GX - A SMALLTALK-BASED PLATFORM FOR GREENHOUSE ENVIRONMENT CONTROL .2. SUPPORTING AND IMPLEMENTING CONTROL STRATEGIES

GX is a software system designed to control greenhouse climates using a knowledge-based approach. In this article, the constructs, modules, and mechanisms which are used within GX to implement and operate ''smart'' climate control strategies are examined. The objective was to allow the formulation of strategies that can be deployed on various sites with a minimal amount of adaptation. The set of design criteria which have governed the design of the GX strategy formulation and operation toolbox is presented as well as the various components of the toolbox. The components are described in terms of Smalltalk entities and examples of the use of the object-oriented paradigm are given. A GX strategy can be designed and used for different applications and in various contexts. It can provide insight on the reaction of a greenhouse system to different control strategies and thus serve as a test bench for the control programs. It can also be used as a high-level control system which ''tunes'' environmental parameters and setpoints in real time. As such, GX and the underlying technology constitutes a powerful knowledge transfer vehicle that can be used to provide growers with optimized solutions to some of the most important problems that they encounter in their field of activity.