Needle dynamics modelling and control in prostate brachytherapy

Although `Needle steering` is considered a challenge in needle insertion strategies, needle control becomes a crucial training tool for evaluating surgeon`s skills in such critical incision. In this study, a model-based dynamics equation for the needle movement through the soft tissue is developed. In the proposed control scheme, the force estimation calculated through the simulated tissue deformation data and the dynamic finite element as the tissue model, is used as the force feedback. To point out the role of mechanical properties of the soft tissue, an inverse dynamics control method is used to demonstrate the system performance in presence of uncertainty in tissue mechanical parameters. Moreover, it is shown that the uncertainty in the tissue mechanical parameters dramatically affects the system performance as well as causing instability. Hence subsequently, a robust control approach is designed to compensate for the undesirable effect of parameter uncertainty in the system.