Sensitivity Analysis of HD-sEMG Amplitude Descriptors Relative to Grid Parameter Variation

Abstract

The aim of this work is to perform a sensitivity analysis of a high density surface electromyogram (HD-sEMG) amplitude descriptors according to several grid parameters. For this purpose, an analytical limb model is used, where the upper limb is modeled as a multilayered cylinder with three layers: muscle, fat tissue and skin tissue. Using this model, HD- sEMG signals are computed over the skin as a 2D surface along angular and longitudinal directions. Electrode recording is performed through a surface integration on the 2D surface according to the electrode shape. 3 simulations with the same anatomy (350 Motor Units) were computed for 3 constant contraction levels: 30%, 50% and 70% of the Maximal Voluntary Contraction (MVC). Then, a global sensitivity analysis using Morris formalism is performed to explore the sensitivity of amplitude descriptors (ARV, RMS and HOS) relative to vary parameters from the electrode grid (inter-electrode distances, electrodes radius, position and rotation). The obtained results clearly exposed a huge impact of the grid rotation on the studied criteria. They also showed that parameters specific to the electrode grid layout (inter-electrode distances) have the less impact.