Authors: None

Abstract:

Keywords:

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00001

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: c1-c1

Authors: None

Abstract:

Keywords:

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00076

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: c4-c4

Authors: C. G. Cassandras; A. Giua; C. Seatzu; J. Zaytoon

Abstract:

Keywords:

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00002

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: V-V

Authors: Vadim Utkin; Hoon Lee

Abstract: In practical applications of sliding mode control, engineers may experience undesirable phenomenon of oscillations having finite frequency and amplitude, which is known as 'chattering'. At the first stage of sliding mode control theory development the chattering was the main obstacle for its implementation. Chattering is a harmful phenomenon because it leads to low control accuracy, high wear of moving mechanical parts, and high heat losses in power circuits. There are two reasons which can lead to chattering. • The chattering can be caused by fast dynamics which were neglected in the ideal model. These 'unmodeled' dynamics with small time constants are usually disregarded in models of servomechanisms, sensors and data processors. • The second reason of chattering is utilization of digital controllers with finite sampling rate, which causes so called 'discretization chatter'. Theoretically the ideal sliding mode implies infinite switching frequency. Since the control is constant within a sampling interval, switching frequency can not exceed that of sampling, which lead to chattering as well. Mechanism of chattering generating is demonstrated for control of inverted an pendulum with unmodeled actuator dynamics

Keywords:

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00003

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 1-1

Authors: Alberto Sangiovanni Vincentelli

Abstract: Embedded controllers are essential in today electronic systems to assure that the behaviour of complex systems as cars, airplanes, trains, building security management systems, is compliant to strict safety constraints. I will review the evolution of embedded systems and the challenges that must be faced in their design. I will also present methodologies aimed at simplifying and speeding the design process. The role of hybrid systems in the development of embedded controllers will be outlined. Future applications such as wireless sensor networks in an industrial plant will also be presented.

Keywords: embedded systems,systems design,systems methodology,control applications,distributed control

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00004

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 2-3

Authors: Claude Iung; Pierre Riedinger

Abstract: Necessary conditions for optimality have been established for hybrid systems. Unfortunately, these conditions lead to multi-point boundary value problems and they do not prevent from the combinatorial explosion when no constraints are given on the transitions. Different approaches have been proposed to approximate the solution, such as relaxed dynamic programming, non linear programming and sensitivity functions.

Keywords: hybrid systems,optimal control,sensitivity functions

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00005

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 4-5

Authors: R. A. van den Berg; A. Y. Pogromsky; J. E. Rooda

Abstract: This paper deals with the design of switching rules for switched linear systems with inputs, in such a way that the resulting closed-loop system is exponentially convergent. Two types of switching rules are addressed, that is state-based and observer-based rules. The developed theory is illustrated by two examples.

Keywords: convergent systems,switched systems,continuous time systems,exponential stability,performance evaluation,observer

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00006

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 6-11

Authors: Abderazik Birouche; Jamal Daafouz; Claude Iung

Abstract: In this paper we consider a class of discrete time piecewise-linear systems composed by linear discrete time LTI subsystems with autonomous switching. The aim is to propose a method for the synthesis of a hybrid observer. The approach proposed here consists on the combination of a discrete observer and a continuous observer. It is shown that under conditions related to minimum dwell time of each mode, one can express the switching law as a linear combination of the system input/output samples. The continuous observer is a piecewise-linear observer whose dynamics depend on the current active mode. Two estimation schemes are analyzed : on-line estimation and off-line estimation.

Keywords: hybrid systems,observer design,piecewise-linear affine systems

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00007

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 12-17

Authors: Stefan Pettersson

Abstract: In this paper, observers are synthesized for switched linear systems, resulting in switched observers including state jumps. The synthesis problem involves multiple Lyapunov functions and is formulated as a linear matrix inequality problem. It is assumed that the current mode (active dynamics) of the switched linear is unknown, and it will be shown that the estimate of the continuous states will be bounded at worst, if the mode is wrongly estimated. If the active dynamics is estimated correctly within a certain time, and the dwell time of the switched linear system is lower bounded, it will be shown that the bound of the estimation error can be reduced significantly.

Keywords: switched systems,hybrid systems,observer design,linear matrix inequalities (LMI),Lyapunov stability

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00008

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 18-23

Authors: M. D. Di Benedetto; S. Di Gennaro; A. D'Innocenzo

Abstract: The analysis of error propagation in an Air Traffic Management (ATM) environment is addressed. The theory of Hybrid Systems is used to model the error evolution, an observability problem for a Markov Chain with discrete output symbols associated to the transitions is stated, and a runtime observer is proposed for estimating the probability of a given discrete state to be active. Sufficient conditions are given for characterizing the decidability of the addressed observability problem. The results are related to previous works on location observability of deterministic hybrid systems, and are used to analyze an ATM case study, the "clearance to change the flight plan".

Keywords: failure detection,Markov chains,air traffic management

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00009

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 24-29

Authors: Jing Xu; Laura Recalde; Manuel Silva

Abstract: A new low-and-high gain algorithm is presented for tracking control of timed continuous Petri Net (contPN) systems working under infinite servers semantics. The inherent properties of timed contPN determine that the control signals must be non-negative and upper bounded by functions of system states. In the proposed control approach, LQ theory is first utilized to design a low-gain controller such that the control signals satisfy the input constraints. Based on the low-gain controller, a high-gain term is further added to improve the system transient performance. In order to guarantee global tracking convergence and smoothness of control signals, in our work, a new mixed tracking trajectory (state step and ramp) is utilized instead of a pure step reference signal.

Keywords:

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00010

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 30-36

Authors: Cristian Mahulea; Alessandro Giua; Laura Recalde; Carla Seatzu; Manuel Silva

Abstract: This paper addresses a sampling problem for timed continuous Petri nets under infinite servers semantics. Different representations of the continuous Petri net system are given, the first two in terms of piecewise linear system and the third one, for the controlled continuous Petri nets systems, in terms of a particular linear constrained system with null dynamic matrix. The last one is used to obtain the discrete-time representation. An upper bound on sample period is given in order to preserve important information of timed continuous nets, in particular the positiveness of the markings. The reachability space of the sampled system in relation to autonomous continuous Petri nets is also studied.

Keywords: Petri-nets,continuous-time systems,discrete-time systems

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00011

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 37-43

Authors: Mariagrazia Dotoli; Maria Pia Fanti; Agostino Marcello Mangini

Abstract: A Distributed Manufacturing System (DMS) is a collection of independent companies possessing complementary skills and integrated with transportation and storage systems. This paper proposes a new model for DMS employing first order hybrid Petri nets, i.e., Petri nets based on first order fluid approximation. More precisely, transporters and manufacturers are described by continuous transitions, buffers are continuous places and products are represented by continuous flows routing from manufacturers, buffers and transporters. Moreover, discrete events occurring stochastically in the system are considered to take into account the start of the retailer requests and the blocking of transports and raw material supply. With the aim of showing the model effectiveness, a DMS example is modelled and simulated under two different operative conditions.

Keywords: manufacturing systems,Petri-nets,dynamic models,simulation,performance indices

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00012

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 44-49

Authors: Fateh Kaakai; Said Hayat; Abdellah El Moudni

Abstract: The purpose of this paper is to present a simulation model for Railway Stations (RS). Firstly, through a systemic description, we have shown that a RS can be considered as a Hybrid Dynamical System (HDS). Then, in order to represent the main intrinsic characteristics of RS, we have built a hybrid Petri net-based model. This model has been analyzed for i) checking purposes, and ii) evaluating some qualitative properties of the system. Finally, for illustrating the suggested methodology of study, a typical subway station has been simulated through a rush period scenario. Owing to a quantitative analysis of the marking evolution of the hybrid model, it is possible to make a performance evaluation of the station facilities and to underline some structural and functional limits of the studied station.

Keywords: transport,stations,hybrid,Petri-nets,model,performance evaluation,design

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00013

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 50-55

Authors: Pieter J. L. Cuijpers; Michel A. Reniers

Abstract: We analyze a control strategy for the pick-and-place module of a component mounting device. We use a combination of techniques from bondgraphtheory, systems theory, process algebra and differential algebra to achieve this, and we show how the hybrid process algebra HyPA aides us in combining these techniques and in using them on a common hybrid model of the device.

Keywords: hybrid systems,process algebra,bondgraph theory,impact control

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00014

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 56-63

Authors: Tatsuya Suzuki; Shinkichi Inagaki; Naoyuki Yamada

Abstract: This paper presents a modeling and analysis strategy of human skill based on stochastic switched dynamics. As a fundamental mathematical model, the Stochastic Switched ARX model (SS-ARX model) is introduced. Then the modeling and analysis strategy of human skill is proposed based on the stochastic switched impedance model which can be regarded as one of the SS-ARX model. Finally, the developed strategy is applied to peg-in-hole task which involves interesting dexterous human skill, and the effectiveness of the proposed strategy is discussed.

Keywords: human skill,switched impedance model,parameter estimation

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00015

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 64-70

Authors: Christopher D. Beers; Eric-Jan Manders; Gautam Biswas; Pieter J. Mosterman

Abstract: Embedded systems and their corresponding hybrid models are pervasive in engineering applications, therefore, systematic mathematical analysis using these models has become an important research area. Our approach to hybrid modeling with Hybrid Bond Graphs allows for seamless integration of physical system principles with discrete computational structures, but simulating the hybrid behaviors can be difficult and computationally expensive. In this paper, we develop a methodology that transforms Hybrid Bond Graphs into computational block diagrams and incrementally modifies the block diagram when mode changes occur. This forms the basis for a computationally efficient hybrid simulation algorithm.

Keywords: hybrid bond graphs,causality,hybrid systems,simulation

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00016

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 71-76

Authors: Dario Bauso; Franco Blanchini; Raffaele Pesenti

Abstract: In this paper we consider multi-inventory systems in presence of uncertain demand. We assume that i) demand is unknown but bounded in an assigned compact set and ii) the control inputs (controlled flows) are subject to assigned constraints. Given a long-term average demand, we select a nominal flow that feeds such a demand. In this context, we are interested in a control strategy that meets at each time all possible current demands and achieves the nominal flow in the average. We provide necessary and sufficient conditions for such a strategy to exist and we characterize the set of achievable flows. Such conditions are based on linear programming and thus they are constructive. In the special case of a static flow (i.e. a system with 0-capacity buffers) we show that the strategy must be affine. The dynamic problem can be solved by a linear-saturated control strategy (inspired by the previous one). We provide numerical analysis and illustrating examples.

Keywords: inventory control,robust control,bounded disturbances,manufacturing systems,linear programming

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00017

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 77-82

Authors: F. Bacconi; A. Casavola; E. Mosca

Abstract: This paper proposes a centralized solution to the problem of formation reconfiguration and keeping for fleets of satellites in the presence of persistent disturbances and under input-saturation and formation accuracy constraints. Relative position and attitude dynamics are considered. For suitable initial conditions the proposed control scheme produces system evolutions that fulfill the coordination constraints at any time and satisfy desirable control performance. This is accomplished by using a bank of Command Governor units in a hybrid framework. An example is provided in order to exhibit the effectiveness of the technique.

Keywords: formation flying control,leader following,saturation constraints,accuracy constraints,hybrid command governor

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00018

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 83-88

Authors: Vadim Azhmyakov; Jorg Raisch

Abstract: We investigate optimal control problems for a class of non-stationary hybrid systems with autonomous location transitions. Using the Lagrange approach and the technique of the reduced gradient, we derive necessary optimality conditions for the considered class of problems. These optimality conditions are closely related to a variant of the Hybrid Maximum Principle and can be used for constructive optimization algorithms.

Keywords: hybrid systems,optimal control,computational algorithms

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00019

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 89-94

Authors: Henrik Axelsson; Mauro Boccadoro; Yorai Wardi; Magnus Egerstedt

Abstract: This paper concerns an optimal control problem defined on a class of switchedmode hybrid dynamical systems. Such systems change modes whenever the state intersects certain surfaces that are defined in the state space. These switching surfaces are parameterized by a finite dimensional vector called the switching parameter. The optimization problem we consider is to minimize a given cost-functional with respect to the switching parameter under the assumption that the initial state of the system is not completely known. Instead, we assume that the initial state can be anywhere in a given set. We will approach this problem by minimizing the worst possible cost over the given set of initial states using results from minimax optimization. The results are then applied in order to solve a navigation problem in mobile robotics.

Keywords: hybrid systems,switching modes,optimal control,gradient descent,numerical algorithms,minimax techniques,mobile robotics

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00020

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 95-100

Authors: Mauro Boccadoro; Magnus Egerstedt; Paolo Valigi; Yorai Wardi

Abstract: In this paper we report of a technique to design optimal feedback control laws for hybrid systems with autonomous (continuous) modes. Existing techniques design the optimal switching surfaces based on a singular sample evolution of the system; hence providing a solution dependent on the initial conditions. On the other hand, the optimal switching times can be found, providing an an open loop control to the system, but those also are dependent on the initial conditions. The technique presented relies on a variational approach, giving the derivative of the switching times with respect to the initial conditions, thus providing a tool to design programs/algorithms generating switching surfaces which are optimal for any possible execution of the system.

Keywords: hybrid systems,switching surfaces,optimal control,variational methods

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00021

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 101-105

Authors: Antoine Girard; A. Agung Julius; George J. Pappas

Abstract: Approximate simulation relations have recently been introduced as a powerful tool for the approximation of discrete and continuous systems. In this paper, we extend this notion to hybrid systems. Using the so-called simulation functions, we develop a computationally effective characterization of approximate simulation relations which can be used for hybrid systems approximation. An example of application in the context of safety verification is shown.

Keywords: approximation of hybrid systems,approximate simulation relation

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00022

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 106-111

Authors: Elena De Santis; Maria Domenica Di Benedetto; Giordano Pola

Abstract: In this paper, we focus on a particular subclass of hybrid systems, the class of linear switching systems. We propose hybrid state space decompositions, based on hybrid invariant subspaces, which reduce the computational effort required for checking the structural property of asymptotic stabilizability.

Keywords: switching systems,asymptotic stabilizability,state space reduction,Kalman decomposition

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00023

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 112-117

Authors: Othman Nasri; Marie-Anne Lefebvre; Herve Gueguen

Abstract: Reachability computation is the central problem arising in the verification of hybrid or continuous systems. One approach, among others, to compute an over approximation of the reachable space is to split the continuous state space and to abstract the continuous dynamics in each resulting cell by a linear differential inclusion for which the reachable space may be computed with polyhedra. A previous work proposed to use characteristics of the affine continuous dynamics to guide the polyhedral partition. This paper presents an extension of this approach to uncertain planar systems where one parameter of the model may take its value in a polytope. It is shown that the result for all values of the parameter may be deduced from the computation for a finite number of values. An algorithm that performs the reachability computation and determines the minimum number of values of the parameter required at each step is proposed and exemplified.

Keywords: hybrid systems,reachability,abstractions

Digital Object Identifier (DOI): 10.3182/20060607-3-IT-3902.00024

Conference: 2nd IFAC Conference on Analysis and Design of Hybrid Systems, 2006

Location: Hotel Calabona, Italy

Start Date: Wed Jun 07 2006 - End Date: Fri Jun 09 2006

Page Numbers: 118-123