Closed-loop monitoring systems for detecting impending instability

Monitoring systems are proposed for the detection of impending instability in uncertain nonlinear systems. The work employs generic features associated with the response to noise inputs of systems bordering on instability. These features, called "noisy precursors" in the work of Wiesenfeld, also yield information on the type of bifurcation that would be associated with the predicted instability. The closed-loop monitoring systems proposed in the paper have several advantages over simple open-loop monitoring. The advantages include the ability to influence the frequencies at which the noisy precursors are observed, and the ability to simultaneously monitor and control the system.