Plant Diseases Detecting Based On Near-field Acoustic Holography

As food safety problem constantly dash forward show, more and more people begin to pay close attention to diet. The crop is the important part of the people’s livelihood, through spraying pesticide to prevent the occurrence of diseases is essential, but the phenomenon of spraying excess drug is still widespread problem. Although excessive pesticide can kill the disease completely, but too much pesticide not only waste of resources and cause the environmental pollution, but also harm to people’s physical health. As a result, the crops need to be sprayed accurately to avoid excessive health parts of the spraying. Implement precise spray first to realize the accurate positioning of crop diseases. Therefore, the crops for accurate disease detection and scientific spraying pesticide have become more and more urgent requirements.This paper turns from "visual identification" to "auditory identification". Take tomato as the research object, through collect the acoustic emission signal, use near-field acoustical holography technology, respectively by plane and cylinder near field acoustical holography principle to establish disease stress field model, and respectively by means of space sound field transform method and statistical method of optimal reconstruction of 3D sound field model of crop source signal recognition and sound field analysis, to determine the source signal and damage degree. By use acoustic emission signal to identification the sound sources’location, opened up a new method of crop disease recognition.First of all, this paper introduces the main crop disease information detection technology of acoustical holography measurement analysis technology research dynamic is discussed. Second, introduce the plane and cylinder near field acoustical holography basic principle in detail, based on spatial sound field transformation method and the statistical optimal method of near field acoustical holography reconstruction formula to built the crop disease stress testing experiment model. Write algorithm simulation program and analysis the near field sound acoustical holography reconstruction simulations, discusses two kinds of technology based on the crop disease detection feasibility and accuracy. Third, this paper also discusses the noise on the near field acoustical holography simulation results, the influence of found after window function for filtering and the high frequency signal sound field reconstruction for experimental parameters corresponding to relax, and can get better reconstruction effect, which offers the possibility to realize the reality. Fourth, the holographic signal acquisition hardware circuit of a simple description, and the measured data and the simulation algorithm, realize the source point identification and positioning. Finally, summaries all of the research, and put forward some suggestions for further research.