Decentralized PI/PID controllers based on gain and phase margin specifications for TITO processes.

Area of Science:

• Control Systems Engineering
• Process Control
• Automation Technology

Background:

• Two-input-two-output (TITO) systems present significant control challenges due to inherent loop interactions.
• Traditional control methods often struggle to achieve desired performance in such complex, coupled systems.
• Robust controller design requires addressing both system dynamics and interaction effects.

Purpose of the Study:

• To propose a novel decentralized PI/PID controller design methodology for TITO interactive processes.
• To ensure robust control performance by meeting specific gain and phase margin requirements.
• To validate the effectiveness and practical applicability of the proposed method through simulations and experimentation.

Main Methods:

• Decouplers were designed to minimize interaction between control loops in TITO systems.
• Frequency response fitting was employed to obtain First-Order Plus Dead Time (FOPDT) models for decoupled subsystems.
• Independent PI/PID controllers were designed for each subsystem based on gain and phase margin specifications.

Main Results:

• The proposed method effectively reduced interaction in TITO systems.
• Decoupled subsystems were accurately modeled using FOPDT approximations.
• Designed PI/PID controllers achieved desired gain and phase margins, demonstrating effective control.
• Simulations and experimental results confirmed the method's validity and practical applicability.

Conclusions:

• The decentralized PI/PID controller design offers an effective solution for controlling TITO interactive processes.
• The method provides a systematic approach to achieve robust control with specified stability margins.
• The successful application to a Level-Temperature reactor highlights its practical relevance in industrial automation.