Single twistable tendon-driven continuum robots

Abstract

Abstract Tendon-driven continuum robots with spatial manipulability face fundamental challenges in miniaturization, stemming from the space required to accommodate multiple actuation tendons. Conventional multi-tendon designs create an inherent trade-off between miniaturization, 3D manipulability, and force output. Here, we introduce a class of continuum robots that achieves controllable body twist and full omnidirectional motion driven by pushing, pulling, and twisting a single tendon, breaking this long-standing design constraint. The resulting robot features an outer diameter of 2.0-3.5 mm and a circumferential hollow ratio exceeding 57%, nearly doubling spatial utilization efficiency over multi-tendon designs. Compared to conventional mechanisms, manipulability improves by over 1000-fold while retaining at least 70% of tip force across all directions. We derive the kinematics for this robot class and provide an open-source simulator. We demonstrate capabilities in teleoperation, navigation in tortuous environments, chopstick-like continuum grippers for in-gripper manipulation, and potential medical applications. Our design redefines actuation paradigms for tendon-driven continuum robots.