Enhancing dexterity: Soft pneumatic actuation utilizing granular jamming for a human finger flexo-extension

Area of Science:

• Robotics
• Biomimetics
• Materials Science

Background:

• Human finger movement involves complex flexo-extension.
• Soft actuators offer advantages in safety and adaptability for human interaction.
• Stiffness modulation is crucial for advanced prosthetic and rehabilitation devices.

Purpose of the Study:

• To design and evaluate a bioinspired pneumatic soft actuator mimicking human finger movement.
• To investigate the effectiveness of granular jamming for stiffness modulation.
• To compare different chamber geometries and jamming materials for optimal performance.

Main Methods:

• Fabrication of a three-chamber pneumatic soft actuator using Mold Star 15 Slow elastomer.
• Evaluation of honeycomb, rectangular, and half-round chamber geometries for curvature.
• Implementation of passive and active granular jamming using chia and quinoa grains.
• Experimental testing of stiffness modulation and force output.

Main Results:

• The honeycomb geometry achieved the closest trajectory to the human index finger.
• Stiffness modulation ranged from 0-0.47 N/mm/° (quinoa) to 0-0.9 N/mm/° (chia).
• Force output increased by 16% (quinoa) and 71% (chia) compared to the non-jammed state.
• Active granular jamming, particularly with chia, demonstrated superior adaptability.

Conclusions:

• The bioinspired soft actuator with granular jamming shows promise for hand rehabilitation.
• Honeycomb geometry and active chia jamming offer optimal performance for adaptive stiffness and force modulation.
• This technology is well-suited for wearable robotic applications in rehabilitation.