Multi-task control strategy exploiting redundancy in RMIS

Intrauterine fetal surgery allows a minimally invasive surgery (FMIS) approach to the treatment of congenital defects. This surgical technique allows the correction of the Twin-to-Twin Transfusion Syndrome (TTTS) [1]. TTTS is a severe complication in monochorionic twins’ pregnancies that occurs when there is communication (anastomoses) between the fetuses’ blood systems, which leads to cardiovascular disturbances and results in their death in 90% of cases. A minimally invasive approach is less harmful and allows the preservation of the tissues of the amniotic sac. Fetoscopic Laser Photocoagulation (FLP) is a MIS intervention to ablate all the intertwin anastomoses to make independent the twins’ vascular systems from each other [2]. A single master single slave teleoperation platform was developed to assist the surgeon during FLP, Fig. 1. The master is composed of a 6DoF haptic device and an interactive user interface containing fetoscopic view, interactive navigation map, etc. The slave is composed of 6DoF robot holding a fetoscope, an active trocar insertion depth control and an automated coagulation laser control system. The platform has been tested by 14 surgeons with different fetoscopic surgical experience, obtaining the face validity. Two main issues have been detected. First, the need of a redundant robot to overcome the kinematic restrictions imposed by the Remote Center of Motion (RCM) and the workspace placement, defined by the placenta position. Second, the need of active humanrobot interaction during pre and post-operative phases (insertion and extraction of the fetoscope) and during surgery to enable a safe shared workspace between medical staff (e.g. auxiliary surgeon with an echographer probe) and robot. Following the generalized framework for control of redundant manipulators in RMIS proposed in [3], this paper proposes a multi-task control strategy exploiting redundancy to improve dexterity and reachability as well as enable human-robot interaction to deal with humanrobot collisions and co-manipulation while performing the surgical task. This work is based on a 7 DoF KUKA LWR 4, a redundant and collaborative robot.