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The virtual energy regulator (VER) enables natural, coordinated locomotion in lower-limb exoskeletons, reducing muscle effort by up to 17.7% compared to passive walking. This technology improves gait naturalness and preserves user engagement in control.

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Area of Science:

  • Robotics
  • Biomechanics
  • Rehabilitation Engineering

Background:

  • Lower-limb exoskeletons show promise for gait rehabilitation but struggle with human-exoskeleton coordination.
  • Coordination issues, or mismatches in intended vs. desired trajectories, reduce gait performance, especially for users with residual motor ability.

Purpose of the Study:

  • To investigate the virtual energy regulator (VER)'s effectiveness in generating coordinated locomotion with lower-limb exoskeletons.
  • To assess gait coordination, naturalness, and muscle effort reduction using VER compared to passive and natural walking.

Main Methods:

  • Experimented VER on nine healthy individuals across various speeds (0.6-0.85 m/s).
  • Compared VER-assisted gait with natural and passive (zero-torque) walking using muscle activity, kinematic, spatiotemporal, and kinetic measures.
  • Presented VER convergence proof and a metric for user contribution to gait.
  • Compared VER with a phase-based path controller for muscle effort and joint kinematics.

Main Results:

  • VER demonstrated natural, coordinated locomotion with 13.1%-17.7% average muscle effort reduction compared to passive walking.
  • VER improved natural gait indicators versus zero-torque walking, enhancing knee extension by 3.9-4.1 degrees.
  • VER achieved 13.9%-15.1% muscle effort reduction compared to the phase-based path controller.
  • A novel metric showed resultant locomotion is a linear combination of user and VER limit cycles.

Conclusions:

  • The virtual energy regulator (VER) effectively promotes natural and coordinated locomotion in lower-limb exoskeletons.
  • VER reduces user muscle effort and enhances gait kinematics, preserving natural variability and user engagement.
  • Findings offer insights into the central nervous system's control of locomotion and VER's potential in rehabilitation.