Philippe Zanne

Robotic Assistance to Flexible Endoscopy by Physiological-Motion Tracking

Flexible endoscopes are used in many diagnostic exams, like gastroscopies or colonoscopies, as well as for small surgical procedures. Recently, they have also been used for endoscopic surgical procedures through natural orifices [natural orifice transluminal endoscopic surgery (NOTES)] and for single-port-access abdominal surgery (SPA). Indeed, flexible endoscopes allow access of operating areas that are not easily reachable with only one small external or internal incision. However, their manipulation is complex, especially for surgical interventions. This study proposes to motorize the flexible endoscope and to partly robotize its movements in order to help the physicians during such interventions. The paper explains how the robotized endoscope can be used to automatically track an area of interest despite breathing motion. The system uses visual servoing and repetitive control strategies and allows stabilization of the endoscopic view. All required parameters are automatically estimated. In vivo experiments show the validity of the proposed solution for the improvement of the manipulation of flexible endoscopes.

A Parallel Robotic System with Force Sensors for Percutaneous Procedures Under CT-Guidance

This paper presents a new robotic framework for assisted CT-guided percutaneous procedures with force feedback and automatic patient-to-image registration of needle. The purpose is to help practitioners in performing accurate needle insertion while preserving them from harmful intra-operative X-rays imaging devices. Starting from medical requirements for needle insertions in the liver under CT-scan, a description of a dedicated parallel robot is made. Its geometrical and physical properties are explained. The design is mainly based on the accuracy and safety constraints. A real prototype is presented that is currently tested.

Control of a multiple sections flexible endoscopic system

The use of flexible endoscopes in new surgical procedures such as NOTES, i.e. Natural Orifice Transluminal Endoscopic Surgery, raises many problems. Indeed, the movements of conventional flexible endoscopes are limited and surgeons can only perform basic tasks with these systems. In order to enhance endoscope possibilities and workspace, we are currently developing a robotized system. The prototype we propose is based on the combination of several flexible endoscopes. The kinematic model of the system is detailed in order to develop a method of control. The paper presents the implementation of a control strategy using an external sensor which allows to deal with non linearities induced by the cable mechanism of the endoscopes.

Design of a telemanipulated system for transluminal surgery

Flexible endoscopes have been recently used for new surgical procedures called NOTES, i.e. Natural Orifice Transluminal Endoscopic Surgery. However, the movements of conventional flexible endoscopes are limited and surgeons can only perform basic tasks with these systems. In order to enhance endoscopes possibilities and workspace, several solutions have been proposed to redesign the whole endoscopic system. New devices have been proposed recently which are made up of a classical endoscope basis with two additionnal arms. However, these mechanical devices are not completely adequate to properly perform NOTES. That is why we are currently developing a robotized system which can be simultaneously teleoperated while performing autonomous motions. This article presents the constraints of transluminal surgery, existing devices and our new system together with its mathematical modeling.

Improvements in the control of a flexible endoscopic system

The use of flexible cable-driven systems is common in medicine (endoscope, catheter...). Their flexiblity allows surgeons to reach internal organs through sinuous and constrained ways. Unfortunately these systems are subject to backlash due to their internal mechanism. These non linearities raise many difficulties when robotizing and controlling such systems. In this article we propose an approach to improve the cartesian control of a four ways flexible endoscopic system with strong and unknown backlash-like non linearities. The method is based on an automatic off-line hystereses learning. We show that, despite coupling between degrees of freedom, it is possible to extract information from the hystereses which allow to improve cartesian control. Experiments on a real endoscopic system show the validity and the interest of the approach.

Robust visual servoing: bounding the task function tracking errors

This article deals with the well known problem of robust visual servoing (VS), which is formulated by the use of the general task function approach. Robustness is provided with respect to calibration parametric errors not only in terms of stability, but also in terms of tracking errors boundness. As a result, the proposed approach allows the user to choose a bound on the tracking error so as to guarantee the visibility of the target during the task execution. Most importantly, the error boundness is obtained while avoiding the use of large gains. Rather, one uses bounded gains, together with the modulation of the desired velocity along the desired path. An application of this general approach is developed and experimentally validated.

A robotized positioning platform guided by computed tomography : practical issues and evaluation

Medical robotics is a field where dedicated mechanisms have an increasing importance. The strong operating room constraints, both medical and practical, lead to heavily customized solutions. In this paper, we consider the practical problems that must be solved to build a robotic system dedicated to medical interventions under CT-scan guidance. This compact robotic assistant is placed on the patient what raises new generic robotic design problems. Practical solutions together with the evaluation of a prototype are presented in this paper

Robust 3D vision based control and planning

In this paper, we present a method to plan and control the 6 DOF displacements of a manipulator from an eye-in-hand camera image. With this method, even in the presence of camera calibration errors, we can formally guarantee that the system is stable and that the entire target remains visible during any visually servoed motion.

Introducing STRAS: A new flexible robotic system for minimally invasive surgery

In this paper we present a new robotic system, called STRAS, designed for endoluminal and transluminal surgery. The system is based on the Anubis® platform - a manual flexible system designed by Karl Storz for transluminal operations. Our new robot is a modular robotic system, compatible with the medical environment, allowing an easy setup in the operating room. It provides up to 10 Degrees of Freedom (DoFs), enabling the 3D positioning of an endoscopic camera, positioning of two instruments and offering grasper opening / closing functionalities. The paper presents for the first time the mechanical, electrical and control design of STRAS. An initial characterization of the system shows that, because of complex mechanical interactions, the kinematic modeling is not sufficient for cartesian control. However, first experiments, demonstrate that the robotic system can be telemanipulated using joint control and that the robotic system enables a single user to perform complex tasks with the underlying flexible system.

A Model-free Vision-based Robot Control for Minimally Invasive Surgery using ESM Tracking and Pixels Color Selection

This paper deals with the visual servoing of textured surfaces inside the human abdomen with a laparoscope for the robot-assisted minimally invasive surgery (MIS). The well-known image-based visual servoing (IBVS) is one of the most common approaches used for model-based servoing. When no CAD model is available, the efficient second-order minimization (ESM) tracking developed by Malis (2002, 2004) for grey-level images is one of the powerful recent techniques which is extended here to color images so as to handle occluded parts of the region of interest (ROI). Firstly, the ROI is splitted into small areas and a histogram-based color feature comparison of image areas is presented. For each frame and for each area, a metric based on the Bhattacharyya criterion is used to select the contributing areas for the computation of the planar homography between views. Secondly, since for any MIS technique, the endoscopic lens is passing through an insertion point on the abdominal wall, a specific control strategy is developed to perform the ESM tracking with a 4-DOF surgical robot. The method presented in this paper has been validated with several video sequences. Experimental results show that the tracking method is efficient even with more than 75 % of the tracked ROI occluded. Finally, the model-free visual servoing has been performed with the AESOP surgical robot and a training box. Even if the convergence rate is a little bit slow, the desired region is always reached.