Optimal input design for identification in closed-loop

The closed-loop-control-relevant (CLCR) identification for inverse stable (IS) and inverse unstable (IU) processes is discussed computing the necessary optimal reference signal excitation. In case of an IS plant the optimal excitation depends only on the performance design goal, however, in case of an IU plant it depends on the invariant factors of the process, too, so only adaptive algorithms can be applied.