Motor Imagery Classification Based on EEG Sensing with Visual and Vibrotactile Guidance

Abstract

Motor imagery (MI) is a technique of imagining the performance of a motor task without actually using the muscles. When employed in a brain-computer interface (BCI) supported by electroencephalographic (EEG) sensors, it can be used as a successful method of human-computer interaction. In this paper, the performance of six different classifiers, namely linear discriminant analysis (LDA), support vector machine (SVM), random forest (RF), and three classifiers from the family of convolutional neural networks (CNN), is evaluated using EEG MI datasets. The study investigates the effectiveness of these classifiers on MI, guided by a static visual cue, dynamic visual guidance, and a combination of dynamic visual and vibrotactile (somatosensory) guidance. The effect of filtering passband during data preprocessing was also investigated. The results show that the ResNet-based CNN significantly outperforms the competing classifiers on both vibrotactile and visually guided data when detecting different directions of MI. Preprocessing the data using low-frequency signal features proves to be a better solution to achieve higher classification accuracy. It has also been shown that vibrotactile guidance has a significant impact on classification accuracy, with the associated improvement particularly evident for architecturally simpler classifiers. These findings have important implications for the development of EEG-based BCIs, as they provide valuable insight into the suitability of different classifiers for different contexts of use.

Keywords: BCI; EEG; machine learning; motor imagery; somatosensory guidance.

Figure 4

Descriptive statistics on classification accuracy for the KGU dataset.

Figure 1

International 10/20 EEG system cap montage [38].

Figure 2

Paradigm of the experiment trial of ULM dataset [39].

Figure 3

Paradigm of the experiment trial of the KGU dataset [38]. The top row of the image (shaded in green and blue) depicts the position and activation of the tactors that delivered vibrotactile input (guidance) in congruence with the visual input (depicted in the middle row of the image). Timings are shown in the bottom row of the image.