A distributed control system for citric fruits conservation and maturation based on CAN and Internet networks

In citric fruits conservation and maturation systems it is very important to have precise information about parameters that indicate the citric fruit state. This information allows computing the appropriate control actions in order to achieve an optimum controlled citric fruit conservation and maturation. Last technological advances must be also used in this agriculture field to forget the rudimentary control systems that are being used at the present time. This paper describes a new distributed control system devoted to control citric fruits cold chambers that applies the last computer and electronics techniques. It is structured over different communication networks, making possible a remote pursuit and control in real-time over Internet networks and offers an improved features of flexibility and reliability. In each cold chamber, there are a strategically distributed set of sensors and actuators that are interconnected by means of a C.A.N network. In each cold chamber, one control node centralizes the chamber information and calculates the control actions. The control node information is also overturned on a backbone C.A.N network that interconnects all cold chambers with a personal computer. This computer is in charge of carrying out a second treatment and storage of the information and its diffusion to Internet. Finally, each user can be connected to his plant via an Internet connection or using a GPRS or WAP mobile telephone, to see the process evolution or to modify the parameters of each cold chamber.

I. Introduction

Nowadays it is necessary to obtain a high quality in all type of industrial and technological processes. In the citric fruits conservation and maturation sector a modernization of control systems employed are necessary in order to improve the quality of the products by means of a more detailed pursuit of the chemical and biological processes of fruits conservation and maturation phases. Also, last technological advances in computation and communication must arrive to this sector. From an internet viewer the fruit state must be observed: graphical representation of temperature or humidity, remote control of the cold chambers or to receive a sms message in the telephone if some alarm condition is detected is nowadays technologically possible and control systems for this sector must offer these features.