Themes

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The AVR research group is developing a scientific activity in the field of vision, control and mechatronic design. Main emphasis is given to medical and surgical applications, and in particular to robotic assistance for minimally invasive surgery and interventional radiology. The research activity can be decomposed into 4 themes:


Computer vision for robotics and medical applications

Contact: F. Nageotte and J. Gangloff

Overview

This research theme is focused on the use of external sensors for measuring and analyzing medical gestures and controlling robotic systems. The sensors are mainly medical imaging devices (MRI, CT scanners, fluoroscopy, US transducers, endoscopic cameras) for intra-coporeal measurements but also optical sensors (cameras, set of cameras) and navigation devices (optical or magnetic) for extra-corporeal measurements. Underlying issues are related to the lack of structure in medical scenes, their specific lighting conditions, the deformable nature of the environment or the cluttered environement of the operating room and the fusion of multi-sensors informations for improving the accuracy of measurements.


Research topics

Real-time surfaces reconstruction using coded structured light: The objective is to improve the coding scheme of most techniques based on neighbourhood coding so as to achieve real-time image segmentation and reconstruction for dynamic sceneries, in particular in vivo environments by means of minimally invasive surgery. The coding scheme is directly based on the epipolar geometry and is driven by a desired minimal Hamming distance. Most applications concern surfaces modeling, augmented reality, visual tracking and robot positioning. The underlying issues are real-time performance and the robustness to occlusions, organ deformations and specularities.

Visual servoing: Medical image is often the only available information, especially concerning the robot configuration with respect to the patient. Several issues prevent however today a wide use of visual servoing techniques in medical robotics. Visual servoing must be robust to the specific, weakly structured and deformable environment. Moreover medical robotic devices are often difficult to model because of their flexibilities or their single-use nature. We are thus mainly interested in improving visual servoing stability robustness and accuracy robustness in regard to the following elements :

  • robustness and performance in regard to visual features selection and extraction
  • robustness and performance to model errors
  • use of new visual primitives for medical imaging devices
  • dynamics in fast visual servoing.

Registration: Development of original markers and workflows for improving robot positioning accuracy for CT-scanner and fluoroscopy applications.

Development of vision control using new medical devices: Fusion of multiple imaging modalities.

Assistance to diagnostic and monitoring: New markers (ERM) and new MRI sequences are being developed

Projects

Projects directly related to the theme:

Projects partly related to the theme:

  • STRAS / EASE : development and control of robots for minimally invasive surgery (F. Nageotte, Ph. Zanne, M. de Mathelin, L. Zorn)
  • ProteCT : development of robots for interventional radiology (B. Bayle)
  • Cable driven robots (J. Gangloff, L. Cuvillon)
  • TMS-Robot : development of a dedicated navigation system (M. de Mathelin, L. Goffin)

Previous projects:

  • Beating heart surgery
  • Laparoscopic surgery
  • Needle insertion in small animals
  • Stereo Visual servoing using Plucker equations (C. Doignon)
  • US Comp (J. Gangloff)

Modeling, Identification and Control

Contact : E. Laroche and J. Gangloff

Overview

The dynamic nature of the systems often needs to be considered for their control. The control complexity comes from different aspects: nonlinearities of the system (smooth or non-smooth); the number of input or output variables; the complexity of the control objectives; the presence of system flexible modes. These features are usually encountered in our applications. Research topics include the identification of the system dynamical model and its use for analysis or controller design. The research activity varies from theoretical work to applied one, mainly in medical robotics but also in the industry.

Research topics

Identification, control and observation of complex dynamical systems: Even if many systems have a nonlinear nature, most of them can be considered as linear systems with varying parameters (LPV) for which a general methodology relying on the Lyapunov stability theory can be used. The research activity aims at developing new tests for analysis and controller synthesis that bring improvements first in the kind of parameter dependence that can be considered, and second in reducing the pessimism of the tests.

Control of cable-driven parallel robots: Cable-driven parallel robots can offer very large workspace, low invasiveness and are safe for interactions with human operators. Our research activities investigate the use of exteroceptive sensors such as vision to improve the positioning accuracy.

Modeling and control of the backlash in flexible endoscopy: The goal is to improve the performance of the control of telemanipulated flexible endoscopes used in single-trocar endoscopy. These devices are subject to significant backlash that varies with respect to the localization in the workspace. Proposed control strategies rely on backlash models, or the use of additional sensors.

Telemanipulation and comanipulation with force feedback: Our activities aim at developing solutions that improve the telemanipulation schemes used in robotized surgery that must satisfy some specific features. The efforts must indeed be accurately restituted to the surgeon so that he can feel accurately the crossed layers. The control schemes must be robust with respect to the variations of both the environment and the operator behavior.

Projects

Projects directly related to the theme:

Projects partly related to the theme:

  • ISIS : development and control of robots for endoluminal and transluminal surgery (F. Nageotte, Ph. Zanne, M. de Mathelin, L. Zorn)
  • US Comp (J. Gangloff)

Previous projects:

Mechanical Design and Mechatronics

Contact : O. Piccin and P. Renaud

Overview

This research theme is focused on the design of medical robotic assistants which are compatible with various medical imaging modalities such as MRI, CT scanners or fluoroscopy. In this perspective, the use of compliant mechanisms allows a reduction in the number of parts and affords a greater compactness of the designed devices. Moreover, compliant mechanisms using polymer materials can be considered as a promising research pathway to cope with the requirements of medical imaging and the need to develop lightweight systems.

Research topics

Compliant mechanisms synthesis: It is now widely recognized that robotic devices should specifically be designed to match the requirements of a targeted medical application. The question of compliant mechanisms synthesis remains an opened issue particularly for spatial systems. Stochastic methods for topology optimization are possible candidates to synthesize such mechanisms. In this process, mechanical architectures may be optimized with an early consideration of the manufacturing constraints.

Simulation driven design: When using polymer materials, one important concern relates to the prediction and the description of the behavior of the resulting device. The inherent nonlinearities induced by such materials should be taken into account via the numerical simulation tools. In the same line, local properties stemming from the means of manufacture need to be carefully considered to improve the design process efficiency.

Embedding functions into systems: As compliant mechanisms can be formed by quasi-monolithic structures, it seems interesting to embed means of perception and actuation within the compliant parts. Some manufacturing methods are now available to produce parts with spatially variable mechanical properties in which mobilities can be obtained locally using low rigidity materials. One central question is then to develop adequate methodologies for selecting not only the location of such mechanical features but also define properly the actuation and required sensors. From a technological viewpoint, producing parts with embedded actuation and sensing is still a challenging goal compared to existing rapid prototyping techniques

Toward new robotic assistive devices: Our preferred medical fields for robotic assistance include single-trocar minimally invasive surgery, interventional radiology and in vivo imaging modalities. As the robotic devices we seek to develop are intended to be used by medical staff and in close interaction with patients, safety issues, transparency, lightness are prominent concerns during the design process. In interventional radiology, assistive devices must be compatible with intraoperative imaging modalities (scanner, fluoroscopy, MRI, echography) and possibly may include teleoperation or comanipulation with force feedback which is required for needle insertion procedures. In single port surgery, one central need relates to the design of partly flexible surgical instruments that can be operated remotely.

Projects

  • ProteCT: development of robotic assistants for interventional radiology (B. Bayle, O. Piccin)
  • MRGuide: development of a robotic asisstant for MR-guided prostate cryotherapy (P. Renaud, B. Bayle)
  • Beating heart surgery (GyroLock, Cardiolock)


Interventional imaging and image-guided therapies

Contact: E. Breton and P. Renaud

This research theme concerns the assistance to image guided medical procedures as well as clinical activities of the team. It is divided in 4 axes: a) radioprotection in interventional radiology, b) assistance to MRI-guided percutaneous procedures, c) translational research in flexible endoscopy, and d) clinical research in interventional radiology. This research theme arises from our strong partnerships with the Interventional Radiology Department of Strasbourg Hospital (Pr. A. Gangi), and IRCAD and the Digestive Surgery Department of Strasbourg hospital (Pr. J. Marescaux). The team also leads research projects within the IHU Strasbourg, Institute of Image-Guided Surgery.

Research topics

Radioprotection in interventional radiology: The research group CAMMA (Computational Modeling and Analysis of Medical Activities) aims at developing new tools and methods to perceive, model and analyze clinician and staff activities in the operating room (OR).

Assistance to MRI-guided percutaneous procedures:

Interventional MR Elastography (MRE) Our work focuses on developping real-time MRE, as opposed to diagnostic MRE, with faster acquisition and reconstruction schemes, for use during MRI-guided minimally invasive interventional procedures. First in vivo experiments show promising results for the real-time monitoring of thermal ablations.

Realtime object tracking during MRI-guided procedures MRI offers the possibility of imaging any image plane position and orientation. This strong advantage arises the need for automatic detection of, for instance, surgical tools in order to automatically align the images to these objects. Two projects focus on this difficulty. The hybrid tracking approach relies on the coupling of detection within the MR images and with optical sensors . The XYZ-MRI approach is led in collaboration with the SMH team in the ICube laboratory, which developped a 3D Hall effect sensors on a chip.

Translational research in flexible endoscopy: STRAS is a teleoperated robotic prototype for assistance to flexible endoscopic surgery. They are conventionally realized using standard colonoscopes, but due to the difficulty of the task, at the limit between gastro-enterology and surgery, only a few experts are actually able to perform the procedure in western countries. STRAS provides a large set of advantages for physicians during intraluminal colorectal procedures. The platform, based on Karl Storz® Anubis® system, allows the simultaneous standard use of two (and up to three) flexible instruments in a triangulated, laparoscopic-like, configuration

Clinical research in interventional radiology: Pr. A. Gangi, head of the Interventional Radiology Dpt. in Strasbourg hospital, pioneer for numerous percutaneous procedures in interventional radiology, is an active member of our team. His clinical departments hosts a CT, a 1.5T opened MRI, a C-arm room, ultrasound systems, all dedicated to interventional radiology. Numerous collaborations with various medical specialties allow for cutting edge precedures. The team is the most active clinically in interventional MRI worldwide, with a strong partnership between the laboratory and Siemens Healtcare.

High intensity focused ultrasound (HIFU) percutaneous ablations:This topic deals with the pre-clinical validation of an external HIFU ablation protocol and the definition of the most adapted clinical indications compared to existing procedures. A robotic system integrating the HIFU transducer will be used for targeting and physiological motion compensation.

Projects

Projects directly related to the theme:

Projects partly related to the theme: