Design of an optimal step-by-step sliding mode observer for multiple fractional-order chaotic synchronisation with an application to secure communication

The aim of this study is to achieve the best synchronisation in a secure communication scheme by using two fractional-order chaotic systems (FOCS), one for the transmitter and the other for the receiver. This synchronisation is done with the assistance of the step-by-step sliding mode observer (SBS-SMO). To improve the observer's performance, a novel optimisation algorithm called the artificial hummingbird algorithm (AHA) had been used, which leads to selecting the best parameters for the observer instead of selecting them randomly. The proposed scheme succeeded in recovering the secret message that could be (signal, voice, etc.) in the receiver section in a finite period of time.