References of "Sepulchre, Rodolphe"
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See detailBursting modeling in dopaminergic neurons
Drion, Guillaume ULg; Seutin, Vincent ULg; Sepulchre, Rodolphe ULg

Conference (2009, March)

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See detailAutonomous rigid body attitude synchronization
Sarlette, Alain ULg; Sepulchre, Rodolphe ULg; Leonard, Naomi

in Automatica (2009), 45(2), 572-577

Control laws to synchronize attitudes in a swarm of fully actuated rigid bodies, in the absence of a common reference attitude or hierarchy in the swarm, are proposed in [Smith, T. R., Hanssmann, H ... [more ▼]

Control laws to synchronize attitudes in a swarm of fully actuated rigid bodies, in the absence of a common reference attitude or hierarchy in the swarm, are proposed in [Smith, T. R., Hanssmann, H., & Leonard, N.E. (2001). "Orientation control of multiple underwater vehicles with symmetry-breaking potentials". In Proc. 40th IEEE conf. decision and control (pp. 4598–4603); Nair, S., Leonard, N. E. (2007). "Stable synchronization of rigid body networks". In Networks and Heterogeneous Media, 2(4), 595–624]. The present paper studies two separate extensions with the same energy shaping approach: (i) locally synchronizing the rigid bodies’ attitudes, but without restricting their final motion and (ii) relaxing the communication topology from undirected, fixed and connected to directed, varying and uniformly connected. The specific strategies that must be developed for these extensions illustrate the limitations of attitude control with reduced information. [less ▲]

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See detailConsensus optimization on manifolds
Sarlette, Alain ULg; Sepulchre, Rodolphe ULg

in SIAM Journal on Control & Optimization (2009), 48(1), 56-76

The present paper considers distributed consensus algorithms that involve N agents evolving on a connected compact homogeneous manifold. The agents track no external reference and communicate their ... [more ▼]

The present paper considers distributed consensus algorithms that involve N agents evolving on a connected compact homogeneous manifold. The agents track no external reference and communicate their relative state according to a communication graph. The consensus problem is formulated in terms of the extrema of a cost function. This leads to efficient gradient algorithms to synchronize (i.e., maximizing the consensus) or balance (i.e., minimizing the consensus) the agents; a convenient adaptation of the gradient algorithms is used when the communication graph is directed and time-varying. The cost function is linked to a specific centroid definition on manifolds, introduced here as the induced arithmetic mean, that is easily computable in closed form and may be of independent interest for a number of manifolds. The special orthogonal group SO(n) and the Grassmann manifold Grass(p,n) are treated as original examples. A link is also drawn with the many existing results on the circle. [less ▲]

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See detailFrom subspace learning to distance learning: a geometrical optimization approach
Meyer, Gilles ULg; Journée, Michel; Bonnabel, Silvère et al

in Proceedings of the 2009 IEEE Workshop on Statistical Signal Processing (SSP2009) (2009)

In this paper, we adopt a differential-geometry viewpoint to tackle the problem of learning a distance online. As this prob- lem can be cast into the estimation of a fixed-rank positive semidefinite (PSD ... [more ▼]

In this paper, we adopt a differential-geometry viewpoint to tackle the problem of learning a distance online. As this prob- lem can be cast into the estimation of a fixed-rank positive semidefinite (PSD) matrix, we develop algorithms that ex- ploits the rich geometry structure of the set of fixed-rank PSD matrices. We propose a method which separately updates the subspace of the matrix and its projection onto that subspace. A proper weighting of the two iterations enables to continu- ously interpolate between the problem of learning a subspace and learning a distance when the subspace is fixed. [less ▲]

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See detailSynchronization in Networks of Identical Linear Systems
Scardovi, Luca; Sepulchre, Rodolphe ULg

in Automatica (2009), 45(11), 2557-2562

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See detailAdaptive Regulation of Vector Controlled Induction Motors
Jadot, Fabrice; Malrait, Francois; Moreno, Javier et al

in IEEE Transactions on Control Systems Technology (2009), 17(3),

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See detailRiemannian Metric and Geometric Mean for Positive Semidefinite Matrices of Fixed Rank
Bonnabel, Silvère; Sepulchre, Rodolphe ULg

in SIAM Journal on Matrix Analysis & Applications (2009), 31(3), 1055--1070

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See detailNonlinear Drillstring Dynamics Analysis
Germay, Christophe; deWouw, Nathan Van; Nijmeijer, Henk et al

in SIAM Journal on Applied Dynamical Systems (2009), 8(2), 527--553

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See detailCoordination on Lie groups
Sarlette, Alain ULg; Bonnabel, Silvère; Sepulchre, Rodolphe ULg

in Proceedings of the 47th IEEE Conference on Decision and Control (2008, December)

This paper studies the coordinated motion of a group of agents evolving on a Lie group. Left- or right-invariance with respect to the absolute position on the group lead to two different characterizations ... [more ▼]

This paper studies the coordinated motion of a group of agents evolving on a Lie group. Left- or right-invariance with respect to the absolute position on the group lead to two different characterizations of relative positions and two associated definitions of coordination (fixed relative positions). Conditions for each type of coordination are derived in the associated Lie algebra. This allows to formulate the coordination problem on Lie groups as consensus in a vector space. Total coordination occurs when both types of coordination hold simultaneously. The discussion in this paper provides a common geometric framework for previously published coordination control laws on SO(3), SE(2) and SE(3). The theory is illustrated on the group of planar rigid motion SE(2). [less ▲]

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See detailClustering behaviors in networks of integrate-and-fire oscillators
Mauroy, Alexandre ULg; Sepulchre, Rodolphe ULg

in Chaos (2008), 18

Clustering behavior is studied in a model of integrate-and-fire oscillators with excitatory pulse coupling. When considering a population of identical oscillators, the main result is a proof of global ... [more ▼]

Clustering behavior is studied in a model of integrate-and-fire oscillators with excitatory pulse coupling. When considering a population of identical oscillators, the main result is a proof of global convergence to a phase-locked clustered behavior. The robustness of this clustering behavior is then investigated in a population of nonidentical oscillators by studying the transition from total clustering to the absence of clustering as the group coherence decreases. A robust intermediate situation of partial clustering, characterized by few oscillators traveling among nearly phase-locked clusters, is of particular interest. The analysis complements earlier studies of synchronization in a closely related model. [less ▲]

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See detailGlobal synchronization on the circle
Sarlette, Alain ULg; Tuna, Sezai Emre; Blondel, Vincent et al

in Proceedings of the 17th IFAC World Congress (2008, July)

The convexity arguments used in the consensus literature to prove synchronization in vector spaces can be applied to the circle only when all agents are initially located on a semicircle. Existing ... [more ▼]

The convexity arguments used in the consensus literature to prove synchronization in vector spaces can be applied to the circle only when all agents are initially located on a semicircle. Existing strategies for (almost-)global synchronization on the circle are either restricted to specific interconnection topologies or use auxiliary variables. The present paper first illustrates this problem by showing that weighted, directed interconnection topologies can be designed to make any reasonably chosen configuration of the agents on the circle a stable equilibrium of a basic continuous-time consensus algorithm. Then it proposes a so-called “gossip algorithm”, which achieves global asymptotic synchronization on the circle with probability 1 for a large class of interconnections, without using auxiliary variables, thanks to the introduction of randomness in the system. [less ▲]

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See detailRobotics and neuroscience: A rhythmic interaction
Ronsse, Renaud; Lefèvre, Philippe; Sepulchre, Rodolphe ULg

in Neural Networks (2008), 21(4), 577-583

At the crossing between motor control neuroscience and robotics system theory, the paper presents a rhythmic experiment that is amenable both to handy laboratory implementation and simple mathematical ... [more ▼]

At the crossing between motor control neuroscience and robotics system theory, the paper presents a rhythmic experiment that is amenable both to handy laboratory implementation and simple mathematical modeling. The experiment is based on an impact juggling task, requiring the coordination of two upper-limb effectors and some phase-locking with the trajectories of one or several juggled objects. We describe the experiment, its implementation and the mathematical model used for the analysis. Our underlying research focuses on the role of sensory feedback in rhythmic tasks. In a robotic implementation of our experiment, we study the minimum feedback that is required to achieve robust control. A limited source of feedback, measuring only the impact times, is shown to give promising results. A second field of investigation concerns the human behavior in the same impact juggling task. We study how a variation of the tempo induces a transition between two distinct control strategies with different sensory feedback requirements. Analogies and differences between the robotic and human behaviors are obviously of high relevance in such a flexible setup. [less ▲]

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See detailStabilization of Planar Collective Motion With Limited Communication
Sepulchre, Rodolphe ULg; Paley, Derek; Leonard, Naomi E.

in IEEE Transactions on Automatic Control (2008), 53(3), 706-719

This paper proposes a designmethodology to stabilize relative equilibria in a model of identical, steered particles moving in the plane at unit speed. Relative equilibria either correspond to parallel ... [more ▼]

This paper proposes a designmethodology to stabilize relative equilibria in a model of identical, steered particles moving in the plane at unit speed. Relative equilibria either correspond to parallel motion of all particles with fixed relative spacing or to circular motion of all particles around the same circle. Particles exchange relative information according to a communication graph that can be undirected or directed and time-invariant or timevarying. The emphasis of this paper is to show how previous results assuming all-to-all communication can be extended to a general communication framework. [less ▲]

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See detailGeometric framework for coordination on Lie groups
Sarlette, Alain ULg; Bonnabel, Silvère ULg; Sepulchre, Rodolphe ULg

Conference (2008, March)

Detailed reference viewed: 28 (11 ULg)