Optimal design of I-PD controller for disturbance rejection of time delayed unstable and integrating-unstable processes

Disturbance rejection has always been a major phenomenon in control theory. Disturbances that arise in control of unstable or integrating unstable processes with time delay present considerable difficulties for classical PID controllers. This paper supplies analytical tuning rules, derived from optimum disturbance rejection responses to minimise the error signal according to several integral performance criteria to identify the tuning parameters of the I-PD controller. The provided analytical rules offer the advantage of calculating controller parameters without the necessity of employing an optimisation algorithm. This simplifies the tuning process and allows for a straightforward determination of the controller's parameters, making it more convenient and efficient for practical implementation in control systems. Comprehensive simulations were performed to validate the effectiveness of the proposed I-PD controller in terms of disturbance rejection responses, control signals, perturbation in process parameters, measurement noises, TV values, Ms values, and integral performance indicators. Overall, the outcomes demonstrate that the introduced method for the tuning of I-PD controllers offers notable advantages when compared to other tuning methods found in the literature.