Robustness redesign of continuous-time adaptive schemes

In a recent paper we have established that several adaptive schemes are robust with respect to modeling errors consisting of fast parasitics which are weakly observable in the plant output. We now show that the weak observability assumption is crucial, that is when the parasitics are strongly observable the adaptive schemes are no longer robust. However, the addition of a low pass filter at the output makes the parasitics weakly observable and hence guarantees the robustness of the enlarged scheme.