Enhanced disturbance rejection for open-loop unstable process with time delay.

Area of Science:

• Control Systems Engineering
• Process Control
• Chemical Engineering

Background:

• Open-loop unstable processes with time delay present significant control challenges.
• Existing high-order disturbance estimators can be complex to design and tune.
• A two-degree-of-freedom control scheme is a recent advancement for such processes.

Purpose of the Study:

• To propose a simplified and effective disturbance estimator design method.
• To enhance the performance of a two-degree-of-freedom control scheme for unstable processes.
• To provide a unified and easy-to-tune approach for industrial process engineers.

Main Methods:

• A PID controller cascaded with a lead-lag filter replaces the traditional high-order estimator.
• A novel analytical method based on the Internal Model Control (IMC) design principle is developed.
• The proposed method features a single user-defined tuning parameter.

Main Results:

• The proposed disturbance estimator demonstrates superior performance compared to existing methods.
• Effectiveness is confirmed in both nominal and robust control scenarios.
• Illustrative examples from previous works validate the superiority of the proposed method.

Conclusions:

• The developed disturbance estimator offers enhanced performance and robustness for unstable processes with time delay.
• The method simplifies design and tuning, making it highly advantageous for industrial applications.
• It provides a unified approach for various classes of unstable time-delay processes.