本文選題：雜草識別 + 光譜分析　； 參考：《江蘇大學》2017年碩士論文

【摘要】：雜草是一種人類不會主動培育而自由生長的草本植物。在中國種植面積較大的農(nóng)作物中,油菜受草害尤為嚴重,在一般年份雜草大概會導致油菜減產(chǎn)10%到20%,而在一些極端條件下由于雜草的影響油菜甚至減產(chǎn)達到50%以上。鑒于雜草對農(nóng)作物產(chǎn)生的嚴重危害,在田間往往需要對其進行主動防治,而噴施化學除草劑由于其操作簡單且對雜草的防除效果好得到廣泛的應(yīng)用,然而,研究學者在除草劑過去許多年的使用中發(fā)現(xiàn)除草劑粗放式的大面積均勻噴施會對生態(tài)環(huán)境和人體健康會產(chǎn)生嚴重的不良影響。因此,具有空間選擇性的對靶變量噴施方法成為目前最理想的除草劑施用方式,而實現(xiàn)對靶噴施的前提條件是解決對雜草的自動識別問題�；诠庾V分析原理的傳感器由于其檢測實時性好、對樣品無破壞、儀器成本相對較低等優(yōu)勢成為雜草自動識別領(lǐng)域的研究熱點,并且已有基于此技術(shù)的傳感器實現(xiàn)商業(yè)應(yīng)用。但因為傳感器本身組成原理方面的原因,傳感器易受環(huán)境雜散光的干擾而降低其識別精度。光調(diào)制解調(diào)技術(shù)可以通過對光源發(fā)光強度進行調(diào)制并基于離散傅里葉變換進行解調(diào)剔除環(huán)境雜散光疊加在檢測信號上的直流分量,從而減少環(huán)境雜散光對光譜檢測儀器檢測精度的影響。本文以冬油菜苗期雜草為檢測對象,在項目組前期研究的基礎(chǔ)上,使用590nm、710nm、750nm和940nm這四個檢測波長,采用光調(diào)制解調(diào)技術(shù),搭建了一套田間雜草光譜識別試驗系統(tǒng),并對其抗環(huán)境雜散光的能力進行了試驗研究。主要研究內(nèi)容如下:1.雜草識別光譜傳感器識別精度影響因素分析:分別分析了傳感器自身因素和外界環(huán)境干擾因素。傳感器自身因素主要為光學系統(tǒng)設(shè)計的不合理、光電器件工作過程中產(chǎn)生的噪聲以及信號采集處理系統(tǒng)在采樣過程中產(chǎn)生的誤差;外界環(huán)境干擾因素主要為天空背景光以及人造光源在傳感器工作時對其產(chǎn)生的干擾。最后確定了外界環(huán)境雜散光是對測量精度產(chǎn)生影響的主要因素。2.基于光調(diào)制解調(diào)的田間雜草光譜識別試驗系統(tǒng)的搭建:對光調(diào)制技術(shù)進行了簡要介紹,對光信號的調(diào)制在抑制外界雜散光干擾和消除探測器自身產(chǎn)生噪聲方面的作用進行了說明。運用光調(diào)制解調(diào)技術(shù)基于優(yōu)選的四個特征波長(590nm、710nm、750nm和940nm)設(shè)計了一套實驗系統(tǒng),這套實驗系統(tǒng)主要包括實驗設(shè)備(光信號調(diào)制設(shè)備和光電信號采集設(shè)備)和實驗數(shù)據(jù)處理LabVIEW程序。實驗系統(tǒng)采用LED主動光源并對光源發(fā)光強度進行調(diào)制,采用基于光電二極管的增益可調(diào)的集成光電探測器檢測反射光信號強度,采用工控機實時對探測器信號進行AD采樣。用LabVIEW編寫了實驗數(shù)據(jù)處理程序,程序主要完成波形數(shù)據(jù)采樣、波形數(shù)據(jù)收集、波形的數(shù)字濾波、濾波后波形的頻譜測量和調(diào)制頻率處信號幅值(即被測樣品反射率表征值)的提取。3.光調(diào)制解調(diào)對環(huán)境雜散光干擾的剔除效果試驗:為了驗證應(yīng)用了光調(diào)制解調(diào)技術(shù)的實驗系統(tǒng)在剔除環(huán)境雜散光方面的效果,進行了兩組驗證試驗,試驗結(jié)果表明在外界環(huán)境雜散光緩慢變化和劇烈變化時,實驗系統(tǒng)都能得到穩(wěn)定的反射率表征值,這說明反射率表征值不受環(huán)境雜散光變化影響,光調(diào)制解調(diào)技術(shù)的應(yīng)用極大的提升了測量的信噪比,為提高基于光譜原理的傳感器測量精度提供了新的思路。4.實驗系統(tǒng)靜態(tài)性能試驗:基于搭建的實驗系統(tǒng)進行了靜態(tài)性能試驗,包括系統(tǒng)重復性測試、與光譜儀之間的標定試驗及其驗證試驗。實驗系統(tǒng)重復性測試結(jié)果的變異系數(shù)均小于1.5%,這表明實驗系統(tǒng)的測試結(jié)果的一致性較好,實驗系統(tǒng)穩(wěn)定性較好,抗干擾能力強。對實驗系統(tǒng)進行了標定試驗,基于不同波長擬合出的四個擬合方程的決定系數(shù)分別為0.8692、0.9817、0.9812、0.9812,并以冬油菜為樣本進行了驗證試驗,試驗結(jié)果的相對誤差都在10%以內(nèi),最大為8.82%,其中750nm和940nm的試驗結(jié)果相對誤差較小,大部分都在3%以內(nèi),最大為3.08%。從試驗結(jié)果可以看出測得的反射率與被測樣品的實際光譜反射率密切相關(guān),可以通過標定后換算得到剔除了環(huán)境雜散光干擾的實際光譜反射率值。
[Abstract]:Weeds are a kind of herbaceous plants that are free to grow and grow freely. In large crops grown in China, rape is particularly severely damaged by grass. In general years, weeds will probably reduce the yield of rape by 10% to 20%, and in some extreme conditions, the effect of weeds on rape is more than 50%. The serious harm produced by crops is often required to be controlled actively in the field, and the spray chemical herbicide is widely used because of its simple operation and good effect on the prevention of weeds. However, researchers have found that the large area and uniform spraying of herbicides in the past many years in the use of herbicides will be applied to the ecological environment and the ecological environment. Human health will have serious adverse effects. Therefore, the spatial selectivity of the target variable spraying method has become the most ideal method of applying the herbicide, and the prerequisite for the implementation of the target spraying is to solve the problem of automatic identification of the weeds. The sensor based on the principle of spectral analysis is not able to break the sample because of its good real-time detection. The relative low cost of instrument has become a hot spot in the field of automatic weed identification, and the sensor based on this technology has been used for commercial applications. But because of the principle of the composition of the sensor, the sensor is susceptible to the interference of the ambient stray light to reduce its recognition accuracy. The luminescence intensity is modulated and based on the discrete Fourier transform to remove the DC component of the ambient stray light superimposed on the detected signal, thus reducing the influence of the environmental stray light on the detection precision of the spectral detection instrument. In this paper, the weeds at the seedling stage of the winter rape were tested on the basis of the preliminary study of the item group, using 590nm, 710nm, 7. The four detection wavelengths of 50nm and 940nm, using the optical modulation and demodulation technology, set up a set of field weed spectral identification test system, and carried out an experimental study on its ability to resist the environmental stray light. The main contents are as follows: 1. the influence factor analysis of the recognition accuracy of the weed identification spectral sensor: the factors of the sensor itself and the outside of the sensor are analyzed. The main factors are the unreasonable design of the optical system, the noise produced in the process of the optoelectronic devices and the error produced by the signal acquisition and processing system in the sampling process, and the interference factors of the external environment are mainly the background light of the sky and the interference of the artificial light source to the sensor when working in the sensor. Finally, the external ambient stray light is the main factor affecting the measurement accuracy,.2. based on the optical modulation and demodulation in the field of the field weed spectrum identification test system. The light modulation technology is briefly introduced, the modulation of the light signal is used to suppress the external stray light interference and eliminate the noise of the detector itself. The optical modulation and demodulation technology is based on the optimum four characteristic wavelengths (590nm, 710nm, 750nm and 940nm) to design an experimental system. The experimental system mainly includes the experimental equipment (optical signal modulation equipment and photoelectric signal acquisition equipment) and the experimental data processing LabVIEW program. The experimental system uses the LED active light source and the light. The intensity of the source luminescence is modulated. The integrated photoelectric detector based on the gain of photodiode is used to detect the intensity of the reflected light signal. The AD sample is sampled in real time by the industrial control machine. The experimental data processing program is written in LabVIEW. The program is mainly used to complete the data sampling, the waveform data collection and the digital filtering of the waveform. The spectrum measurement after filtering and the amplitude of the modulated frequency at the modulated frequency (i.e. the measured value of the measured sample reflectivity) the elimination effect of.3. light modulation and demodulation on the ambient stray light interference: in order to verify the effect of the experimental system using the optical modulation and demodulation technology in eliminating the environmental stray light, two sets of verification tests are carried out. The results show that the experimental system can obtain a stable reflectance characterization value when the external ambient stray light changes slowly and violently, which indicates that the reflectance characterization value is not affected by the change of ambient stray light. The application of the optical modulation and demodulation technology greatly improves the signal to noise ratio of the measurement, and improves the measurement precision of the sensor based on the principle of spectrum. The static performance test of the new.4. experimental system is provided: the static performance test based on the built experiment system, including the system repeatability test, the calibration test and the verification test between the spectrometer and the spectrometer. The coefficient of variation of the experimental system repeatability test results is less than 1.5%, which indicates the consistency of the test results of the experimental system. The experimental system has good stability and strong anti-interference ability. The calibration test of the experimental system is carried out. The determination coefficients of four fitting equations based on different wavelengths are 0.8692,0.9817,0.9812,0.9812 respectively. The test results are tested with winter rape as samples, and the relative error of the test results is within 10% and the maximum is 8.82%. The relative error of the experimental results of 750nm and 940nm is relatively small, most of which are within 3%. The maximum of 3.08%. is that the measured reflectance is closely related to the actual spectral reflectance of the measured samples. The actual spectral reflectance of the ambient stray light interference can be obtained by the calibration.
【學位授予單位】：江蘇大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TP212;S451

【參考文獻】

相關(guān)期刊論文 前10條

1 丁玨;黃傳偉;陳s，

本文編號：2027842