A 2-Dof LQR based PID controller for integrating processes considering robustness/performance tradeoff.

Area of Science:

• Control Systems Engineering
• Process Control
• Industrial Automation

Background:

• Integrating processes with time delays present significant control challenges.
• Traditional control methods often struggle to balance regulatory and servo responses effectively.
• Existing PID tuning methods for these systems may not offer optimal performance or robustness.

Purpose of the Study:

• To analytically design a Two-Degree-of-Freedom (2-Dof) control system for integrating processes with time delay.
• To develop a novel Proportional Integral and Derivative (PID) controller combined with a unique set point filter.
• To achieve precise control over both regulatory and servo responses while minimizing control effort.

Main Methods:

• PID controller tuning using Linear Quadratic Regulator (LQR) and dominant pole placement.
• Design of a set point filter with a single time constant (λ) using calculated PID parameters.
• Validation using real industrial integrated process models and analysis of trade-offs between robustness (M_s) and disturbance rejection (IAE).

Main Results:

• The proposed 2-Dof control system demonstrates improved closed-loop responses for both regulatory and servo operations.
• The methodology achieves superior performance compared to recent PID tuning methods for integrating systems.
• A comprehensive range of PID parameters is identified, balancing system robustness and disturbance rejection.

Conclusions:

• The developed analytical design provides an effective solution for controlling integrating processes with time delays.
• The combined PID controller and set point filter offer enhanced performance and reduced control effort.
• This approach represents a significant advancement in PID control for challenging industrial processes.