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雙頻率交替法電容土壤水分測(cè)試技術(shù)研究

發(fā)布時(shí)間:2018-09-10 16:49
【摘要】:在信息技術(shù)和人工智能技術(shù)迅猛發(fā)展的浪潮下,逐漸產(chǎn)生了對(duì)農(nóng)作物實(shí)施定位管理、對(duì)農(nóng)作物進(jìn)行按需投入等農(nóng)業(yè)生產(chǎn)的精準(zhǔn)管理思想,最終形成了精準(zhǔn)農(nóng)業(yè)的概念。精準(zhǔn)農(nóng)業(yè)中一個(gè)極其關(guān)鍵的環(huán)節(jié)即是獲得土壤的各種參數(shù),例如:土壤有機(jī)質(zhì)含量、土壤壓實(shí)度、土壤電導(dǎo)率、土壤含水量等。這些參數(shù)中,土壤含水量是必不可少的。 在國(guó)內(nèi),用來(lái)檢測(cè)土壤含水量的儀器基本都是便攜式,而新的時(shí)代會(huì)提出新的要求,本文的目的是設(shè)計(jì)一個(gè)車(chē)載土壤含水量檢測(cè)系統(tǒng)。目前國(guó)內(nèi)外土壤含水量測(cè)量常用方法有以下幾種:外觀觸摸法、烘干法、張力計(jì)法、電阻法、中子法、遙感法、時(shí)域反射法、頻域反射法、駐波率法、電容傳感器法等。其中許多方法顯而易見(jiàn)不適合車(chē)載,只能于實(shí)驗(yàn)室使用;有的性能不錯(cuò),但是成本太高;有的受力則容易損壞。在對(duì)土壤含水量檢測(cè)機(jī)理進(jìn)行探究之后,對(duì)比分析了國(guó)內(nèi)外常用的土壤含水量檢測(cè)方法,結(jié)合實(shí)際情況,最后選用介電特性法中的電容傳感器法為基礎(chǔ)來(lái)設(shè)計(jì)車(chē)載土壤含水量檢測(cè)系統(tǒng)。電容傳感器法的優(yōu)點(diǎn)是顯而易見(jiàn)的,如容易構(gòu)建、適合車(chē)載、安裝簡(jiǎn)單、操作方便等。 本文在電容法的基礎(chǔ)上,提出了三種檢測(cè)方法:附加電阻法;交直流交替法;雙頻率交替法。并對(duì)這三種方法進(jìn)行了理論分析和數(shù)學(xué)推導(dǎo),在比較分析后,采用雙頻率交替法來(lái)測(cè)量土壤含水量。首先測(cè)量計(jì)算出土壤電容傳感器的等效電容值,然后依據(jù)等效電容值與土壤含水量之間的擬合關(guān)系曲線,來(lái)獲得土壤含水量的值;谏鲜鲈,作者開(kāi)發(fā)了一套車(chē)載土壤含水量檢測(cè)系統(tǒng),該系統(tǒng)能實(shí)現(xiàn)車(chē)載的土壤含水量測(cè)量,操作方便,響應(yīng)速度快,測(cè)試數(shù)據(jù)可以直接顯示,也可傳輸給上位機(jī)處理顯示,精度較好。為了進(jìn)一步論證此方法的可行性,在安徽省懷遠(yuǎn)縣龍亢農(nóng)場(chǎng)進(jìn)行了實(shí)地檢測(cè),結(jié)果表明:用此方法測(cè)量土壤含水量,結(jié)果較為準(zhǔn)確;土壤含水量與土壤等效電容可近似擬合成直線關(guān)系。
[Abstract]:With the rapid development of information technology and artificial intelligence technology, the concept of precision agriculture was gradually formed, such as positioning management of crops, input of crops on demand and so on. One of the most important steps in precision agriculture is to obtain soil parameters, such as soil organic matter content, soil compactness, soil conductivity, soil moisture content and so on. Among these parameters, soil moisture content is essential. In China, the instruments used to detect soil moisture content are basically portable, and new requirements will be put forward in the new era. The purpose of this paper is to design a vehicle-mounted soil moisture detection system. At present, there are several common methods for measuring soil water content at home and abroad: appearance touch method, drying method, tensometer method, resistance method, neutron method, remote sensing method, time-domain reflection method, frequency-domain reflection method, standing wave rate method, capacitance sensor method and so on. Many of these methods are obviously unsuitable for vehicles and can only be used in the laboratory; some have good performance, but the cost is too high; others are easily damaged. After probing into the measuring mechanism of soil water content, this paper compares and analyzes the common methods of soil water content measurement both at home and abroad, combining with the actual situation, Finally, based on the capacitance sensor method of dielectric characteristic method, a vehicle soil moisture detection system is designed. The advantages of capacitive sensor method are obvious, such as easy to build, suitable for vehicle, easy to install and easy to operate. On the basis of capacitance method, three detection methods are proposed in this paper: additional resistance method, alternating AC / DC method and double frequency alternating method. The theoretical analysis and mathematical derivation of the three methods were carried out. After comparison and analysis, the soil moisture content was measured by the double frequency alternating method. The equivalent capacitance of the soil capacitance sensor was measured and calculated firstly, and then the soil moisture content was obtained according to the fitting curve between the equivalent capacitance value and the soil moisture content. Based on the above principle, the author has developed a set of on-board soil moisture content measurement system. The system can realize the measurement of soil water content on the vehicle, which is easy to operate, quick to respond, and can be displayed directly. Can also be transmitted to the upper computer processing display, the accuracy is good. In order to further prove the feasibility of this method, a field test was carried out in Longkang Farm, Huaiyuan County, Anhui Province. The results showed that the method was more accurate in measuring soil moisture content. The relationship between soil moisture content and soil equivalent capacitance can be approximately quasi-synthetic linear.
【學(xué)位授予單位】:中國(guó)科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】:碩士
【學(xué)位授予年份】:2015
【分類(lèi)號(hào)】:S152.7

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