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《Journal of Forestry Engineering》 2019-01
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Analysis method of pesticide on-line-mixing uniformity based on principal component analysis

CHEN Junyang;XU Youlin;College of Mechanical and Electronic Engineering,Nanjing Forestry University;  
Pesticide spraying is an effective way to prevent from pest attacks and increase agricultural crop yields.However,current pesticide application methods and equipment are inefficient,resulting in wasting pesticides,environmental pollution,and serious ill-health even death to human and animals. On-line-mixing inside the pesticide mixers is an effective way to use pesticides precisely and the on-line-mixing uniformity is the key factor that affects the pesticide application. Therefore,howto measure the uniformity of pesticide on-line-mixing is needed to be solved currently. In this study,the high-speed imaging technology and principal component analysis(PCA) were used to analyze the uniformity of pesticide on-line-mixing as the brightness difference between water and pesticides with fluorescent substance,which could be distinguished easily under the ultraviolet lamp. Under the condition of a certain mixing concentration,the stream fields under eight different flowrates were used as study objects and images were collected by using an image acquisition system. Firstly,the region of interest(ROI) of 20 images in every flowrate were acquired(100×300),and processed by mean filtering and simple rescaling from the range [0,255] to [0,1]. The receptive fields were selected by the way of stride search with a size of 50× 50 pixels and stride of 5 pixels,and processed by the average pooling with a size of 2×2 pixels and stride of 2 pixels. Secondly,the statistical method of principal component analysis with 98% percentage of variance retained was used to establish a generative model for all receptive fields,and the principal component features and the principal component coefficients distribution were visualized for easy-understanding the PCA results of pesticide on-line-mixing images. The visualization showed a little clustering effect of receptive fields in eight different flowrates. Finally,the uniformity was visualized through the similarity heap maps and the non-uniformity value was calculated according to the feature similarity of the principal components. The experimental results showed that,when the flowrate decreased gradually,the average non-uniformity value increased from 6.492 to 18.262 and the standard deviation increased from 0.536 to 3.625,and the uniformity of pesticide on-line-mixing became worse. The results revealed that the proposed method is a promising method to evaluate uniformity of pesticide on-line-mixing. This method provided powerful technical support for the optimization of the structure of mixers and for the realization of the precision pesticide spraying.
【Fund】: 江苏省农机三新工程项目(NJ2014-11);; 江苏高校优势学科建设工程资助项目(PAPD)
【CateGory Index】: TQ450.7;TP391.41
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