Design and Analysis of an Autonomous Active Ankle-Foot Prosthesis with 2-DoF

Area of Science:

• Biomedical Engineering
• Robotics
• Biomechanics

Background:

• Most commercial ankle prostheses offer limited functionality, typically one active degree of freedom (1-DoF).
• Enhancing gait stability and naturalness requires multi-planar ankle motion, including sagittal and frontal plane movements.
• Transtibial amputees can benefit from advanced prosthetic devices that restore natural locomotion.

Purpose of the Study:

• To develop, model, and analyze an autonomous active ankle prosthesis with two degrees of freedom (2-DoF).
• To reproduce physiological movements in the sagittal (dorsiflexion/plantarflexion) and frontal (inversion/eversion) planes.
• To enhance user gait stability and naturalness for improved mobility.

Main Methods:

• Utilized CAD modeling (SolidWorks 2024) for prototype design.
• Performed dynamic modeling and finite element analysis (FEA) to simulate performance and structural integrity.
• Integrated a lightweight mechanical design with a screw drive, stepper motor, and microcontroller-based control system.

Main Results:

• Achieved physiological angular ranges of ±20-22 degrees in both sagittal and frontal planes.
• FEA confirmed structural robustness with maximum stress and deformation within elastic limits (safety factor ~3.3).
• Estimated average power consumption of 7-9 W and operational runtime exceeding 3 hours per charge.

Conclusions:

• The developed 2-DoF autonomous active ankle prosthesis demonstrates potential for precise, energy-efficient, and adaptive motion control.
• The design offers enhanced gait stability and naturalness, suitable for real-world locomotion on uneven surfaces.
• This research advances affordable, functionally autonomous prosthetic solutions for individuals with transtibial amputation.