A REAL-TIME SIMULATION FOR PATH PLANNING IN NEEDLE INSERTION TASKS

In the last two decades it has been proposed to use actuation forces of shape memory alloy wires to develop an active needling tool to facilitate the conventional needle-based procedures. In these procedures it is always desired to guide the needle though an accurate trajectory reaching the target location. In some cases it is also desired to maintain a curved path to avoid obstacles and prevent damage to sensitive organs. Therefore, it is of a great importance to investigate the interactions of needle within tissue and understand the mechanics of the needle insertion procedure. The nonlinear properties of the deforming tissue while needle is inserted make the prediction of the needle tip placement difficult. Previous studies include experimental and analytical investigations based on a particular tissue properties and needle shape. In this work mechanics of a bevel-tipped needle inserted into soft tissue has been investigated via numerical simulation. The nonlinear properties of the tissue have been implemented in the model. This model has been generated in LS-DYNA software using Arbitrary-Eulerian-Lagrangian formulation for the solid-fluid interactions. Total insertion depth of 150mm of a 0.5mm diameter needle has been modeled. The small stiff element sizes of the needle dictate an expensive computational time. In order to have reasonable computational costs many assumptions were made such as decreasing the Young's Modulus of the needle and tissue by the same factor. Needle insertion tests have also been performed to evaluate the accuracy of the simulations. The error of less than 10% was found and therefore validated our simulation approach. Using this model it would be possible to predict the steerability of different configurations of the needle inside the tissue. It can also be used for surgical simulation and training purposes and path planning.