Matrix Water Content Conductivity Wireless Detection System And Its Application Research

In the process of substrate culture,it is significant for plants growth to monitor and adjust moisture content,conductivity and temperature of substrate.To develope the stability and accuracy of wireless detection system,this dissertation presented a new wireless detection system for monitoring moisture content and conductivity of substrate which adopts wireless networks technologies and based on multi-sensor information fusion technique.This work is well worth and useful for improving automation production efficiency of agriculture and substrate culture technique.The research contents and results of this dissertation are shown as below.(1)Firstly,substrate moisture content and conductivity sensor is designed and simulated.After analyzing the research status of the detection of substrate moisture content and conductivity,capacitance method was employed for moisture content measuring and alternating current-voltage four terminal method was employed for conductivity measuring.Considering different physicochemical properties of substrate from soil,the sensor structure was determined which can guarantee contact between sensitive elements.ANSYS electrostatic field simulation analysis was carried out to determine the size of sensitive elements.Then,the circuit and PCB circuit board was developed.(2)Secondly,substrate moisture content and conductivity wireless detection system and its software is designed.Based on ZigBee technology,the software program of sensor node and sink node is designed,and then Wireless detection system is builded.We also employed LabVIEW software management platform to realize upper computer software for observing detection result and changing curve of each sensor.(3)Thirdly,performance calibration and temperature compensation of wireless detection system is experimentalized.In order to calibrate and compensate moisture content and conductivity,we applied linear regression technique to establish temperature compensation model.After adjusting the moisture content andconductivity through this model,this system can give more accurate result to promote its environmental adaptability.(4)Lastly,after a series of experiments,we found that detection precision of moisture content is 1.88%,maximum moisture content error is 0.0171,relative error is smaller than 6.72%,detection precision of conductivity is 2.12%,maximum conductivity error is 0.14mS/cm,relative error is smaller than 5.26%.The statistic result of 30 continuous test showed moisture content variable quantity is less than0.0018 and conductivity variable quantity is less than 0.04mS/cm.And this result also illustrates this system is quite stable.The test results show that the wireless detection system can accurately detect the moisture content and conductivity of the substrate and then transfer the results to the host computer.This dissertation completely presented the process of design and realizing a moisture content and conductivity wireless detection system hardware and software.Some repeated application experiments declared that this system is very stable and useful for moisture content and conductivity detection and valuable for substrate culture.