Iiirena

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Upper limb control

Commercial solutions exploit superficial EMG signals to control the prosthesis. However, several drawbacks are related to surface electrodes (e.g., movement artifacts, cross-talk error, variable skin conductance). Hence, researchers are investigating alternative solutions that exploit different biological sources:

• implanted electrods (neural, intramuscular and epymisial electrods) to record neural or muscle activity;
• pressure sensor matrices to detect force changes during muscle contraction;
• the myokinetic approach to measure muscle deformation.

Myokinetic control

The myokinetic control represents an alternative to standard myoelectric control. It aims at measuring muscle deformation during contraction instead of muscle electrical activity. A novel approach recently emerged in 2017 which is based on sensing the magnetic field of permanent magnets directly implanted into residual muscles . Localizing the position of the magnet is equivalent to measuring the contraction/elongation of the muscle it is implanted in as the magnet moves with it. This information can be used to interpret the voluntary movement of the subject and consequently control the prosthesis. The magnetic signals generated by the magnets are detected by external sensors placed around the residual limb. Localization is then implemented by an optimization method that performs the tracking by solving the magnetic inverse problem (e.g., Levenberg–Marquardt algorithm).