The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Robust human face recognition is one of the most important open tasks in computer vision. This study deals with a challenging subproblem of face recognition: the aim of the paper is to give a precise estimation for the 3D head pose. The main contribution of this study is a novel non-rigid Structure from Motion (SfM) algorithm which utilizes the fact that the human face is quasi-symmetric. The input...
Various approaches to the mixed H2/H∞· control problem are proposed in the literature. The solution is often obtained by means of classical techniques (i.e. solving a Riccati problem) or by means of convex optimization procedures. With the aim to synthesize a fixed-structure controller for an uncertain plant, a global optimization approach to a single-input single-output (SISO) H2/H∞ problem is proposed...
The paper suggests the asymptotic stability condition for control systems characteristic polynomial families with interval coefficient perturbations and the method of their synthesis based on it. The combined approach of algebraic and analytical root locus methods is used.
Although stability guarantees are available for predictive controllers, closed-loop instability may arise due to system uncertainty. The T-design and the Q-parametrisation methods are often used to enhance the robustness of predictive controllers. The former is heuristic, whereas optimisation rules exist for the latter, which makes it systematic. However, the T-design tends to producing larger robustness...
This paper considers the problem of determining the minimum euclidean distance of a point from a polynomial surface in Rn. It is well known that this problem is in general non-convex. The main purpose of the paper is to investigate to what extent Linear Matrix Inequality (LMI) techniques can be exploited for solving this problem. The first result of the paper shows that a lower bound to the global...
Based on recent robust control results mixing polynomial techniques and LMI optimization, a bunch of new functions implemented in version 3.0 of the Polynomial Toolbox for Matlab are described with the help of illustrative numerical examples.
This paper presents a methodology for enhancing the robustness of a GPC controlled system by convex optimisation of the Youla parameter. This methodology requires, as a first step, the design of an initial GPC controller; this controller is then robustified considering frequency and temporal constraints. By means of the Youla parametrisation, frequency and temporal constraints are formulated within...
This paper is concerned with the stability and control of linear systems with uncertain physical parameters. The case where the characteristic equations of the systems are polynomially dependent on uncertain parameters is studied. A new algorithm is presented for the calculation of stability margins in the parameter space in general / p-norms. The stability is defined with respect to a desired region...
The solution of a H2/H∞ stochastic feedback and feedforward optimal control problem is discussed where the structure of the controller is assumed to be fixed apriori. The controller may be chosen to be of reduced order, lead/lag, or PID forms, and the optimal causal controller is required to minimize H2 or H∞ cost-indices. The continuous-time system includes at tracking controller and a feedforward...
The reliability of a communication network is important, as the Internet is an important social infrastructure. However, especially in a large network, it is difficult to avoid the failures due to various factors. It is necessary to design a network that keeps communication among nodes even during failures. However, in many actual networks, there exists the risk of telecommunication blackout by a...
This note provides sufficient robust stability conditions for continuous time polytopic nonlinear systems. Parameter-dependent Lyapunov function is introduced in order to make possible the state feedback robust controller synthesis, and less conservative sufficient conditions are formulated in terms of nonlinear state dependent matrix inequalities. These conditions can be verified by the technique...
A number of methods has been published in the recent years in order to demonstrate a stable and satisfactory solution for the benchmark test problem of a flexible transmission system. This paper presents a new approach for PID stabilization for the benchmark problem via generation of stable segments in the controller coefficient space and their subsequent optimization methods in order to find the...
This paper tackles with the design of robust fault detection filter (RFDF) for a class of linear time invarient (LTI) systems with constant output state time delays including the effects of both parameter uncerttainties and parameter uncertainties. The approach used is to remove the time delays of the system i.e. to transform it to a delay free system by using bicausal change of coordinates approach...
In this paper, we propose a new method for digital RST controller design based on the Particle Swarm Optimization metaheuristic. It is a systematic RST synthesis and tuning procedure to deal with the complexity of the known classical poles placement methods. The case of an electric DC drive benchmark has been successfully obtained to illustrate the efficiency of the proposed PSO-based RST control...
Motivated by problems of uncertainty propagation and robust estimation we are interested in computing a polynomial sublevel set of fixed degree and minimum volume that contains a given semialgebraic set K. At this level of generality this problem is not tractable, even though it becomes convex e.g. when restricted to nonnegative homogeneous polynomials. Our contribution is to describe and justify...
This paper deals with the problem of finding a polytopic outer approximation P* of a compact semialgebraic set S ⊆ ℝn. The computed polytope turns out to be an approximation of the linear hull of the set S. The evaluation of P* is reduced to the solution of a sequence of robust optimization problems with nonconvex functional, which are efficiently solved by means of convex relaxation techniques. Properties...
The paper considers a problem of robust control system synthesis based on the modified algorithm of Coefficient Diagram Method (CDM) with robustness index optimization. The proposed solution is expected to enable improvement of system robustness against parametric uncertainty. As a measure of assessment an aim function (robustness index) defined for the system with an additional filter block is introduced...
A min-max re-formulation of the robust parameter design problem was introduced in [S. Mukhopadhyay and D. Chakraborty, "A computational algorithm for selecting robust designs in safety and quality critical processes," Sankhya B, 73, May 2011]. This formulation poses a computationally challenging problem: that of finding the min-max value of a polynomial in several variables. It has been...
This paper discusses an approach for closed loop robustness evaluation of nonlinear networked control systems (NCSs). The continuous-time nonlinear multi-input plant is controlled via several predesigned nonlinear discrete-time controllers which are connected to the plant through a time-triggered communication network. In particular, the communication scheduling for the actuator signals are considered...
In this paper we address the problem of robust pole placement for linear-time-invariant systems whose uncertain parameters are assumed to belong to a semialgebraic region. A dynamic controller is designed in order to constrain the coefficients of the closed-loop characteristic polynomial within prescribed intervals. Two main topics arising from the problem of robust pole placement are tackled by means...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.