title: A dynamical model improves reconstruction of handwriting from multichannel electromyographic recordings.
abstract: In recent years, several assistive devices have been proposed to reconstruct arm and hand movements from electromyographic (EMG) activity. Although simple to implement and potentially useful to augment many functions, such myoelectric devices still need improvement before they become practical. Here we considered the problem of reconstruction of handwriting from multichannel EMG activity. Previously, linear regression methods (e.g., the Wiener filter) have been utilized for this purpose with some success. To improve reconstruction accuracy, we implemented the Kalman filter, which allows to fuse two information sources: the physical characteristics of handwriting and the activity of the leading hand muscles, registered by the EMG. Applying the Kalman filter, we were able to convert eight channels of EMG activity recorded from the forearm and the hand muscles into smooth reconstructions of handwritten traces. The filter operates in a causal manner and acts as a true predictor utilizing the EMGs from the past only, which makes the approach suitable for real-time operations. Our algorithm is appropriate for clinical neuroprosthetic applications and computer peripherals. Moreover, it is applicable to a broader class of tasks where predictive myoelectric control is needed.
authors.affiliation: Centre for Cognition and Decision Making, National Research University Higher School of Economics Moscow, Russia.
authors.forename: Elizaveta
authors.initials: E
authors.lastname: Okorokova
authors.affiliation: Department of Neurobiology, Duke University Durham, NC, USA.
authors.forename: Mikhail
authors.initials: M
authors.lastname: Lebedev
authors.affiliation: Department of Biomedical Engineering, Norconnect Inc. Ogdensburg, NY, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Linderman
authors.affiliation: Centre for Cognition and Decision Making, National Research University Higher School of Economics Moscow, Russia ; Laboratory of Control of Complex Systems, Institute of Problems of Mechanical Engineering, Russian Academy of Sciences St. Petersburg, Russia.
authors.forename: Alex
authors.initials: A
authors.lastname: Ossadtchi
keywords: dynamical modeling; electromyography; handwriting; pattern recognition; the Kalman Filter; the Wiener Filter