Design and Shared Control of a Flexible Endoscope with Autonomous Distal Tip Alignment

Open womb surgery for prenatal therapy is an extreme option which may induce severe side effects on both the fetus and the mother. Minimal invasive surgery (MIS) is, in general, less strenuous than open surgery. Unfortunately, the current tools and techniques are not optimized for the unique environment of the womb. Used in prenatal MIS, the physician visually assesses the in-utero environment, the fetus and the placenta. This work deals with the use of fetoscopic instruments in photocoagulation therapy using lasers for Twin-to-Twin Transfusion Syndrome (TTTS). The TTTS procedure consists of identifying and coagulating the anastomosing vessels. We propose a fetoscopic instrument with a flexible steerable distal tip as opposed to currently used rigid scopes. The enhanced dexterity improves the ability of the surgeon to coagulate otherwise hard to access regions. We anticipate usability issues and a potentially steep learning curve as currently surgeons solely work with non-bendable instruments. To alleviate this problem, a shared control approach is proposed in which the surgeon controls the position of the instrument inside the uterus while an autonomous controller controls the orientation. The system is validated by testing on a novel instrument with 2 actuated degrees of freedom in an in-silico setup featuring a real placenta image, a motion tracking system and a mechanical fulcrum point to mimic the incision port. The autonomous distal tip controller achieved an overall 4.75° RMSE with respect to the desired orientation, which is within the targeted range of orientations.