Hybrid control of greenhouse temperature system based on crop temperature integration theory

Greenhouse temperature system is a typical hybrid system, on account of the inputs of the system include discrete state variables, namely switching status of the environmental control equipment, as well as continuous state variables, namely the external environment factors. Therefor this paper presents a hybrid automata for greenhouse system based on crop temperature integration theory. Firstly, the model parameters of each discrete state is identified for transforming the value of outdoor environment factors into the predictive value of indoor temperature. Then taking the predictive value as the switching condition of the discrete states, and the hybrid control system based on predictive temperature is designed. At last, on the basis of the temperature accumulation of the previous period, the temperature plane can be divided into three different subareas, adjusting the setpoint curve dynamically. Experimental results show that the hybrid automata could switch the device status in a timely and reasonable manner, and there is a significant reduction to action frequency of equipment by applying temperature integration theory.