Robust tuning of uncertainty and disturbance estimator-based control for stable processes with time delay

To expand the potential of uncertainty and disturbance estimator (UDE)-based control in practical application to most industrial stable processes, this paper proposes a convenient yet robust tuning rule according to the widely used first-order plus time delay (FOPTD) plant. The Smith predictor is first introduced to anticipate the delay-free output, which guarantees signal synchronizations in three control modules and enables remarkable restorations of nominal stability and performance. Then a second-order filter is employed in UDE to decouple the trade-off between disturbance rejection and noise attenuation. Based on this improvement and fixing both tracking speed and feedback gain to suggested patterns, the exhaustive evaluations for robustness against model distortion are executed through scanning the dimensionless filter bandwidth. The boundary demarcation triggered by the plunge of the continuous range of tolerable mismatched delays subsequently facilitates the formulation of an intuitive tuning rule with prescribed robustness. Its inherent model-based scaling property largely enables this rule to be implemented readily in industrial processes just like the proportional-integral-derivative (PID) controller. Several representative simulations are performed to demonstrate the merits of the proposed method over the related control strategies. And the promising prospect of the UDE-based control in the practical application is further illustrated by conducting a water level control experiment. (c) 2023 The Franklin Institute. Published by Elsevier Inc. All rights reserved.

Automated summary

This paper proposes a convenient and robust tuning rule for uncertainty and disturbance estimator (UDE)-based control in practical industrial stable processes. The Smith predictor is introduced to anticipate delay-free output, enabling signal synchronizations and restoring stability and performance. A second-order filter is employed in UDE to balance disturbance rejection and noise attenuation. A intuitive tuning rule with prescribed robustness is formulated based on exhaustive evaluations for robustness against model distortion. The promising prospect of UDE-based control in practical application is illustrated through representative simulations and a water level control experiment.