Controlling industrial dead-time systems: When to use a PID or an advanced controller

Abstract

This work presents a comparative analysis of PID, DTC and MPC strategies when used to control SISO processes with dead time considering characteristics commonly found in industry, such as noisy measurements in the process output and modeling error. For unconstrained processes, it is shown that the performance improvement obtained by using a more advanced control strategy instead of a PID is small or nonexistent for cases which require high robustness. However, for cases with well-known process models it is shown that the improvement obtained by using a more complex control structure is justified even for small delays. For constrained processes it was demonstrated that a PID with anti-windup is able to provide similar or even better results than MPC when robust solutions are considered.

Keywords: Constraints; Dead-time compensators; Model predictive control; PID control; Time delay.