Design, Development, and Control of a Fabric-Based Soft Ankle Module to Mimic Human Ankle Stiffness

Area of Science:

• Robotics
• Biomechanics
• Materials Science

Background:

• The human ankle joint's complex kinematics, dynamics, and anatomy are crucial for natural walking.
• Existing robotic ankles often lack the compliance and lightweight properties of biological joints.

Purpose of the Study:

• To design and develop a fabric-based, soft ankle module for robotic applications.
• To achieve 50% of human ankle stiffness in both plantarflexion and dorsiflexion for walking.
• To closely replicate the human ankle's stiffness trajectory.

Main Methods:

• Studied human ankle joint biomechanics to define functional requirements.
• Utilized fabric-based inflatable actuator arrays for a compliant and lightweight soft ankle design.
• Developed models for human ankle stiffness and a data-driven model for the soft ankle module.
• Implemented a high-level stiffness controller with a low-level pressure controller.

Main Results:

• The soft ankle module successfully generated 50% of human ankle stiffness.
• The module demonstrated the ability to closely follow the target ankle stiffness trajectory.
• The design is compliant and lightweight, suitable for mimicking natural ankle function.

Conclusions:

• The developed fabric-based soft ankle module effectively replicates key aspects of human ankle stiffness.
• This advancement holds potential for more natural and efficient robotic locomotion.
• The integrated control system enables precise stiffness modulation.