Nonlinear adaptive control based on fuzzy sliding mode technique and fuzzy-based compensator

- The solutions for relieving the negative impact of the time-varying rate of UAD on the control effectiveness, avoiding the singular cases, and reducing the calculating cost.
- The design of the FSMC for the nonlinear systems without external disturbance.
- The design of the DO and the coordinating the FSMC and DO in the form of CO-FSMC for the nonlinear systems subjected to disturbance.
- The real application of the CO-FSMC to the semi-active MRD train-car suspension.

It is difficult to efficiently control nonlinear systems in the presence of uncertainty and disturbance (UAD). One of the main reasons derives from the negative impact of the unknown features of UAD as well as the response delay of the control system on the accuracy rate in the real time of the control signal. In order to deal with this, we propose a new controller named CO-FSMC for a class of nonlinear control systems subjected to UAD, which is constituted of a fuzzy sliding mode controller (FSMC) and a fuzzy-based compensator (CO). Firstly, the FSMC and CO are designed independently, and then an adaptive fuzzy structure is discovered to combine them. Solutions for avoiding the singular cases of the fuzzy-based function approximation and reducing the calculating cost are proposed. Based on the solutions, fuzzy sliding mode technique, lumped disturbance observer and Lyapunov stability analysis, a closed-loop adaptive control law is formulated. Simulations along with a real application based on a semi-active train-car suspension are performed to fully evaluate the method. The obtained results reflected that vibration of the chassis mass is insensitive to UAD. Compared with the other fuzzy sliding mode control strategies, the CO-FSMC can provide the best control ability to reduce unwanted vibrations.

The disturbance observer DO and the B-Controller are designed independently based on any the well-known methods. They are then combined with each other in the form of the CO-FSMC via a mechanism depicted by function Uc(x,t)120