- Email: [email protected]
Hybrid Systems and Applications
Nonlinear Analysis 65 (2006) 1103–1105 www.elsevier.com/locate/na
Editorial
Hybrid Systems and Applications Hybrid systems have become a very active research area in recent years. Dynamic systems are termed hybrid if they contain both continuous dynamics (usually described by differential equations) and discrete elements, from simple switching logic to complex computer programs for control, supervision, redundancy management etc. Almost all technical systems are in fact hybrid systems, but in the past this aspect has mostly been abstracted away, and the systems were considered as either purely continuous or as purely discrete. Hybrid systems pose many challenging problems and exhibit very complex dynamics. The treatment of hybrid systems requires knowledge and tools both from the area of continuous dynamics and control, and from computer science which has since long developed formalisms for treating discrete dynamic systems. For this special issue, the authors of nine papers related to different aspects of Hybrid Systems were initially invited to submit an original paper presenting their newest results, related to their presentation at the IFAC World Conference held in Prague, Czech Republic, in July 2005. Also, four papers were directly solicited by the Guest Editor. These submissions were carefully reviewed, and eight of them are accepted for inclusion in this special issue, while two others will appear in the following issue. The area of hybrid systems research can be structured into the areas of modelling and design, verification, and synthesis. Modelling and design on the one hand is concerned with the faithful representation and userfriendly (i.e. modular and partly graphical) modelling of complex continuous–discrete systems as they arise in real applications. The first paper in this issue, “Hybrid port–Hamiltonian systems: from parametrized incidence matrices to hybrid automata” by Valentin, Magos and Maschke, is a representative of this area of research. On the other hand, general formalisms are sought which can represent important features of hybrid systems in a unified framework. Prominent examples are Petri nets. The second paper, “Hybrid stochastic approach for the modelling and analysis of fire safety systems” by Villani, Kaneshiro and Miyagi, presents an approach for modelling and analysis of fire safety systems on the basis of Petri nets associated with algebraic and differential equations, and Monte Carlo simulation. Many verification and control synthesis techniques of hybrid systems are based on model abstraction to reduce the computation complexity of the analysis of the reachable state space. Lefebvre and Gu´eguen in their paper consider the problem of building a set of hybrid abstractions for affine systems in order to compute over approximations of the reachable space. The paper by Stursberg proposes a different approach, based on model abstraction and guided search for an efficient synthesis of supervisory control. In contrast, the paper by Seatzu et al. uses discrete c 2005 Elsevier Ltd. All rights reserved. 0362-546X/$ - see front matter doi:10.1016/j.na.2005.12.011
1104
Editorial / Nonlinear Analysis 65 (2006) 1103–1105
abstractions to address an optimal control problem for a class of discrete-time hybrid automata under safety and liveness constraints. The next two papers also investigate the issue of optimal control design for hybrid systems. The approach proposed by Pang, Spathopoulos and Xia is based on the use of model predictive control, whereas Lin, Zhai and Antsaklis investigate the problem of optimal persistent disturbance attenuation control for linear hybrid systems. Finally, the paper by Yu and Cassandras considers the problem of perturbation analysis of communication networks with feedback control using stochastic hybrid models. The two papers that will appear in the following issue deal with switching systems, which represent another important class of hybrid systems. The application paper “Digital idle speed control of automotive engines: a safety problem for hybrid systems”, by De Santis, Di Benedetto and Pola is a representative of this area of research with abrupt switching between controllers. In contrast, the paper by Essounbouli et al. uses a fuzzy hybrid supervisor to guarantee a smooth combination of controllers instead of abrupt switching between them. The papers in the special issue show that hybrid systems theory not only is a vibrant and growing area of scientific research but also has meanwhile generated results and techniques which can be applied successfully to real-world problems and in helping to develop control and automation systems in a more systematic and less failure-prone fashion. Last but not least, I am grateful to the reviewers for their valuable assistance and contribution to the reviewing process for this special issue. List of Papers of the Special issue J. Zaytoon Editorial C. Valentin, M. Magos, B. Maschke, Hybrid port–Hamiltonian systems: From parametrized incidence matrices to hybrid automata E. Villani, P.J.I. Kaneshiro, P.E. Miyagi, Hybrid stochastic approach for the modelling and analysis of fire safety systems M.-A. Lefebvre, H. Gu´eguen, Hybrid abstractions of affine systems O. Stursberg, Supervisory control of hybrid systems based on model abstraction and guided search C. Seatzu, D. Gromov, E. Mayer, J. Raisch, D. Corona, A. Giua, Optimal control of discrete-time hybrid automata under safety and liveness constraints Y. Pang, M.P. Spathopoulos, H. Xia, Suboptimal control for target problems of hybrid automata using model predictive control H. Lin, G. Zhai, P.J. Antsaklis, Optimal persistent disturbance attenuation control for linear hybrid systems H. Yu, C.G. Cassandras, Perturbation analysis of communication networks with feedback control using stochastic hybrid models
Editorial / Nonlinear Analysis 65 (2006) 1103–1105
1105
Papers to appear in the following issue: N. Essounbouli, N. Manamanni, A. Hamzaoui, J. Zaytoon, Switching controllers’ synthesis using a fuzzy supervisor approach E. De Santis, M.D. Di Benedetto, G. Pola, Digital idle speed control of automotive engines: A safety problem for hybrid systems Guest Editor Janan Zaytoon ∗ University of Reims, France E-mail address: [email protected].
∗
Tel.: +33 3 2691 3226; fax: +33 3 2691 3106.
Editorial
Hybrid Systems and Applications Hybrid systems have become a very active research area in recent years. Dynamic systems are termed hybrid if they contain both continuous dynamics (usually described by differential equations) and discrete elements, from simple switching logic to complex computer programs for control, supervision, redundancy management etc. Almost all technical systems are in fact hybrid systems, but in the past this aspect has mostly been abstracted away, and the systems were considered as either purely continuous or as purely discrete. Hybrid systems pose many challenging problems and exhibit very complex dynamics. The treatment of hybrid systems requires knowledge and tools both from the area of continuous dynamics and control, and from computer science which has since long developed formalisms for treating discrete dynamic systems. For this special issue, the authors of nine papers related to different aspects of Hybrid Systems were initially invited to submit an original paper presenting their newest results, related to their presentation at the IFAC World Conference held in Prague, Czech Republic, in July 2005. Also, four papers were directly solicited by the Guest Editor. These submissions were carefully reviewed, and eight of them are accepted for inclusion in this special issue, while two others will appear in the following issue. The area of hybrid systems research can be structured into the areas of modelling and design, verification, and synthesis. Modelling and design on the one hand is concerned with the faithful representation and userfriendly (i.e. modular and partly graphical) modelling of complex continuous–discrete systems as they arise in real applications. The first paper in this issue, “Hybrid port–Hamiltonian systems: from parametrized incidence matrices to hybrid automata” by Valentin, Magos and Maschke, is a representative of this area of research. On the other hand, general formalisms are sought which can represent important features of hybrid systems in a unified framework. Prominent examples are Petri nets. The second paper, “Hybrid stochastic approach for the modelling and analysis of fire safety systems” by Villani, Kaneshiro and Miyagi, presents an approach for modelling and analysis of fire safety systems on the basis of Petri nets associated with algebraic and differential equations, and Monte Carlo simulation. Many verification and control synthesis techniques of hybrid systems are based on model abstraction to reduce the computation complexity of the analysis of the reachable state space. Lefebvre and Gu´eguen in their paper consider the problem of building a set of hybrid abstractions for affine systems in order to compute over approximations of the reachable space. The paper by Stursberg proposes a different approach, based on model abstraction and guided search for an efficient synthesis of supervisory control. In contrast, the paper by Seatzu et al. uses discrete c 2005 Elsevier Ltd. All rights reserved. 0362-546X/$ - see front matter doi:10.1016/j.na.2005.12.011
1104
Editorial / Nonlinear Analysis 65 (2006) 1103–1105
abstractions to address an optimal control problem for a class of discrete-time hybrid automata under safety and liveness constraints. The next two papers also investigate the issue of optimal control design for hybrid systems. The approach proposed by Pang, Spathopoulos and Xia is based on the use of model predictive control, whereas Lin, Zhai and Antsaklis investigate the problem of optimal persistent disturbance attenuation control for linear hybrid systems. Finally, the paper by Yu and Cassandras considers the problem of perturbation analysis of communication networks with feedback control using stochastic hybrid models. The two papers that will appear in the following issue deal with switching systems, which represent another important class of hybrid systems. The application paper “Digital idle speed control of automotive engines: a safety problem for hybrid systems”, by De Santis, Di Benedetto and Pola is a representative of this area of research with abrupt switching between controllers. In contrast, the paper by Essounbouli et al. uses a fuzzy hybrid supervisor to guarantee a smooth combination of controllers instead of abrupt switching between them. The papers in the special issue show that hybrid systems theory not only is a vibrant and growing area of scientific research but also has meanwhile generated results and techniques which can be applied successfully to real-world problems and in helping to develop control and automation systems in a more systematic and less failure-prone fashion. Last but not least, I am grateful to the reviewers for their valuable assistance and contribution to the reviewing process for this special issue. List of Papers of the Special issue J. Zaytoon Editorial C. Valentin, M. Magos, B. Maschke, Hybrid port–Hamiltonian systems: From parametrized incidence matrices to hybrid automata E. Villani, P.J.I. Kaneshiro, P.E. Miyagi, Hybrid stochastic approach for the modelling and analysis of fire safety systems M.-A. Lefebvre, H. Gu´eguen, Hybrid abstractions of affine systems O. Stursberg, Supervisory control of hybrid systems based on model abstraction and guided search C. Seatzu, D. Gromov, E. Mayer, J. Raisch, D. Corona, A. Giua, Optimal control of discrete-time hybrid automata under safety and liveness constraints Y. Pang, M.P. Spathopoulos, H. Xia, Suboptimal control for target problems of hybrid automata using model predictive control H. Lin, G. Zhai, P.J. Antsaklis, Optimal persistent disturbance attenuation control for linear hybrid systems H. Yu, C.G. Cassandras, Perturbation analysis of communication networks with feedback control using stochastic hybrid models
Editorial / Nonlinear Analysis 65 (2006) 1103–1105
1105
Papers to appear in the following issue: N. Essounbouli, N. Manamanni, A. Hamzaoui, J. Zaytoon, Switching controllers’ synthesis using a fuzzy supervisor approach E. De Santis, M.D. Di Benedetto, G. Pola, Digital idle speed control of automotive engines: A safety problem for hybrid systems Guest Editor Janan Zaytoon ∗ University of Reims, France E-mail address: [email protected].
∗
Tel.: +33 3 2691 3226; fax: +33 3 2691 3106.