  As a very well-known classical fact, non-minimum phase zeros of the process
put some limitations on the performance of the feedback system. The source of
these limitations is that such non-minimum phase zeros cannot be cancelled by
unstable poles of the controller since such a cancellation leads to internal
instability. The aim of this paper is to propose a method for fractional-order
cancellation of nonminimum phase zeros of the process and studying its
properties. It is specially shown that the proposed cancellation strategy
increases the phase and the gain margin without leading to internal
instability. Since the systems with higher gain and phase margin are easier to
control, the proposed method can be used to arrive at more effective controls.

Optimization and Control