Analytical design of two-degree-of-freedom control scheme for open-loop unstable processes with time delay

A New PID Tuning Method Based on Transient Response Control

“…This extra controller is tuned in terms of the PID controller. This is an important advantage of the proposed method because the main controller and the extra feedforward controller in other methods are tuned separately [17,18]. Furthermore, a graphical optimization step is included for modifying the standard Manabe form values to obtain the closed loop response which meets the transient response specifications determined before the design.…”

Predictor-Based Disturbance Rejection Control for Sampled Systems With Input Delay

“…In fact, the classical SP or the similar internal model control (IMC) scheme can only be used for stable processes with time delay due to the internal stability issue [13]. Modified SP or IMC designs have been proposed in the literature (e.g., [4,5,[14][15][16][17][18]) for application to integrating and unstable processes with time delay. It was demonstrated that the filtered SP (FSP) [4,5], which gives a delay-free output prediction, could be generally used for open-loop stable, integrating and unstable processes with time delay.…”

Analytical design of a generalised predictor‐based control scheme for low‐order integrating and unstable systems with long time delay

“…Concerning the use of a proportional-integral (PI) or proportional-integral-derivative (PID) controller, improved tuning methods were proposed in the references [3][4][5][6][7][8] to enhance disturbance rejection performance. Due to the fact that the standard internal model control (IMC) structure cannot hold internal stability for integrating and unstable processes 9 , a few IMC-based control schemes were developed in terms of a two-degree-of-freedom (2DOF) control strategy in the literature [10][11][12][13][14][15][16] , based on using different tracking error specifications and stability margins. In dealing with time delays, the Smith predictor (SP) has been effectively used to control stable processes with long time delay 17 , but it cannot be used for integrating and unstable processes due to the problem of internal instability 18 .…”

“…For fair comparison, the 2DOF IMC control method presented in Chapter 8 of the bibliography 2 is used here, of which the control structure had been studied in the references 10,11 . The corresponding controllers for set-point tracking and load disturbance rejection are obtained, respectively, as …”