Development of a robotic manipulator system for congenital diaphragmatic hernia: Bending control of the robotic manipulator to approach fetal trachea

The clinical target of this study is intratracheal balloon occlusion from minimally invasive fetal surgery for Congenital Diaphragmatic Hernia (CDH). The target for the surgery is a prenatal temporary tracheal occlusion, which enlarges the fetal lungs, and is a promising procedure for severe cases. A balloon is supposed to be inserted for tracheal occlusion using the manipulator. We propose a novel robotic manipulator for intrauterine fetal surgery for tracheal occlusion. In this study, the 3-unit robotic manipulator with ball joint-shaped arthroses and a shaft diameter of 2.4 mm using a wire-driven mechanism has been developed to approach the fetal trachea without the risk of damage to fetal tissue. The robotic manipulator has a thin structure and 7 degrees of freedom to avoid damage to the fragile fetal cells. However, the positioning control of the robotic manipulator is very difficult. In this paper, the mechanism of the robotic manipulator positioning control was confirmed by measuring the motion of each unit through the experiment. Additionally, a simulation was developed to estimate the mechanism of the robotic manipulator positioning control, and an approach method was considered. The results of the evaluation experiment suggested that the robotic manipulator could approach the fetal trachea through the mouth, and that the contact force was controlled to under 0.05 [N].