Motion control of the ankle joint with a multiple contact nerve cuff electrode: a simulation study

Area of Science:

• Biomedical Engineering
• Neuroscience
• Rehabilitation Engineering

Background:

• Flat interface nerve electrodes (FINE) offer selective nerve stimulation.
• Developing trajectory tracking control for musculoskeletal systems using FINE remains a challenge.
• Previous work established a control system for multiple-input multiple-output (MIMO) systems.

Purpose of the Study:

• To develop and test a trajectory tracking motion control algorithm for musculoskeletal systems using FINE.
• To create a realistic computational model of the ankle/subtalar joint and sciatic nerve.
• To evaluate the control system's performance in modulating joint angles via FINE stimulation.

Main Methods:

• Developed a computational ankle/subtalar joint model with a finite element model of the sciatic nerve.
• Implemented a control system to modulate pulse amplitude on a FINE.
• Tested the system with various reference trajectories (sinusoidal, filtered random) and simulated disturbances.

Main Results:

• The control strategy achieved small output tracking errors for diverse trajectories.
• The method demonstrated robustness against external disturbances and muscle fatigue.
• Spatial selectivity of multi-contact FINE enabled limb motion control despite limited muscle selectivity.

Conclusions:

• A novel control algorithm successfully utilizes FINE for precise limb motion control.
• The approach shows promise for restoring neural function in paralyzed individuals.
• This technology advances functional electrical stimulation by leveraging advanced nerve electrode capabilities.