Search

International audience; This paper proposes a general approach to design a feedback control law for DC/DC power converters. These last ones can be modeled as switched port-Hamiltonian systems. Based on Lyapunov theory, a candidate Lyapunov function representing the energy of the system is proposed. Advantages of the resulting control law include ease of design and implementation in real time applications. The proposed control is applied in simulation for Buck, Buck-Boost, SEPIC and Ćuk converters. A comparison with a PWM state feedback control law is given for the last two converters.

International audience; The only way to insure a good satellite communication data rate on a moving vehicle is to maintain an antenna bore-sight in the satellite direction. To do so, the antenna is mounted on an Antenna Positioning Systems(APS). The APS is a motorized gimbals that make the antenna move in order to maintain a proper pointing, regardless the vehicle movements. This kind of satellite communication is called SATCOM On The Move (SOTM). In this paper, an hybrid pointing strategy, using least squares identification and gyroscopes is proposed and tested through realistic simulation. The main difference with other strategies is that the scanning is made using only the motion due to measurement noise and gyroscope drift, making unnecessary the introduction of a pointing dither on purpose, as it is usually done. Such a dither is referred as self-induced dither. The main advantage of this strategy is its robustness with respect to non-linearities due to mechanical faults since no precise dither trajectory has to be followed. Another benefit is that attitude measurements are not used during tracking, making the strategy proposed especially interesting for low cost applications.

International audience; In this paper, a presentation of Tchebychev polynomials’ properties and a formulation derived using these polynomials are performed. The identification method presented consists in applying a linear transformation to the set of equations of the process. For this, the mathematical operator used is based on a decomposition of the signal in a basis of orthogonal polynomials. We show that this projection acts as a bandpass filter, so that only one operation is required for the data preprocessing before the identification, namely the choice of the Chebyshev polynomials basis size. An experimental closed-loop identification of a 2-axis robot with this method is performed in a final section. The results are compared and analyzed with other techniques used in robotics.; Dans cet article, une présentation des propriétés des polynômes de Tchebychev et une formulation dérivée utilisant ces polynômes sont effectuées. La méthode d'identification présentée consiste à appliquer une transformation linéaire sur le système d'équations qui régit le processus. Pour cela, l'opérateur mathématique utilisé s'appuie sur une décomposition du signal dans une base formée de polynômes orthogonaux. Nous montrons que cette projection se comporte comme un filtre passe-bande, de telle sorte qu'une seule opération est nécessaire pour le pré-traitement des données avant le processus d'identification, à savoir choisir la dimension de la base des polynômes Tchebychev. Une identification expérimentale en boucle fermée d'un robot à 2 axes avec cette méthode est effectuée dans une dernière partie. Les résultats obtenus sont comparés et analysés avec d'autres techniques utilisées en robotique.

Adresse Internet du journal : http://www.sciencedirect.com/science/journal/15320464; International audience; This paper focuses on the gesture analysis in order to compare two human gestures. The orientations and the positions of the gestures are both taken into account and the similarity rate between two gestures is calculated. In our case, the application is in obstetrics and the aim is to evaluate forceps blade placement. The method is based on the curvature analysis of the paths during the gesture. The 3-D position paths are expressed according to their cumulated chord length and the orientation paths in the quaternion unit space. These parameterizations lead to analyze data in space independently to time as requested by physicians. After filtering data in order to minimize sensor noises, the gestures are then compared by calculating the correlation between the position and the orientation curvatures of a novice gesture and an expert one. The results clearly show that novice skills in handling forceps increase in becoming smoother and closer to the reference placement. A childbirth simulator allows novices to acquire experience without any risks, however the training have to be completed with the extraction gesture evaluation and a compulsory training period in the delivery ward.

International audience; Hand human gesture recognition has been an important research topic widely studied around the world, as this field offers the ability to identify, recognize, and analyze human gestures in order to control devices or to interact with computer interfaces. In particular, in medical training, this approach is an important tool that can be used to obtain an objective evaluation of a procedure performance. In this paper, some obstetrical gestures, acquired by a forceps, were studied with the hypothesis that, as the scribbling and drawing movements, they obey the one-sixth power law, an empirical relationship which connects path curvature, torsion, and euclidean velocity. Our results show that obstetrical gestures have a constant affine velocity, which is different for each type of gesture and based on this idea this quantity is proposed as an appropriate classification feature in the hand human gesture recognition field.

International audience; In this paper, we present a completed Hybrid/Plug-in Hybrid Electric Vehicle (HEV/PHEV) model including an Electrified Auxiliary System (EAS), and an impact analysis of this auxiliary system on the vehicle energy efficiency. Our approach focus-es only on three auxiliaries (an electrified air supply system, an electrified refrigerator, and an electric hydraulic power steering) but could be applied on other devices. Numerical simulation shows that this system has a high impact on the energy efficiency of the HEV/PHEV, while its energy consumption could reach up to 18.6% of the total energy requirement for vehicle propulsion. For the purpose of improving the vehicle energy efficiency thank to the electrified auxiliary management, an optimization approach based on forward dynamic programming is developed to determine the optimal auxiliary power consumption profile. The results of this work conduct to some prominent suggestions for the design of the electrified auxiliary management.

International audience; Auxiliary electrification becomes a potential solution to reduce the vehicle energy consumption. However, electrified auxiliaries operate mostly in individual way, non-cooperative in regardless of the vehicle state. In this paper, a new control strategy for electrified auxiliary system is proposed in order to improve the coordination among auxiliaries. This new control strategy is not only based on a game theoretic approach but also a model predictive control (MPC). In this approach, each electrified auxiliary is considered as a player participating in an energy consumption game, where players have incentive to cooperate and improve the global vehicle consumption. Simulation results on a plug-in hybrid electric vehicle show that this new control design provides a promising and simple approach to control the electrified auxiliary system.

International audience; In this article, the design of a feedback control law for DC-DC power converters in continuous conduction mode based on hybrid optimal control theory is presented. The proposed technique consists in determining the singular arcs when a solution of the original optimal control problem cannot be provided. The closed loop stability analysis uses a Lyapunov function based on a port-Hamiltonian representation of the system. The proposed control law is applied to SEPIC converter and validated in simulation.

International audience; This paper presents a new algorithm, called Dynamic Arc-Length Warping algorithm (DALW) for hand gesture recognition based on the orientation data. In this algorithm, after calculating the quaternion for each orientation measurement, we use DALW algorithm to obtain a similarity measure between different trajectories. We present the benefits of using quaternion alongside the implementation of Dynamic Arc Length Warping to present an optimized tool for gesture recognition.We show the advantages of this approach compared with other techniques. This tool can be used to distinguish similar and different gestures. An experimental validation is carried out to classify a series of simple human gestures.

International audience; This paper presents an upper extremity exoskele- ton with an original application in neuroscience. The novelty of this study is the investigation of the self-advantage phenomenon under various experimental conditions. Usually this kind of experiments lies only on human visual ability to explicitly and/or implicitly recognize their own arm movements. Using an exoskeleton to replay recorded trajectories allows to give another perspective to the previous studies in including the proprioceptive ability of humans. Twelve healthy subjects were involved in this study. The results show that the self advantage phenomenon is even more present in the implicit tasks.

International audience; This paper presents a new observer for a class of DC-DC power converters based on a hybrid system approach. The considered class of switched systems contains two modes. Interestingly, the observability of each mode is not required. An original observer is designed to estimate the state over all modes by using available information provided by current and previous observable states. We show that the stability of the observer is guaranteed independently of the switching sequence. An application to a Single-Ended Primary Inductor Converter (SEPIC) is presented in simulation.

International audience; This paper presents a nonlinear observer based control of a Single Ended Primary Inductor Converter. A Lyapunov-based control law of the voltage output is proposed. This control law has the property to be simple to implement. The proposed technique uses a nonlinear observer of an averaged model of the converter. The asymptotic stability of the observer error is shown using port Hamiltonian formalism. Stability of the closed loop, including the observer and the control law, is discussed. The proposed observer and control law were validated in simulation and experimentation.

International audience; This paper presents a nonlinear observer for DC-DC power converters based on an averaged Port- Hamiltonian model. The averaged model of the standard port control Hamiltonian is used to describe the switching behavior and to design a nonlinear observer. Alike a state-space averaged model of the kind of systems, properties of port-Hamiltonian modeling and Lyapunov theory allows to overcome an observability issue encounters in the observer design for switched systems and to guarantee that the convergence of the observer error is independent of the cycle duty. An application to a Single-Ended Primary Inductor Converter (SEPIC) is presented in simulation. An extended observer is proposed to estimate the load resistor. Experimental results on a real process conrm the performances of the proposed observer.

International audience; Auxiliary electrification in Hybrid Electric Vehicle (HEV) and Plug-in Hybrid Electric Vehicle (PHEV) represents a promising solution in energy management of vehicle. The work presented in the following paper focuses on the design of a controller able to reduce the electrical energy consumption of electrified auxiliaries during a driving cycle. A Model Predictive Control (MPC) is proposed and applied to the air supply system of a PHEV. A comparison of energy consumption between this method and two others (Hysteresis Control and Dynamic Programming) is carried out in order to verify the performance of the MPC controller. Numerical simulations show that this technique allows to obtain a significant gain on energy consumption compared to a standard Hysteresis Control. Furthermore, the difference in term of energy consumption between MPC and Dynamic Programming is weak.

Over the last 50 years, master-slave teleoperation has become a widespread and successful field of research. This discipline explores how to perform tasks using a robot on an environment with haptic feedback about robot-environment interaction being provided to the human operator. Most of the master and slave manipulators used in teleoperation are electrically actuated. However, in some particular applications such as inside an MRI for image-guided surgery, ferromagnetic materials including electrical wiring is prohibited. Thus, non-ferromagnetic actuators like pneumatic or hydraulic actuators are a solution to this problem. This specific application also requires teleoperation in the sense of “tele-actuation” because of the lack of space inside the MRI chamber to put the robot’s actuators and the presence of electrical components in pneumatic servovalves. In this paper, we study the case of a teleoperation system composed of two identical pneumatic cylinders (as the master and the slave) equipped with servovalves, making a symmetric teleoperation system. This serves as a one-degree-of-freedom system to outline the design and analysis in terms of teleoperation transparency and stability. Simulation and experimental results check the validity of the theory without and with classical transmission delays.

International audience; Minimally Invasive Surgery (MIS) has definitively changed the procedures performed in operating rooms. In many cases, MIS has become the recommended standard technique, replacing the traditional open surgery. Effective training and objective assessment of surgeons in these techniques become a major concern in hospitals in recent years, encouraged primarily by patients and a society that demands safer surgical procedures, which is associated with better surgeons training. In the framework of surgery, the difficulty of defining objective metrics for performance evaluation lies in the strict dependency between tasks and the difficulty of defining the meaning of optimal performance, related to the characterization of gestures made by the experts. An objective method to compare 3D gestures between an expert and novice surgeons through multidimensional data analysis is proposed in this paper. A survey of different algorithms for surgical gestures analysis in time domain is carried out. These ones include the Multi-dimensional Dynamic Time Warping (MD-DTW) and Multi-Dimensional Derivative Dynamic Time Warping (MD-DDTW) . Simulation and experimental results are given with this different techniques.

Texte complet disponible : http://www.sciencedirect.com/science/article/pii/S0957415811001966; International audience; For robotic systems that use on/off (solenoid) pneumatic actuators, a sliding mode control law for precise position control and low switching (open-close) activity of the valves is presented in this paper. Given a pneumatic actuator with two chambers and four solenoid valves, there are sixteen possible input combinations defined directly from the state of the four on/off valves present in the system; however, only seven of these discrete operating modes are considered both functional and unique. Therefore, we introduce a novel seven-mode sliding controller that minimizes the position tracking error using modes that have both the necessary and sufficient amounts of drive energy and, thus, involve reduced switching activity. An analysis of the closed-loop system stability is carried out. The performance of the proposed control design is experimentally verified on a single pneumatic actuator setup comprising of two chambers with four on/off valves.

International audience; This paper presents an enhanced sliding mode control for pneumatic master-slave teleoperation systems that are actuated by low-cost solenoid valves. A five-mode sliding control is incorporated into position-position, force-force, and force-position teleoperation architectures. While on/off valve pneumatic actuators have previously been modeled as having three discrete operating modes, an extension to five discrete control levels as proposed here helps to improve the actuator dynamic performance and reduce the switching activities of the valves. Stability and transparency analyses of the closed-loop teleoperation system are carried out. The proposed control design is experimentally tested on a single-degree-of-freedom pneumatic teleoperation system. Experimental results demonstrate high accuracies in terms of position and force tracking in the teleoperation system.

International audience; The paper deals with the dynamic identification in noisy environment of a class of nonlinear systems whose parameters depend linearly on the unknown parameters. The identification algorithm is based on an extended sliding modes observer and a least square estimation using an instrumental variable technique. The study of the measurement noise effect on the measured signals shows that the proposed solution is consistent. An application on a permanent magnet synchronous machine highlights the efficiency of the technique.

National audience; Dans ce papier, une présentation des propriétés des polynômes de Tchebychev et une formulation dérivée utilisant ces polynômes sont e ffectuées. La méthode d'identifi cation présentée consiste à appliquer une transformation linéaire sur le système d'équations qui régit le processus. Pour cela, l'opérateur mathématique utilisé s'appuie sur une décomposition du signal dans une base formée de polynômes orthogonaux. Nous montrons que cette projection se com- porte comme un filtre passe-bande, de telle sorte qu'une seule opération est nécessaire pour le pré-traitement des données avant le processus d'identi cation, à savoir la di- mension de la base des polynômes Tchebychev. L'identi fication expérimentale en boucle fermée d'un robot à 2 axes avec cette méthode est effectuée dans une dernière partie. Les résultats obtenus sont comparés à une technique utilisée classiquement en robotique et montrent des résultats identiques.

International audience; Dans ce papier, une méthode d'identification dynamique pour des systèmes non linéaires linéairement paramétrés est développée. La technique proposée repose sur l'utilisation d'un observateur d'état étendu aux paramètres combinée à une technique des moindres carrés et une approche par variable instrumentale. L'étude de l'effet du bruit sur l'identification montre la consistance et la robustesse de la technique. L'application en expérimentation sur une machine synchrone à aimants permanents confirme les résultats obtenus par simulation.

International audience; This paper presents a new predictive hybrid control law for a pneumatic teleoperation system using solenoid valves. Based on a predictive model of the mass flow rate of the valves, this method is used within a four-channel (4CH) bilateral control architecture for haptic teleoperation. An analysis of the controller parameters is carried out in order to achieve acceptable performances. The results show that a good accuracy in position and force tracking of the teleoperation system is obtained.

International audience; This paper presents a new predictive hybrid control law for a pneumatic teleoperation system using solenoid valves. Based on a predictive model of the mass flow rate of the valves, this method is used within a four-channel (4CH) bilateral control architecture for haptic teleoperation. An analysis of the controller parameters is carried out in order to achieve acceptable performances. To evaluate the new strategy, a comparison study has been performed with a classical PWM control of a teleoperation system. The results show that the accuracy in position and force tracking in steady state but also the dynamic behavior of the pressures are better in the case of hybrid control than PWM control.

International audience; This paper describes a new analysis method dedicated to the comparison of human gestures. The orientations and the positions of the gestures are first digitized using active 3D sensors and then compared to a 6-D template using curvature analysis. The proposed algorithm first starts by computing the invariant curvature of 3D position and orientation of a surgical tool using Frenet-Serret frames in 3D and quaternion space. The resulting curvature calculation is matched and compared to the template using a Dynamic Time Warping method. The proposed method is invariant to sensor position and orientation. An experimental study shows the efficiency of the new algorithm for an application in obstetrics, where the aim is to compare forceps blade placements between a senior medical doctor and a novice.

This paper presents a new gravity compensation method for an upper extremity exoskeleton mounted on a wheel chair. This new device is dedicated to regular and efficient rehabilitation training for post-stroke and injured people without the continuous presence of a therapist. The exoskeleton is a wearable robotic device attached to the human arm. The user provides information signals to the controller by means of the force sensors around the wrist and the arm, and the robot controller generates the appropriate control signals for different training strategies and paradigms. This upper extremity exoskeleton covers four basic degrees of freedom of the shoulder and the elbow joints with three additional adaptability degrees of freedom in order to match the arm anatomy of different users. For comfortable and efficient rehabilitation, a new heuristic method have been studied and applied on our prototype in order to calculate the gravity compensation model without the need to identify the mass parameters. It is based on the geometric model of the robot and accurate torque measurements of the prototype's actuators in a set of specifically chosen joint positions. The weight effect has been successfully compensated so that the user can move his arm freely while wearing the exoskeleton without feeling its mass.

Minimally Invasive Surgery represents the future of many types of medical inter- ventions such as keyhole neurosurgey or transluminal endoscopic surgery. These procedures involve insertion of surgical instruments such as needles and endoscopes into human body through small incision/ body cavity for biopsy and drug delivery. However, nearly all surgical instruments for these procedures are inserted manu- ally and there is a long learning curve for surgeons to use them properly. Many research efforts have been made to design active instruments (endoscope, needles) to improve this procedure during last decades. New robot mechanisms have been used to improve the dexterity of current endoscope. In recent years, several con- tinuum robots have been investigated as mechanisms for medical surgery. Those are characterized by the fact that their mechanical components do not have rigid links and discrete joints in contrast with traditional robot manipulators. The de- sign of these robots are inspired by movements of natural animals such as tongues, elephant trunks and tentacles. The unusual compliance and redundant degrees of freedom of these robots provide strong potential to achieve delicate tasks success- fully even in cluttered and unstructured environments. This chapter will present a complete application of continuum robot, called Colobot, for Minimally Invasive Surgery of colonoscopy. This system is composed of a micro-robotic tip, a set of position sensors and a real-time control system for guiding the exploration of colon. Details will be described on the modeling of the pneumatic actuators used, the design of the mechanical component, the kinematic model analysis and the control strategy for automatically guiding the progression of the device inside the human colon. Experimental results will be presented to check the performances of the whole system within a transparent tube.

International audience; This paper presents a method to evaluate medical gestures. The objective is to objectively assess a gesture carried out by novice doctors compared to experienced doctors. The proposed method is based on the study of the curvature of the 3D gesture and provide a global performance index for one manipulation. The study of the number of peaks on the curvature indicates if the gesture is smooth or not. The application is the obstetric gestures linked to the forceps use but the method can be applied to different gestures without loss of generality. Seven residents carried out 30 forceps blade placements. The results clearly show a difference between the gestures carried out. This highlights the difficulty of the gesture according to the fetal head presentation.

Adresse électronique du journal : http://www.sciencedirect.com/science/journal/01415425; International audience; New contraceptive methods like the subcutaneous implant offers a new kind of comfort for women with an efficiency similar to the contraceptive pill. Unfortunately the few numbers of unintended pregnancies that have been reported are generally due to a bad insertion of the implant. In order to give more security to patients, we have designed, in close collaboration with physicians, a new kind of medical simulator. This paper focuses on a device dedicated to a specific subcutaneous implant but it is worth noting that this simulator is relatively generic since it will be used for other subcutaneous techniques or other implant instruments. This simulator can be used for two purposes: one for training novice physicians in the correct manipulation and the other for physician certification which will help determine if they are capable of inserting the implant in vivo. This paper describes the approach which has led to the design of this simulator. It describes its functionalities, its several components but also methods used to analyze the manipulation of the implant insertion inside the patient. Finally first experimental results are reported and discussed. The system used in this paper makes possible to carry out training in a constraint-free context and provides the first mean of visualizing a maneuver that, until now, has been performed blindly.

IDS Number: BIB31 ISSN: 1050-4729 ISBN: 978-1-4244-1646-2; International audience; This paper presents a new available feature on the childbirth simulator BirthSIM. This feature offers a risk-free training for novice obstetricians to proceed to forceps extractions. The different forces involved during deliveries are described and modeled. The choice of a control strategy in order to reproduce all these forces is explained and argued. This paper also introduces the concepts of simple and double synchronization during deliveries. Its application allows to minimize the amount of forces exerted with forceps during an instrumental delivery to make it as safe as possible. Simulations of forceps extraction carried out by two junior obstetricians are provided and analyzed. The corresponding results are compared to the literature and to the results obtained by an expert.

International audience; New contraceptive methods like the subcutaneous implant offers a new kind of comfort for women with an efficiency similar to the contraceptive pill. Unfortunately, the few numbers of unintended pregnancies that have been reported, are generally due to a bad insertion of the implant. In order to give more security to patients, we have designed, in close collaboration with physicians, a new kind of medical simulator. This simulator can be used for two purposes: one for training novice physicians in the correct gesture and the other for doctor certification which will help to determine if they are capable of inserting the implant in vivo. This paper describes the approach which has led to the design of this simulator. It describes its functionalities, its several components but also methods used to analyze the gesture of the implant insertion inside the patient. Finally, first experimental results are reported and discussed.

This paper presents the advantages of an instrumented childbirth simulator, called BirthSIM, in the framework of training in obstetrics. This simulator has been developed to surpass the constraints linked to the traditional training in a childbirth ward. Simulator training is designed to complete the traditional training used in teaching hospitals. Such a training allows novices to acquire a beginning experience before training in a childbirth ward but it also allows instructors to improve the teaching gestures without constraints. A clinical study of the forceps blades placement gesture with several novices who trained on a childbirth simulator was conducted. The results clearly show the progress in the obstetric gestures of the novices after using the simulator.

International audience; In this paper, the authors describe the design of a bendable robotic tip for semi-autonomous colonoscopy called COLOBOT. It is a flexible robotic manipulator made of silicone rubber in view of the compact size and biocompatibility. The outer diameter of the tip is 17 mm which is lesser than the average diameter of colon (20 mm). Three servo-valves are used to control the pressure of each chamber of this tip to obtain its flexible movement. The experimental results of this new prototype show that it can bend until 120 degrees under the pressure of 2 bar. Based on the geometric deformation and a nonlinear analysis of the silicone behavior, a direct kinematic model analogous to the forward kinematics of a conventional industrial robot kinematics chain has been put forward. The proposed kinematic model of this bendable tip is an extended model of classical models found for such a mechanism. At first a polynomial approximation is used to characterize the non linear behavior of each chamber of the actuator. Next the coupling phenomena between each chamber are highlighted through experimental tests. A new correction parameter is then proposed to take into account these interactions and a non linear optimization is made to compute this coefficient. Finally, the proposed kinematic model is experimentally validated

International audience; This paper presents work resulting from a collaboration between obstetricians and researchers. It shows the benefits from the use of an instrumented childbirth simulator for the training of obstetricians and midwives. This new tool allows to surpass the constraints linked to the traditional training in a childbirth ward. This simulator training is designed to complete the traditional training used in teaching hospitals. Such a training allows residents to acquire a beginning experience before training in a childbirth ward but it also allows instructors to improve the teaching gestures without constraints. A clinical study of the forceps blades placement gesture with several residents who trained on a childbirth simulator is made. The results clearly show the progress in the obstetric gestures of all the residents who have used the simulator

International audience; Birth represents for each human being one the most wonderful days of his life but also one of the most dangerous. Being born in safe conditions requires to be surrounded by professionals who acquire a rigorous knowledge of diagnostic and therapeutic procedures. Nowadays, midwives and obstetricians learn mainly in delivery ward during real childbirths. For difficult childbirths, the use of obstetrical instruments (forceps, spatulas or vacuum extractors) is unavoidable. However, the use of such instruments increases the risks of lesions for the mother and the fetus. In practical, only clinical experience acquired in the delivery ward enables these risks to be reduced. Nowadays, simulators in medicine have a real appeal in the medical environment. These tools enable doctors to visualize the position of the organs in the human body, to plan their movements or to carry out a more complete post operational control. A birth simulator provides a training tool and a research tool to compare various techniques for the use of obstetrical instruments or to validate new methods. It is in this context that we have developed, in collaboration with researchers and medical doctors, a new type of instrumented forceps to offer new solutions for training obstetricians for the safe use of obstetrical forceps delivery. The main contributions of this paper are the design of instrumented forceps coupled with the BirthSIM simulator and the path analysis during the forceps blades placement. This analysis leads to the comparison of the repeatability of the movement between novice obstetricians and expert obstetricians. The results highlight the lack of teaching tool to correctly train the novice obstetricians