Closed loop identification method using a subspace approach

Abstract

This paper presents a free model reduction closed loop subspace identification method for multivariable systems operating in a well posed closed loop environment. This allows to determine the impulse response of the system from the identification of the control system sensitivity functions. The rational behind the proposed method is twofold. Firstly, the general purpose design features of the subspace system identification approach and its inherent numerical robustness. Secondly, the model reduction performed in the available subspace identification is removed by a proper order selection procedure. A bias analysis is carried out to emphasize the robustness features.