Figure 7From: Brain-Computer Interface Controlled Functional Electrical Stimulation System for Ankle MovementOnline EEG classification illustrated on training data. (A) A goniometer trace delineating idling and dorsifiexion states. (B) The corresponding EEG signal trace recorded at the Cz electrode. (C),(D) One-dimensional spatio-spectral EEG features extracted using Eq. (1) shown in the subspaces corresponding idling ( I ) and dorsifiexion ( D ) states, respectively. The pink and green bands represent the mean ± 2 standard deviations (SD) of features corresponding to idling and dorsifiexion training data, respectively. (E) The average posterior probability of dorsifiexion given feature, f⋆. Dashed lines correspond to the thresholds, T1 (green) and T2 (red) as determined in the Calibration section. As outlined in Fig. 4, when the average posterior probability P ̄ ( D | f ⋆ ) > T 1 , the BCI-FES system transitions to dorsifiexion state (shown as green block). Conversely, when P ̄ ( D | f ⋆ ) < T 2 , the BCI-FES system transitions to idling state (pink block).Back to article page