Experiments on synchronization and control of chaos on coupled electrochemical oscillators

Experiments were carried out on synchronization and control of complex chaotic dynamics observed during the dissolution of two and four coupled nickel electrodes in sulfuric acid under potentiostatic conditions. In a given potential range the individually measured currents exhibit asynchronous chaotic oscillations. The complexity (as measured by the correlation dimension) of the chaotic oscillations depends on the extent of coupling among the electrodes. Thus, the effectiveness of a combined synchronization-delayed-feedback procedure can be tested on systems with increasing complexity. We show that the asynchronous chaotic oscillations can be converted to synchronized and simple, periodic current oscillations by a two-step procedure. The chaotic current oscillations of coupled electrodes are first synchronized by perturbations of external resistors that are connected individually to each electrode. Then, the desired periodic orbit is stabilized by perturbations of the potential. We also observed that certain nonvanishing perturbations could lead to only partially synchronized, so-called "clustered" chaotic states.