Kevin Luo (MASc): Design of Concentric Tube Manipulators Using Topology Optimization

October 25, 2017 @ 9:30 am – 10:00 am
Rosebrugh Building
Rosebrugh Bldg, Toronto, ON M5S 3G9

Room: RS 211


Recently, there has been intensive research in the use of concentric tube robots for minimally invasive surgery. A concentric tube manipulator consists of one or more pre-curved tubes inserted within another tube that is fixed. Relative rotational and translational motion between the tubes will result in movement of the distal tip of the manipulator. One major issue associated with concentric tube manipulators is the occurrence of the undesirable snapping phenomenon. This research evaluates methods of eliminating the snapping problem by laser cutting topologies, (i.e. grooves/slots) in order to reduce the ratio between bending stiffness and torsional stiffness of the tube (BTSR). The SIMP topology optimization algorithm is used in the generation of the cut topologies. The generated designs are then tested through finite element analysis. The results show
through finite element analysis that reductions in BTSR can indeed be achieved by designing based on topology optimization. Different variables and features can also have great impacts on the optimization outcome. This research could potentially make the choice of concentric tube cutting topologies easier and more systemized in the future, so that the snapping problem can be better avoided. Further work will include testing the tubes in a concentric system and observing the improvements in the system’s stable workspace. This research can make the use of concentric robots in minimally invasive surgery more accurate and precise, thus making them more feasible for clinical use.