Publications of Christophe Collette
Bookmark and Share    
Full Text
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 ▲]

Detailed reference viewed: 71 (7 ULiège)
Full Text
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 ▲]

Detailed reference viewed: 21 (2 ULiège)
Full Text
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 ▲]

Detailed reference viewed: 25 (1 ULiège)
Full Text
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)
Full Text
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)