Patient-driven control of FES-supported standing up: a simulation study

Area of Science:

• Biomedical Engineering
• Neurorehabilitation
• Biomechanics

Background:

• Functional electrical stimulation (FES) is used to aid movement in paraplegic patients.
• Existing control strategies like CHRELMS rely on upper body effort and hand reactions.
• A need exists for FES control strategies that do not require hand reaction estimation.

Purpose of the Study:

• To present and test an alternative FES control strategy for paraplegic standing.
• To compare this new strategy with the CHRELMS approach using a neuromusculoskeletal model.
• To evaluate the effectiveness of both strategies in reducing arm forces and achieving standing movements.

Main Methods:

• Development of a generic two-dimensional (2-D) neuromusculoskeletal model.
• Simulation of FES-supported standing-up movements in paraplegic patients.
• Application and comparison of two closed-loop control strategies: CHRELMS and an alternative without hand reaction estimation.
• Optimization of controller parameters using the model.

Main Results:

• Both tested FES control strategies enabled satisfying standing-up movements in the model.
• Significant reduction in arm forces was observed with both strategies compared to no FES.
• The alternative strategy effectively controlled movements without requiring hand reaction data.
• Model-based optimization avoided extensive trial-and-error experimentation.

Conclusions:

• Closed-loop FES control strategies utilizing upper body effort are effective for paraplegic standing.
• An alternative strategy eliminating the need for hand reaction estimation shows promise.
• Neuromusculoskeletal modeling can optimize FES controllers, reducing experimental burden.
• Further experimental validation is planned to confirm these findings.