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Published on: July 22, 2014
Nonlinear neuromuscular electrical stimulation tracking control of a human limb
Nitin Sharma1, Keith Stegath, Chris M Gregory
1Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA. robero@ufl.edu
Summary
This study developed a novel neuromuscular electrical stimulation (NMES) controller for precise knee movement. The controller enables leg shank tracking of various trajectories without needing a muscle model, improving functional task achievement.
Area of Science:
- Biomedical Engineering
- Rehabilitation Technology
- Control Systems
Background:
- Neuromuscular electrical stimulation (NMES) aims to restore function through muscle activation.
- Controlling NMES for dynamic tasks like trajectory tracking remains challenging.
- Existing methods often require complex muscle models and are sensitive to disturbances.
Purpose of the Study:
- To develop a model-free NMES controller for accurate human shank trajectory tracking.
- To achieve asymptotic stability in knee position control during non-isometric contractions.
- To enable functional tasks by enabling the leg to follow desired movement paths.
Main Methods:
- A nonlinear control strategy was designed for the quadriceps femoris muscle.
- The controller operates without a specific muscle model.
- Closed-loop experiments were conducted on human subjects to validate performance.
Main Results:
- The NMES controller successfully enabled the human shank to track continuous trajectories.
- The system demonstrated accurate tracking of single and multiple period trajectories with varying ranges of motion.
- The controller showed robustness in tracking desired step changes under different load conditions.
Conclusions:
- A model-free NMES controller can achieve precise knee position control for functional tasks.
- The developed controller offers asymptotic stability and robustness against disturbances like spasticity and fatigue.
- This approach advances NMES applications in rehabilitation and assistive technologies.
