IMC-PID tuning method based on sensitivity specification for process with time-delay

Abstract

To overcome the deficiencies addressed in the conventional PID control and improve the dynamic performance and robustness of the system, a simple design and parameters tuning approach of internal model control-PID (IMC-PID) controller was proposed for the first order plus time-delay (FOPTD) process and the second order plus time-delay (SOPTD) process. By approximating the time-delay term of the process model with the first-order Taylor series, the expressions for IMC-PID controller parameters were derived, and they had only one adjustable parameter λ which was directly related to the dynamic performance and robustness of the system. Moreover, an analytical approach of selecting λ was given based on the maximum sensitivity M s . Then, the robust tuning of the system could be achieved according to the value of M s . In addition, the proposed method could be extended to the integrator plus time-delay (IPTD) process and the first order delay integrating (FODI) process. Simulation studies were carried out on various processes with time-delay, and the results show that the proposed method could provide a better dynamic performance of both the set-point tracking and disturbance rejection and robustness against parameters perturbation.

Characterization and analysis of real-time capillary convective PCR toward commercialization

“…To simplify tuning, a PID control with an internal model control feature (IMC-PID) was adopted for this work. In addition to automatic gain parameter optimization ("auto-tuning"), IMC-PID has excellent robustness and stability 35,36 even when the plant model changes with the aged rubberized resistive heater. The schematic diagram of IMC-PID negative feedback temperature control is depicted in Fig.…”

Tuning of PID Controller Based on Phase Margin for Stable Processes Via IMC Principles

“…Here, the paper uses maximum sensitivity which is the index of robustness to prove the robustness of system. The value of Ms (1.2-2.0 [7]) is the reciprocal of the shortest distance from the Nyquist curve of the open loop transfer function to the critical point (-1, j0). So the distance function d can be expressed as following: …”

“…Besides, the robustness of control system is very important because the models are usually imprecise and the parameters of all physical systems may vary with the operating conditions and time. Hence, the robustness against parameters perturbation of the system is an important concern in process control [6,7]. Phase margin is reflection of system robustness.…”

“…Furthermore, the most important thing in IMC controller designation is to dispose of the time delay in the denominator of controller. The low order approximate [7] always engenders the disadvantage that the resulting PID may not maintain the property of IMC controller exactly. Therefore, the proposal method devotes to handle the time delay without any approximation.…”

IMC-PID controller for pure integrating process with large dead time

“…A simple IMC tuning rule is proposed in [9] where the filter time constant is equal to the time delay of the process model. Maximum sensitivity based IMC-PID tuning is reported in [10] which provides good robustness in controller performance. To obtain faster response IMC tuning parameter is derived by using Laurent series in [11].…”