Fuzzy Sugeno Based Temperature and Humidity Control for a Hybrid PLC-ESP32 Based Automatic Chili Drying Machine

Abstract

Maintaining stable temperature and relative humidity during chili drying is essential to produce high-quality dried products while reducing moisture content efficiently. This study presents a hybrid PLC–ESP32-based automatic chili drying machine employing a Fuzzy Sugeno controller for simultaneous regulation of temperature and humidity. The proposed system utilizes a Mitsubishi FX3U programmable logic controller (PLC) for real-time actuator control and an ESP32 for executing the Fuzzy Sugeno inference algorithm. Temperature error and relative humidity error are used as the controller inputs, while the outputs consist of PWM signals for the heater and the circulation fan. Communication between the ESP32 and PLC is established through the Modbus RTU protocol, enabling intelligent decision-making while maintaining industrial-grade control reliability. Experimental results demonstrate that the proposed controller successfully maintained the drying chamber temperature at the 60 °C setpoint with a maximum overshoot of 0.1 °C and a steady-state error of approximately ±0.17 °C. Compared with the conventional ON–OFF method, the proposed controller produced a more stable thermal response and improved drying performance. After four hours of drying, the average moisture content of the chili decreased to 2.6% on the upper rack and 1.0% on the lower rack, indicating relatively uniform drying throughout the chamber. Visual comparison with commercially available dried chili also showed that the proposed drying process produced a brighter red color, suggesting better preservation of product appearance under controlled drying conditions. Although no chemical composition analysis was conducted, these observations indicate that maintaining stable drying conditions contributes to improved visual quality. Overall, the proposed hybrid PLC–ESP32 architecture integrated with the Fuzzy Sugeno controller provides an effective solution for intelligent agricultural drying applications. Keywords: Automatic Chili Dryer, Fuzzy Sugeno, PLC-EPS32, Humidity Control, Temperature Control.