A QSS approach for particle source identification in Tore Supra tokamak

International audienceIn this work, we consider the problem of particle source identification from distributed electron density measurements in fusion plasmas, such as the ones obtained in Tore Supra tokamak. A transport model, suitable for identification purposes, is first proposed based on a simplification of classical particle transport models. We then derive a quasi-steady state (QSS) description, which is shown to converge exponentially towards the true solution. Finally, an identification method is proposed based on the QSS model and a shape approximation of the source term. ToreSupra data is used to illustrate the different results with experimental measurements

Modeling and Feedback Control for Air Flow Regulation in Deep Pits

International audienceWe consider the problem of regulating the air quality in underground extraction rooms for mining industry. This is a challenging control problem where the flow dynamics, the interconnections between subsystems and the time-varying topology have to be taken into account along with real-time computation constraints. Our work is focused on the deep pit part of the ventilation system, which brings fresh air at a specified pressure to the extraction levels. The flow interactions and main automation elements are first presented, with a real-time engineering model of the complete mine ventilation system. A novel control-oriented model focused on the pressure dynamics is then introduced, as a convective-resistive partial differential equation (PDE) with multiple inputs where the time-varying transport coefficients are estimated based on the distributed measurements. A fast predictive controller (FPC) is finally proposed to compensate the pressure losses due to friction and multiple flow exhausts thanks to the ventilation pit input pressure regulation. Simulation results illustrate the efficiency of the modeling and control algorithms

Compositional abstraction and safety synthesis using overlapping symbolic models

In this paper, we develop a compositional approach to abstraction and safety synthesis for a general class of discrete time nonlinear systems. Our approach makes it possible to define a symbolic abstraction by composing a set of symbolic subsystems that are overlapping in the sense that they can share some common state variables. We develop compositional safety synthesis techniques using such overlapping symbolic subsystems. Comparisons, in terms of conservativeness and of computational complexity, between abstractions and controllers obtained from different system decompositions are provided. Numerical experiments show that the proposed approach for symbolic control synthesis enables a significant complexity reduction with respect to the centralized approach, while reducing the conservatism with respect to compositional approaches using non-overlapping subsystems

Controllability and invariance of monotone systems for robust ventilation automation in buildings

International audienceThe problem considered is the temperature control in a building equipped with UnderFloor Air Distribution (UFAD). Its 0-D model is derived from the energy and mass conservation in each room, and also presents discrete components to describe the disturbances from heat sources and doors opening. Using the monotonicity of this model, we can characterize two concepts of robust control, the Robust Controllability and the Robust Controlled Invariance introduced in this paper, and determine their limits for control design objectives. The validity of these results is then illustrated in a simulation of a two-room example

Safety control with performance guarantees of cooperative systems using compositional abstractions

International audienceIn this paper, the monotonicity property is exploited to obtain symbolic abstractions, in the sense of alternating simulation, of a class of nonlinear control systems subject to disturbances. Both a centralized and a compositional approaches are presented to obtain such abstractions, from which controllers are synthesized to satisfy safety specifications and optimize a performance criterion using a receding horizon approach. Performance guarantees on the trajectories of the controlled system can be obtained with both approaches. The controller synthesis and performance guarantees are illustrated and compared on the temperature regulation in a building

Modelling and Control of the Moisture in a Test Bench Flow with Time-delay

International audienceMoisture control in systems with time delay is studied in this work to be assessed in a process-control system (Test bench). To further investigate the phenomenon of transport delay in flows, the test bench system has been studied. In this work it is presented the design and validation of a model which describes the dynamics of mass transport phenomena. In order to control the moisture in the test bench, it is design a state-feedback controller such that the closed-loop system is robustly stable has an upper bound for the time delay

Estimation de la diffusion thermique dans les plasmas de Tokamak

6 pagesInternational audienceCe travail concerne l'étude du profil de transport de la température des électrons du plasma. Une approximation numérique basée sur la méthode de Galerkin est proposée. Le coefficient de diffusion est estimé grâce à la projection spatiale qui réduit le problème à une dimension finie. Le filtre de Kalman étendu est proposé pour cette identification. Le travail est accompagné par un ensemble de simulations et de comparaisons avec les données expérimentales

Dynamic Boundary Stabilization of First Order Hyperbolic Systems

International audienceIn this chapter, we address the problem of the dynamic boundary stabilization of linear, quasilinear and LPV first-order hyperbolic systems. We provide sufficient conditions for the exponential stability for this class of infinite dimensional systems by means of Lyapunov based techniques and matrix inequalities. We develop an applicative example of a temperature boundary control in a Poiseuille flow using some of our main results and we present simulation results that illustrate the efficiency of our approach

Adaptive Space-Time Distributed Parameter and Input Estimation in Heat Transport with Unknown Bounds

International audienceIn this paper, we discuss on-line adaptive estimation of distributed diffusion and source term coefficients for a non-homogeneous linear parabolic partial differential equation describing heat transport. An estimator is defined in the infinite-dimensional framework having the system state and the parameters' estimate as its states. Our scheme allows to estimate spatially distributed and space-time distributed parameters. While the parameters convergence depends on the plant signal richness assumption, the state convergence is established using the Lyapunov approach. Since the estimator is infinite- dimensional, the b-splines Galerkin finite element method is used to implement it. In silico simulations are provided to illustrate the performance of the proposed approach

Adaptive Distributed Parameter and Input Estimation in Plasma Tokamak Heat Transport

International audienceIn this paper, the adaptive estimation of spatially varying diffusion and source term coefficients for a linear parabolic partial differential equation describing tokamak plasma heat transport is considered. An estimator is defined in the infinite-dimensional framework having the system state and the parameters' estimate as its states. Our scheme allows to estimate constant, spatially distributed and spatio-temporally distributed parameters as well as input with known upper bounds in time. While the parameters convergence depends on the plant signal richness assumption, the state convergence is established using the Lyapunov approach. Since the estimator is infinite-dimensional, the Galerkin finite-dimensional technique is used to implement it. In silico simulations are provided to illustrate the performance of the proposed approach