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SIGMA2 Research team

Signal, models, algorithms

  • Leader : François Le gland
  • Research center(s) : CRI Rennes - Bretagne Atlantique
  • Field : Algorithmics, Programming, Software and Architecture
  • Theme : Algorithms, Certification, and Cryptography

Team presentation

The objectives of the SIGMA2 project are the design, analysis, and implementation of statistical model-based algorithms, for identification, monitoring and diagnosis of complex industrial systems. The models considered are on one hand the stochastic state-space models of automatic control, with increasing emphasis on nonlinear models in industrial applications, and on the other hand some partially stochastic models (HMM, Petri nets, nets of automata, etc.) on discrete structures (trees, graphs, etc.), e.g. to model distributed discrete events systems. The major methodological contributions of the project, which make the scientific background for the current research activities, consist of the use of the local asymptotic approach for monitoring and diagnosis of continuous systems, the design of particle filters for the statistical inference of HMM with general state-space, and the design of distributed Viterbi-like state reconstruction algorithms, for monitoring and diagnosis of distributed discrete events systems. The main applications considered are monitoring and diagnosis of vibrating mechanical structures (automobile, aerospace, civil engineering), monitoring and diagnosis of automobile subsystems, and fault diagnosis in telecommunications networks.

Research themes

  • observers and filters for monitoring and diagnosis of nonlinear dynamical systems,
  • subspace methods for modal analysis and monitoring,
  • statistics of HMM with general state space, and associated particle methods,
  • monitoring and diagnosis of distributed discrete events systems,
  • approximate state estimation algorithms in graphical models and Bayesian networks, and application to turbo algorithms.

International and industrial relations

  • industrial projects : with Renault on identification of the dynamical behaviour of road vehicle, and on monitoring and diagnosis of automobile subsystems, with Alcatel on transparent BER estimation in optical network,
  • multi-parter projects : at national level on fault diagnosis in telecommunications networks (RNRT), and at european level on model-based structural monitoring using in-operation system identification (Eurêka), on exploitation of flight test data under natural excitation conditions (Eurêka), on distributed control and stochastic analysis of hybrid systems (IST),
  • academic research networks : at national level on hidden Markov chains and particle filtering (MathSTIC), and at european level on system identification (TMR), on structural dynamics (COST), on statistical methods for dynamical stochastic models (IHP).

Keywords: Adaptive system Dynamic system modelling Diagnostics Array processing Speech processing Speaker verification Speech recognition Signal processing Multi-resolution analysis Wavelets