A lightweight robotic ankle prosthesis with non-backdrivable cam-based transmission

Area of Science:

• Biomedical Engineering
• Rehabilitation Engineering
• Prosthetics and Orthotics

Background:

• Below-knee amputation severely limits ambulation, with current passive prostheses unable to fully replicate natural limb function.
• Powered prostheses offer improved function but are often heavy, increasing socket-residual limb interface stress.
• Existing active prostheses like the Össur© PROPRIO FOOT® have limitations in build height and weight.

Purpose of the Study:

• To develop a compact and lightweight powered ankle-foot prosthesis for transtibial amputees.
• To overcome the limitations of existing active prostheses, specifically build height and weight.
• To improve gait energetics, foot clearance, and user comfort through active foot repositioning.

Main Methods:

• Development of a novel non-backdrivable cam-based transmission for the prosthesis.
• Design and construction of a compact, lightweight ankle-foot prosthesis incorporating the novel transmission.
• Bench-top testing and preliminary experiments with an able-bodied subject to evaluate performance.

Main Results:

• The proposed prosthesis design actively repositions the foot during the swing phase to increase foot clearance.
• The design adapts ankle position to ground inclination during the stance phase.
• Preliminary tests indicate potential for improved gait and user experience.

Conclusions:

• The novel cam-based transmission enables a compact and lightweight powered ankle-foot prosthesis.
• This design addresses key limitations of current active prostheses, offering a promising alternative for transtibial amputees.
• Further research and clinical trials are warranted to validate the benefits for amputee users.