Finite Element Dynamics of a Concentric Tube Robot Motion and Interaction with Environment Using SOFA-framework

Abstract

The concept of continuum and soft robotics has opened new abilities that were previously unachievable by rigid robotics alone, such as squeezing, growing, and morphing to their environments. As an example, Concentric Tube Robots (CTR) are continuum robots made of a series of pre-curved, elastic tubes where each tube can individually be rotated, as well as extended and recalled; interactions between each tube allows for turns and twists, giving control over the length and configuration of the robot. CTRs can assist in minimally invasive surgery (MIS) to access difficult to reach areas, due to the intricate human anatomy, with advantages including single-site entry and their malleable nature [1]. However, utilizing CTRs, and continuum robots in general, are not without their own challenges. Due to the complex nature of a continuum structure, fast and accurate simulations are still in development and require specific skills to operate. These simulations are not usually accurate due to the complex behaviours of the materials used and their deformable nature. SOFA (Simulation Open Framework Architecture) was introduced as an open-source platform to address some of the challenges with real-time physics-based simulation of interaction with deformable tissue in medical applications and later for modelling soft robots. More specifically, a BeamAdapter plugin2 was developed based on interpolation of a continuous geometry over multiple consecutive Timoshenko beam segments to address the simulation challenges of neurovascular interventions using interleaved catheters and guidewires [2]. The BeamAdapter plugin has been also utilized for interactive planning of coil embolization in brain aneurysms [3] and interactive training system for interventional electrocardiology procedures [4]. We have recently developed a Reduced-Order dynamic model for CTRs based on the shape interpolation of the robot backbone and showcased its real-time performance, correct estimation of the path-dependent motions and snapping instances, accurate simulations of stable and post-snapping motions in an experimental comparative study [5]. In this paper, we outline the process and the code on how a CTR model can be implemented into an example scene provided as a part of the SOFA-framework ‘BeamAdapter’ plugin [2].