1. A method of calibrating a motor imagery detection module, the method comprising, acquiring Electroencephalography (EEG) data from a subject; decomposing the acquired EEG data into a plurality of frequency and time segment components; computing a projection matrix for spatial filtering for each of the plurality of frequency and time segment components; selecting classification features from the plurality of frequency and time segment components for calibrating the motor imagery detection module; wherein the feature selection comprises modelling an idle state ω n of the subject by M sub-classes χ j , j=1,. .. , .