A Novel Soft Pneumatic Artificial Muscle with High-Contraction Ratio

Area of Science:

• Robotics
• Materials Science
• Mechanical Engineering

Background:

• Soft actuators are crucial for human-friendly robotics but struggle to balance large working distances with high force output.
• Conventional pneumatic artificial muscles, like McKibben muscles, face limitations in achieving both substantial contraction and significant force generation.

Purpose of the Study:

• To introduce a novel high-contraction ratio pneumatic artificial muscle (HCRPAM) capable of substantial contraction and high force generation.
• To present an easy and quick prototyping method for HCRPAMs, considering various design variables.
• To develop and validate a mathematical model for HCRPAM design optimization.

Main Methods:

• Derived a mathematical model for HCRPAM actuation based on the virtual work principle.
• Validated the mathematical model through experimental testing.
• Conducted simulations for design optimization using the validated model.
• Fabricated prototypes using a novel, rapid prototyping method.

Main Results:

• The HCRPAM demonstrated a 183.3% greater contraction ratio compared to conventional pneumatic artificial muscles.
• The HCRPAM achieved a 37.1% higher force output than conventional pneumatic artificial muscles.
• The actuator exhibited compatible position tracking performance (1.0 Hz) and low hysteresis error (4.8%).
• Controllable bending characteristics were discussed, enabled by heterogeneous materials and asymmetrical structure.

Conclusions:

• The HCRPAM offers a significant advancement over conventional soft actuators, providing superior contraction and force for robotic applications.
• The developed prototyping method and mathematical model facilitate efficient design and optimization of HCRPAMs.
• The HCRPAM's characteristics, including controllable bending, make it suitable for human-wearable robotic applications.