Technical Note An algorithm for detecting the onset of muscle contraction by EMG signal processing

The Generalized Likelihood Ratio (GLR) test is proposed for estimating the time instant of muscle contraction onset via electro- myographic (EMG) signal processing. In contrast to commonly used threshold-based estimation methods, the proposed algorithm proves to be reasonably accurate even for low levels of EMG activity; the improved behaviour of the GLR test comes with just a modest increase in the computational complexity. A set of computer simulation experiments are presented, where the proposed algorithm and two different threshold-based estimators are studied; also, we discuss the results of analysing the EMG recordings of selected proximal muscles of the upper limb in a hemiparetic subject. © 1998 IPEM. Published by Elsevier Science Ltd