Switching adaptive controllers to control fractional-order complex systems with unknown structure and input nonlinearities

This article investigates the chaos control problem for the fractional-order chaotic systems containing unknown structure and input nonlinearities. Two types of nonlinearity in the control input are considered. In the first case, a general continuous nonlinearity input is supposed in the controller, and in the second case, the unknown dead-zone input is included. In each case, a proper switching adaptive controller is introduced to stabilize the fractional-order chaotic system in the presence of unknown parameters and uncertainties. The control methods are designed based on the boundedness property of the chaotic system's states, where, in the proposed methods the nonlinear/linear dynamic terms of the fractional-order chaotic systems are assumed to be fully unknown. The analytical results of the mentioned techniques are proved by the stability analysis theorem of fractional-order systems and the adaptive control method. In addition, as an application of the proposed methods, single input adaptive controllers are adopted for control of a class of three-dimensional nonlinear fractional-order chaotic systems. And finally, some numerical examples illustrate the correctness of the analytical results. (c) 2014 Wiley Periodicals, Inc.