Robust stabilization of a class of nonlinear systems via multiple model sliding-mode control.

The robust tracking problem for a family of nonlinear uncertain plants is considered. The solution presented is in terms of a deterministic time-varying compensator and of a supervisor. The compensator is based on sliding-mode control, and may assume a finite number of possible different configurations, at least one of which stabilizes the plant. The task of the supervisor is that of guiding the scanning among the elements of the family, according to a suitably defined experimental test, and of determining the switching instants. The proposed approach noticeably improves the performances of sliding-mode control in the presence of large plant uncertainties, which cannot be easily dealt with in practice. Another appealing feature of the paper consists in the inclusion of an intelligent adaptation scheme in the control algorithm. The idea is that of defining a suitable performance index, and to switch the time-varying controller to the configuration producing the minimum index at each time instant. The convergence of the algorithm has been proved