Adaptive fuzzy moving sliding mode control for a class of perturbed underactuated nonlinear systems

This paper presents an adaptive fuzzy moving sliding mode control for a class of uncertain Multi-Input Multi-Output (MIMO) nonlinear underactuated systems. The proposed control law involves a Proportional Integral control (PI) to reduce the chattering phenomenon caused by the discontinuous term in the classical sliding mode technique. The uncertain system functions are predicted by fuzzy logic systems and free parameters can be updated on-line by adaptive laws based on Lyapunov theory. The moving sliding mode is introduced to enhance the control law robustness in the presence of disturbance and parameter variations, hence the sliding surfaces are moved by changing the magnitude of the slopes by adaptive laws. The stability analysis is verified and the proposed approach is applied to an inverted pendulum and achieves satisfactory results.