This work focuses on the modeling and control of integrating processes that exhibit dead-time, which are commonly found in chemical and process control systems. These systems are challenging to control due to their inherent delay and lack of steady-state gain.
Problem Context:
Integrating processes with dead-time (IPDT) occur when the system output is a time-integral of the input, and thereâs a delay before the input has an effect.
Examples include liquid level control in tanks, batch processes, and thermal systems.
Controller Design:
The work evaluates and compares multiple control strategies tailored to IPDT systems:
PI and PID tuning rules customized for integrating systems.
Smith Predictor-based control, which compensates for dead-time.
IMC (Internal Model Control) structure adapted to IPDT models.
Modified MPC (Model Predictive Control) for time-delay systems.
Performance Indices:
Multiple performance measures are used for comparison: IAE (Integral of Absolute Error), ISE (Integral of Squared Error), and settling time.
Analysis is done under both setpoint tracking and disturbance rejection.
Tuning and Robustness:
Parametric tuning formulas are derived based on the model parameters (dead-time and time constant).
Robustness of the controllers is evaluated through sensitivity analysis and gain/phase margin analysis.
Simulation Studies:
Simulations validate the proposed control strategies for first-order integrating plus dead-time (FOIPDT) systems.
MATLAB/Simulink is used extensively to simulate and compare controller performance.
Industrial Relevance:
Many real-world systems behave like integrating processes with delay, especially in industries such as petroleum refining, food processing, and wastewater treatment.
Practical tuning recommendations for such systems.