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Most systems used in hydroponics management use switching or simple PID controllers to regulate the electrician conductivity EC and the acidity PH of the irrigation water supplied to the crop. In contrast, in the Macqu Hydroponics system, using the flexibility provided by the virtual variables and the virtual control loops, more complex control strategies can be implemented for EC and PH control. Such control strategies are:
use of bumbles control and gain scheduling techniques to achieve smooth transition in irrigation line changing and good performance in all operating conditions
use of Smith Predictors to overcome large delays specially in the case of PH control
use of auto-tuning techniques for easy controller tuning
The next figure presents an example of one control strategy implemented by Macqu for the control of the EC using virtual control loops.
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PD-0F structure with a Self Adjusting Smith Predictor