Novel Design of a Cable-Driven Continuum Robot With Multiple Motion Patterns

Cable-driven continuum robots exhibit accessing and manipulation capabilities in constrained and cluttered environments that are unachievable for traditional robots composing of discrete links and joints. However, the existing continuum robots structured by non-scalable backbones are monofunctional, merely capable of providing bending degree of freedom, not allowing regional elongation that is necessary for dexterous manipulation. In this paper, we present a particular tensegrity topology for the continuum robotic design with an additional stretching degree of freedom, by which the robot can achieve high flexibility in both bending and contraction motion patterns for more configurable operations. To quantify kinematics of the robot under various motion patterns, we build a mechanical model following a positional formulation finite element method. Guided by the theoretical results, a triple-segmented continuum robot is designed and fabricated. To reduce the control complexity, we regulate the individual stiffness of each segment, by which the motion coupling among the segments can be eliminated. Moreover, we also demonstrate the potential applications of this robotic design in tasks of traveling through holes and avoiding obstacles.