Cédric Clévy

Bio: Cédric Clévy is an academic researcher from Centre national de la recherche scientifique. The author has contributed to research in topics: Actuator & Contact force. The author has an hindex of 22, co-authored 100 publications receiving 1331 citations. Previous affiliations of Cédric Clévy include Universite de technologie de Belfort-Montbeliard & University of Franche-Comté.

Complete Open Loop Control of Hysteretic, Creeped, and Oscillating Piezoelectric Cantilevers

Abstract: The feedforward compensation of nonlinearities, i.e., hysteresis and creep, and unwanted vibrations in micromanipulators is presented in this paper. The aim is to improve the general performances of piezocantilevers dedicated to micromanipulation/microassembly tasks. While hysteresis is attenuated using the Prandtl-Ishlinskii inverse model, a new method is proposed to decrease the creep phenomenon. As no model inversion is used, the proposed method is simple and easy to implement. Finally, we employ an input shaping technique to reduce the vibration of the piezocantilevers. The experimental results show the efficiency of the feedforward techniques and their convenience to the micromanipulation/microassembly requirements.

Modeling, fabrication, and validation of a high-performance 2-DoF piezoactuator for micromanipulation

Abstract: A high-performance compact micromanipulation system is presented. The system, called the microgripper microrobot on chip (MMOC), was developed at Laboratoire d'Automatique de Besancon (LAB), France. Two main parts in the MMOC design of the MMOC are discussed: 1) the piezoactuator and 2) the end-effectors. The micromanipulator is partially fabricated in a clean room and the piezoactuator system has been machined using the ultrasonic technique. Tests of micromanipulation have been carried out under both standard laboratory conditions as well as inside a scanning electronic microscope (SEM) chamber. Displacements in the plane and out of the plane are 80 and 200 /spl mu/m, respectively, at 100 V and the MMOC seems to be particularly useful for pick-and-place tasks. Modeling has been performed using the Smits' model and the results confirm the validity of the model for static boundary conditions. The authors have also developed a combined charge and voltage control called Q/V, which results in an order of magnitude reduction in the hysteresis of the piezoactuator. Future work will include integrating force sensors in the micromanipulator in order to measure the manipulation force. This will allow the implementation of the feedback control in the MMOC.

Robotic microassembly and micromanipulation at FEMTO-ST

Abstract: This paper deals with a historical overview of the activities of the French FEMTO-ST institute in the field of microrobotic manipulation and assembly. It firstly shows tools developed for fine and coarse positioning: 4 DOF microgrippers, 2 DOF modules and smart surfaces. The paper then goes on the automation of tridimensional microassembly of objects measuring between 10 and 400 microns. We are especially focusing on several principles. Closed loop control based on micro-vision has been studied and applied on the fully automatic assembly of several 400 microns objects. Force control has been also analyzed and is proposed for optical Microsystems assembly. At least, open loop trajectories of 40 microns objects with a throughput of 1,800 unit per hour have been achieved. Scientific and technological aspects and industrial relevance will be presented.

Towards micro-assembly of hybrid MOEMS components on a reconfigurable silicon free-space micro-optical bench

Abstract: The 3D integration of hybrid chips is a viable approach for the micro-optical technologies to reduce the costs of assembly and packaging. In this paper a technology platform for the hybrid integration of MOEMS components on a reconfigurable silicon free-space micro-optical bench (FS-MOB) is presented. In this approach a desired optical component (e.g. micromirror, microlens) is integrated with a removable and adjustable silicon holder which can be manipulated, aligned and fixed in the precisely etched rail of the silicon baseplate by use of a robotic micro-assembly station. An active-based gripping system allows modification of the holder position on the baseplate with nanometre precision. The fabrication processes of the micromachined parts of the micro-optical bench, based on bulk micromachining of standard silicon wafer and SOI wafer, are described. The successful assembly of the holders, equipped with a micromirror and a refractive glass ball microlens, on the baseplate rail is demonstrated.

A micromanipulation cell including a tool changer

Abstract: This paper deals with the design, fabrication and characterization of a tool changer for micromanipulation cells. This tool changer is part of a manipulation cell including a three linear axes robot and a piezoelectric microgripper. All these parts are designed to perform micromanipulation tasks in confined spaces such as a microfactory or in the chamber of a scanning electron microscope (SEM). The tool changer principle is to fix a pair of tools (i.e. the gripper tips) either on the tips of the microgripper actuator (piezoceramic bulk) or on a tool magazine. The temperature control of a thermal glue enables one to fix or release this pair of tools. Liquefaction and solidification are generated by surface mounted device (SMD) resistances fixed on the surface of the actuator or magazine. Based on this principle, the tool changer can be adapted to other kinds of micromanipulation cells. Hundreds of automatic tool exchanges were performed with a maximum positioning error between two consecutive tool exchanges of 3.2 µm, 2.3 µm and 2.8 µm on the X, Y and Z axes respectively (Z refers to the vertical axis). Finally, temperature measurements achieved under atmospheric pressure and in a vacuum environment and pressure measurements confirm the possibility of using this device in the air as well as in a SEM.

Principles Of Optics Electromagnetic Theory Of Propagation Interference And Diffraction Of Light

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Additive manufacturing

Abstract: Propulsion system development requires new, more affordable manufacturing techniques and technologies in a constrained budget environment, while future in-space applications will require in-space manufacturing and assembly of parts and systems. Marshall is advancing cuttingedge commercial capabilities in additive and digital manufacturing and applying them to aerospace challenges. The Center is developing the standards by which new manufacturing processes and parts will be tested and qualified. Rapidly evolving digital tools, such as additive manufacturing, are the leading edge of a revolution in the design and manufacture of space systems that enables rapid prototyping and reduces production times. Marshall has unique expertise in leveraging new digital tools, 3D printing, and other advanced manufacturing technologies and applying them to propulsion systems design and other aerospace materials to meet NASA mission and industry needs. Marshall is helping establish the standards and qualifications “from art to part” for the use of these advanced techniques and the parts produced using them in aerospace or elsewhere in the U.S. industrial base.

Modeling and Control of Piezo-Actuated Nanopositioning Stages: A Survey

Abstract: Piezo-actuated stages have become more and more promising in nanopositioning applications due to the excellent advantages of the fast response time, large mechanical force, and extremely fine resolution. Modeling and control are critical to achieve objectives for high-precision motion. However, piezo-actuated stages themselves suffer from the inherent drawbacks produced by the inherent creep and hysteresis nonlinearities and vibration caused by the lightly damped resonant dynamics, which make modeling and control of such systems challenging. To address these challenges, various techniques have been reported in the literature. This paper surveys and discusses the progresses of different modeling and control approaches for piezo-actuated nanopositioning stages and highlights new opportunities for the extended studies.

Bouc–Wen Modeling and Inverse Multiplicative Structure to Compensate Hysteresis Nonlinearity in Piezoelectric Actuators

Abstract: A new approach to compensate the strong hysteresis nonlinearity in piezoelectric materials is proposed. Based on the inverse multiplicative scheme, the approach avoids models inversion as employed in existing works. The compensator is therefore simple to implement and does not require additional computation as soon as the direct model is available. The proposed compensation technique is valuable for hysteresis that are modeled with the Bouc-Wen set of equations.