Fabien Courreges

Robotized Tele-echography

Intensive multidisciplinary research work has been carried out by several research teams, to improve every part of the tele-echography system. More recently, the efficiency of the diagnosis has also been proved, emphasizing the interest in the concept. Various conception approaches have been explored, for instance, to the robot design, according to the targeted usage. The design of a universal usage system is, however, very challenging owing to the constraints specification described in this chapter. Nevertheless, to date, the light-weight body-mounted robot design approach tends to satisfy the general use requirements. Improvement of the robot control has also permitted this kind of approach. Improvements to the other part of the teleoperation equipment have allowed the setting up in France of a medical center network equipped with on-duty tele-echography systems for real-time routine examination.

A complete methodology to design a safety mechanism for prismatic joint implementation

The majority of recent researches have been focused on developing compliant joint for rotary motion. Few authors contributed to the problematic of safety in pure linear motion, i.e. prismatic joint. The contribution of this work is to present a new design capable of achieving, passively, a nonlinear elastic behavior for prismatic joint implementation, the so-called Prismatic Compliant Joint (PCJ). This new device is based on a six-bar mechanism equipped with a linear spring. Hence, this structure generates the desired nonlinear stiffness behavior under a specified external force. The elastic characteristic will comply with force safety criteria of physical Human/Robot interaction (pHRI); a Hunt-Crossley model based one. In order to fit the PCJ response curve to the established safety measures, an optimization based on genetic algorithm method tunes PCJ intrinsic parameters subject to the chosen constraints.

Erratum to: Design of a discrete algebraic robust differentiation FIR filter using an annihilator of the Z-transform; frequency response analysis and parameter tuning

The seminal work of Mboup et al. [1] has opened a new approach of robust differentiator design based upon the concept of annihilator of the Laplace transform of a continuous input signal. Our work is an investigation of the derivation and analysis of a new discrete FIR estimator designed using this same concept. We have specifically considered a discrete input signal and derived an annihilator of its Z-transform. The resulting new estimator expression shows to be very simple to implement as two cascaded stages: 1. Signal smoothing with a low-pass filter; 2. Euler finite differentiation. We could also derive fast algorithms for the parameters tuning in case of ripple noise. Our experimental results show the ease of parameter tuning and efficacy of the estimator.

An in Vivo Experiment to Assess the Validity of the Log Linearized Hunt-Crossley Model for Contacts of Robots with the Human Abdomen

A key issue in Human-Robot physical interaction is the real-time perception of contact impedance by the robot. The Hunt-Crossley (HC) model is a popular model of contact force with soft biological tissues as it enjoys accuracy with low-complexity properties and its parameters are physically sound. Because the original HC model is non-linear, the current best known approach of real-time identification consists in identifying the parameters of a log linearized version of the HC model, by means of a Recursive Least Squares (RLS) algorithm. But, the final model used for exploitation in robot control, is the original non-linear HC model with the previously identified parameters. Hence, this approach may be questionable concerning the modeling accuracy and some authors prefer rejecting the HC model. This paper presents for the first time an in vivo experiment to assess the performances of contact models with the human abdomen. In particular we show here through a statistical analysis, that the log linearized HC model should be considered as a contact model on its own and replace the original non-linear HC model for both identification and exploitation.

DOF analysis of the ultrasonography technique for improving ergonomy in tele-echography

This paper proposes a new ergonomic frame to describe the attitude of an input device used for human-machine interface in tele-echography application. The data acquired from medical experts through polling and recording medical trajectories enabled us to design this new system of angles exhibiting a good decorrelation among its degrees of freedom. A decorrelation improvement of up to 83% can be noticed compare to the standard 3-1-3 Euler angles. This new frame can be exploited for low cost man-machine interface design.

Ergonomic mouse based interface for 3D orientation control of a tele-sonography robot

This paper proposes a new ergonomic frame to describe the attitude of a robot arm and to be used for human-machine interface in telerobotic with application to telesonography. A three part psychophysical analysis enabled us to design this new system of angles exhibiting a good decorrelation among its degrees of freedom. A decorrelation improvement of up to 83% can be noticed compare to the standard 3-1-3 Euler angles. This new frame has been exploited to conceive human-machine interface with a low cost input device such as the standard IT mouse. Psychophysical results show indisputable superiority of our new system compare to the standard Euler one for orientation tracking in teleoperation conditions.

Effect of thermal treatment of a clay-based raw material on porosity and thermal conductivity: experimental approach, image processing and numerical simulation

This work aims to reveal the influence of thermal treatment on thermal conductivity of a clay-based raw material. The analysis of the effect of the porous network and solid skeleton on thermal conductivity has been performed by numerical simulation. Three steps were combined: (i) elaboration, (ii) characterisation, (iii) validation and comparison with experimental results. In filigree, the objective is to make an insulating material for the building field while decreasing energy of fabrication. After the step of elaboration, the porosity was evaluated experimentally by pycnometer and mercury intrusion porosimeter and numerically by means of micrographs observations. The effective thermal conductivity was evaluated using the laser flash technique and compared to results obtained by numerical simulation using ABAQUS software. The influence of the microstructure characteristics was highlighted by the numerical study which enables to overcome the limitation of the classical analytical models. As results, we observe that when the temperature of fabrication decreases of about 200 °C, the pore volume fraction is multiplied by six while the thermal conductivity decreases four times. The mechanical properties remain acceptable for a construction field. These tendencies were confirmed by both experimental and numerical approaches.

Accounting for respiratory motions in online mechanical impedance estimation

The aim of this work is to improve the safety and control robustness of robots interacting physically with humans by enhancing their contact perception. More specifically in the abdominal area, respiratory motions are clearly influencing the contact dynamics but have not yet been accounted for in the estimation of the contact impedance. We propose here a combined mechanical-respiratory model of impedance along with its on-line identification. Numerical and practical experiments with living subjects validate the identification process and show the relevance in accuracy of accounting for the respiratory beats.

Complete design methodology of biomimetic safety device for cobots’ prismatic joints

Abstract Making robots collaborate safely with humans has created a new design paradigm involving the biomimetic mechanical behavior of robots’ joints. However, few authors have contributed to the problems of safety in pure linear motion, i.e. a prismatic joint, in contrast to rotary motion. The contribution of this work is to present a new design that is capable of achieving, passively, an implementation of nonlinear elastic behavior for prismatic joints—the so-called Prismatic Compliant Joint (PCJ). This new device is based on the association of a six-bar mechanism with a linear spring. Hence, this structure generates a nonlinear stiffness behavior under a specified external force. The elastic characteristics of the PCJ are derived from a generic biological muscle mechanical behavior model and then customized according to the force-safety criteria of physical Human/Robot Interaction (pHRI) into a Hunt–Crossley contact model. A further investigation is carried out, via simulation, to verify the shock absorption capacity of the PCJ with a dummy head obstacle. In order to fit the PCJ response curve to the established safety measures, an optimization based on a genetic algorithm method is employed to tune the PCJ’s intrinsic parameters subject to some chosen constraints.

On the development of a portable, cost effective and compact master/slave system for robot-assistec Minimally Invasive Surgery

Making robots joint compliant is an interesting design paradigm for achieving safe Human Robot (HR) collaboration. Until now the researchers focus has mainly been on revolute joint, in contrast to a few works on prismatic joint. This work introduces a new design capable of achieving, passively, a nonlinear elastic behavior for prismatic joint implementation that we refer to as Prismatic Compliant Joint (PCJ). This new device is based on a six-bar mechanism equipped with a linear spring. Hence, this structure generates the desired nonlinear stiffness behavior under a specified external force. The elasticity characteristic complies with Hunt-Crossley (HC) contact model derived from the conducted experimental work on the human abdomen. Furthermore, a simulation of HR collision is performed in order to verify the shock absorption capacity of the PCJ on the rigid skull. Finally, a 3D printed prototype is presented as a proof of concept of the mechanical feasibility of the desired behavior.