EMG-based demodulation of pathological tremor using the Iterated Hilbert Transform

This paper presents an approach for the estimation of the characteristics of pathological tremor from the surface EMG signal based on the Iterated Hilbert Transform (IHT). The method was tested on signals generated by a recent model for tremor generation as well as experimentally recorded from patients affected by pathological tremor. The results showed the ability of the proposed approach to demodulate effectively the tremor amplitude (average correlation with imposed amplitude: R² = 0.52), the frequency (root mean square error in frequency estimation: 2.6 Hz), and phase, as well as, the degree of voluntary activity (correlation with simulated inertial load: R² = 0.62). The application of the method to the experimental data indicated that the estimated tremor-component closely resembles inertial measurements of limb movement (peak cross-correlation across 4 patients: 0.62±0.15). The method can be used as part of a control system in strategies for suppression of tremor.