Control System for Electrical Conductivity in Hydroponic Cultivation of Lettuce

This study investigates the proportional integrator (PI) controller for the automation of a hydroponic cultivation system of crespa lettuce, with the nutrient film technique (NFT). With the research conducted, in recent times in the sectors where the different plants have been cultivated, the soil has been degraded, for that reason it must be fertilized with organic and chemical products, during the harvest it must be moistened with fungicides to dispense with diseases and pests within the crop, there is a water irrigation system to keep the soil moist during growth and development. The hydroponic cultivation system consists of transmitting a nutrient fluid through pipes where the plants are housed for their development, the amount of nutrients required by the plants for their growth is injected into the crop allowing the variable electrical conductivity (EC) is 1.2 and 1. 8 uS, for this a PI control system must be made, in closed loop using the programmable logic controller logo V8, for the design of the controller samples are taken of the behavior of the variable of the EC at the time of adding the nutrients and the integral process is applied to determine the mathematical model of the system with this the tuning of the constants of the PI controller is made, applying methods such as: Ford, Astrom, Hay and Zou Brigham to determine the constants of the controller perturbations are applied to the process to verify the control action of the hydroponic system.