Designing Concentric Tube Manipulators for Stability Using Topology Optimization

Ai Xin Jue Luo, Kevin 1, 2; Looi, Thomas 1, 2; Sabetian, Saba 1, 2; Drake, James 1, 2

 1. The Institute of Biomaterials & Biomedical Engineering, University of Toronto; 2. The Centre for Image-Guided Innovation and Therapeutic Intervention, Hospital for Sick Children

One of the major problems facing the development and road to practical usage of concentric tube continuum robots in surgical environments is that of instability. This issue, also known as the snapping problem, is caused by a tube having a high bending to torsional stiffness ratio (BTSR). Past efforts have shown that by cutting patterns on the tubes, this problem can be avoided. This paper seeks to redesign the topology of the tubes so that BTSR is decreased and the snapping problem is resolved in a particular tube set. The generated designs are then tested through finite element analysis as well as experimental testing to demonstrate the elimination of the snapping problem. Using this novel tube design on a concentric tube robotic system can increase its stable workspace because it allows the usage of greater tube curvatures and/or curve lengths.