Experimentally validated fractional-order PI with anti-windup for fractional-order plus time delay processes

Nonlinearity constraints are inherent in all physical systems and can impact the system output. The windup issue occurs when actuators reach their limits, causing a disparity between the system input and the controller output. To eliminate or minimize the impact of saturation, controllers are designed with anti-windup techniques. This paper proposes a new target loop-based simple analytical design of a fractional-order proportional integral (FOPI) anti-windup controller for non-integer-order (NIO) processes with time delay. Explicit tuning rules in terms of plant parameters are established to meet user-defined criteria such as phase margin ( \(\phi _\text {m}\) ${\varphi }_{\text{m}}$ ) and maximum sensitivity \((M_\text {s})\) $(M_{\text{s}})$ . To check the performance and robustness of the proposed control law, case studies are conducted and compared with recently developed control laws. The robustness of the proposed controller is examined with parameter variations. Lastly, real-time validation of the proposed control approach is carried out in a two-tank level loop.