Research Of Reflection-type Microwave Moisture Detection Method Based On μC/OS-Ⅱ And Kinetis60Chip

Both in daily life and in industrial and agricultural production, water playsan important role, whether as preservative or additive, the amount of increaseand decrease is very important. Especially in grain storage and transport,tobacco processing, paper making, coal, rock, soil testing, fertilizer production,wood processing, textile industry, concrete mixture ratio and oil processingindustry, the moisture content of material influences the whole process andresult of production, understanding and controlling the moisture content ofmaterials timely will improve the quality and efficiency of the whole project.The method of testing moisture content include neutron method,capacitance method, resistance method, infrared method and microwavemethod, etc. Each method have different principle and applied scope. In orderto achieve real-time online nondestructive test, and meet the needs of theequipment’s exquisite volume in production line, my thesis choose microwavemethod to detect moisture content.Water is a polar molecule, and it will produce polarization under microwavefrequency concussion, the part of the microwave energy will be absorbed bymaterial, through testing the change of parameter before and after microwavethrough material, and transforming it into electrical signal for subsequenthardware and software processing, then we will get the moisture content value.Based on the physical reaction such as reflection and transmission which isoccurred during microwave transmission, we can use microwave reflectionmethod and transmission method to detect the moisture content. Microwavetransmission method has request for the thickness of the measured object, andneed two microwave antenna which is responsible for sending and receivingmicrowave; However microwave reflection method is not restricted by the thickness of the measured object, and a single microwave antenna can sendand receive microwave at the same time, the device structure is simple, whichis suitable for real-time online detection, so my paper uses the microwavereflection method to detect the moisture content.According to the principle of mixing the microwave signal and the reflectedsignal, output direct current voltage signal which contains the information ofmoisture content. Then process the electrical signal through amplifier, currentmode conversion output, integral average circuit, and other hardware circuits,for coming true four testing functions, real-time detection, average detection,signal current/voltage output, and RS485signal transfer.In the aspect of software, based on Kinetis60chip, through transplantingμC/OS-Ⅱ operate system, set up12mission: real-time model task, averagevalue model task, current/voltage output task, RS485serial port transmissionvoltage signal task, internal signal parameters fitting calibration task, Flashstorage task, temperature testing task, test time task, model primary task,3.5inch TFT color screen display task, LED detection running state task, watchdogmonitoring task, and communication and cooperation between task and task,realizing four testing moisture content functions, and before testing the devicecan chose primary function, primary material, and determine the environmenttemperature and time, the test result and some information will display on theLCD screen at the same time.This paper designs one device which use the microwave reflection methodto detect moisture content, transceiver integration, low cost, simple operation,based on freescale Kinetis60chip which is detection precision, anti-jamming,and there will be wide applicable scope.