Regularization approach for an immersion-based observer design

This paper is about immersion-based observer design for nonlinear systems. Starting from the fact that direct immersion may result in stability issues, which may in turn affect the observer performance, a method is proposed to overcome such problems, by somehow `stabilizing' the transformation (or `regularizing' it). A couple of examples are presented to illustrate the effectiveness of the method, including the challenging case of state and parameter estimation in a speed sensorless induction machine.