Control System of Nutrient Solution pH Using Fuzzy Logic for Hydroponics System

The crop yield of automatic hydroponic increased by 40% more than conventional hydroponic. The pH level of nutrient solution is one of factors that greatly affect the quality and quantity of hydroponic plants. The pH level of nutrient solution of 5.5 was used as a set point. Water spinach was used as hydroponic plant. Nutrient solution was a mixing of AB Mix General Vegetable, pH Up solution (KOH 10%), pH Down solution (H3PO4), and distilled water. Hydroponic Deep Flow Technique (DFT) system was used in this research. ESP32 microcontroller is used to control the degree of opening the servo valve based on the data provided by the pH meter module sensor. There are two types of membership functions used, i.e. the trapezoidal type and the triangular type. The error value and the delta error of the difference in the pH of nutrient solution measured with the pH set point are used as input in the fuzzy logic rule base. Results of the control system response with fuzzy logic appear to be following with the set point of 5.5. However, weather conditions will affect the absorption of nutrients so that changes in the pH value of the nutrient solution are in a steady-state between 5.0-6.0. Results of the best response control system using fuzzy logic were the rise time value of 336.07 s, maximum overshoot of 0.54, and steady-state error of 0.37 (2.6%).