Control of Chaos in Driven Fitzhugh-nagumo Circuit by Means of Filtered Feedback

We report on the feedback control of a periodically driven FitzHugh-Nagumo system displaying various dynamical regimes, regular and chaotic, including chaotic spiking. The feedback term is composed of a high-pass or an all-pass filter. We provide a characterization of the efficiency of the filters in controlling the dynamical state of the system, both experimentally (electronic circuit) and numerically (model equations). We demonstrate the better efficiency of the all-pass filter as we change the coupling strength of the feedback. Moreover, we show that both filters change the appearance of bifurcations, that is the main result of the controlling effect. However, all-pass filter revealed to have a stronger efficiency in the bifurcation control. Finally, we discuss the relation of the feedback method based on filters with the delayed feedback control scheme.