Automatica, Vol.40, No.1, 155-162, 2004
Two-degree-of-freedom l(2)-optimal tracking with preview
A simple SISO two-degree-of-freedom pole-placement design method is presented that provides l(2)-optimal tracking of a given reference signal. The closed-loop pole locations are first chosen by the system designer. The closed-loop zeros are then placed in an optimal fashion by a computationally inexpensive algorithm to achieve asymptotic tracking with an optimal transient response. The preview approach, which has become a common method for dealing with systems which have non-minimum phase behavior, can then optionally be used to further improve the transient behavior for both minimum phase and non-minimum phase systems. Unlike previous results based on the preview approach, the solution presented here takes into consideration the closed-loop pole dynamics, and is l(2) optimal with respect to all other two-degree-of-freedom preview controllers with the same closed-loop poles. A simple solution to the H-2 model matching problem, where the design parameter Q is not rational, but polynomial, is the heart of the solution method. (C) 2003 Elsevier Ltd. All rights reserved.
Keywords:discrete-time control;non-minimum phase systems;optimality;zero assignment;two-degree-of-freedom controllers;trajectory tracking;preview control