Preliminary study of utilizing plastic tubes as a component of continuum robots

Continuum robots, new class of dexterous and thin robots, can be applied in great variety of minimal invasive surgical operations. These robots consist of two parts: manipulator, also called active cannula, and control unit. Manipulators, which are composed of concentric precurved tubes(usually 2-3), commonly made from nitinol, can enter human body through small incisions or natural orifices and, after reconfiguration into more complex structure, guide surgical instruments to the target regions avoiding obstacles. In this paper, we propose to use plastic as the material for innermost tube. Variations in the shape of lab-made concentric precurved plastic tube prototypes after numerous extension-retractions are investigated. We also use kinematic model, based on beam mechanics, for capturing the end-effector tip position and the shape of the two manipulators (I - manipulator is composed of one nitinol tube and one plastic tube prototype; II - manipulator is composed of two nitinol tubes and one plastic tube prototype). The model predictions are compared with the experimental results. Preliminary results show that plastic tubes may have small radii of precurvature, and sustain extension-retraction without self-damage thus potentially can be used as a component of continuum robots.