A Continuum Robot and Control Interface for Surgical Assist in Fetoscopic Interventions

Abstract

Twin–twin transfusion syndrome requires interventional treatment using a fetoscopically introduced laser to sever the shared blood supply between the fetuses. This is a delicate procedure relying on small instrumentation with limited articulation to guide the laser tip and a narrow field of view to visualize all relevant vascular connections. In this letter, we report on a mechatronic design for a comanipulated instrument that combines concentric tube actuation to a larger manipulator constrained by a remote centre of motion. A stereoscopic camera is mounted at the distal tip and used for imaging. Our mechanism provides enhanced dexterity and stability of the imaging device. We demonstrate that the imaging system can be used for computing geometry and enhancing the view at the operating site. Results using electromagnetic sensors for verification and comparison to visual odometry from the distal sensor show that our system is promising and can be developed further for multiple clinical needs in fetoscopic procedures.

Refractive Structure-from-Motion Through a Flat Refractive Interface

“…This will require to develop robust underwater registration methods adapted to intended applicative context (e.g learning-based approaches) or combine it with robotic imaging [8]. It will also be interesting to evaluate such a framework for deep underwater imaging as [2] observed that the thin refractive plane assumption well approximate for thick refractive interface.…”

“…The interface to camera centre distance along the camera's axis is denoted as d. An image point i observed in view j is denoted p [2,2], [2,4], [3,5], [4,3], [4,7], [5,6], [5,8], [6,9]) = 1.…”

Hand-Eye Calibration With a Remote Centre of Motion

“…This limits the camera motion to only 4DoF (3 in rotation and 1 in translation) and results in illconditioned hand-eye constraints. While a possible solution would be to allow a surgical robot to freely move in 6DoF during a calibration phase, this is neither practical nor possible for mechanisms with mechanical RCM implementations [3]. However, as we will show in this paper, it is possible to take advantage of the RCM constraints to improve hand-eye calibration for such robot configurations.…”

“…The schematic shows a magnified version of the type of movement of the camera when being used in RMIS. RCM is denoted at the trocar point to minimise a chance of a robot arm damaging the surrounding tissues [2], [3]. The camera motion is restricted around the RCM and this provides a very small motion range which is not sufficient for a decent calibration.…”

ToolNet: Holistically-nested real-time segmentation of robotic surgical tools

“…With the reduction in size, complex actuation systems are required. Long kinematic chains (12 active joints in the da Vinci robot [5], Intuitive Surgical, USA), micro-machined super-elastic tool guides with pneumatic artificial muscles [6] and concentric tubes [7] are recent examples of these highly complex actuation mechanisms. As a consequence, the kinematics of such robotic manipulators become less stable due to hysteresis, friction and backlash.…”