Research Of The Measurement System Of Leaf Thickness And Area Based On LabVIEW

In the agricultural production, the geometry parameters of plant leaves are important indexes in measuring moisture content and dry matter content etc. It can directly reflect the plants'growing conditions under different environmental conditions. Therefore, by studying the leaf thickness and are we can achieve the goal to monitor changes in moisture content and dry matter content etc. This is of great significance to guide rational close planting, population structure adjustment, variable rate fertilization and irrigation to achieve high production and improve the development of economy, resources and environment.As the new technology in agriculture, leaf thickness and area measurement technology has received more and more attention. Based on the research status of national and abroad leaf thickness and area detection technology and advanced technologies already been developed in related fields, a leaf thickness sensor based on resistance strain and a leaf area sensor based on optoelectronic devices were designed. The two signals were amplified by amplified circuits and the output signals were collected by data acquisition card. Finally, the detection technology was combined with LabVIEW Virtual Instrument and a data analysis, processing and display interface was designed based on LabVIEW software which could realize real time display, monitoring and control.The main contents and results of this paper are as follow:(1) By analyzing the shear, the bridge circuit, deflection angle and the calculation process, the relationship between leaf thickness and the output voltage was deduced. The BE120-3AA was selected to build the corresponding resistance strain gauge thickness sensor. By loading analog signal, the static resistance strain gauge YJ—31 was used to measure the strain value of greater than 120με.(2) By analyzing the amplitude and frequency characteristics of signals, instrumentation amplifier AD620 and dual op-amp TL082 amplifier were selected to design the amplified circuit. And then by adjusting the corresponding external potentiometer connected, the input signal was magnified by about 1000 times and realized magnifying achieved (mV) signal to the level required for analog-digital conversion (V) level signal range. (3) Acquisition card PCI2013 and the upper function in LabVIEW were used to achieve AD acquisition. Sequence structure design was applied to compile initialization program, recycling collection program, stop acquisition program and the corresponding acquisition interface. The combination of system hardware and software was completed.(4) Virtual instrument software was used to design the main interface program which included: real-time data display, data parameter settings and alarm functions, data storage and call, waveform display of data during certain time, other system function keys and the whole show. And AD acquisition program was collected to complete the software portion of the system.This study attempted an exploration of the leaf thickness and area of real-time monitoring. Domestic and foreign tester of leaf thickness and area are rich, but the experimental materials of this system were relatively simple, basically some common components with high cost performance. Experimental results basically met the requirements of the measurement precisions.