Design, modeling, and experimental study of variable stiffness pneumatic bio-inspired soft actuators

Area of Science:

• Soft Robotics
• Bio-inspired Engineering
• Materials Science

Background:

• Octopus tentacles exhibit remarkable dexterity and variable stiffness, inspiring novel robotic designs.
• Existing soft actuators often lack precise stiffness control and robust load-bearing capabilities.

Purpose of the Study:

• To develop a pneumatic soft actuator with variable stiffness inspired by octopus tentacles.
• To enhance load-bearing capacity and manipulation performance in soft robotic systems.
• To provide a theoretical framework for optimizing soft actuator design.

Main Methods:

• Numerical simulations were used to analyze the impact of chamber geometry, wall thickness, and length.
• A deformation analysis model was developed using the Yeoh hyperelastic constitutive model and moment equilibrium.
• A variable stiffness model was formulated using the pseudo-rigid-body model and energy equivalence principles.
• Prototypes were fabricated using rapid prototyping and validated experimentally.

Main Results:

• The actuator demonstrated multi-modal deformation: elongation, bending, and circumferential deflection.
• Experimental validation confirmed the accuracy of the static and variable-stiffness models.
• A 40% increase in stiffness and a 23.59% enhancement in horizontal contact force were achieved.

Conclusions:

• The proposed pneumatic soft actuator effectively achieves variable stiffness and improved performance.
• The study provides valuable insights for designing advanced pneumatic and hydraulic soft robots.
• The bio-inspired approach offers a practical and efficient solution for soft robotics applications.