Steady-state performance optimisation for nonlinear control systems of Lur'e type

In this paper, we develop a methodology for the steady-state performance optimization, in terms of the sensitivity to disturbances, for Lur’e type nonlinear control systems. For linear systems, steady-state performance is well defined and related to frequency-domain characteristics. The definition and analysis of steady-state performance of nonlinear systems are, however, far from trivial. For a practically relevant class of nonlinear systems and disturbances, this paper provides a computationally efficient method for the computation of the steady-state responses and, therewith, for the efficient performance assessment of the nonlinear system. Based on these analysis tools, a strategy for performance optimization is proposed, which can be employed for the optimized tuning of system and controller parameters. The results are illustrated by application to a variable gain controlled short-stroke wafer stage of a wafer scanner.