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Three-Dimensional Printable Ball Joints with Variable Stiffness for Robotic Applications Based on Soft Pneumatic
Jin Guo1, Jin-Huat Low2, Jun Liu3
1School of Life Science, Beijing Institute of Technology, Beijing 100081, China.
Polymers
|September 9, 2022
Summary
This study introduces a novel 3D-printable robotic ball joint with controllable stiffness using pneumatic actuation. This design allows for adjustable stiffness in robotic systems, enhancing their adaptability and performance.
Area of Science:
- Robotics and Mechanical Engineering
- Materials Science and Engineering
- Actuation and Control Systems
Background:
- Traditional robotic joints often lack variable stiffness, limiting adaptability in dynamic environments.
- The integration of soft pneumatic actuators offers a promising avenue for achieving tunable mechanical properties in robotic components.
- 3D printing technologies enable the fabrication of complex, integrated mechanisms with tailored material properties.
Purpose of the Study:
- To design and develop a novel three-dimensional printable robotic ball joint with controllable stiffness.
- To investigate the modulation of joint stiffness through pneumatic actuation and friction-based braking.
- To demonstrate the feasibility of creating variable stiffness robotic structures by assembling multiple joints.
Main Methods:
- Fabrication of the ball joint using polyamide-12 (PA12) via selective laser sintering (SLS) technology.
- Integration of a soft pneumatic elastomer actuator and a friction-based support platform for stiffness control.
- Finite element analysis (FEA) for optimizing the support platform design and experimental stiffness testing.
Main Results:
- The developed ball joint exhibits 'zero' stiffness in its natural state, allowing free rotation and twisting.
- Pneumatic actuation enables rapid stiffening, locking the joint's position and orientation.
- Significant stiffness enhancement achieved, reaching up to 508.11 N·mm (rotational) and 571.93 N·mm (twisting) at 400 kPa.
- Demonstrated MRI compatibility and potential for miniaturization due to SLS fabrication.
Conclusions:
- The proposed 3D-printable variable stiffness ball joint offers a novel solution for adaptable robotic linkages.
- The pneumatic actuation effectively controls stiffness, enabling a transition from free movement to locked states.
- The design's modularity allows for the construction of complex variable stiffness robotic structures with independent control.
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