Design and Modeling of a Cable-Driven Hollow Continuum Manipulator

Continuum manipulators (CMs) have redundancy and flexibility and show good adaptability in unstructured environments. Traditional CMs mostly utilize a backbone to provide structural support and produce bending, which limits the internal space. In this paper, an internally hollow CM is designed. The orthogonal segment ensures two bending degrees of freedom in a single module. In this design, each module contains four cables that can be divided into two pairs driven by two motors respectively, forming a closed-loop cable drive mechanism. For each pair of cables, they have different length change when the module bends. Thus, the actuation space of the manipulator is further mapped to the “motor space” to form the complete kinematic model. As the multi-moduled body has motion coupling, kinematic decoupling is achieved through using Bowden tube. Simulated and experimental results show that the CM designed in our work has high structural load capacity and flexible motion ability.