Single-Trial Classification of Different Movements on One Arm Based on ERD/ERS and Corticomuscular Coherence

Zhichuan Tang,Chunfu Lu,Pengcheng Liu,Xuexue Jin,Hongnian Yu

doi:10.1109/access.2019.2940034

Abstract

Electroencephalography (EEG)-based brain-machine interface (BMI) is widely applied to control external devices like a wheel chair or a robotic arm, to restore motor function. EEG is useful to distinguish between left arm and right arm movements, however, it is difficult to classify the different movements on one arm. In this paper, a two-step single-trial classification method is proposed to recognize three movements (make a fist, hand extension and elbow flexion) of left and right arms: (1) distinguish between left arm and right arm movements by decoding event-related (de) synchronization (ERD/ERS) and (2) recognize the specific movement of this arm using corticomuscular coherence as features. Four healthy subjects are employed in a cue-based motor execution (ME) experiment. In Step one, ERD and post-movement ERS are found over the contralateral sensorimotor area; in Step two, for each movement, only the beta-band coherence between C3/C4 and the corresponding agonistic muscle is significant. The classification results show the best accuracy of Step one and Step two is 88.10% and 93.33%, respectively. This proposed method achieves a total accuracy of 82.22%. This study demonstrates that our method is effective to classify different movements on one arm, and provides the theoretic basis and technical support for the practical development of BMI-based motor restoration applications.

Highlights

As a direct means of communication combining human brain with the external devices, the electroencephalography (EEG)-based brain-machine interface (BMI) can be considered as being the main way of communication for people affected by motor disabilities [1]–[3]
FEATURE EXTRACTION AND CLASSIFICATION In this paper, we proposed a two-step single-trial classification method to classify different movements on one arm: (1) distinguish between left and right arm movements by decoding ERD/ERS and (2) recognize the specific movement of this arm using EEG-EMG coherence as features
EEG is useful to distinguish between left arm and right arm movements, it is difficult to classify the different movements on one arm

Summary

Introduction

As a direct means of communication combining human brain with the external devices, the electroencephalography (EEG)-based brain-machine interface (BMI) can be considered as being the main way of communication for people affected by motor disabilities [1]–[3]. When we collect the EEG signals through surface electrodes placed on the scalp, the noise levels are increased because of multiple artefacts (motion of electrodes and cables, gel drying, electrode polarization, etc.). To this problem, lots of previous studies have focused on looking for reliable features and pattern recognition algorithms to improve the classification accuracy of EEG signals [13], [14]. Pfurtscheller et al [18] found the ERD/ERS features in alpha frequency bands (9-14 Hz) and beta frequency bands

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