Thumb Attitude Analysis using High Density Surface EMG: A Preliminary Survey

Cybernetic hand prostheses are usually governed by the features extracted from the surface-electromyography signals (sEMG) measured from the residual muscles of the amputee's limb. The control of multi-articulated thumb as an opposable digit is vital to realize various hand grip attitudes. Current techniques to record the sEMG signal are centered at the thumb musculature, intrinsic to the hand. The other four extrinsic muscles governing the thumb lie on the deep compartment of the forearm posing a challenge to capture their characteristics. For trans-radial amputees, despite the loss of access to the intrinsic muscles controlling the thumb movement, the access to the information from the extrinsic muscle would be non-negotiable. Thus, it is important to study the relationship of muscle synergies that act upon different thumb attitudes from the forearm musculature, directly or indirectly engaged in thumb movement. A systematic study on forearm musculature and the sEMG generated during thumb movement need to be carried out as before develop an advance prosthetic hand. This is due to the fact that these are important contributing factors for the governance of other digits and the wrist as well. A High Density Surface Electromyogram (HD-SEMG) measurement device together with corresponding software can be used to measure HD-EMG signals and generate corresponding colour maps which show regions of muscle activation. The cues from the HD-SEMG signals and colour maps will be used to select the features to be used in classification algorithms. The findings of this study provide information about the dominant regions of muscle activity during thumb movements. This information will be useful for the control of cybernetic prosthetic hands for tansradial amputees.