Composite learning sliding mode synchronization of chaotic fractional-order neural networks

In this work, a sliding mode control (SMC) method and a composite learning SMC (CLSMC) method are proposed to solve the synchronization problem of chaotic fractional-order neural networks (FONNs). A sliding mode surface and an adaptive law are constructed to update parameter estimation. The SMC ensures that the synchronization error asymptotically tends to zero under a strict permanent excitation (PE) condition. To reduce its rigor, online recording data together with instantaneous data is used to define a prediction error about the uncertain parameter. Both synchronization error and prediction error are used to construct a composite learning law. The proposed CLSMC method can ensure that the synchronization error asymptotically approaches zero, and it can accurately estimate the uncertain parameter. The above results obtained in the CLSMC method only requires an interval-excitation (IE) condition which can be easily satisfied. Finally, comparative results reveal the control effects of the two proposed methods.