Publications of Christophe Collette
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See detailActive nonlinear inerter damper for vibration mitigation of Duffing oscillators
Zhao, Guoying; Raze, Ghislain ULiege; Paknejad, Ahmad et al

in Journal of Sound and Vibration (2020), 473

In this paper, a nonlinear active damping strategy based on force feedback is proposed. The proposed device is composed of a pair of collocated actuator and force sensor. The control law is formed by ... [more ▼]

In this paper, a nonlinear active damping strategy based on force feedback is proposed. The proposed device is composed of a pair of collocated actuator and force sensor. The control law is formed by feeding back the output of the force sensor, through one single, one double integrator and another double integrator of its cube. An equivalent mechanical network which consists of a dashpot, an inerter and a cube root inerter is developed to enable a straightforward interpretation of the physics behind. Closed-form expressions for the optimal feedback gains are derived. Numerical validations are performed to demonstrate the proposed control strategy. [less ▲]

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See detailControl-Based Continuation of Nonlinear Structures Using Adaptive Filtering
Abeloos, Gaëtan ULiege; Renson, Ludovic; Collette, Christophe ULiege et al

Scientific conference (2020, February 10)

Control-Based Continuation uses feedback control to follow stable and unstable branches of periodic orbits of a nonlinear system without the need for advanced post-processing of experimental data. CBC ... [more ▼]

Control-Based Continuation uses feedback control to follow stable and unstable branches of periodic orbits of a nonlinear system without the need for advanced post-processing of experimental data. CBC relies on an iterative scheme to modify the harmonic content of the control reference and obtain a non-invasive control signal. This scheme currently requires to wait for the experiment to settle down to steady-state and hence runs offline (i.e. at a much lower frequency than the feedback controller). This paper proposes to replace this conventional iterative scheme by adaptive filters. Adaptive filters can directly synthesize either the excitation or the control reference adequately and can operate online (i.e. at the same frequency as the feedback controller). This novel approach is found to significantly accelerate convergence to non-invasive steady-state responses to the extend that the structure response can be characterized in a nearly-continuous amplitude sweep. Furthermore, the stability of the controller does not appear to be affected. [less ▲]

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See detailActive Nonlinear Energy Sink Using Integral Force Feedback
Zhao, Guoying; Raze, Ghislain ULiege; Paknejad, Ahmad et al

in Proceedings of the International Modal Analysis Conference (IMAC) XXXVIII (2020, February)

Excessive vibrations in mechanical structures can cause many problems such as reducing structural integrity and compromising the commissioning of precise instruments. Tuned mass dampers (TMDs) are often ... [more ▼]

Excessive vibrations in mechanical structures can cause many problems such as reducing structural integrity and compromising the commissioning of precise instruments. Tuned mass dampers (TMDs) are often employed to suppress undesirable vibrations. However, they are known to be effective only in a frequency band limited around one vibration mode and to be sensitive to the variation of primary structures. Alternatively, nonlinear energy sinks (NESs) can be used as they do not have a preferential resonance frequency making them more robust and capable of damping multiple resonances. In this paper, the performance of an active nonlinear energy sink (ANES) is investigated, which is realized using a novel integral force feedback controller. Unlike the traditional NES, which is realized by a cubic spring, a dashpot and an inertial mass, the proposed ANES is equivalent to a mechanical system which consists of a cubic root inerter, a dashpot and a linear spring. Because of the full analogy with a mechanical network, the stability of the proposed active system is guaranteed. Although the form of the proposed ANES is different from that of traditional NESs, it is found that the targeted energy transfer phenomenon also occurs with the ANES and the control effectiveness is similar to traditional NESs. [less ▲]

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See detailMultimodal vibration damping using a simplified current blocking shunt circuit
Raze, Ghislain ULiege; Paknejad, Ahmad; Zhao, Guoying et al

in Journal of Intelligent Material Systems and Structures (2020)

The tuning of a simplified current blocking shunt circuit able to mitigate the vibration amplitude of multiple structural resonances is addressed in this paper. The proposed strategy exploits the two-port ... [more ▼]

The tuning of a simplified current blocking shunt circuit able to mitigate the vibration amplitude of multiple structural resonances is addressed in this paper. The proposed strategy exploits the two-port network formalism in combination with physically-motivated approximations to tune sequentially the electrical elements of the different branches of the shunt circuit. The resulting tuning method does not resort to optimization algorithms and requires only the knowledge of quantities that are easy to measure experimentally. It is demonstrated both numerically and experimentally using a piezoelectric beam. [less ▲]

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See detailComplementary Filters Shaping Using H-Infinity Synthesis
Dehaeze, Thomas ULiege; Verma, Mohit; Collette, Christophe ULiege

Conference (2019, November)

For many applications, large bandwidth and dynamic ranges are requiring to use several sensors, whose signals are combined using complementary filters. This paper presents a method for designing these ... [more ▼]

For many applications, large bandwidth and dynamic ranges are requiring to use several sensors, whose signals are combined using complementary filters. This paper presents a method for designing these complementary filters using H-Infinity synthesis that allows to shape the filter norms. This method is shown to be easily applicable for the synthesis of complex complementary filters. [less ▲]

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See detailA multimodal nonlinear piezoelectric vibration absorber
Raze, Ghislain ULiege; Lossouarn, Boris; Paknejad, Ahmad et al

in Desmet, Wim; Pluymers, Bert; Moens, David (Eds.) et al Proceedings of ISMA2018 and USD2018 (2018, September)

This paper presents a design methodology for a piezoelectric vibration absorber able to damp multiple nonlinear resonances. The design of multimodal linear piezoelectric absorbers is first reviewed. Next ... [more ▼]

This paper presents a design methodology for a piezoelectric vibration absorber able to damp multiple nonlinear resonances. The design of multimodal linear piezoelectric absorbers is first reviewed. Next, based on the dynamics of the structure to which linear absorbers are attached, the design is extended to the nonlinear regime. The methodology is inspired from a principle of similarity: if a nonlinearity of one type is present in the host structure, the same type of nonlinearity is used in the absorbers. An explicit semi-analytical expression of the nonlinear coefficients in the absorber is obtained thanks to a first-order harmonic balance and a straightforward series expansion. Numerical examples are analysed to demonstrate the efficiency of the proposed approach. [less ▲]

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See detailSample Stabilization for Tomography Experiments in presence of large plant uncertainty
Dehaeze, Thomas ULiege; Magnin-Mattenet, Muriel; Collette, Christophe ULiege

Poster (2018, July)

A new low emittance lattice storage ring is under construction at the ESRF. In this new instrument, an upgraded end station for ID31 beamline must allow to position the samples along complex trajectories ... [more ▼]

A new low emittance lattice storage ring is under construction at the ESRF. In this new instrument, an upgraded end station for ID31 beamline must allow to position the samples along complex trajectories with a nanometer precision. In order to reach these requirements, samples have to be mounted on high precision stages, combining a capability of large stroke, spin motion, and active rejection of disturbances. First, the end station will be presented with the associated requirements. However, the precision is limited by thermal expansion and various imperfections that are not actively compensated. Our approach is to add a Nano Active Stabilization System (NASS) which is composed of a 6DoF Stewart platform and a 6 DoF metrology system. A 3D model of the end station updated with experimental data is developed. As the mass of the samples may vary by up to two orders of magnitudes, robust control strategies are required to address such plant uncertainty. The proposed control strategy are presented and applied on the developed model by conducting time domain simulations of tomography experiment in presence of instrumentation noise and system uncertainty. [less ▲]

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See detailSample Stabilization For Tomography Experiments In Presence Of Large Plant Uncertainty
Dehaeze, Thomas ULiege; Magnin-Mattenet, Muriel; Collette, Christophe ULiege

Scientific conference (2018, June 27)

A new low emittance lattice storage ring is under construction at the ESRF. In this new instrument, an upgraded end station for ID31 beamline must allow to position the samples along complex trajectories ... [more ▼]

A new low emittance lattice storage ring is under construction at the ESRF. In this new instrument, an upgraded end station for ID31 beamline must allow to position the samples along complex trajectories with a nanometer precision. In order to reach these requirements, samples have to be mounted on high precision stages, combining a capability of large stroke, spin motion, and active rejection of disturbances. First, the end station will be presented with the associated requirements. However, the precision is limited by thermal expansion and various imperfections that are not actively compensated. Our approach is to add a Nano Active Stabilization System (NASS) which is composed of a 6DoF Stewart platform and a 6 DoF metrology system. A 3D model of the end station updated with experimental data is developed. As the mass of the samples may vary by up to two orders of magnitudes, robust control strategies are required to address such plant uncertainty. The proposed control strategy are presented and applied on the developed model by conducting time domain simulations of tomography experiment in presence of instrumentation noise and system uncertainty. [less ▲]

Detailed reference viewed: 29 (2 ULiège)
See detailTowards Broadband Seismic Isolation Systems: a one d.o.f. isolation stage study
Ding, Binlei; Watchi, Jennifer; Collette, Christophe ULiege

Report (2018)

Detailed reference viewed: 45 (4 ULiège)
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See detailCoil-free active stabilisation of extended payloads with optical inertial sensors
Watchi, Jennifer; Ding, Binlei; Tshilumba, David et al

in Measurement Science and Technology (2018)

This paper presents a new active isolation strategy and system which is dedicated to extended payloads, and compatible with particle accelerator environment. In comparison to the current isolation systems ... [more ▼]

This paper presents a new active isolation strategy and system which is dedicated to extended payloads, and compatible with particle accelerator environment. In comparison to the current isolation systems used in this environment, the system proposed does not contains any coil or elastomer and the supporting frame is dedicated to isolate long payloads from seismic motion. The concept proposed has been tested numerically on 3 and 6 degrees of freedom models, and validated experimentally on a one degree of freedom scaled test set-up. An attenuation of 40 dB at 1 Hz has been reached with the stage built. The complete description of performance and a noise budgeting are included in this paper. [less ▲]

Detailed reference viewed: 33 (4 ULiège)
See detailObservation of gravitational waves from a binary black hole merger
Abbott, B. P.; Collette, Christophe ULiege; others

in Observation of gravitational waves from a binary black hole merger (2017)

Albert Einstein's general theory of relativity, first published a century ago, was described by physicist Max Born as "the greatest feat of human thinking about nature."We report on two major scientific ... [more ▼]

Albert Einstein's general theory of relativity, first published a century ago, was described by physicist Max Born as "the greatest feat of human thinking about nature."We report on two major scientific breakthroughs involving key predictions of Einstein's theory: the first direct detection of gravitational waves and the first observation of the collision and merger of a pair of black holes. This cataclysmic event, producing the gravitational-wave signal GW150914, took place in a distant galaxy more than one billion light years from the Earth. It was observed on September 14, 2015 by the two detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO), arguably the most sensitive scientific instruments ever constructed. LIGO estimated that the peak gravitational-wave power radiated during the final moments of the black hole merger was more than ten times greater than the combined light power from all the stars and galaxies in the observable Universe. This remarkable discovery marks the beginning of an exciting new era of astronomy as we open an entirely new, gravitational-wave window on the Universe. [less ▲]

Detailed reference viewed: 33 (5 ULiège)
See detailRutting Corrugation Study on a Scaled Roller Rig
Collette, Christophe ULiege; others

Report (2005)

Detailed reference viewed: 33 (3 ULiège)
See detailTribologie numerique et expertises tribologiques au service d'un contact modele : le contact "roue-rail
BERTHIER, Yves; SAULOT, Aurélien; DESCARTES, Sylvie et al

in Journees Francophones de Tribologie (2005)

Detailed reference viewed: 20 (3 ULiège)
See detailWheel rail Corrugation in Urban Transport
Collette, Christophe ULiege

Report (2002)

Detailed reference viewed: 31 (3 ULiège)