1,721,791 research outputs found
An Application of the Singular Perturbation Decomposition to Plasma Position and Shape Control
No full textThis paper deals with the problem of designing a plasma current, position, and shape controller for the ITER-FEAT tokamak. Exploiting the features of the plant, we show that it is possible to design separately two control loops: a first loop which stabilises the vertical position by means of a simple derivative action, and a second loop which drives the plasma current and the plasma geometrical shape descriptors as close as possible to the reference values by means of a multivariable PI controller. The reduced-order model for the design of the external loop has been obtained via a singular perturbation decomposition. © 2003 EUCA
Model predictive control of resistive wall mode for ITER
No full textActive feedback stabilization of the dominant resistive wall mode (RWM) for an ITER H-mode scenario at high plasma pressure using infinite-horizon model predictive control (MPC) is presented. The MPC approach is closely-related to linear-quadratic-Gaussian (LQG) control, improving the performance in the vicinity of constraints. The control-oriented model for MPC is obtained with model reduction from a high-dimensional model produced by CarMa code. Due to the limited time for on-line optimization, a suitable MPC formulation considering only input (coil voltage) constraints is chosen, and the primal fast gradient method is used for solving the associated quadratic programming problem. The performance is evaluated in simulation in comparison to LQG control. Sensitivity to noise, robustness to changes of unstable RWM dynamics, and size of the domain of attraction of the initial conditions of the unstable modes are examined
A Framework for the Design of a Plasma Current and Shape Controller in the Next Generation Tokamaks
No full textAnnular Stochastic Finite-Time Stability Using Piecewise Quadratic Lyapunov Functions
No full textIn this paper we present some new sufficient conditions for the annular stochastic finite-time stability of a class of stochastic linear time-varying systems. These new conditions are obtained adopting time-varying piecewise quadratic Lyapunov functions rather than the classical quadratic ones. The proposed approach allows us to extend the class of consider domains, which are typically limited to ellipsoidal domains. The proposed finite-time stability conditions can be converted into a feasibility problem based on a set of differential linear matrix inequalities. Two numerical examples are considered to perform a comparison with the previous results, and they show that the new proposed conditions are less conservative than the previous ones
A Framework for the Design of a Plasma Current and Shape Controller in the Next Generation Tokamaks
No full textReduced Order Solutions for the Singular H-infinity Filtering Problem
No full textIn this note, we consider the filtering H∞problem for linear time-varying systems. This problem has been already solved in the case when the direct feedthrough matrix F between the disturbance and the output vectors is full-row rank. Here, we consider the case when the problem is singular, that is when this feedthrough matrix is not full-row rank. We show that in this case a reduced-order observer can be designed to meet the desired performance. Moreover, we apply the obtained results to solve a particular H∞singular output feedback problem
A Framework for the Design of a Plasma Current and Shape Controller in the Next Generation Tokamaks
No full textState Feedback Stabilization Over A Finite Time Interval of Linear Systems Subject to Norm Bounded Uncertainties
No full textIn this paper we consider the state feedback, finite-time robust stabilization
problem for linear systems subject to time-varying norm-bounded uncertainties.
We provide a sufficient condition for state feedback finite-time stabilization in terms
of the solution of a Generalized Eigenvalue Problem. The proposed technique is
illustrated via a detailed numerical example
Finite-time control of linear time-varying systems via output feedback
No full textThis paper deals with various finite-time analysis and design problems for continuous-time time-varying linear systems. We present some necessary and sufficient conditions for finite-time stability and then we turn to the design problem. In this context, we consider both the state feedback and the output feedback problems. For both cases, we end up with some sufficient conditions involving Linear Differential Matrix Inequalities. © 2005 AACC
Conditions for annular finite-time stability of Itô stochastic linear time-varing systems with Markov switching
No full textIn this study, the authors tackle some control problems related to the class of continuous-time, stochastic linear time-varying systems with Markov switching. First, the annular stochastic finite-time stability problem is considered, and two sufficient conditions are derived by considering the Itô formalism. Both conditions require the solution of a feasibility problem based on differential linear matrix inequalities. The former turns out to be less conservative and, therefore, is exploited in the analysis context; however, it cannot be converted into a computationally tractable condition for feedback purposes. The latter, which is based on a more conservative assumption, allows us to solve the state-feedback design problem. They show that the proposed approach obtains less conservative results with respect to the previous literature. Moreover, the application of the methodology to the finite-time control of a satellite illustrates the effectiveness of the proposed approach when facing engineering problems
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