Temperature and humidity control in greenhouses using the Takagi-Sugeno fuzzy model

The control of air temperature and humidity concentration in greenhouses is described by means of simultaneous ventilation and heating systems. To solve the problem of bi-linearity of greenhouse models, this paper proposes the construction of a Takagi-Sugeno (T-S) fuzzy model from a simplified nonlinear dynamic model of the greenhouse climate. Using this T-S fuzzy model, the stability analysis and control design problems can be reduced to sufficient conditions expressed as linear matrix inequalities (LMIs). This paper shows that it is possible to successfully control the greenhouse climate by using T-S fuzzy models and the parallel distributed compensation (PDC) concept. Simulation results for several tests showing the good performance and stability obtained with the proposed design methodology are presented.