Advancements in Nonlinear PID Controllers: a Comprehensive Review

Abstract

Proportional-integral-derivative (PID) controllers have been widely used in control engineering due to their simplicity, robustness, and effectiveness. However, traditional linear PID (L-PID) controllers face challenges in handling nonlinear dynamics, uncertainties, and varying operating conditions. To overcome these limitations, nonlinear PID (N-PID) controllers have emerged as a powerful alternative, offering improved adaptability, robustness, and transient response. Despite their increasing adoption, a comprehensive review of N-PID controllers, including their theoretical advancements, tuning methodologies, and applications, remains lacking. This paper provides an in-depth review of N-PID controllers, highlighting their advantages over L-PID controllers and their effectiveness in various engineering applications. It discusses the necessity of N-PID controllers, explores key advancements in their structural modifications, and analyses different tuning approaches, including adaptive, bio-inspired, and optimization-based methods. Additionally, the review covers their applications in process control, power converters, motor drives, and robotic manipulators, demonstrating their superior performance in handling complex dynamic systems. The paper concludes by identifying future research directions, emphasizing the potential of N-PID controllers in advancing control engineering by improving system stability, energy efficiency, and precision control. This review serves as a valuable resource for researchers and engineers seeking innovative control solutions for nonlinear and uncertain systems.