Deadlock avoidance problems are investigated for automated manufacturing systems with flexible routings. Based on the Petri net models of the systems, this paper proposes, for the first time, the concept of perfect ma...Deadlock avoidance problems are investigated for automated manufacturing systems with flexible routings. Based on the Petri net models of the systems, this paper proposes, for the first time, the concept of perfect maximal resourcetransition circuits and their saturated states. The concept facilitates the development of system liveness characterization and deadlock avoidance Petri net supervisors. Deadlock is characterized as some perfect maximal resource-transition circuits reaching their saturated states. For a large class of manufacturing systems, which do not contain center resources, the optimal deadlock avoidance Petri net supervisors are presented. For a general manufacturing system, a method is proposed for reducing the system Petri net model so that the reduced model does not contain center resources and, hence, has optimal deadlock avoidance Petri net supervisor. The controlled reduced Petri net model can then be used as the liveness supervisor of the system.展开更多
During the past years, the distributed computing approach has become very popular due to various advantages over centralized approach. In the distributed approach, the execution of a process has reduced and also it re...During the past years, the distributed computing approach has become very popular due to various advantages over centralized approach. In the distributed approach, the execution of a process has reduced and also it requires low cost for installation. Many of the researchers are using the modeling approach for solution of the software and hardware architecture research problems. The most popular approach of modeling is known as Unified Modeling Language based on the object-oriented technology. In the present work, a method of deadlock detection is explained for the newly proposed static step topology for the distributed network. In the step topology, the processes are taken as a task, sub task, macro, subroutine, etc which are executed in reflexive and symmetric manners when the systems are interconnected to each other under distributed environment and avoidance technique is also presented for the same. The deadlock detection technique is presented through a UML class model.展开更多
In unstructured environments, dynamic resource assignment is required for effective cooperation of robot teams. In some scenarios, robots are in charge of executing multiple missions simultaneously. This creates risks...In unstructured environments, dynamic resource assignment is required for effective cooperation of robot teams. In some scenarios, robots are in charge of executing multiple missions simultaneously. This creates risks of deadlock due to the presence of shared resources among various missions. The main contribution of this paper is the development of a novel approach that combines the one-step look-ahead deadlock avoidance policy with dynamic resource assignment. The dynamicresource assignment is achieved using greedy resource assignment for multi-mission robot teams in the framework of a matrix-based discrete event controller. Simulation results are presented in MATLAB to discuss in detail the proposed control strategy. The paper also discusses the toolkit developed in LabVIEW which is used to implement this control framework using a suitable example.展开更多
基金the State Key Laboratory for Manufacturing System Engineering at Xi'an Jiaotong University. China.
文摘Deadlock avoidance problems are investigated for automated manufacturing systems with flexible routings. Based on the Petri net models of the systems, this paper proposes, for the first time, the concept of perfect maximal resourcetransition circuits and their saturated states. The concept facilitates the development of system liveness characterization and deadlock avoidance Petri net supervisors. Deadlock is characterized as some perfect maximal resource-transition circuits reaching their saturated states. For a large class of manufacturing systems, which do not contain center resources, the optimal deadlock avoidance Petri net supervisors are presented. For a general manufacturing system, a method is proposed for reducing the system Petri net model so that the reduced model does not contain center resources and, hence, has optimal deadlock avoidance Petri net supervisor. The controlled reduced Petri net model can then be used as the liveness supervisor of the system.
文摘During the past years, the distributed computing approach has become very popular due to various advantages over centralized approach. In the distributed approach, the execution of a process has reduced and also it requires low cost for installation. Many of the researchers are using the modeling approach for solution of the software and hardware architecture research problems. The most popular approach of modeling is known as Unified Modeling Language based on the object-oriented technology. In the present work, a method of deadlock detection is explained for the newly proposed static step topology for the distributed network. In the step topology, the processes are taken as a task, sub task, macro, subroutine, etc which are executed in reflexive and symmetric manners when the systems are interconnected to each other under distributed environment and avoidance technique is also presented for the same. The deadlock detection technique is presented through a UML class model.
基金supported by the Army Research Office(ARO)(DAAD 19-02-1-0366,ARO W91NF-05-1-0314)the National Science Foundation(IIS-0326505,CNS-0421282)+1 种基金the Singapore SERC TSRP(0421120028)the NI Lead User grant,and the Texas Advanced Research Program(ARP)(14-748779)
文摘In unstructured environments, dynamic resource assignment is required for effective cooperation of robot teams. In some scenarios, robots are in charge of executing multiple missions simultaneously. This creates risks of deadlock due to the presence of shared resources among various missions. The main contribution of this paper is the development of a novel approach that combines the one-step look-ahead deadlock avoidance policy with dynamic resource assignment. The dynamicresource assignment is achieved using greedy resource assignment for multi-mission robot teams in the framework of a matrix-based discrete event controller. Simulation results are presented in MATLAB to discuss in detail the proposed control strategy. The paper also discusses the toolkit developed in LabVIEW which is used to implement this control framework using a suitable example.
