ON OUTPUT FREQUENCY-WEIGHTED CONTROLLER REDUCTION

In this paper, the author developed a controller reduction method vie pseudo output frequency-weighted balanced realization. The criterion chosen is based on the considerations of the system's stability and closed-loop transfer function approximation. A procedure to reduce the controller order by modifying the observability gramian and using a balanced truncation technique is presented, and an L(infinity)-norm bound on the weighted reduction error is also derived. The effectiveness of using this approach is demonstrated by reducing a high-order Grumman F-14 pitch axis controller, designed by some H-infinity method, to a relative low-order one. The comparison of the closed-loop frequency responses by using two different reduced-order controllers is also shown. The method proposed can be easily extended to its corresponding input frequency-weighted version, and is also applicable for both discrete- and continuous-time systems.