A possible extension of H∞ control to the nonlinear context

The aim of this paper is to show how some basic notions of robust control can be set in a nonlinear context making use of the concept of incremental norm. The approach here proposed provides a natural framework for extending well-known H_∞ linear control concepts and to take into account robust stability, desensitivity, input-output and internal stability requirements. Moreover, it further justifies classical techniques such as gain scheduling and extended linearization. Finally an algebraic type condition ensuring incremental stability of a nonlinear system is given