Analyse d'une description énergétique de l'actionnement pour le calcul du mouvement des masses.

Colloque avec actes et comité de lecture. Internationale.National audienceCet article introduit un modèle mécanique décrivant l'évolution de deux masses en interaction, en choisissant volontairement de traiter le problème sous une forme énergétique. Cette perspective impose de définir une grandeur qui agit sur les masses et dont la nature est inhabituelle, puisqu'il s'agit d'une puissance dirigée. Le modèle, une fois posé, est étudié et comparé aux approches de la mécanique relativiste et classique

Analysis of a passive microforce sensor based on magnetic spings and upthrust buoyancy.

International audienceThis paper is focused on the design and modeling of a new micro and nano force sensor using magnetic springs. The force sensitive part is a macroscopic horizontal rigid platform used as a oating seismic mass. This platform presents a naturally stable equilibrium state for its six degrees of freedom (dof) thanks to the combination of upthrust buoyancy and magnetic forces. This force sensor allows the measurement of the external horizontal force and the vertical torque applied to the platform. Thanks to the magnetic springs con guration used, the seismic mass presents a 0.02 N/m horizontal mechanical sti ness (similar to the sti ness of a thin AFM micro-cantilever). The measurement range typically varies between 50 N. The resolution depends on the displacement sensors used to measure the seismic mass displacement and on the environmental conditions (ground, liquid and air vibrations). In steady state, this displacement is proportional to the applied force. Resolution of less than 10 nN can be reached with the use of an anti-vibration table

Microforce sensor for microbiological applications based on a floating-magnetic principle.

International audienceIn this paper, we present the design of a new magentic nano and microforce sensor for microbiological applications. The sensing part of the sensor presents a naturally stable six degrees of freedom equilibrium state using the combination of upthrust buoyancy and magnetic force. The sensor allows force measurement without deformation of the sensing element using a feedback control loop and is able to measure the components, in the horizontal plan, of the external force applied. The measurement range varies between around ± 100 µN with a resolution of 20 nN and a linear output. The mechanical stiffness of the passive system is about 0.018 N.m−1(same order of magnitude than an AFM micro-cantilever). A complete static study and experimental validation of the used principle are presented in this paper

Nanoforce estimation based on Kalman filtering and applied to a force sensor using diamagnetic levitation

International audienceNanoforce sensors based on passive diamagnetic levitation with a macroscopic seismic mass are a possible alternative to classical Atomic Force Microscopes when the force bandwidth to be measured is limited to a few Hertz. When an external unknown force is applied to the levitating seismic mass, this one acts as a transducer that converts this unknown input into a displacement that is the measured output signal. Because the under-damped and long transient response of this kind of macroscopic transducer cannot be neglected for time-varying force measurement, it is then necessary to deconvolve the output to correctly estimate the unknown input force. The deconvolution approach proposed in this paper is based on a Kalman filter that use an uncertain a priori model to represent the unknown nanoforce to be estimated. The main advantage of this approach is that the end-user can directly control the unavoidable trade-off that exists between the wished resolution on the estimated force and the response time of the estimation

Analysis of the trade-off between resolution and bandwidth for a nanoforce sensor based on diamagnetic levitation.

International audienceNanoforce sensors based on passive diamagnetic levitation with a macroscopic seismic mass are a possible alternative to classical Atomic Force Microscopes when theforce bandwidth to be measured is limited to a few Hertz.When an external unknown force is applied to the levitating seismic mass, this one acts as a transducer that converts this unknown input into a displacement that is the measured output signal. Because the inertia effect due to the mass of such macroscopic transducers cannot be neglected for timevarying force measurement, it is necessary to deconvolve the displacement to correctly estimate the unknown input force.A deconvolution approach based on a Kalman filter and controlled by a scalar parameter has been recently proposed.The adjustement of this parameter leads to a trade-off that is analysed in this paper in term of resolution and bandwidth of the estimated force. Associated tools to help the end-user to set this parameter are also described

Nanoforce estimation with Kalman filtering applied to a force sensor based on diamagnetic levitation.

International audienceNano force sensors based on passive diamagnetic levitation with a macroscopic seismic mass are a possible alternative to classical Atomic Force Microscopes when the force bandwidth to be measured is limited to a few Hertz. When an external unknown force is applied to the levitating seismic mass, this one acts as a transducer that converts this unknown input into a displacement that is the measured output signal. Because the little damped and long transient response of this kind of macroscopic transducer can not be neglected, it is then necessary to deconvolve the output to correctly estimate the unknown input force. The deconvolution approach proposed in this article is based on a Kalman filter that use an uncertain a priori model to represent the unknown nanoforce to be estimated. The main advantage of this approach is that the end-user can directly control the unavoidable trade-off that exists between the wished resolution on the estimatedforce and the response time of the estimation

Estimation robuste par synthèse H2 de micro- et nanoforce à l'aide de ressorts magnétiques actifs.

National audienceThis article deals with the problematic of micro- and nanoforce measurement. The force is the unknown excitatory signal of a transducer whose only the output is measurable. This general problematic of an unknown input signal reconstruction from a noisy output signal is developed inside the H2 synthesis framework. The resulting methodology is implemented in a micro- and nanoforce sensor that uses a macroscopic seismic mass controlled by active magnetic springs. This methodology uses only a very basic knowledge on the force dynamic and thanks to H2 synthesis, ensures that the force estimation remains correct despite the transducer dynamic, the noise measurement, the uncertainty on the force dynamic and the sensor modeling errors

Modeling of a new SMA micro-actuator for active endoscopy applications.

International audienceShape memory alloys (SMA) are good candidates to actuate endoscope heads but the cooling problem must be solved particularly in confined situations. For these reasons, a new SMA micro-actuator specially designed for active endoscopy applications has been developed in our laboratory. This work is a new step in the approach of using integrated thermoelectric cooling with SMA actuators. In fact, the Peltier effect is very attractive in such a case because this reversible phenomenon reduces the overheating of the external environment and provides forced cooling that decreases the response time. In this paper the actuator design and its working principle are presented. A fine modeling of the coupled mechanical and thermal behaviors gives a better understanding of the physical phenomenon involved in the actuator. Finally an experimental prototype has been developed and tested in order to verify the model predictions

Modelling and optimization of a floating triangular platform used for nano and microforces sensing.

International audienceThis paper presents the dynamic behaviour modelling of a horizontal triangular platform, used as the sensing part of a microforce sensor. This sensor is based on a magnetic and a buoyancy principle. A particular configuration used to obtain a linear model is presented. This linear model will be essential for the futur control of the system, in order to achieve force measurement without displacement of the platform. The determination of the platform position and orientation in the horizontal plane is done thanks to three laser range sensors. Sensors configuration provide a linear transformation between the three measured ranges and the position and orientation of the platform. Finally, an open loop result comparison is done between the linear state model and a more complex 3D non linear model

Magnetic manipulation with several mobile coils towards gastrointestinal capsular endoscopy.

Traditional techniques of endoscopy based on flexible endoscopes are fairly reliable but poorly tolerated by patients and do not give access to the small bowel. It has been demonstrated that magnetic fields are usable for manipulating an untethered magnet, either using fixed coils or mobile permanent magnets.We introduce a novel approach for magnetic manipulation and present the preliminary results obtained by simulating a planar manipulation system including multiple mobile coils