Design and analysis of hybrid-driven origami continuum robots with extensible and stiffness-tunable sections

Tendon-driven continuum robots have increasingly attracted attention these years. Conventionally, such kind of robots utilizes elastic central backbones to hold the structure, which makes the robots inextensible, as well as reduces the dexterity and the workspace. Inspired by the reconfigurable feature of origami structures, this paper presents the design, analysis, and validation of a hybrid-driven continuum robot without an elastic backbone. The fabric-based, soft, and unstretchable origami pneumatic chamber holds the continuum structure and makes the robot exhibit a high extension ratio, low input pressure, and no radial expansion. With the antagonistic actuation of tendon-pulling and air-pushing, the robot can perform 3DoF motion with variable stiffness. The kinetostatics modeling and analysis are developed based on a discretization-based approach to predict the motion behavior and control the proposed robot. To validate the proposed design principle and the modeling method, a prototype is built, on which a series of experiments have been conducted. The results show that, with the proposed kinetostatics model, the prototype possesses acceptable positioning accuracy and tracking performances, while the structural stiffness can also be effectively adjusted.