Disturbance observer based adaptive fuzzy synchronization controller design for uncertain fractional-order chaotic systems

Abstract

This study premeditated the synchronization of two fractional-order chaotic systems (FOCSs) with uncertainties and external disturbances. We utilized fuzzy logic systems (FLSs) to estimate unknown nonlinearities, and implemented disturbance observers to estimate unknown bounded external disturbances. Then, a robust control term was devised to compensate for the unavoidable approximation error of the fuzzy system. In addition, a sliding mode surface was devised to construct an adaptive fuzzy sliding mode controller (AFSMC) that can guarantee that the synchronization error converges to a small neighborhood of zero. Finally, the validity of the proposed control strategy was verified via a numerical simulation.

Fixed-time synchronization of fractional-order chameleon hyperchaotic systems based on hyperbolic sliding mode

“…In 1992, A synchronous study of two different chaotic systems with the same initial values was carried out by Pecora and Carroll [5]. Later, there has been increasing researches on chaotic synchronization, and many methods have emerged, such as fuzzy [6], sliding mode [7] [8], adaptive [9] and projection methods [10].In fact, chaotic systems often contain parameter uncertainties and external disturbances, and researchers have become very interested in how to get the state trajectories of two chaotic systems to synchronize in finite or fixed time [11]. The terminal sliding mode control is not only simple to operate, but also has finite-time convergence and robustness to external disturbances, and is widely used to study finite and fixed time synchronization [12][13][14][15].…”