The Research Of Greenhouse WSN Node Test Platform On Harsh Environment

This paper presents a development of WSN node test platform on harsh environment in greenhouse.The aim is to construct a testing platform with characteristics of high temperature and humidity.Presently,such a testing platform is relatively rare.The designs of platform are based on characteristics and requirements of WSN node.The platform can simulate the temperature and humidity enviroment in greenhouse and provide the performance testing function.To study new strategies to improve the control precision is also necessary.The designs of the softwave and hardware of the platform are primarily discussed in the paper.The testing system collects the temperature and the humidity of the platform and then sent the analog signals to the microprocessor c8051f410 to dispose by A/D and output controlled through fuzzy self-tuning PID algorithm.The PTC heater and ultrasonic humidifier power are controlled by the pwm outputted through fuzzy self-tuning PID algorithm.The refrigeration and dehumidifacation functions are controlled by the multi-way switch relay driver outputs.The platform designed may be conveniently set fixed-point run through PC monitor interface,record and analysis the data of expected or acture temperature and humidity by using database.In this paper PID algorithm is mainly studied,analysis several commonly used control algorithms and choice the suitable control algorithm.PID control is suit for the process of general model,but this algorithm is base on known exact sharacteristics or unchanged properties of model,so there are many difficulties to use PID to control system.based on characteristics of the platform system,we study the fuzzy control theory and the design fuzzy reasoning self-tuning PID controller combine with PID algorithm.VB6.0 is used to develop the entire monitoing softwave of testing platform to monitor the real-time data and manually or automatically control functions can be operated by the PC minitoing softwave.This testing platform designed in this paper has the feature of wider temperature and humidity test-range,portable design,small in size,simple operation,steady work state and strong anti-interference ability.