Groningen-Lyon Seminar: Lucas Brivadis

18Mar2021

Title: Output feedback stabilization at an unobservable target point

14:00 - 15:00

online (please contact the organizer Bayu Jayawardhana to receive login details)

Abstract: When only part of the state of a control system is known, a state stabilizing feedback can not be directly implemented. One must achieve output feedback stabilization instead. A sufficient condition for a (globally) state feedback stabilizable control system to be (semi-globally) output feedback stabilizable is the uniform observability of the system, that is observability for all inputs. However, some systems present an observability singularity at the target: the value of control at the target point is an input making the system unobservable. Then, the challenge lies in according the antagonistic nature of the state estimation and stabilization. While the system approaches the target, observability properties vanish, hence the state estimation is getting worse, which in turn prevents stabilization.
On examples of systems with linear conservative dynamics and nonlinear output, we illustrate two main guidelines to tackle this problem:
- using well chosen perturbations of the state feedback law can yield new observability properties of the closed-loop system;
- embedding the original control system into a new (finite or infinite-dimensional) system admitting an observer with dissipative error allows to mitigate the observability issues.

Speaker: Lucas Brivadis (Univ. de Lyon)

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