Agonist-antagonist active knee prosthesis: a preliminary study in level-ground walking.

Area of Science:

• Biomedical Engineering
• Robotics
• Biomechanics

Background:

• Developing advanced prosthetic limbs is crucial for restoring mobility in amputees.
• Existing prostheses often lack the nuanced control and efficiency of biological limbs.
• Series-elastic actuators offer potential for compliant and efficient robotic systems.

Purpose of the Study:

• To design and evaluate a powered knee prosthesis with a variable-impedance control system.
• To emulate humanlike knee mechanics during level-ground walking.
• To assess the energy efficiency of the novel prosthetic knee design.

Main Methods:

• Developed a prosthetic knee model incorporating a variable damper and series-elastic clutches.
• Utilized human gait data and an optimization scheme to define model parameters.
• Implemented a variable-impedance control strategy for the prosthesis.
• Compared prosthetic knee mechanics with non-amputee gait data.

Main Results:

• The prosthetic knee exhibited qualitative agreement with human knee mechanics during walking.
• The optimized design achieved humanlike joint movement patterns.
• The prosthesis demonstrated a low electrical power requirement of 8 W during level-ground walking.
• This low power consumption allows for smaller onboard batteries.

Conclusions:

• A variable-impedance control design can achieve humanlike knee mechanics in a powered prosthesis.
• The developed knee prosthesis is energy-efficient for level-ground walking.
• The findings support the potential for practical, lower-profile powered prosthetic knees.