Abstract. In a commercial greenhouse, variables, such as
temperature and humidity, should be controlled with minimal human
intervention. A systematically designed climate control system can enhance
the yield of commercial greenhouses. This study aims to formulate a
nonlinear multivariable transfer function model of the greenhouse model
using thermodynamic laws by taking into account the variables that affect
the Greenhouse Climate Control System. To control its parameters, Mamdani
model-based Fuzzy PID is designed which is compared with the performance of
proportional-integral (PI) and proportional-integral-derivative (PID)
controllers to achieve a smooth control action. The Fuzzy logic based PID
provides robust control actions eliminating the need for conventional tuning
methods. The robustness analysis is performed using values obtained from
real-time implementation for the greenhouse model for Fuzzy based PID, PI
and PID controllers by minimizing the Integral Absolute Error (IAE) and
Integral Square Error (ISE). The greenhouse model has strong interactions
between its parameters, which are removed by Relative Gain Array (RGA)
analysis, thereby providing an effective control strategy for complex
greenhouse production. Further, the stability analysis of non-linear
greenhouse model is conducted with the help of the bode plot and Nyquist
plot. Results show that good control performance can be achieved by tuning
the gain parameters of controllers via step responses such as small
overshoot, fast settling time, less rise time, and steady-state error. Also,
smoother control action was obtained with Fuzzy based PID making the
Greenhouse Climate Control System stable.