Toward improving path following motion: Hybrid continuum robot design

Continuum manipulators possess the ability to travel on nonlinear paths and avoid obstacles in confined environments. A variety of designs were proposed for several applications, such as minimally invasive surgery or inspections and maintenance in hazardous spaces. While hyperredundant robots can follow a path on the large scale, path following behavior on small the scale is still a challenge. Only a limited number of paths can be followed by small continuum robots due to design constraints such as fixed curvatures or fixed segment lengths. For most applications, continuum robot parameters have to be optimized and selected according to specific task and design constraints. This is time consuming and limits the utilization of the manipulator to specific application scenarios. In this work, we propose a hybrid continuum robot design to overcome these disadvantages and offer a universal tool which is able to follow any constant curvature path. The design is comprised of a telescopic composition of several tendon driven patterned elastic tubes. Each one can be translated and bent independently. With this design we achieve improved path deviation errors (max 0.6 mm) in comparison to previously proposed continuum robots in simulation. We prove the path following behavior on random paths with a two segment prototype robot with overall outer diameter of 6 mm in an experimental setup with average path deviation errors lower than 5 mm.