New conditions for robust stability of linear systems subject to a bounded rate parameter

In this paper we consider a closed loop system composed of a SISO asymptotically stable linear plant and an uncertain time-varying parameter. Referring to this setup, Amato and Celentano (1997) introduced the stability margin defined as the maximum allowable rate of variation of the parameter which still guarantees stability of the closed loop system. This paper is devoted to show how the proposed technique can be used into a synthesis context to improve the value of the open loop stability margin. An example illustrates the benefits of the method.