A new observer for nonlinear fractional order systems

In this work an observer structure for a certain class of nonlinear fractional order systems is proposed. For solving this task we introduce a Fractional Algebraic Observability (FAO) property which is used as a main tool in the design of the observer system. We apply our proposals in the master-slave synchronization problem, where the coupling signal is viewed as output and the slave system is regarded as observer (the slave is requested to recover the unknown state trajectories of the master). Finally, as numerical example we consider a fractional order Rössler hyperchaotic system and by means of some simulations we show the effectiveness of the suggested approach.