Fabric-Based Soft Ankle Module to Mimic Human Ankle Stiffness



Lower extremity amputation affects approximately 1.3 million people in the United States. In addition to difficulty with daily activities, the loss of a lower limb increases the metabolic rate of the amputee. For this reason, more recent prosthetic devices provide propulsion of the body through the ankle to aid movement. These systems focus on torque and power generation at the ankle joint across different phases of walking. Although required ankle stiffness is achieved, inherent compliance of the ankle is unaccounted for.

Invention Description

Researchers at Arizona State University have developed a soft robotic ankle module that is compliant, lightweight, and capable of generating 50% of the human ankle quasi-stiffness in plantarflexion and dorsiflexion for walking. Kinematics, dynamics, and anatomy of the human ankle joint are analyzed to set functional requirements of the module in order to produce high stiffness along with high compliance. Actuation is achieved through fabric-based inflatable arrays managed by a switching low-level controller. 

Potential Applications

•       Lower limb prosthetics

Benefits and Advantages

•       Fabric-based actuators provide high force-to-weight ratio

•       Module produces both high stiffness and high compliance

Related Publication

Laboratory Homepage of Professor Thomas Sugar

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