A low-power ankle-foot prosthesis for push-off enhancement

Area of Science:

• Biomedical Engineering
• Prosthetics and Orthotics
• Robotics

Background:

• Passive ankle-foot prostheses lack the power generation needed for natural amputee gait.
• Existing robotic prostheses actively manage energy storage and release.
• Restoring net positive power is crucial for gait rehabilitation.

Purpose of the Study:

• To propose an innovative low-power active prosthetic module for off-the-shelf passive energy-storage-and-release (ESAR) prostheses.
• To actively augment energy storage and control energy return for improved push-off.
• To adapt control strategies to user cadence and loading conditions.

Main Methods:

• Developed a low-power active prosthetic module placed parallel to existing ESAR prostheses.
• Utilized parallel elastic actuation to augment stored energy and command energy return.
• Implemented adaptive control strategies for cadence and loading variations.
• Conducted early verification on two transtibial amputees during treadmill walking.

Main Results:

• Increased peak dorsiflexion by 15.2% and 41.6% in two subjects.
• Achieved an approximate 2% increase in walking cadence.
• Observed significant increases in energy return (26% and 45% for the two subjects).

Conclusions:

• The proposed active prosthetic module effectively enhances energy storage and return in passive prostheses.
• The system demonstrates potential for improving amputee gait dynamics and push-off.
• Further research and development could lead to more natural and efficient prosthetic limbs.