Design and performance analysis of continuum manipulator with twisting rotation

The continuum manipulator exhibits excellent flexibility, enabling it to navigate through unstructured and narrow spaces. However, the current motion capabilities of the continuum arm are limited to expansion, bending, or their combination, which restricts its application range and potential uses. Designing a continuum manipulator capable of twisting motion around its axis poses a significant challenge. In this study, we propose a torsion module for the continuum manipulator that enables twisting motions. This module comprises a central trunk made of a torsion spring and a driving mechanism consisting of two tendons arranged in cylindrical helix symmetry. By stretching these driving cables, the module can achieve twisting motion. We describe the principle behind torsional motion, establish a kinematic model for the continuum torsional module, and analyze how structural parameters affect its performance in terms of twisting motion. Furthermore, we construct a continuum arm incorporating this torsion module to enable both twisting and bending motions. We present examples showcasing the versatile capabilities of this continuum manipulator in various specialized scenarios. Experimental results demonstrate that the addition of torsional functionality enhances dexterity and expands design possibilities for continuum manipulators.