Fuzzy Moving Sliding Surface Approach to the Hierarchical Sliding Mode Control

This paper proposes fuzzy moving sliding surface (FMSS) approach to the hierarchical sliding mode control (HSMC) for a class of second-order under-actuated systems. The HSMC design is based on using separate first-level sliding surfaces for two subsystems that are combined in the second-level comprising a unique control input for both subsystems and therefore, it necessitates several design parameters to be obtained after a time-consuming trial-and-error procedure. In this study, we propose both the sliding surface coefficients and the coupling ratio between the sliding surfaces, which are used by the HSMC method, to be obtained by fuzzy logic control (FLC) method using FMSS approach. Computer simulation studies have shown that the proposed control approaches are able to determine necessary coefficients dynamically.