Reactive stepping with functional neuromuscular stimulation in response to forward-directed perturbations

Area of Science:

• Neuroscience
• Biomedical Engineering
• Rehabilitation Technology

Background:

• Implanted motor neuroprostheses enhance mobility for individuals with spinal cord injuries.
• Current systems lack responsiveness to dynamic postural changes.

Purpose of the Study:

• To develop a closed-loop controller for detecting forward body disturbances.
• To initiate a stabilizing step response in individuals with spinal cord injury.

Main Methods:

• Utilized three body-mounted accelerometers to detect forward pulls.
• Implemented a finite state machine to trigger muscle stimulation and a protective step.
• Defined thresholds based on jerk signals to initiate responses.

Main Results:

• The controller successfully initiated steps for perturbations between 10-17.5% body weight.
• Postural responses were observed even at 5% body weight perturbations.
• Reactive steps were faster for stronger perturbations, mimicking able-bodied responses.

Conclusions:

• This research advances controllers for implanted neuroprostheses.
• The developed system improves safety and independence for spinal cord injury patients.
• The controller shows promise for enhancing standing stability and mobility.