Pneumatic AFO Powered by a Miniature Custom Compressor for Drop Foot Correction

Area of Science:

• Biomedical Engineering
• Rehabilitation Technology
• Biomechanics

Background:

• Pneumatic active ankle-foot orthoses (AFOs) offer advantages in back-drivability and system simplicity.
• Existing pneumatic AFOs are limited by the need for large, stationary air compressors, hindering practical daily use.

Purpose of the Study:

• To develop and evaluate a wearable, custom-designed pneumatic compressor for powering an active AFO.
• To assess the system's effectiveness in providing dorsiflexion assistance for drop-foot patients.

Main Methods:

• A wearable custom pneumatic compressor was designed and optimized for size and weight, with compression rate matched to AFO consumption.
• The system was tested on five hemiplegic drop-foot patients, measuring assistive torque and ankle kinematics.
• The compressor was designed to generate up to 1050 kPa of pressurized air.

Main Results:

• The finalized system delivered a maximum assistive torque of 9.8 Nm at 1 Hz, with minimal average resistive torque (0.03 Nm).
• Patients experienced an average improvement of 12.3° in peak ankle dorsiflexion during the mid to late swing phase.
• The wearable compressor successfully powered the unilateral active AFO.

Conclusions:

• A wearable pneumatic compressor system can effectively power active AFOs, enhancing mobility for drop-foot patients.
• This innovation overcomes the tethering limitations of conventional pneumatic systems, enabling greater practical application.
• The developed system demonstrates significant potential for improving gait in individuals with hemiplegic drop-foot.