Multirate feedforward control with state trajectory generation based on time axis reversal for plant with continuous time unstable zeros

Abstract

Plant with unstable zeros is known as difficult to be controlled because of initial undershoot of step response and unstable poles of its inversion system. There are two reasons why plant has unstable zeros in discrete time domain: 1) non-collocation of actuators and sensors, 2) discretization by zero-order-hold. Problem 2) has been solved by multirate feedforward control proposed by our research group. This paper extends this method to solve problem 1) by the state trajectory generation based on time axis reversal. The validity of the proposed methods is demonstrated by simulations.