Speed Motor and Temperature Controller for Coffee Roasting Machine Using PID

Control techniques are used during the coffee roasting process to enhance the quality of roasted beans. The roasting machine features a drum and motor that rotates to prevent burning. The aim of this research is to design an efficient control system for a coffee roasting machine using PID methods to ensure consistent temperature and drum speed throughout the roasting process. By implementing both open-loop and closed-loop Ziegler-Nichols tuning, this study seeks to optimize machine performance for different roast levels, minimizing steady-state error (Ess) and improving the overall quality of roasted coffee beans. The process starts by heating the drum to 150 degrees Celsius, then adjusting the temperature to achieve the desired roast level. The PID control method is used to maintain consistent temperature and drum rotation speed. The Ziegler-Nichols open-loop tuning method provides the control parameters for temperature regulation, with Kp (33.99) and Ki (0.39). Meanwhile, the closed-loop Ziegler-Nichols method is applied for controlling drum speed, resulting in Kp (3.6), Ki (2.4), and Kd (1.35). Testing at different roast levels (light, medium, and dark) showed Ess values of 0.24 percent, 2.2 percent, and 0.067 percent, respectively. Additionally, during motor speed testing, the lowest Ess was 0.5 percent at 300 rpm. These findings validate the success of the PID and PI control methods in optimizing the coffee roasting machine’s performance, contributing to better quality roasted beans.