Figure 8.

Average combined quality measure 〈Q〉 for different values of κ in the ϵ-η-parameter space of the Hopf oscillator with AFDC mechanism. For every parameter triple of coupling strength ϵ, frequency learning rate η and correlation learning rate κ, the average adaption quality measure 〈Q〉 over the logarithmically sampled space of initial intrinsic frequencies f₀ and frequencies of the external signal f_ext is shown (0.1 < f₀, f_ext < 10). In each case, the external signal is a sine-wave with unit amplitude. The red circles indicate the four cases shown in Figure 7. Comparing these results to the ones obtained for the standard AFO in Figure 5, the AFDC mechanism provides significant higher quality values indicating versatility with respect to different initial intrinsic and external target frequencies.