Virtual reference feedback tuning for two degree of freedom controllers

The Virtual Reference Feedback Tuning (VRFT) is a data based method for the design of feedback controllers; it has been presented by the same authors in previous work. In the original formulation the VRFT method gives a solution to the one degree of freedom model-reference control problem in which the objective is to shape the I/O transfer function of the designed control system. This paper delivers the extension of the method to the design of two degree of freedom controllers so as to shape both the I/O transfer function and the sensitivity transfer function.