  The non-minimum phase (NMP) zero of a linear process located in the feedback
connection cannot be cancelled by the same pole of controller according to the
internal instability problem. However, such a zero can partly be cancelled by
the same fractional-order pole of a pre-compensator located in series with
process without facing internal instability. This paper first presents new
theoretical results on the properties of this method of cancellation, and
provides design techniques for the pre-compensator. It is especially shown that
by appropriate design of pre-compensator this method can simultaneously
increase the gain and phase margin of the system under control without a
considerable reduction of open-loop bandwidth, and consequently, it can make
the control problem easier to solve. Then, a method for realization of such a
pre-compensator is proposed and performance of the resulted closed-loop system
is studied through an experimental setup.
