VRFT permits to tune a 1 or 2 degree of freedom linear controller within a specified class on the basis of a single set of input/output data collected from an experiment on the plant.

The control specifications are assigned via a model-reference discrete time transfer function. Given a single set of input/output data (either collected in open-loop or in closed-loop), the VRFT method can be applied in order to obtain the controller that satisfies the assigned specifications.

The "design engine" of VRFT is an solver of a model-reference optimization problem. Lack of knowledge of the plant transfer function is compensated for via I/O measurements.