Authors: Chalh, Z.; Achir, A.; Sueur, C.

Abstract: The paper deals with the characterization of invariant zeros of MIMO linear time varying systems using the bond graph methodology. Thanks to the exploitation of the algebraic framework of modules, a direct procedure for the computation of the invariant zeros is developed. The paper ends with an example illustrating the implementation of the proposed approach.

Keywords: invariant zeros,bond graphs,modules,LTV systems

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00087

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 542-547

Authors: El'youssef, Ebrahim Samer; Moreno, Ubirajara F.; De Pieri, Edson R.; Neto, Eugenio B. Castelan

Abstract: In this work the application of a high-gain observer approach to the robust feedback linearization control is proposed to control a class of nonlinear systems, which all states can not be measured. The robust feedback linearization technique is used to transform the nonlinear system into its linear approximation around an equilibrium and the high-gain observer to estimate the states of the system.

Keywords: robust feedback linearization,high-gain observer,nonlinear systems

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00011

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 64-69

Authors: Poussot-Vassal, C.; Sename, O.; Dugard, L.; Gaspar, P.; Szabo, Z.; Bokor, J.

Abstract: In this paper we consider the design and analysis of a semi-active suspension controller. In the recent years different kinds of semi-active control strategies, like two-state Skyhook, LQ-clipped or model-predictive, have already been developed in the literature. In this paper we introduce a new semi-active suspension control strategy that achieves a priori limitations of a semi-active suspension actuator (dissipative constraint and force bounds) through the Linear Parameter Varying (LPV) theory. This new approach exhibits some interesting advantages compared to already existing methods (implementation, performance flexibility, robustness etc.). Both industrial criterion evaluation and simulations on nonlinear quarter vehicle model are performed to show the efficiency of the method and to validate the theoretical approach.

Keywords: semi-active suspension,linear parameter varying (LPV),H∞ control,linear matrix inequality (LMI)

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00018

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 106-111

Authors: Vries, D.; Keesman, K. J.; Zwart, H.

Abstract: Inspired by the UV disinfection processes in food and water treatment industry, we design a Luenberger observer which works at the boundary of the infinite dimensional bilinear system. Existence of a solution, stability and some observer design issues are shown. Simulations of a disinfection process and its observer illustrate the results.

Keywords: bilinear systems,infinite dimensional systems,observers,boundary control,eigenvalue analysis

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00108

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 667-672

Authors: Colaneri, Patrizio; de Souza, Valeska M.

Abstract: In this paper we study the almost sure stability of continuous-time jump linear systems with a finite-state Markov form process. A new sufficient condition is derived based on an extended Lyapunov-Metzler inequality. This condition is proven to be less conservative with respect to the existing sufficient conditions. The inequalities generalize those associated with mean square stability and establish a clear link between the two notions. The problem of almost sure stabilizability and detectability is finally discussed.

Keywords: Markov jump systems,switched systems,Lyapunov functions,stochastic stability

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00041

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 244-249

Authors: Welsh, James S.; Goodwin, Graham C.; Garnier, Hugues

Abstract: This paper examines the issue of bias that arises when applying least squares identification to continuous-time models of resonant systems. We propose a simple method to reduce the impact of this bias by pre-processing the data. This new method requires no knowledge of the noise colouring. An example is presented that shows the superior performance of the proposed method over that of a traditional method.

Keywords: least squares,time domain,parameter estimation

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00095

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 590-595

Authors: Pomar, Martin J.; Normey-Rico, Julio E.; Gutierrez, Gloria; de Prada, Cesar

Abstract: Frequently, the design of many processes or systems is performed without taking into account its dynamical behaviour. This leads to lost of performance when the process has to operate dynamically, as the design may impose constraints on the physically reachable dynamic. The joint design of equipment and its control system is an integration technique that incorporates control requirements in the process design stage. This paper illustrates the technique with a buck boost converter. The design has been performed including its control system and allows obtaining a system that complies not only with the static performance requirements but with certain previously fixed dynamic characteristics. The parameters of the converter are obtained through mathematical programming, together with the tuning parameters of the controller, in this case an Sliding Model Control strategy, this one being in charge of ensuring that the process responds adequately under a wide range of demands.

Keywords: integrated process and control design,sliding mode control,buck-boost converter

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00048

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 286-291

Authors: Rodriguez-Angeles, E.; Torres-Munoz, J. A.; Mendez-Barrios, C. F.

Abstract: An algorithmic criterion is proposed for checking the stability of a bivariate polynomial in the sense of the so-called Stable class. For this, a novel graphical test for the Schur Stable bivariate class is introduced. The approach relies on the fact that both the Schur Stable and the Stable bivariate classes are nicely related by a bilinear transformation.

Keywords: stability criteria,bivariate polynomials,bilinear systems

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00036

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 214-219

Authors: Silveira, H. B.; da Silva, P. S. Pereira

Abstract: This paper shows that, for flat affine time-invariant continuous-time nonlinear systems with two controls and five or less state variables, there exists a smooth change of coordinates and a time-invariant regular static state feedback such that the system is described by a triangular form. The presentation is based on an infinite-dimensional differential geometric approach to nonlinear control systems.

Keywords: nonlinear control systems,structural properties,control theory,differential geometric methods,co-ordinate transformations,state feedback

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00020

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 118-123

Authors: Hara, Shinji

Abstract: This paper formally introduces a concept named "Reciprocal Transform" for unifying analytical expressions on control performance limits achievable by feedback for continuous-time systems. The transform swaps the role of poles and zeros and takes the reciprocal values. We first show its several properties and the state-space form. We then review Bode integral type relations and investigate performance limits for H2 tracking and regulation problems and H∞ control problems including loop shaping design. The investigations confirm the role of reciprocal transform in control performance limitations.

Keywords: feedback control,control performance limitation,bode integral relation,H2 control,H∞ control,H∞ loop shaping design,reciprocal transform

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00100

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 620-625

Authors: Kurdyukov, A. P.; Tchaikovsky, M. M.; Vladimirov, I. G.

Abstract: Stochastic anisotropy-based robust control design problem for linear systems is a rather difficult problem as it reduces to solving some equation system consisting of several cross-coupled algebraic Riccati equations, Lyapunov equation and a special type nonlinear equation. In this paper we describe a new Matlab package called ABO aimed at solving Anisotropy-Based Optimization problems. It employs homotopy method for solving cross-coupled equations. Some numerical examples of this package use are presented.

Keywords: stochastic robust control,Riccati equations,numerical methods

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00029

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 172-177

Authors: Bender, Fernando Augusto; da Silva, Joao Manoel Gomes

Abstract: A method for synthesizing dynamic output feedback controllers for discrete time systems presenting actuators constrained in amplitude, rate and acceleration is proposed. The considered controller structure, composed by two saturating integrator blocks and a linear compensator, allows to deliver to the actuator input a signal inside all its bounds. Anti-windup loops in the controller are simultaneously designed and add degrees of freedom to the synthesis process, besides improving performance. Sufficient LMI conditions for such stabilizing controller existence are derived and exemplified. Optimization problems for maximizing disturbance tolerance and rejection are considered.

Keywords: anti-windup,saturation,L2 performance,discrete time,LMI

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00082

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 512-517

Authors: Augusta, P.; Hurak, Z.; Rogers, E.

Abstract: In this paper we develop new results on control systems design for spatially distributed linear systems using an n-D systems approach. The basic ideas are explained using as an example heat conduction in a rod where the measurements and control action applied are based on an array of sensors and heaters. The first part of the analysis given shows how the process dynamics for this case can be approximately described by a 2-D transfer function, i.e. a fraction of two bivariate polynomials. This is followed by stability analysis and tests. Finally, a Youla-Kučera parametrization of all stabilizing controllers is used to develop a simple design procedure for H2-optimal control laws.

Keywords: distributed-parameter systems,spatially distributed systems,multidimensional systems,multivariate polynomials

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00033

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 196-201

Authors: De Caigny, J.; Camino, J. F.; Paijmans, B.; Swevers, J.

Abstract: This work investigates an application of interpolating gain-scheduling control for a structural acoustic problem. The dynamics of the system under consideration are highly sensitive to variation in the temperature. Therefore, linear time invariant H2 output feedback controllers are designed for different temperature conditions. Afterwards, these controllers are interpolated to provide a global discrete-time linear parametervarying controller. The closed-loop stability is a posteriori guaranteed using recent less conservative analyses that consider bounds on the rate of variation of the temperature.

Keywords: active noise control,time varying system,parametric variation,discrete-time

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00015

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 88-93

Authors: Mohammadpour, Javad; Meisami-Azad, Mona; Grigoriadis, Karolos M.

Abstract: The paper presents a linear matrix inequality (LMI)-based approach for the simultaneous optimal design of the output feedback controller and damping parameters in structural systems with collocated actuators and sensors. The proposed integrated design is based on H2 norm upper bound expression for a collocated structural system. Using these upper bound results, the combined design of the damping parameters and the H2 static controller is formulated as an LMI optimization problem with respect to the damping coefficients of the structural system and the feedback gains associated with the controller. A numerical example motivated from an engineering application demonstrates the advantages and computational efficiency of the proposed technique for integrated structure and control design. The effectiveness of the proposed integrated design becomes apparent, especially in very large scale structural systems where the use of classical methods for solving Lyapunov equations, associated with H2 design, is time-consuming or intractable.

Keywords: integrated design,H2 controller,collocated structural systems

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00030

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 178-183

Authors: Yagoubi, Mohamed; Chevrel, Philippe; Claveau, Fabien

Abstract: This paper investigates the design of an "extended" state-feedback H2 controller for continuous-time descriptor systems. In such problem, the controller, which is in descriptor form, is found such that: - The closed-loop transfer matrix is strictly proper and has minimum H2-norm. - Only the internal stability of the physical system (and not the overall descriptor standard model) is required. An explicit characterization of the solution based on a generalized algebraic Riccati equation and two Sylvester equations is given. Under some additional assumptions, a LMI-based solution is proposed. A numerical example is also included to show the applicability of the proposed results.

Keywords: descriptor systems,H2 control,generalized algebraic Riccati equation,LMI

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00064

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 386-391

Authors: Ozgoli, Sadjaad; Turner, Matthew C.

Abstract: This paper considers the design of fuzzy error governors for multivariable systems subject to input saturation. Improvements are made to an existing fuzzy error governor, which expands the class of systems to which the technique can be applied. The various fuzzy techniques are then compared to some existing anti-windup techniques where it is demonstrated, through simulation, that the fuzzy schemes can deliver comparable performance to the "optimal" anti-windup schemes.

Keywords: constrained control,saturation control,anti windup,fuzzy,actuators

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00084

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 524-529

Authors: Kurina, G.; Nekrasova, N.

Abstract: The asymptotic expansion of the solution of a nonlinear discrete optimal control problem for one class of weakly controllable systems is constructed as series of non-negative integer powers of a small parameter. The estimates are obtained for the closeness of the approximate solutions to the exact one and it is proved that the values of the minimized functional do not increase when higher-order approximations for the optimal control are used.

Keywords: asymptotic approximation,discrete-time systems,optimal control

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00057

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 344-349

Authors: Perez-Cruz, J. Humberto; Poznyak, Alexander

Abstract: In this paper, the automatic startup of a nuclear reactor subjected to period scram constraint is considered. To achieve this operation in a minimum time avoiding the difficulties associated with the application on-line of maximum principle or dynamic programming, first the optimal trajectory is calculated off-line. Next, the nuclear plant considered as a black box is identified by a differential neural network. The structure provided by this neural identifier is fed back to follow the optimal trajectory. The modeling error is compensated by the usage of the power derivative. Thus, the asymptotic stability of the tracking error can be guaranteed.

Keywords: nuclear reactor,differential neural network,constrained control

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00019

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 112-117

Authors: Lam, H. K.; Seneviratne, L. D.

Abstract: This paper presents the stability and performance design of fuzzy-model-based control systems subject to parameter uncertainties. A nonlinear controller with a favorable characteristic to relax the stability conditions is proposed to drive the system states of the nonlinear plant to follow those of a stable reference model. Stability and performance conditions in terms of bilinear matrix inequalities are derived based on a Lyapunov-based approach. A genetic-based convex programming technique process is developed to solve the solution to the bilinear matrix inequalities. An application example is given to show the merits of the proposed approach.

Keywords: fuzzy control,stability

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00014

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 82-87

Authors: Santos, Valerie Dos; Prieur, Christophe

Abstract: The problem of stability of the non-linear Saint-Venant equations stated by two conservation laws perturbed by non-homogeneous terms is presented. Under some assumptions on those non-homogeneous functions, previous results on the stability of two conservation laws are developed using the Riemann coordinates approach. This stability result applied to the regulation of the water flow and level of the shallow water equations is validated by simulations and experimentations on a real river data and a micro-channel respectively.

Keywords: stability,Saint-Venant equations,non-linear system of conservation laws,Riemann coordinates

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00110

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 679-684

Authors: Verde, C.; Gentil, S.; Sanchez-P, M.

Abstract: This paper discusses some issues associated to the generation of the residual structure for fault detection and isolation using graph theory tools. It is shown that the residual structure of a causal dynamic system is as well causal, since a complete matching is only manipulation of internal variables of the graph. Then, no additional conditions are required during the matching process to get causal analytical redundancy relations. Moreover, the consideration that at least a pair of known variables, cause-effect, is necessary for each matching reduces substantially the number of cases which allows to span the residual structure.

Keywords: causal structural analysis,complete matching,residual structure,fault detection and isolation

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00088

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 548-553

Authors: Araujo, Jose M.; Castro, Alexandre C.; Silva, Fabricio G. S.; Santos, Eduardo T. F.; Dorea, Carlos E. T.

Abstract: State feedback is a modern control technique that, amongst diverse applications, is distinguished by its arbitrary pole-placement of a controllable, linear time-invariant system. This benefit brings a series of consequences, such as the stabilization of a system or designing control using one single technique. On the other hand, the state-derivative feedback was introduced later, and it is capable to arbitrarily place poles, with some restrictions in particular cases. This work aims to establish a comparative study between these two techniques, from the point of view of simple, but important concepts in control theory, as well as confirming some relations between respective advantages from these two techniques.

Keywords: linear systems,state feedback,state-derivative feedback,pole-placement

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00005

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 28-33

Authors: de Oliveira, Vincius Menezes; Lages, Walter Fetter

Abstract: In this paper we present the control of an underactuated brachiation robot with only one unactuated joint using the nonlinear model based predictive approach for the motion control. The robot used has 3 links, i. e., two arms and a body. We adopt the MPC to control the underactuated brachiation robot due to its advantages, mainly the construction of an optimal stabilizing control law and due to its ability to consider, in a direct way, the constraints into the optimization problem. At the end we present computational simulations with their respective results and we highlight some important considerations.

Keywords: underactuated nonlinear systems,brachiation robot,NMPC

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00068

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 430-435

Authors: Vargas, Alessandro N.; Furloni, Walter; do Val, Joao B. R.

Abstract: This paper presents necessary optimality conditions for the control problem of discrete-time Markov jump linear systems (MJLS) with linear feedback gains, subject to constraints on the system state and input control variables. Instead of hard, deterministic constraints, the constraints considered here are given in terms of the first and second moments of the state and input variables, thus adequate to in the stochastic setting. The jumping state of the Markov chain and the continuous part of the MJLS are assumed to be accessible to the controller. The necessary conditions are derived and they are attained numerically by means of a method that iteratively performs a variational search using a set of LMI's. It searches through monotonically decreasing costs and converges to a sequence of feedback gains that satisfies the optimality conditions. The usefulness of the method is illustrated by a numerical example.

Keywords: Markov jump linear systems,state and input constraints,variational method

Digital Object Identifier (DOI): 10.3182/20071017-3-BR-2923.00042

Conference: 3rd IFAC Symposium on Power System, Structure and Control (2007)

Location: Mabu Thermas Convention Center, Brazil

Start Date: Wed Oct 17 2007 - End Date: Fri Oct 19 2007

Page Numbers: 250-255