Temperature Control System For Greenhouse Based On ZigBee

In the environment of the weather changed suddenly outside the greenhouse, the shocks of temperature control curve increase significantly and immediately by using grey prediction fuzzy PID control algorithm.In order to solve the problem of poor adaptability of the gray prediction fuzzy PID control algorithm, the algorithm is improved by adding the mode control algorithm based on the changes of the outdoor temperature.The improved algorithm has a better effect on real-time response with Grey prediction step adjusting freely.The temperature control system was constructed by temperature acquisition nodes、temperature control nodes、a center node and the PC. The hardware of the center node、temperature acquisition nodes and temperature control nodes were designed. The software of ZigBee nodes and the main algorithm are programmed in the environment of IAR Embedded Workbench IED and Visual C++6.0.Four groups of comparison experiments were designed to compare the effects of the grey prediction fuzzy PID control algorithm and the improved algorithm. The experiments dates were also analyzed by using variance、the maximal error and energy efficiency of the sensors.And the control accuracy of the two algorithms were also evaluated based on the theory of Harris.The results show that the improved algorithm get a better result of control precision of0.2℃higher than the original algorithm, and make the life of the ZigBee wireless network longer.