Motor Imaging EEG Signal Recognition of ResNet18 Network Based on Deformable Convolution

Abstract

EEG signals with a weak amplitude, complex background noise, randomness, significant individual differences, and small data volume lead to insufficient feature extraction and low classification accuracy. Spurred by these concerns, this paper proposes a motor imaging EEG signal classification method based on fusing the improved ResNet18 network with the deformable convolutional network (DCN). Specifically, the original signal’s local airspace characteristics are enhanced by the common spatial patterns (CSP), and the time-frequency domain characteristics are displayed using the short-time Fourier transform (STFT). Then, the signal is converted into a time-frequency map, where a deformable convolution is applied to capture the contour characteristics of the time-frequency map. This strategy solves the problems of traditional convolution related to hard rules, i.e., the convolutional kernel shape can only be a square or rectangular core and cannot be dynamically changed according to the recognition target, resulting in a low recognition rate, prohibiting the network from extracting hidden features and affording enhanced identification and classification. Experimental results demonstrate that our method attains an average classification accuracy on a two-classification and two four-classification motor imaging EEG signals of 90.30%, 86.50%, and 88.08%, respectively, which is much higher than current work, proving our method’s effectiveness.