A robust globally asymptotically stabilizing feedback: The example of the artstein’s circles

We study a two dimensional system which is globally asymptotically stabilizable with a discontinuous feedback but for which there exists no smooth stabilizing feedback. However this asymptotic stability is not robust to measurement, actuator or external noise. We show that such a robustness property can be achieved with an hybrid controller. In doing so we need to introduce an appropriate notion of solutions for hybrid systems.