Edouard Laroche

Methodological Insights for Online Estimation of Induction Motor Parameters

This paper presents contributions for online estimation of states and parameters of an induction motor with Kalman filter. In order to ensure a good level of confidence of the estimation, a suitable methodology is proposed and two of its main points are investigated. First, an original method is used for tuning the covariance matrices, relying on the evaluation of the state noise due to modeling errors. Second, an observability analysis is developed, allowing to validate the model and the proposed excitation trajectory. Experimental results show that, with the chosen input signal, the parameters can be estimated with good accuracy in less than two seconds.

Cardiolock: An active cardiac stabilizer. First in vivo experiments using a new robotized device

Off-pump Coronary Artery Bypass Grafting (CABG) is still a technically difficult procedure. The mechanical stabilizers used for local suppression of the heart excursion have been demonstrated to exhibit significant residual motion, which could lead to a lack of accuracy in performing the surgical task, particularly when using a minimally invasive surgery (MIS) approach. We therefore propose a novel active stabilizer to compensate for the residual motion whose architecture is compatible with MIS. An experimental evaluation of a commercially available totally endoscopic stabilizer is first presented to demonstrate the unsatisfactory behavior of this device. Then, the interaction between the heart and a mechanical stabilizer is assessed in vivo using an animal model. Finally, the principle of active stabilization, based on the high-speed vision-based control of a piezo-actuated compliant mechanism, is presented, along with in vivo experimental results obtained using a prototype to demonstrate its efficiency.

CONTINUOUS-TIME MODEL IDENTIFICATION OF ROBOT FLEXIBILITIES FOR FAST VISUAL SERVOING

This paper presents a general methodology for identifying the dynamical part of the continuous-time model of an articulated arm including flexibilities dedicated to visual servoing. Based on this model, a H-infinity control law is designed and implemented, allowing to reach high dynamics.

Design and control of a new active cardiac stabilizer

Off-pump coronary artery bypass grafting (CABG) is probably an important milestone in the cardiac surgery history. This technique is currently made possible thanks to the use of mechanical stabilizers. Nevertheless, the available stabilizers are not fully satisfying. Indeed, they have been demonstrated to exhibit significant residual motion. In this paper we propose a novel piezo-actuated compliant stabilizer, whose architecture is compatible with a minimally invasive surgery context. This active stabilizer is controlled using high speed visual feedback in order to compensate in real time for the residual cardiac motion. In vivo experimental results using the developed prototype are given to demonstrate the efficiency of the adopted approach.

A Result on State Estimation of Nonlinear Systems with Application to Fuel Cell Stacks

Abstract In this paper, the observation issue of the partial pressure of oxygen and nitrogen and the mass flow rate of dry air in the cathode channel of a fuel cell stack is addressed. The proposed approach considers the mass flow rate of dry air as an unknown input and uses the voltage and the total pressure as measurements. By using the Jacobian of the nonlinear functions and the convexity principe, the observer design problem is turned into a LMI feasibility problem. Simulation results with a detailed model show the good convergence properties of the observer.

Active heart stabilization using adaptive noise cancelling techniques with gyroscopic actuation

Active cardiac stabilization contributes to the development of less invasive surgical techniques in the cardiac field. We propose a device insuring this function by using the gyroscopic effect to generate the compensation torque. This solution avoids any linkage to the environment and allows to design a completely independant system, pluggable on commercial instruments. After presenting the principle and the design aspects, we focus on an adaptive approach for the control and how it can be combined with frequency estimation in order to cope with variable heart frequency. Finally we present experimental results highlighting the efficiency of the method with a 70% reduction of the displacements and a highly accurate cardiac frequency tracking.

Cardiolock2: Parallel singularities for the design of an active heart stabilizer

In this paper, the design of a new active cardiac stabilizer, Cardiolock2, is presented. Following the proof of concept Cardiolock [7], this device allows an active stabilization of the surface of a beating heart in two directions, which is considered sufficient for a complete stabilization. Piezoelectric actuation is combined with a compliant architecture to obtain high dynamics and accuracy. A remote center of motion is obtained with a serial architecture, and parallel mechanisms in configurations close to singularity are used to increase the workspace. A kinematic analysis is first presented, before detailing the main properties of the device and the current development of the prototype.

A new scheme on robust unknown input nonlinear observer for PEM Fuel Cell Stack system

This paper presents an unknown input observer design method for a class of nonlinear systems in the presence of disturbances in both the systems dynamics and the output. The main motivation of this work is to develop a state estimator for PEM-Fuel Cell Stack systems. More precisely, the paper addresses the observation issue of the main variables of the fuel cell systems that are the compressor speed, the supply manifold pressure, the mass of the gas accumulated in the supply manifold volume, the partial pressure of oxygen and the partial pressure of nitrogen in the cathode channel. The proposed approach considers the current as an unknown input and uses the air flow rate through the compressor and the total pressure as measurements. By means of regular transformations, the Jacobian of the nonlinear functions and the convexity principle, the observer design problem is turned into a LMI feasibility problem. Simulation results with a refined model show the good convergence properties of the observer.

User adapted control of force feedback teleoperators: Evaluation and robustness analysis

This paper addresses the influence of human operators on telemanipulators bilateral control. A method to deal with the user variability is proposed, based on the auto-tuning of the force controller at the master side. First, the approach is evaluated experimentally with a group of users in the context of nonlinear interactions with soft tissues, showing very good tracking performances, for both force and position. Second, a robustness analysis is presented that allows to prove the stability of the system for large variations of the behavior of both the environment and the user. This analysis is based on an original uncertain model of the user.

Cardiolock: An Active Cardiac Stabilizer

Off-pump Coronary Artery Bypass Grafting (CABG) is still today a technically difficult procedure. In fact, the mechanical stabilizers used to locally suppress the heart excursion have been demonstrated to exhibit significant residual motion. We therefore propose a novel active stabilizer which is able to compensate for this residual motion. The interaction between the heart and a mechanical stabilizer is first assessed in vivo on an animal model. Then, the principle of active stabilization, based on the high speed vision-based control of a compliant mechanism, is presented. In vivo experimental results are given using a prototype which structure is compatible with a minimally invasive approach.