Development of a coordinated controller for robot-assisted shape memory alloy actuated needle for prostate brachytherapy

This paper deals with the development of a coordinated control system for a robot and robot-driven shape memory alloy (SMA) actuated needle to follow a curvilinear path for percutaneous intervention. The robot driving the needle is considered as the outer loop and the non-linear SMA actuated flexible needle system forms the inner loop. The two feedback control loops are coordinated in such a way that the robot drives the needle considering the needle´s actual deflection so that the needle tip reaches the target location with an acceptable accuracy. Simulation results are presented to verify the efficacy of the controller for tracking the overall desired trajectory which includes the combined trajectory of the robot and the needle.