Inverse real-time Finite Element simulation for robotic control of flexible needle insertion in deformable tissues

International audienceThis paper introduces a new method for automatic robotic needle steering in deformable tissues. The main contribution relies on the use of an inverse Finite Element (FE) simulation to control an articulated robot interacting with deformable structures. In this work we consider a flexible needle, embedded in the end effector of a 6 arm Mitsubishi RV1A robot, and its insertion into a silicone phantom. Given a trajectory on the rest configuration of the silicone phantom, our method provides in real-time the displacements of the articulated robot which guarantee the permanence of the needle within the predefined path, taking into account any undergoing deformation on both the needle and the trajectory itself. A forward simulation combines i) a kinematic model of the robot, ii) FE models of the needle and phantom gel iii) an interaction model allowing the simulation of friction and puncture force. A Newton-type method is then used to provide the displacement of the robot to minimize the distance between the needle's tip and the desired trajectory. We validate our approach with a simulation in which a virtual robot can successfully perform the insertion while both the needle and the trajectory undergo significant deformations

Steering of flexible needles combining kinesthetic and vibratory force feedback

Needle insertion in soft-tissue is a minimally invasive surgical procedure which demands high accuracy. In this respect, robotic systems with autonomous control algorithms have been exploited as the main tool to achieve high accuracy and reliability. However, for reasons of safety and acceptance by the surgical community, autonomous robotic control is not desirable. Thus, it is necessary to focus more on techniques enabling clinicians to directly control the motion of surgical tools. In this work we address that challenge and present a novel teleoperated robotic system able to steer flexible needles. The proposed system tracks the position of the needle using an ultrasound imaging system, and, from that, it computes needle's ideal position and orientation to reach a given target. The master haptic interface then provides mixed kinesthetic-vibratory navigation cues about this ideal position and orientation to the clinician as she steers the needle. Six subjects carried out an experiment of teleoperated needle insertion into a soft-tissue phantom. They showed a mean targeting error of 1.36 mm. An additional experiment of remote teleoperation has been carried out to highlight the passivity-based stability of the proposed system