Research Of Key Technology About Harmful Gas Leakage Monitoring Based On WSN

With the development of wireless sensor network (WSN) technology, relevant applications are increasingly extensive. Chemical dangerous gas leakage monitoring technology is one of the WSN technology applications. In the area of chemical factory, getting accurate harmful gas concentration of the environment and localize gas leakage position accurately is not only beneficial to saving lives, but also helpful for the emergency rescue work. How to get perceive environmental hazard gas concentration, and quickly and accurately localize positioning gas leakage source becomes one of the hot technologies of WSN.The paper briefly describes the gas monitoring system for chemical factory based on WSN. We narrate working principle and circuit design of the nodes for the system in detail. We also analyze and process the data.The paper discusses several algorithms currently used in WSN positioning, including algorithm based on the time of arrival (TOA), the time difference of arrival (TDOA) and energy decay(ED) and particle swarm optimization (PSO) algorithm. Algorithms base on TOA, TDOA and ED use the ultrasonic wave generated by gas leakage to localize the leakage position.Under the assumption that release and spread of chemical release can be modeled as a Gaussian-puff model, the paper proposes a new localization algorithm based on Gaussian model and Best Linear Unbiased Estimator (BLUE). The mathematical model of the concentration difference between sensors is nonlinear model. We use Taylor expansion to linearize this model and use BLUE to estimate gas leakage position. We will obtain more accurate gas leakage position through various iterations.Finally, we made a comparison of the algorithm based on BLUE and PSO algorithm based on the minimum MSE. The simulation results show that the algorithm we propose has high positioning accuracy, fast calculation and need less memory space.