Computationally advantageous and stable hierarchical fuzzy systems for active suspension

Abstract

A new type of hierarchical fuzzy system (HFS), namely, hierarchical classifying-type fuzzy system (HCTFS), is developed and proposed in paper. While HCTFS enjoys full benefits of a traditional HFS, one of which is to suppress effects of unwanted phenomenon, the curse of dimensionality, it also offers one great advantage that all rule strengths are preserved when passing through subsystem layers. To demonstrate potential of HCTFS, computational complexity analysis will be conducted on complete rule-base models of a conventional fuzzy system and HCTFS. Furthermore, a methodology of stability analysis is proposed incorporating use of HCTFS, providing reader with another option of hierarchical fuzzy controller design upon stability concerns. To verify and conclude our proposal, a mathematical example and simulations are provided. In our simulated example, HCTFS controller incorporating proposed stability analysis technique are applied to active suspension system. The results obtained from active suspension system are then discussed and compared with results of ideal and passive suspension systems.