Disturbance observer-based fuzzy adaptive switched tuning control of uncertain nonlinear systems with full state constraints

This article examines the issue of disturbance observer-based fuzzy adaptive switched tuning output feedback control for a family of uncertain nonlinear systems subjected to full state constraints. By introducing monotonically bounded positive time-varying gain functions (TVGFs), a set of improved intermediate-variable-based disturbance observers (IVBDOs) is devised. Applying the convex combination technique and the LMI toolbox, the solution of the observation gain matrix is realized. Combining the switched tuning control function and the composite integral barrier Lyapunov method, a new switching nature controller is constructed. Particularly, the developed framework overcomes the conservatism of conventional constraints. Through theoretical analysis, it is exhibited that for any given initial value of the system, all states of the system are enclosed within predetermined compact sets while all signals are bounded. Lastly, simulation and experimental results under unknown disturbances attest the validity and superiority of the suggested strategy.