Active-Bending Six-Bar Tensegrity Modular Robot Driven by Thin Artificial Muscles

Significant progress has been achieved in the development of tensegrity robots with rolling capabilities. However, because rolling robots operate passively due to gravity, they are limited to certain environments. So, our aim is to enhance the versatility of tensegrity robots by modularizing a six-bar tensegrity structure, enabling the robot to operate in more diverse environments. Thus far, we have developed an active and large stretch module and a torsion module with six-bar tensegrity. In this study, we present the design and development of an active and large-bend module for a six-bar tensegrity robot using thin McKibben muscles. Similar to the stretch module developed previously, we employed the 4/3 muscle winding method to create the bend module. This approach enabled approximately 45 deg bending in six different directions. The arrangement of artificial muscles within the bend module is identical to that in the stretch module, allowing not only bending but also stretching and contracting. Further, we successfully constructed a tensegrity arm with bending functionality to demonstrate the capabilities of the bend module. We also conducted a pick-and-place demonstration using the arm to demonstrate the potential application of the bend module.