Direct adaptive fuzzy decoupled sliding control for a class of under-actuated uncertain systems

Based on the hierarchical sliding mode, a novel direct adaptive fuzzy control design for a class of uncertain under-actuated systems is proposed in the paper. A sliding control law can be derived from the hierarchical sliding mode such that all system states are stabilized at the same time. However, since the system considered is assumed to be uncertain, the sliding control law becomes uncertain too and then cannot be implemented directly. Thus, in our study, a direct adaptive fuzzy control design is proposed to estimate the sliding control law, and a robust control law is further provided to enhance the control performance. Simulations are conducted and the obtained results clearly demonstrate the effectiveness of the proposed approach.