Refining PI/PID Controller Design with Stability Margins: A Survey on Simplicity and Flexibility

PI/PID controllers are widely used in power systems and the process industry, which highlights their importance because of their versatility, simplicity, and ease of installation. Despite this, the tuning of PI/PID controllers is still a rich area of study, with modern techniques building on foundational methods like those developed by Ziegler-Nichols. Because industrial processes are diverse and complicated, many techniques, including Cohen-Coon, internal model control, and error-integral criteria, have been developed over time to address specific control objectives. It is essential to comprehend the dynamics and behavior of the process in order to develop an efficient control system. This entails determining the kind of process and choosing the right design strategies to satisfy specific system requirements, like robustness, noise reduction, disturbance rejection, and set-point tracking. Achieving the required control outcomes is made flexible by the range of control designs available, including Smith predictors, internal model control, and unity negative feedback.