Figure 11

Control performance. (a) Root-mean-square (RMS) of tracking error (RMS e) and the mean and standard deviation of tracking error (mean e), (b) RMS of control u (RMS u) and the mean and standard deviation of u. These indexes are calculated using the last 12 seconds signals. (c) and (d) Power spectral density of different signals for Case 1 and Case 2 respectively. Case 1: the uncontrolled system is in a background state. Case 2: the desired EEG tracing is in normal alpha band. The four different control strategies are 1: feedback, 2: feedback and RBFNN, 3: feedback and SMC, and 4: feedback, RBFNN and SMC.