Design of a fuzzy gain scheduler using sliding mode control principles

Fuzzy gain schedulers are designed on the basis of a conventional modeling of the nonlinear controlled system and the division of the state space into a finite number of fuzzy regions. Linearization of the nonlinear system at the center of each fuzzy region leads to the design of a set of linear con trol laws that locally stabilize the linearized system, and consequently th e original nonlinear system at the corresponding operating point. Gain sche duling control of the original nonlinear system can be therefore realized a long an a priori unknown, but slowly time varying desired trajectory. In th is paper we analyze the stability and robustness of the gain-scheduled clos ed-loop system by adopting ideas from sliding mode control. It is shown tha t gain scheduling control of the original nonlinear system can be realized along an a priori unknown, but slowly time-varying desired trajectory. It i s shown how the advantages of the sliding mode types of analysis of a fuzzy gain scheduler can also be used for its design. (C) 2001 Elsevier Science B.V. All rights reserved.