Analysis of a predictor-regulator system

A high-performance control system called "predictor-regulator" is proposed, its governing laws are derived, and it is applied to simulated processes to evaluate its characteristics, and to real processes to demonstrate its feasibility. The proposed system is made up of a two-loop configuration[4]: a fast auxiliary loop consisting of a controller and a simple lag element, and a main loop provided with another controller operating on the process. Both the controllers are conventional PID type commercial controllers. Theoretical study reveals that, by suitable choice of the compensator parameters, the control arrangement could result in remarkably superior performance. While, for the key loads, both steady state and transient errors become practically zero with the aid of only two P-controllers, inclusion of integral action aids in achieving control against secondary (unmeasured) disturbances also. The design and performance of the regulator system are evaluated via simulation. Several practical aspects of the control problem are examined, and criteria for choosing the auxiliary lag, the modes of control, and the controller settings are established. Applicability of the technique to a wide range of processes (e.g. complex higher order and dead time processes) is also discussed. The results obtained confirm that the control approach could match combined feedforward-feedback regulation in its performance, and classical feedback in design simplicity and ease of implementation. © 1976.