Development and Validation of a Closed-Loop Functional Electrical Stimulation-Based Controller for Gait...

Area of Science:

• Biomedical Engineering
• Rehabilitation Science
• Control Systems

Background:

• Functional electrical stimulation (FES) aids lower limb muscle activation for gait rehabilitation.
• Current open-loop FES systems lack feedback, making precise timing of stimulation challenging.
• Accurate FES timing is crucial for effective gait retraining.

Purpose of the Study:

• To develop and validate a closed-loop FES control system for gait rehabilitation.
• To utilize a finite state machine (FSM) model for precise FES timing.
• To compare the effectiveness of closed-loop versus open-loop FES control.

Main Methods:

• Developed a neuromuscular-derived FSM model based on EMG and kinematic data from 12 non-disabled adults.
• Divided gait cycles into four states: swing-to-stance, push off, pre-swing, and toe up.
• Validated the closed-loop FES controller using neuro-musculo-skeletal simulations comparing impaired and healthy gait.

Main Results:

• The closed-loop FES controller resulted in steadier simulated impaired gait compared to an open-loop system.
• Simulation results highlighted the importance of kinematics-informed FES timing for natural gait retraining.
• The developed FSM model effectively guided closed-loop FES activation.

Conclusions:

• A closed-loop FES control solution using an FSM model enhances gait rehabilitation.
• This system offers a simplistic and effective alternative to open-loop FES.
• The proposed controller is suitable for integration with powered exoskeleton technologies.