A remark on model reduction for singular systems

This note comments on the results of the following two papers, ‘model reduction problem for singular systems via covariance approximation’ (Optim. Contr. Appl. Meth. 2004; 25:263–278) and ‘A remark on model reduction for singular systems via covariance approximation’ (Optim. Contr. Appl. Meth. 2006; 27:293–298), which all studied the model reduction for singular systems. In this note the model reduction for singular systems is investigated based on particle swarm optimization and the error criterion via covariance approximation. The reduced model for singular systems obtained in this note is stable and impulse controllable. Furthermore, compared with the above two papers, the reduced-order system approximates the original system better. Finally, an example is provided to show the effectiveness and improvement of the proposed algorithm. Copyright © 2007 John Wiley & Sons, Ltd.