Circuit Optimization Of Crop Growth Monitoring And Diagnostic Apparatus Based On CGMD401

Crop growth monitoring and diagnosis spectrometer of active light source is to acquire the crop growth information by measuring the reflectance spectrum of the light source of the instrument itself,with nondestructive,fast,efficient,and so on,to provide a portable method and equipment for the growth of the seedlings of crop research and production management.In this study,the optimization design of the instrument is accomplished according to the problems of crop growth monitoring and diagnosis spectrometer CGMD401 developed by National Engineering and Technology Center for Information Agricultural of Nanjing Agricultural University.Low measurement accuracy problems are solved based on the reflection spectrum detection based on LED state change and the peak detection based on the fundamental wave.Power dissipation problem is solved based on LED intermittent light and the mode of the chip by voltage classification.The research results provide a reliable,stable and accurate sensing equipment for crop production management,which provides technical support for promoting the information of crop cultivation in our country,and promotes the development of modern agriculture in China.Firstly,this paper introduces the advantages of nondestructive monitoring applications in the field of agriculture,analyzes the research and the problem is about crop growth monitoring and diagnosis spectrometer of active light source,pinpoints the research purpose and significance according to the circuit system of CGMD401,such as low measurement accuracy and large power consumption.A reflection spectrum detection method based on the change of LED luminescence intensity and a method based on the fundamental of the fundamental wave are proposed to solve the defects of low measurement accuracy,the power consumption of the instrument is solved by the method of LED intermittent light and the power supply of the chip by voltage classification,and the research contents and technical routes were planned and determined.Secondly,The circuit system of the CGMD401 was optimized from two parts of hardware circuit and system software.In order to eliminate the LED luminous intensity of instrument measured canopy spectral reflectance effect,through the instrument built-in photodiode get LED luminous intensity,so as to establish a canopy reflectance spectral compensation model,the instrument measured canopy spectral reflectance value compensation,can improve the accuracy of measuring instruments.In order to get the photoelectric signal amplitude from the noise signal,the use of signal processing circuit(by a current voltage conversion circuit,a filter circuit,a voltage conversion circuit three parts)to obtain photoelectric signal of the fundamental wave amplitude,using the Fourier transform of the amplitude of the fundamental transformation for the amplitude of the optical signal to improve the instrument anti-interference.In order to reduce the power consumption of the circuit in the instrumentation and by microprocessor output PWM signal to control the 730 nm and 810 nm band led alternating light,as well as the selection of low power consumption of the chip to complete the circuit design,making the power consumption equipment is reduced to half of what it was before optimization,extending the instrument work time,then the optimized hardware circuit modules are integrated together to complete the design of PCB.The software part of the system is optimized by the hardware circuit as the core,in order to realize the "measurement","monitoring" and"diagnosis" function of the diagnostic instrument,respectively from the main control program and the driver to complete the design.Finally,in order to verify the performance of the instrument,the laboratory test and field test were carried out respectively.Indoor verification test is divided into circuit function test and LED energy consumption test.The field experiment was divided into wheat and rice experiment.Compared to the CGMD401,optimized instrument measuring the value and spectrometer measured value correlation improved(in the experiment with wheat,for example,CGMD401 not of tested rice),NDVI value correlation coefficient of determination R~2=0.8538(CGMD401 R~2=0.7017),RVI values R~2=0.8562(CGMD401 R~2=0.7071).After the optimization of the instrument working hours for more than 10 hours(CGMD401 hours of work time is about 5 hours),the power consumption reduced to more than half of the original.