UDE-Based Non-Fragile Control Design for Interval Type-2 Fuzzy Systems

This paper investigates the tracking control problem for interval-type 2 fuzzy systems that incorporate unknown bounded uncertainty and unknown external disturbances. The control design incorporates the utilization of an uncertainty and disturbance estimator (UDE) to enhance robustness against these factors. Additionally, a non-fragile strategy is employed to effectively handle the impact of gain perturbation. Moreover, interval type-2 fuzzy sets are employed to represent the model uncertainties in the addressed system. The UDE algorithm is utilized based on the assumption that a continuous signal can be approximated and estimated using a filter with the appropriate bandwidth. Subsequently, the tracking control problem of the considered interval type-2 fuzzy system is equivalently transformed into the stability problem of an error system. Furthermore, conditions are derived to guarantee closed-loop system stability and achieve asymptotic disturbance rejection and reference tracking. Finally, simulation results are presented to demonstrate the advantages of the developed theoretical results.