Research On Low-power Consumption Sensor Node In Wireless Gas Monitoring Network

Gas accident is always a major threat to the coal mine safety production. Gas explosion accidents happen frequently, although gas monitoring technoligies have been developed in recent years. It will be more useful to monitor gas concentration with the combination of wireless sensor networks placed on working face and traditional wired networks. But the power consumption of traditional gas sensing elements is very big, which limits the working life of wireless gas sensor nodes. So it is an urgent problem to be solved that how to reduce the power consumption of wireless sensor nodes.The design of low-power consumption gas sensor nodes should be researched from both hardware and software, In the aspect of hardware design, low-power consumption gas sensing elements and wireless transceiver devices were compared and analyzed. MIPEX with very low-power consumption is an infrared sensing element for gas detection produced by OPTOSENSE company in Russia recently. Then MIPEX, voltage stabilizer MH5333and CC2430were selected to design low-power consumption nodes. The power supply of MH5333is controlled by the pin P1.0of CC2430. P1.0outputs low level to close MIPEX and reduce power consumption when data collection is not necessary.In the aspect of software design, the program was concluded into top level module, data collection module, wireless communication module and low-power consumption module. In top level module, sensor node is set into the alternant mode of working and sleeping with the period of10minutes. Nodes can be in sleeping mode at most time of a period as the time of sampling and sending data is very short, which is beneficial to reduce power consumption. A star network including4nodes and a coordinator was built to verify the function of wireless communication module and serial port communication program. ZigBee technology and its stack was introduced in chapter2as the software was designed in ZigBee stack.The power consumption of node was estimated in theory. The working time of nodes was260days by using4AA batteries. Under the condition that the power supply was not controlled, power consumption of node with sleeping mechanism and without sleeping mechanism was estimated, and the working time were4days and70days approximately. So the working time can be prolonged greatly by using sleeping mechanism. At last, the power consumption of node with TP-1.1A sensing element was analyzed; the working time was less than4days with6AA batteries and adopting sleeping mechanism in CC2430. So the low-power consumption of traditional gas sensing elements is nothing compared with MIPEX.At last, the problems remained were analyzed and the further research thinking was proposed.