Adaptive minimum variance control for SISO nonminimum phase systems

The authors are concerned with the extension of the well-known minimum-variance adaptive controllers to include nonminimum-phase systems. By allowing the control signal to assume different values in between two consecutive sampling instants, the zeros of the discrete model of the process to be controlled can be arbitrarily assigned. This permits minimum-variance adaptive controllers to control nonminimum-phase systems properly. As compared with the standard minimum-variance controller, the intersample performance shows improvements if the process has one or more zeros close to the unit circle