Fuzzy Greenhouse Climate Control System based on a Field Programmable Gate Array

Fuzzy control is a practical alternative for the design of a great variety of control applications. It provides an advisable method for the design of non-linear controllers using heuristic information. This article presents the development of a greenhouse intelligent climate control system that uses a fuzzy controller, based on a field programmable gate array (FPGA). The FPGA has a great potential for use in agricultural technology development due to its characteristics to produce fast prototypes of complex hardware designs with an effective production cost. A low-cost intelligent system designed in a single chip with the task to carry out the complete functionality for the greenhouse climate control was developed. The system proposed here is a good option to unload the low-level tasks (monitoring of climate variables and operation of actuators, such as heaters and windows to control the greenhouse inside temperature) from the main control system, in order to leave to the main controller the high-level tasks as plant monitoring, control of vegetative development, production planning, irrigation system control, which need a high computational power. The system developed in this work consists of: a signal conditioning sub-system, a data-acquisition sub-system, digital/analogue conversion sub-system and a FPGA sub-system. The FPGA sub-system has three units: the synchronisation unit, the personal computer interface unit and the fuzzy logic unit, all implemented within a FPGA-integrated circuit, conforming to a system-on-a-chip (SoC). The design, compilation and simulation of the FPGA sub-system were carried out in the Active-HDL environment using the hardware description language VHDL. The Co-simulation Active-HDL/Simulink and experiments that show the performance of the complete system are presented.