執(zhí)行。</p><p>　　本地化是實現(xiàn)冗余的傳感器集是連接到計算機(jī)使用平臺RS232系列動力通信??協(xié)議以及一個CAN2.0b 協(xié)議。主導(dǎo)航傳感器是舊拓普康雙頻載波相位差GPS接收能夠優(yōu)于2厘米的標(biāo)準(zhǔn)偏差的絕對精度，一個KVH的E-CORE2000光纖陀

41、螺儀精確測量的標(biāo)題率，包括測量控制陀螺漂移從磁輪和轉(zhuǎn)向編碼器。相結(jié)合，與絕對位置編碼器，磁強(qiáng)計和陀螺儀的可靠性，標(biāo)題絕對的唯一參考磁鐵爍效應(yīng)，但該計劃包括該行的指導(dǎo)在融合過程中，以抵消這些問題的相機(jī)磁測量的靈敏度。</p><p><b>　　2.3 系統(tǒng)構(gòu)架</b></p><p>　　系統(tǒng)架構(gòu)采用的是類似混合蓄意的做法（阿金，1990年），現(xiàn)在是常見的移動機(jī)器人系

42、統(tǒng)。三層建筑是由以下部分組成：（1）無反饋控制機(jī)制處理穩(wěn)定和跟蹤，（2）計劃執(zhí)行如軌跡生成和處理機(jī)制任務(wù)分解和（3）執(zhí)行費時審議計算和機(jī)制與人類的運營商的互動，即創(chuàng)造就業(yè)機(jī)會。層次結(jié)構(gòu)如圖4.</p><p>　　作者：湯姆斯 貝克；漢克斯 杰克森 </p><p><b>　　國籍：丹麥</b></p><p>　　出處：農(nóng)業(yè)工程學(xué)部，農(nóng)業(yè)