Research And Design Of Indoor Environmental Multi-parameter Wireless Measurement System

With the development of computer technology, electronic technology and communication technology, environmental testing instruments have made significant improvements in the technical aspect of measurement accuracy, data collection, transmission, storage, processing and so on. But it is lack of the research of multi-parameter integrated wireless measurement system with the perfect function. Therefore, this paper designed multi-parameter wireless measurement system for indoor environment based on virtual instrument technology and network communication technology. It is used to measure PMV (thermal comfort) of indoor environment. In addition, this system can also collect the data of indoor temperature, relative humidity, wind speed, CO2concentration, HCHO concentration, C6H6concentration, NH3concentration and TVOC concentration. The main work of this paper includes:(1) Developed a portable indoor environmental measuring instrument based on virtual instrument technology. It can realize the portable measurement of indoor environment parameter and the wireless transmission of collection data. The hardware design work of measuring instrument mainly includes the selection of sensors and conditioning modules, the design of data acquisition system, the selection of power supply module, the structural design of instrument case and the integrated installation of hardware modules.(2) Measurement system software for indoor environment is developed based on Lab VIEW. It has friendly software interface and perfect function module. It can realize the dynamic selection, timing measurement and quantitative analysis of environmental parameter, database management. The design content mainly includes data acquisition program, PMV calculation program, data query and delete program, sensor static calibration program and other program design.(3) In order to realize data remote transmission, this paper developed remote data transmission and accessing system based on Socket communication. In this system, data sending program is developed based on LabVIEW in measurement terminal. Data receiving and display webpage is developed based on PHP language in server-side. The remote terminal can view the field measured data of environmental parameters by accessing the webpage.(4) This paper first studies and analyzes the calculation theory and measuring method for PMV. Then, the impact of each environmental variable (air temperature, relative humidity, air velocity and black globe temperature) and its measurement accuracy on PMV accuracy is analysed via MATLAB. During the measurement system developed in this paper, the measurement accuracy can reach±0.19.(5) Typical indoor environment is chosen for system debugging and environmental verification. The reliability of system running and measurement data are analyzed in the process of testing. It verifies that the system can satisfy the need of practical use.