Synthesis of an Optimal Dynamic Regulator Based on Linear Quadratic Gaussian (LQG) for the Control of the Relative Humidity under Experimental Greenhouse

Abstract

<p><span lang="EN-US">This paper describes one practical approach that suggests a model based technique to control in real time the relative humidity under greenhouse. The humidity level is one of the most difficult environmental factors to be regulated in greenhouse. Moreover, maintaining and correcting for more or less humidity can be a challenge for even the most sophisticated monitoring and control equipment. For these raisons, a Linear Quadratic Gaussian (LQG) controller for relative humidity regulation under greenhouse turns out to be useful. Indeed a LQG controller is proposed for a relative humidity under a greenhouse control task. So, the state space model, which is best fitting the acquired data, was identified using the Numerical Subspace State Space System IDentification (N4SID) algorithm. The mathematical model that is obtained will be used for evaluating the parameters of LQG strategy. The proposed controller is implemented in two steps, in one hand, Kalman filter (KF) is used to develop an observer that estimates the state of relative humidity under greenhouse. In the other hand, the state feedback controller gain is estimated using a linear quadratic criterion function. The suggested optimal implemented controller using Matlab/Simulink environment is applied to an experimental greenhouse. We found, according to the results, that the controller is able to lead the inside relative humidity to the desired value with high accuracy, regardless of the external disturbances.</span></p>

Constrained Discrete Model Predictive Control of a Greenhouse Relative Humidity

“…For more details about (LQR)and Quadratic programming Parameters choice, the reader can refer to (Outanoute et al, 2016) and included references.…”

Diseño de un controlador lineal cuadrático gaussiano y un controlador autosintonizado por asignación de polos para el control del voltaje de un generador CD

“…Para diseñar el controlador LQG se aplica el principio de separación que permite calcular en forma independiente la matriz de realimentación de ganancia K del regulador lineal cuadrático (LQR) y un estimador de estados tipo Kalman, que posteriormente se combinan para formar el controlador [13], [14]. Para calcular la matriz de ganancia K se utiliza una función de costo cuadrática que minimiza el índice de desempeño presentado en la ecuación (7) [15]:…”

Control Based On the Temperature and Moisture, Using the Fuzzy Logic.

“…A couple of sensors can be installed in the inside as in the outside of greenhouses. Thanks to accuracy sensors and effective programs, it is easy to optimize the management of the greenhouse related to certain parameters such as temperature, After the practical implementation of network strategies of commands such as the TOR (All or Nothing) control, the command by cycle of hysteresis , the PID and PI-intelligent [9], the logic Gaussian quadratic [10], and the fuzzy controller for the temperature and humidity inside the greenhouse [11], it has been thought to put into practice an embedded system, while introducing the maximum of its algorithms of commands to simplify to users the use of its system and promote the good climate of greenhouses.…”