Upper-Limb Muscle Synergy Features in Human-Robot Interaction with Circle-Drawing Movements

Area of Science:

• Neuroscience
• Robotics
• Biomechanics

Background:

• Upper-limb rehabilitation robots offer potential for motor function assessment.
• Circle-drawing tasks are utilized for robot-based motor function measurement.
• Muscle synergies during human-robot interaction (HRI) for upper-limb movements are understudied.

Purpose of the Study:

• Investigate muscle synergies during robot-assisted circle-drawing movements.
• Explore the consistency of muscle synergy features in healthy subjects during HRI.
• Assess the potential of muscle synergy analysis for upper-limb motor function evaluation.

Main Methods:

• Utilized robot-assisted constrained circle-drawing tasks (clockwise and counterclockwise) with healthy subjects.
• Recorded surface electromyographic (sEMG) signals from six upper-limb muscles.
• Applied nonnegative matrix factorization (NMF) to analyze muscle synergy patterns and activation coefficients.

Main Results:

• High structural similarity in muscle synergies was observed among subjects during the circle-drawing task.
• This similarity suggests a shared underlying muscle control mechanism in healthy individuals.
• Synergy patterns and activation coefficients provided spatial and temporal insights into muscle control.

Conclusions:

• Muscle synergy analysis during HRI with constrained circle-drawing is a viable method for assessing upper-limb motor function.
• Findings indicate a common motor control strategy for this specific HRI task in healthy populations.
• This research contributes to understanding motor control and developing advanced rehabilitation tools.