Can Elastic Instability be Beneficial in Concentric Tube Robots?

Concentric tube manipulators exhibit elastic instability in which tubes snap from one configuration to another, rapidly releasing stored strain energy. While this has long been viewed as a negative phenomenon to be avoided at all costs, in this paper we explore for the first time whether the effect can be harnessed beneficially for certain applications. Specifically, we show that the energy released in an instability can be useful for challenging, high-force surgical tasks such as driving a needle through tissue. We use concentric tube models to define the energy released during elastic instability and experimentally evaluate a two-tube concentric manipulator that can drive suture needles through tissue by harnessing elastic instability beneficially.