Self-Tuned Fuzzy PID Temperature Controller Implementation in Hot-Air Coffee Roasting Process

—The temperature progression of a pile of roasted coffee beans has been one of the most critical parameters to monitor and control during the roasting process as it provides a significant impact on the product's flavour formation. The application of heat to the coffee bean requires a precise temperature controller, and traditional PID controllers have been frequently utilized in recent years, which present a challenge due to the process's non-linear nature. The implementation of a Self-Tuned Fuzzy PID controller to control temperature was proposed in this study, and the performance in real-time was compared to a conventional PID controller as a benchmark. Several evaluation criteria were chosen, including the controller's capacity to produce a desired setpoint without steady-state error, its ability to keep up with temperature setpoint changes during the process, and its resilience to disturbance. During the step test, the proposed controller improved percent overshoot and settling time by 88.10% and 61.98%, respectively. Meanwhile, during the setpoint change test, the overshoot was reduced by more than 80%, and the settling time was reduced by more than 20%. Furthermore, the proposed controller was able to stabilize the output during the disturbance test within 70 s, as opposed to the PID controller, which showed continuous temperature fluctuations because of the disturbance.