Extraction of Some Relevant Instants from EMG Signal

摘要

In this paper, an algorithm to estimate key instants in EMG signal during pre-motrice and motrice phases is developed. It detects automatically i) the onset of muscle activity when an explicite recommendation of preparation is dictated (pre-motor onset), ii) the onset of effective muscle contraction (motor onset) and iii) the instant of muscle contraction desactivation (motor offset). The algorithm is based on statistical thresholding and counting the number of samples exceeding the threshlold. The counting is ensured by elaborated temporal scanning in forward and backward directions. The threshold calculus is based on statistics of the EMG signal during muscle activity and muscle rest. The algorithm is illustrated for the superficial flexor muscle during a handgrip exercice and is validated using subjective visual inspection and objective evaluation (error rate). The results revealed that relevant instants in EMG signal are well estimated.