5. MEDICAL ROBOTICS
5. MEDICAL ROBOTICS
Medical Robotics is a fast World-Wide developing field. Its many faced aspects encompass highly challenging issues for robotics and broad exciting perspectives at clinical level.
Medical Robotics is certainly for IARP one of the central directions of interest, largely reflected in the efforts led in member countries. France fits well in this pattern with many R&D projects and programmes. The four following sub-sections have being selected, among the global activity spectrum, to provide with a significant over-all picture since they all entail multiple cooperations with french and
5.1. TER, a Robotic System for tele-echography
Echographic examination, which is mainly diagnosis-oriented, turns out to be difficult and highly specialized. Several telemedicine projects have been launched to allow the remote assistance of an expert for such an examination when a patient cannot benefit from the best health care in the place where the examination should take place. These projects have faced communication problems since existing technology was not fast and robust enough at the time the projects started. Moreover, guiding an operator remotely is difficult. On the one hand, the expert loses the haptic feedback of the probe moving onto the patient's body, which is an important information; on the other hand, the non expert operator must interpret the 6D movement orders transmitted by the expert on a purely verbal way. In order to assist such an examination a French consortium has launched, the TER project, for robotic tele-echography.
The principle of the TER system is the following. A virtual probe is mounted on the master interface device. The real probe is placed on the slave robot end-effector. Position and force information are transmitted bi-directionally. Live visual and audio data are also transmitted in both directions. The system is initialised to match the two environments. Then, mainly based on the echographic images and force information he receives back, the expert operator can move the virtual probe to control the real one. The slave robot executes the orders sent from the master site. A non expert operator is located close to the patient and supervises the procedure that he can interrupt. The patient can at any time communicate with him or with the expert. TER is designed to be used with low-bandwidth widespread networks in order to make it usable on a large scale.
We can roughly decompose the echographic examination in two stages. One stage consists in exploring a large region of the body to localize the structure of interest. During these gross motions, control accuracy is not mandatory. In the second stage, the clinician locally explores the detected structure. These fine motions are mostly composed of rotations relatively to the contact surface of the probe. Therefore, it was reasonable to decouple translation and rotation degrees of freedom (dof). An original patented robotic architecture has been proposed by one of the partners (the UJF/CNRS TIMC laboratory). The TER slave robot is based on two parallel kinematic architectures and on artificial Mc Kibben muscle actuation. As it can be seen on the figure, a first parallel structure mounted on the consultation bed is composed of four antagonistic muscles enabling translations. They are connected to a ring supporting the probe and the other dof: this second parallel structure is also actuated by four muscles enabling the 3D orientation of the probe and fine translations. Both subsystems can be controlled simultaneously. This slave robot has been designed preferring safety and natural compliance to accuracy. This is acceptable because the accuracy requirements are generally lower for tele-robotic echography than for surgical applications; moreover, the operator closes the loop and may compensate for positional errors.
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Sketch of the slave robot in use during an obstetrical echographic examination. |
Prototype experiments with a phantom representing the pregnant woman. |
Experiments concerning robot control, tele-gesture and data compression have been successfully realized. The project is entering the integration phase that should be completed by the end of 2001. TER has been supported by the French Ministry of Research and Technology (action line "telemedicine"). It is based on a partnership between universities, companies and hospitals. The partners are the TIMC laboratory from Grenoble University and CNRS, the LVR laboratory of Bourges University, the university hospitals of Tours and Grenoble, and 3 companies: France Télécom R&D, SINTERS et PRAXIM. This project benefits from collaboration with the INSA of toulouse.
5.2. The Programme ChIR (Surgery, Computer Science and
Robotics)
ChIR (Chirurgie, Informatique & Robotique) is a pluri-disciplinar INRIA-Sophia Antipolis team created on January, 1rst 2000. The team main focus is robotics surgery, which belongs to the prioritary applicative domain of HEALTH defined in Inria’s strategy plan for the 1999-2003 period.
ChIR's central objective is the integration of robotic techniques and image processing in surgery aimed at making the planning and execution of surgical interventions more accurate and less invasive. A coronary bypass procedure has been chosen as a test bed for this integration.
This work is done in close cooperation with Prof. Carpentier's team from the Hôpital Européen Georges Pompidou with the tele-operated robot Da Vinci. This robot has been acquired jointly between Inria and Paris VI University for an installation in clinical environment. A high speed network (the VTHD network at 2.5.Gbits) directly links the hospital to Inria Sophia Antipolis and ChIR. A validation experiment is currently under development and will be demonstrated in fall 2001 the integration of the different results performed around a surgical procedure performed on Leonardo, a plastic skeleton. Research and clinical results have been published in robotics and imaging conference such as Miccai 2000 and Miccai 2001, Iser2000, Compte Rendu de l"Académie des Sciences 2001, Icar and Icra 2001.
The main underlying steps of robotic surgery integration in ChIR are:
The modelling and visualisation of dynamic anatomical entities. Today, the main topics investigated in the team are the coronary network (cf figure 1) and the heart modelling. Computer vision and stereovision techniques are investigated to solve this difficult problem.
The planning and simulation of robotic interventions using the above mentioned models combined with robot models. Computational geometry and robotics techniques allow to plan the pose and entry points of high degrees of freedom robotics system in a patient dependant way (cf figure 2). Today, the system integrates numerous surgical robot models and allows their prototyping, the planning and simulation of different surgical procedures for different clinical specialties (e.g. in neurosurgery for hypophysis, digestive surgery...)
The secure real time execution of robotic procedures with augmented reality using image overlay and force feedback. For constraints motions. Real time issues, formal methods and integration are here of prime importance.
ChIR works closely with three other INRIA research teams: Epidaure (Medical Imaging), Prisme (Computational Geometry) and RobotVis (Computer Vision). Several clinical groups in France and abroad collaborate with the team in order to perform clinical validation of the different results.
Collaborations agreements have been signed between ChIR and Prof. Carpentier's team at HEGP (INRIA/Paris VI), as well as Intuitive Surgical, Inc (USA) among others. ChIR participates in several projects funded by the French Ministry of Research:
Figure 1: 3D reconstruction of a coronary network using two angiographic sequences
Figure 2: Planning and simulation: positioning of the Da Vinci robot on Leonardo, the testbed skeleton.
Figure 3: Clinical validation in the Hopital Européen Georges Pompidou. Registration of planning and simulation results (cf Figure 2) in the Operating Room : Da Vinci is positioned on Leornardo.
5.3. The SCALPP Project
Since 1994, the Robotics Department of the LIRMM (Laboratoire d’Informatique, de Robotique et de Microélectronique de Montpellier) is involved in Medical Robotics, namely to create robotics systems intended to serve as assistant to the medical doctors. Starting from an application at hand, the methodology is to find an optimal kinematic arrangement for the robotic arm, to design a suitable control law (involving force control), and to work in close cooperation with hospitals and industrial partners to come up with realistic solutions. Feasibility studies are performed on an industrial redundant robotic arm of the Lab., a PA-10 form Mitsubishi.
An on-going research program, the SCALPP project, concerns the design of a dedicated robot for skin harvesting in reconstructive surgery. This program is run together with Lapeyronie Hospital in Montpellier and SINTERS, an engineering Company in Toulouse. It is supported by the French Ministry of Research and Technology and by the Région Languedoc-Roussillon.
Skin harvesting on human body, for grafting purpose, requires a high accuracy in the gesture and is physically very demanding for the surgeon due to the efforts he has to exert. It aims at harvesting a constant thickness strip of skin (few tenths of millimeter) with a "shaver-like" device. Besides, it requires a long period of training and has to be practiced regularly (for orthopedic physicians for instance, this gesture is not completely mastered since it may not be a daily operation). Skin strips may be harvested on different locations on the patient, mainly thighs, buttocks, head (thus, scars are hidden by hair). Owing to their shape, some of these locations are more difficult to harvest. All these reasons have been analyzed and justify robotization of the harvesting task.
Specified after a feasibility study, an intrinsically safe SCARA robot with a non-spherical wrist has been designed It is force controlled, and easy to operate thanks to a user-friendly interface. The project is currently in the experimental and assessment phase: tests on silicon and on foam rubber (which roughly mimic skin), validation on animals, then cadavers before later in vivo graft harvesting.
Research topics
Design tools and methodologies for medical robots, including kinematic arrangement and optimization,
Analysis of the surgeon motion and of the interactions between surgical instruments and organs,
Physical modeling and parameter identification,
Development of advanced position and force model-based control schemes for non-rigid environments,
Programming complex surgical tasks and skill acquisition.
Photo 1: experimental set-up to measure force and velocity when skin harvesting (feasibility study)
Photo 2: the SCALPP robotic system
5.4. EndociroB Project
endociroB is a robotic system devoted to endoscopic surgery. Based on the latest technological advances in robotics, computer science and micro-mechanics, EndociroB aims at contributing to optimize the accuracy of chirurgical procedures, while improving the comfort of the medical team.
Instruments downscaling, optimization of end effectors, reduction of operating space and setup simplification, are direct benefits for the medical team (as well as for the patients). They allow to put further the limits of minimally invasive surgery.
To summarize, the main objectives of the project are:
endociroB is a French National Co-operative Project supported by RNTS, Réseau National des Technologies pour la Santé (National Network for Health Technologies).
The project was launched in November 2000 and it aims at delivering a prototype ready for clinical assessment by the end of 2002.
EndociroB is carried on by a large consortium of partners:
Endoscopic surgery, also called minimally invasive surgery, makes use, to produce surgical procedures, of at least 3 incisions. One allows the introduction of an endoscope (miniature camera), and the two others the operation of surgical instruments. This type of surgery permits, while preserving the same patient recovery as conventional techniques, to reduce the size of incisions and to limit the dissection areas, thus reducing considerably the surgery trauma. Furthermore, it simplifies post-surgery consequences, it shortens the stay in hospital, and reduces the aesthetic damage.
Using the robotic system EndociroB also improves the comfort of the surgical team and the accuracy of the surgical procedures. This is because of a smaller workspace, of an easier setup, of surgical instruments miniaturization and effectors optimization. All these points will contribute to enhancing health care quality, and they also anticipate the discovery of new surgical possibilities.
The robotics system EndociroB is a product developed for several targets within endoscopic surgery: the heart, the digestive system, the torax, as well as being of interest to urology and gynecology. The system is compatible with the environment and the constraints of surgery rooms.
EndociroB works under the master-slave paradigm, meaning that the master arm motions are reproduced by the slave arms. The master part is made of a console that allows the surgeon to remotely control his/her surgical procedures, and to verify them through a visualization system, while remaining fully integrated in the surgical team. The slave part is made of 3 articulated arms, 2 of them carrying the various surgical instruments, and the last one carrying the endoscope providing the intra-body image.
The robotic system EndociroB is designed to be used within a surgery room. It will be surrounded by hospital workers, and of course will be in contact with patients. Consequently, from the very beginning of the study, the possible failure modes, both at technological level or caused by misuse, are identified, analyzed and subsequently mastered in the system definition, to obtain an intrasically safe machine.
