An Origami-Inspired Pneumatic Continuum Module with Active Variable Stiffness

This paper presents a novel pneumatic continuum module featuring high contraction-ratio, bidirectional actuation, and active stiffness regulation. The module comprises four linear pneumatic actuators integrating rigid polygon origami frame into soft bellow. This integration not only helps to regulate motion but also enhances structural strength, facilitating contraction and bending performance. The contraction resulting from vacuum pressure serves as a limiting layer for one opposing pair of actuators, while the other pair operates in a virtual antagonistic configuration, allowing for active regulation of joint stiffness through pressure control. The paper provides a detailed workflow covering the design, fabrication, and mathematical modeling of the pneumatic module. Furthermore, the paper presents verifications of the module’s actuation capacity and active variable stiffness. The findings of this study can serve as valuable references for the design of manipulators.