Identifiability of MIMO linear dynamic systems operating in closed loop

Identification of multi-input muiti-output [MIMO) Section 3 of the naner is concerned with the case -~~~ ~-. ~-~~r ~ ~ r ~ ------.---~~ ~ ~ ..~.. linear dynamic systems is considered for the c&e when the measurements are obtained during closed loop operation. Both where the disturbances in the feedback path are a noise free and noisv feedback situations are analvsed. For the full rank stochastic Process. Other authors,e.g.rlOl, .case where the distirbances in the feedback path i re a full rank [ll], [14] and 1171 have also studied the case under stochastic process it is shown that, under certain mild conditions, physically meaningful models for the forward and reverse paths different conditions. Gustavsson et al. in 1141 show can be uniquely determined. Far the case where the feedback that the forward path model is strongly system path is noise free it is shown that the forward path model can be identifiable under the assumption that the forward uniquely determined provided the regulator satisfies certain path noise model is minimum phase, Phadke and minimal complexity requirements. Wu[ll] describe a procedure for obtaining forward L INTRODUCTION