Research On A Wood Moisture Measurement System Based On Tiny Capacitance Detection

According to the statistical results,75%of the wood problems were caused by measuringthe moisture content incorrectly in wood drying process. Wood moisture content was a keyparameter in wood drying process. Measuring the wood moisture correctly and decreasing thewaste of wood resources were severe task that we confronted with, because of lacking offorest resources and the wood requirement increasingly. Aiming at designed a online、realtime and non-contact wood moisture measurement system, which measured wood accurately.The characteristics and situations of wood moisture measurement system as well as themoisture measurement methods were summarized in China and abroad. Based on the functionrequirement，the scheme was determined. The sensitive component of the system was singleplane capacitance sensor，established the mathematical model and the numerical solution.Relied on the FlexPDE software and the data fitting toolbox of Matlab, established thefunction between the capacitance value and the dielectric constant.The tiny capacitance detection was the key part of the measurement system. Bothadvantages and disadvantages of the simulation detection circuit and digital detection circuitwere analyzed and compared, designed the tiny capacitance detection circuit based on thecapacitance to digital converter AD7746.The real-time of moisture measurement system mainly relied on the tiny capacitancedetection circuit that passed to the host computer rapidly. Using I2C serial bus，Microcontroller serial port、serial port of Matlab to completed the communication ofmeasurement system, and designed software program which transferred data in real time,processed the data in real time.Finally, printed board, welded board, debugged circuit board, processed equipment,debugged program, established the wood moisture benchmark and also developed the woodmoisture measurement software were all illustrated in this paper. Experimental results showedthat the wood moisture measurement system based on the tiny capacitance detection wasaccurate and workable.