Neuromechanical force-based control of a powered prosthetic foot

Area of Science:

• Biomechanics
• Robotics
• Neuroprosthetics

Background:

• Developing advanced prosthetic limbs requires sophisticated control systems that mimic natural human movement.
• Existing neuromuscular reflex-based controllers offer functional but can be complex.

Purpose of the Study:

• To introduce and evaluate a novel neuromechanical force-based control strategy, Force Modulated Compliant Ankle (FMCA), for powered prosthetic feet.
• To assess FMCA's ability to provide stable walking and replicate human-like ankle biomechanics.

Main Methods:

• FMCA directly uses vertical ground reaction force as sensory feedback to modulate ankle joint impedance.
• Simulations were performed using a transtibial amputee walking model to compare FMCA with a reflex-based controller.
• Experiments were conducted with a non-amputee subject using a powered prosthetic foot equipped with FMCA.

Main Results:

• FMCA successfully predicted human-like ankle torque across various walking speeds in simulations.
• The FMCA strategy enabled stable walking in the amputee simulation model, offering a sufficient push-off.
• Experimental results demonstrated that FMCA could replicate non-amputee reference ankle torque and angle at preferred walking speed.

Conclusions:

• FMCA presents a simpler, bioinspired alternative to existing controllers for powered prosthetic feet.
• The strategy shows significant potential for enhancing prosthetic limb functionality and user mobility.
• Further research should explore FMCA's adaptability to different walking speeds and its efficacy in the target amputee population.