This paper deals with the synthesis of Petri net supervisor enforcing the more expressive constraints including marking terms, firing vector terms and Parikh vector terms. The method is developed to handle uncontrolla...This paper deals with the synthesis of Petri net supervisor enforcing the more expressive constraints including marking terms, firing vector terms and Parikh vector terms. The method is developed to handle uncontrollable and unobservable transitions existing in the constraints. The “greater-than or equal” general constraints can also be transformed into “less-than or equal” Parikh constraints. An example is analyzed to show how the problem is solved. General constraint is first transformed into Parikh vector constraints, and Matrix-Transformation is proposed to obtain the admissible constraints without uncontrollable and unobservable transitions. Then the supervisor can be constructed based on constraints only consisting of Parikh vector terms. The method is proved to be more concise and effective than the method presented by Iordache and Moody especially when applied to large scale systems.展开更多
In this paper, a new reliable hierarchical model is suggested for a two-wagon train Networked Control System. Each wagon has a Controller that carries the control load and an Entertainment server that handles the ente...In this paper, a new reliable hierarchical model is suggested for a two-wagon train Networked Control System. Each wagon has a Controller that carries the control load and an Entertainment server that handles the entertainment. A supervisory controller runs on top of the two controllers and the two entertainment servers. Contrary to a similar model in the literature, the Supervisory node replaces a Controller as soon as it fails (Active Supervisor). All system states are analyzed and simulated using OPNET. It is shown that, for all states, this architecture has zero control packets dropped and the end-to-end delay is below the maximum target delay. A comparison between this Active model and the other model in the literature is presented. It is found that the entertainment in this new architecture is kept available for the passengers in more of the system states when compared to the architecture previously presented in the literature.展开更多
当系统存在较大扰动时,锅炉的变量如蒸汽压力和汽包水位都会产生较大的波动。简单的底层控制器消除这种波动的效果不太理想。提出了两层结构控制方法来改善系统的性能。底层控制采用基于DCS(Distributed control systems)系统的预测PID...当系统存在较大扰动时,锅炉的变量如蒸汽压力和汽包水位都会产生较大的波动。简单的底层控制器消除这种波动的效果不太理想。提出了两层结构控制方法来改善系统的性能。底层控制采用基于DCS(Distributed control systems)系统的预测PID控制方法,根据当前的工况,蒸汽压力和水位的设定点由基于模糊理论的监控层给出。针对一个具体的锅炉系统,改进后的方法其控制性能和经济目标均有了很大的改善。展开更多
基金Project supported by the National Natural Science Foundation of China (No. 60504024), Zhejiang Provincial Education Department(No. 20050905), and "151 Talent Project" of Zhejiang Province,China
文摘This paper deals with the synthesis of Petri net supervisor enforcing the more expressive constraints including marking terms, firing vector terms and Parikh vector terms. The method is developed to handle uncontrollable and unobservable transitions existing in the constraints. The “greater-than or equal” general constraints can also be transformed into “less-than or equal” Parikh constraints. An example is analyzed to show how the problem is solved. General constraint is first transformed into Parikh vector constraints, and Matrix-Transformation is proposed to obtain the admissible constraints without uncontrollable and unobservable transitions. Then the supervisor can be constructed based on constraints only consisting of Parikh vector terms. The method is proved to be more concise and effective than the method presented by Iordache and Moody especially when applied to large scale systems.
文摘In this paper, a new reliable hierarchical model is suggested for a two-wagon train Networked Control System. Each wagon has a Controller that carries the control load and an Entertainment server that handles the entertainment. A supervisory controller runs on top of the two controllers and the two entertainment servers. Contrary to a similar model in the literature, the Supervisory node replaces a Controller as soon as it fails (Active Supervisor). All system states are analyzed and simulated using OPNET. It is shown that, for all states, this architecture has zero control packets dropped and the end-to-end delay is below the maximum target delay. A comparison between this Active model and the other model in the literature is presented. It is found that the entertainment in this new architecture is kept available for the passengers in more of the system states when compared to the architecture previously presented in the literature.
文摘当系统存在较大扰动时,锅炉的变量如蒸汽压力和汽包水位都会产生较大的波动。简单的底层控制器消除这种波动的效果不太理想。提出了两层结构控制方法来改善系统的性能。底层控制采用基于DCS(Distributed control systems)系统的预测PID控制方法,根据当前的工况,蒸汽压力和水位的设定点由基于模糊理论的监控层给出。针对一个具体的锅炉系统,改进后的方法其控制性能和经济目标均有了很大的改善。
