Design and Implementation of Fuzzy Temperature Control System for WSN Applications

摘要

With its low power embedded sensing actuation, computing, wireless RF communications and multihop mesh networking capabilities, Wireless Sensor Network (WSN) has emerged as one of the popular multidisciplinary technologies of the 21st century. Present day research trends focus on application specific deployment of network hardware with information processing, integrating it into commonly used development software and providing high level of abstraction to end user. Motivated by such challenges, this paper represents the design and implementation of rule based, simple, robust closed loop feedback temperature controller for plethora of WSN measurement and control applications in areas like environmental monitoring and control, control environment precision agriculture, building automation and process control. This dual input, three term controller translates the linguistic decision making for temperature control into rule based control strategy, ideal for complex systems which are difficult to be modeled mathematically. Based upon the real time temperature information from wireless nodes and user fed process information, the software controller is well designed and optimized to provide precise temperature control with offset of ±1% within wide temperature range of-10 to 70℃ and time lag of 10s. The modified controller CAP drives the heating and cooling system with low duty cycle thus saving power and increasing the life time of devices. Looking into the practical aspects of deploying the network and actuation systems, this general purpose controller offers high compatibility with WSN using established wired or new generation wireless actuation systems. This paper also discusses the implementation of versatile software with effective GUI that not only integrates the controller with sensor network and control hardware from different vendors for real time PC based temperature monitoring and control but also executes salient features of network, battery and alarm status monitoring, data logging , historical trends viewing and plotting testing controller characteristics. Results obtained with the experimental field set up for ambient room temperature control are also discussed.