VRFT-based digital controller design using a generalized second-order reference model

Abstract

Virtual Reference Feedback Tuning (VRFT) is a data-based controller tuning method wherein tuning is carried out directly from process input-output data without resorting to process identification. Although VRFT eliminates the need for a process model, the design methodology involves the use of a reference model and the selection of an appropriate reference model still remains an open problem. In this work, a generalized second-order reference model containing time delay and zero dynamics is derived. Furthermore, VRFT design equations using this reference model for two classes of linear controllers i.e. PID controller and a high-order controller with integrator, are developed. Simulation results are presented to illustrate the applications of the proposed design method and a comparison with existing data-based design methods and model-based design methods is made.