Research On Modeling And Control Based On Cyber Net Systems

Petri net was first proposed by Professor Carl Adam Petri in his doctoral dissertation in 1962.It is an important tool for modeling,analyzing and controlling discrete event dynamic systems.Through integrating with technologies and methods from different disciplines,Petri net theory is widely used and continuously improved.The cyber net system is a special type of high-level Petri net obtained by further adding the control mechanism,which has stronger description ability than the ordinary Petri net.The introduction of cyber net system not only fills the gap between Petri net theory and modern control theory,but also promotes the integration and reference between the two,meanwhile expands the research field of Petri nets.Based on the theory of cyber net system,the dissertation conducts in-depth discussion and research on the modeling,analysis and control applications of cyber net systems through a combination of related techniques and methods in graph theory,neural network and modern control theory.The main work and innovations of this dissertation are as follows:(1)The definitions of cyber net system and its extension are introduced.The properties of the generalized continuous cyber net system and hybrid cyber net system are analyzed.Cases of modeling discrete systems,continuous systems and hybrid systems using these extended cyber net systems are given,which demonstrate that cyber net systems have important theoretical research significance and extensive applicability.Based on the analysis of the existing Petri net software tools,a modeling tool supporting cyber net systems is designed and developed by using object-oriented technology.The developed software supports the modeling,dynamic properties and static properties analysis of various types of cyber net system models,as well as the functional simulation and VHDL code generation of digital system modeled by generalized synchronous cyber net system,as a result providing a powerful supporting tool for subsequent applications of cyber net system.The developed tool provides a powerful software platform for subsequent applications of cyber net system.(2)The method of modeling a class of hybrid system-switched system based on hybrid cyber net system is studied.For general switched systems,discrete dynamics and continuous dynamics are respectively mapped to the discrete and continuous parts of hybrid cyber net system model.Based on the hybrid cyber net system model of switched linear system,analysis methods of structural controllability,stability and reachability are proposed respectively.Firstly,aiming to determine the structural controllability of switched linear systems,through the mapping of hybrid cyber net system model to colored union graph and using the graph theoretic criterion of structural controllability,the condition for determining the structural controllability on the hybrid cyber net system model is arriaved.Secondly,on the stability analysis of periodically switched linear systems,according to the conclusion that the stability of periodically switched linear systems is the same as that of equivalent non-switched linear systems,based on the hybrid cyber net system model of the periodic switched linear system,the state matrix characteristic polynomial of the equivalent linear system is calculated by the graph theoretic method,and then the stability of the original system is determined.Lastly,a new approach for reachability analysis of switched linear systems is proposed,which combines the modeling ability of hybrid cyber net system with the analysis ability of hybrid automata.By transforming the hybrid cyber net system model to hybrid automata model,and using the mature hybrid automata analysis tools,the system reachability set can be obtained.(3)Two classes of decoupling control methods based on cyber net system are studied.In order to decouple linear systems,a generalized continuous cyber net system model for a linear time-invariant controlled system is established.Based on the state feedback dynamic decoupling principles,a simple and effective method for judging the decouplability of the system and achieving the decoupling control law is proposed by using the graphical structure of the model.In the decoupling control of nonlinear multivariable system,by utilizing the controlled characteristics of arc weight and the firing rules of cyber net system,the generalized cyber net system model of PID controller is established.By introducing learning mechanism into the model,the system control and parameter learning can be unified,and the learning process of different parameters can be executed in parallel,making it easy to implement with FPGA.Based on the principle of single neuron PID decoupling control,the decoupling control of nonlinear system based on generalized cyber net system model is realized.(4)The method of achieving controller in hybrid control system under the unified framework of cyber net system is studied.The supervisor and digital controllers' models are designed based on the generalized synchronous cyber net system.In the proposed method,Petri nets are not only used for high level discrete decision-making,but also for direct physical control of controlled objects.In order to support the hardware implementation of the cyber net system controller,a solution based on the platform of FPGA programmable logic device is proposed.By using multi-input multi-clock D flip-flop with priority,the conversion algorithm from generalized synchronous cyber net system model to VHDL code is designed,and the implementation of generalized synchronous cyber net system model on the FPGA is completed,which also provides a solution for the design and implementation of asynchronous concurrent system.