Feedback stability under simultaneous gap metric uncertainties in plant and controller
Systems & Control Letters
On the gap metric and coprime factor perturbations
Automatica (Journal of IFAC)
Automatica (Journal of IFAC)
Automatica (Journal of IFAC) - Special issue on trends in system identification
Brief Direct iterative tuning via spectral analysis
Automatica (Journal of IFAC)
From experiment design to closed-loop control
Automatica (Journal of IFAC)
Relations between uncertainty structures in identification for robust control
Automatica (Journal of IFAC)
Hi-index | 22.15 |
In iterative schemes of identification and control one of the particular and important choices to make is the choice for a model uncertainty structure, capturing the uncertainty concerning the estimated plant model. Structures that are used in the recent literature encompass e.g. gap metric uncertainty, coprime factor uncertainty, and the Vinnicombe gap metric uncertainty. In this paper, we study the effect of these choices by comparing the sets of controllers that guarantee robust stability for the different model uncertainty bounds. In general these controller sets intersect. However in particular cases the controller sets are embedded, leading to uncertainty structures that are favourable over others. In particular, when restricting the controller set to be constructed as metric-bounded perturbations around the present controller, the so-called double Youla parametrization provides a set of robustly stabilizing controllers that is larger than corresponding sets that are achieved by using any of the other uncertainty structures. This is particularly of interest in controller tuning problems.