A comparison between disturbance observer-based and model-based control of needle in percutaneous applications

In this paper, model-based and disturbance observer (DOB)-based control of needle in precautious applications are compared. In the model-based approach, the force acting on the needle is calculated by evaluating the finite element model (FEM) of the tissue with the tissue deformation. In DOB-based method, the force acting on the needle is considered as an external disturbance and it is estimated using position and velocity of the needle. In both approaches, the calculated/estimated force is used in a sliding mode control scheme to steer the needle to the target. A dynamics equation for the movement of the needle is proposed which includes the force applied by the tissue to the needle. The results are evaluated through simulation and a dynamic finite element model is used to simulate the behavior of the soft tissue. It is shown that the performance of the model-based scheme in presence of the uncertainty in tissue mechanical properties is superior to that of DOB; however it introduces additional system complexity due to the usage of the tissue deformation.