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National Yunlin University of Science & Technology Graduate School of Industrial Engineering & Management A Petri net Approach for Dynamic Control Reconfiguration of Manufacturing Systems with Consideration of Resource Changes Student: Tai-Lin Huang Advisor: Ming-Shan Lu, Ph.D. Slide 2 National Yunlin University of Science & Technology 2 IntroductionLiterature ReviewResearch MethodsExpected Results Outline Slide 3 National Yunlin University of Science & Technology 3 Slide 4 4 Research motive and purpose In the manufacturing process, the manufacturing system may occur unexpected events, that will result changes of the available resources amount. After resources changes, according to the original control rules will cause a lack of system resources. The purpose of this research is the manufacturing system return to normal in the situation of resource changes. Both of adjusting control rules and assigning the other departments resources are the ways of troubleshooting. Introduction Literature ReviewResearch MethodsExpected Results Slide 5 National Yunlin University of Science & Technology 5 Research process Introduction Literature ReviewResearch MethodsExpected Results Slide 6 National Yunlin University of Science & Technology 6 Slide 7 7 Introduction Literature ReviewResearch MethodsExpected Results Petri Net Reconfig- uration RMSDeadlock Slide 8 National Yunlin University of Science & Technology 8 RMS A kinds of manufacturing Systems, that can revise and adjust its structure. It can promise customized flexibility in a short time. (Mehrabi, et al. [2000]) Reconfiguration can mainly divide into two classes: 1.Reconfiguration in plan stage 2.Reconfiguration in control stage Reconfiguration can be classified in terms of two levels: 1.Hardware: Reconfiguration of resources 2.Software: Reconfiguration of control rules (Bi, et al. [2008] Koren, et al. [1999] Malhotra, et al. [2009]) Introduction Literature ReviewResearch MethodsExpected Results Slide 9 National Yunlin University of Science & Technology 9 Petri Net(1/5) Petri net are useful graphical tool for modeling the manufacturing systems. Petri net are an appropriate tool for the study of discrete- event dynamical systems because of their modeling power and flexibility. (Yamalidou, et al. [1996]) (Reddy, et al. [1993]) Introduction Literature ReviewResearch MethodsExpected Results Slide 10 National Yunlin University of Science & Technology 10 Petri Net(2/5) Petri net includes four basic elements: Token Place Transition Arc Introduction Literature ReviewResearch MethodsExpected Results ComponentGraph Token Place Transition Arc Petri net is a five tuple: 1. 2. 3. 4. 5. Slide 11 National Yunlin University of Science & Technology 11 Petri Net(3/5) The analysis method of Petri net. Reachability analysis method Reachability tree Reachability graph Invariant analysis method P-invariant T-invariant Introduction Literature ReviewResearch MethodsExpected Results Slide 12 National Yunlin University of Science & Technology 12 Petri Net(4/5) P-invariant one can find subsets of place over which the sum of the tokens remains unchanged T-invariant one can find that a transition firing sequence bring s the marking back to the same one. Introduction Literature ReviewResearch MethodsExpected Results Define the posive integer solution x of C T x=0 Multiplying X T to both sides Since C T x=0, thus x T C=0 then x is a P-invariant Cu=0, then u is a T-invariant Slide 13 National Yunlin University of Science & Technology 13 Petri Net(5/5) Literature Review about using Petri net on RMS Introduction Literature ReviewResearch MethodsExpected Results AuthorYearMethodApplication Meng2010 Object-oriented methods. Colored Petri nets. Modeling approach of RMSs. Li, et al.2009 Activity diagram of UML. Petri net. Rapidly building Petri net models of RMS. Slide 14 National Yunlin University of Science & Technology 14 Reconfiguration(1/2) Reconfiguration Control rules of the manufacturing system are used to handle the systems. Reconfiguration have to reach two points: 1.To safety the resources constraints 2.To avoid the systems deadlocks Introduction Literature ReviewResearch MethodsExpected Results Slide 15 National Yunlin University of Science & Technology 15 Reconfiguration(2/2) Literature review about reconfiguration Introduction Literature ReviewResearch MethodsExpected Results AuthorYearMethodApplication Yamalidou, et al.1996P-invariant Feedback controller of petri net. Sampath, et al.2008P-invariant Controller of the plant reconfiguration procedure. Kezic, et al2009P-invariant Design maximally permissive controller which stops vessels Baudouel and Oliver. 1998Reconfigurable net. The reconfigurable flow net dynamically modify their own structure Darabi, et al.2003 Control switching model The controller reconfigures the control system. Slide 16 National Yunlin University of Science & Technology 16 Deadlock(1/2) The deadlock situation lead to the manufacturing system can not operate. Deadlock situations are as a result of inappropriate resource allocation policies or exhaustive use of some or all resources. These researches about solving deadlock can be divided into three groups: 1.Schedule 2.Circuit & Cycle 3.Controller Introduction Literature ReviewResearch MethodsExpected Results Slide 17 National Yunlin University of Science & Technology 17 Deadlock(2/2) Literature review about deadlock of manufacturing system. Introduction Literature ReviewResearch MethodsExpected Results AuthorYearMethodApplication Dohi, et al.1996 High speed Petri Net sequence controller Petri net controller with hardware to avoid deadlocks Mohan, et al.2004 Colored Petri net model. The neighborhood deadlock avoidance policy. Deadlock avoidance in automated flexible manufacturing cells Xing, et al.2005Petri net controller. Deadlock avoidance for manufacturing systems with multiple resource service Aybar and Iftar2008 Timed Petri nets. Stretching method. Stretched Petri net. Timed Petri nets. Supervisory controller design approach to avoid deadlock in TPNs Slide 18 National Yunlin University of Science & Technology 18 Summary Introduction Literature ReviewResearch MethodsExpected Results Model Reconfigure level Reconfigure class ReconfigurationDeadlock Other research Activity diagram. Object- oriented. Petri net. Plan stage Reconfigure resource Static reconfiguration. Schedule Circuit & cycle Controller This research Flow of parts. Petri net. Resource controllers. P-invariant method. Control stage Reconfigure control rules Dynamic reconfiguration. Controller Slide 19 National Yunlin University of Science & Technology 19 Slide 20 National Yunlin University of Science & Technology 20 Example This research proposed a example about Reconfigurable manufacturing system(RMS). Machine1: 3 Machine2: 2 Machine3: 3 Machine4: 2 AGV: 4 Part A CIAGVmc1AGVmc3AGVmc4CO. Part B CIAGVmc3AGVmc2AGVmc1CO. Introduction Literature ReviewResearch MethodsExpected Results Machine1: 3 1 Machine2: 2 1 Machine3: 3 2 Machine4: 2 2 AGV: 4 3 Operating Resource changes Slide 21 National Yunlin University of Science & Technology 21 Research methods Because the lack of system resources, it have to reconfigure the system. This research considers the reconfigure methods, including adjust control rules and assign the other departments resources. Petri net P-invariant T-invariant & Reachability analysis This research totally using five petri net model: 1.Flow Petri Net(FPN) 2.Resource Petri Net Controller(RPNC) 3.Original Petri Net(OPN) 4.Deadlock free Petri Net Controller(DPNC) 5.Deadlock free Petri Net(DPN) Introduction Literature ReviewResearch MethodsExpected Results Slide 22 National Yunlin University of Science & Technology 22 Methods process Introduction Literature ReviewResearch MethodsExpected Results Slide 23 National Yunlin University of Science & Technology 23 Modeling(1/8) Establish the Original Petri net. Introduction Literature ReviewResearch MethodsExpected Results Slide 24 National Yunlin University of Science & Technology 24 Modeling(2/8) Step1 : Establish the Flow Petri Net(FPN) 1. 2. 3. 4. 5. 6. Introduction Literature ReviewResearch MethodsExpected Results Slide 25 National Yunlin University of Science & Technology 25 Modeling(3/8) Step2:List the resource constraints. Resource constraints: Introduction Literature ReviewResearch MethodsExpected Results Parameter of limit resources Petri net places s tokens Numbers of limit resources Slide 26 National Yunlin University of Science & Technology 26 Modeling(4/8) Step3:Establish Resources Petri net Controller based on the P- invariant. 1. 2. 3. 4. 5. 6. Introduction Literature ReviewResearch MethodsExpected Results mc1 Slide 27 National Yunlin University of Science & Technology 27 Modeling(5/8) The places of RPNC. P-invariant: Introduction Literature ReviewResearch MethodsExpected Results Place of Petri net Controller Satisfy Resource constraints Slide 28 National Yunlin University of Science & Technology 28 Modeling(6/8) The arc of RPNC P-invariant: Introduction Literature ReviewResearch MethodsExpected Results Slide 29 National Yunlin University of Science & Technology 29 Modeling(7/8) Step4: Establish Original Petri net(OPN). OPN is consisted of FPN and RPNC. 1. 2. 3. 4. 5. 6. Introduction Literature ReviewResearch MethodsExpected Results Slide 30 National Yunlin University of Science & Technology 30 Modeling(8/8) Step5:Test and verify the deadlock of OPN Matlab Petri Net toolbox. Reduction of OPN Introduction Literature ReviewResearch MethodsExpected Results Slide 31 National Yunlin University of Science & Technology 31 Reconfiguration(1/5) The procedure of reconfiguring system: Step1: Decide the dynamic state of the resource changes. Step2: According number of resources to update the resource constraints.(B B*). Step3: According B* to reconfigure the resource controllers token. Step4:Reconfigure the firing sequence. Introduction Literature ReviewResearch MethodsExpected Results Slide 32 National Yunlin University of Science & Technology 32 Reconfiguration(2/5) The procedure of Step3 & Step4. : Reconfigure the resources controllers token : Determine the value of the om(Rp i ) : If the om(Rp i ) 0, to solve the reconfigure firing vector f. : Determine whether the solution is feasible. : If the solution is unfeasible, to revise the lb. : Execute f, to adjust manufacturing systems. : Reconfigure finish. Introduction Literature ReviewResearch MethodsExpected Results Slide 33 National Yunlin University of Science & Technology 33 Reconfiguration(3/5) The reconfiguration of firing sequence. 1.The transition of adjusting control rules. 2.The transition of assigning the other departments resources. Introduction Literature ReviewResearch MethodsExpected Results Slide 34 National Yunlin University of Science & Technology 34 Reconfiguration(4/5) The costs of the firing transition, this research list three scenarios, we try to find the lowest cost of these scenarios: Scenario 1: The costs of assign resources is very expensive. Scenario 2: The costs of adjust control rules is slightly cheaper than assign the other departments resources. Scenario3: The costs of adjust the control rules is equal to assign the other departments resources. Introduction Literature ReviewResearch MethodsExpected Results Slide 35 National Yunlin University of Science & Technology 35 Objective function Reconfiguration(5/5) Mathematical models of solving the objective marking om obj and transition firing vector f Introduction Literature ReviewResearch MethodsExpected Results Correlation matrix of OPN Correlation matrix of assign resource Firing rule of Petri net: Integer and non- negative constraints Cost low bound Cost Firing vector Slide 36 National Yunlin University of Science & Technology 36 Deadlock(1/3) If deadlock occur, it must add Deadlock free Petri net controller(DPNC) to establish Deadlock free petri net(DPN). Deadlock free Petri Net Controller(DPNC) 1. 2. 3. 4. 5. 6. Introduction Literature ReviewResearch MethodsExpected Results Slide 37 National Yunlin University of Science & Technology 37 Deadlock(2/3) Mathematical models of solving the Deadlock free Petri Net Controller: Introduction Literature ReviewResearch MethodsExpected Results Nonreachability restrictions Circulation restrictions Reachability restrictions Slide 38 National Yunlin University of Science & Technology 38 Deadlock(3/3) The procedure of Minimum controller search method (Yun-Yi Wang [2011]) Introduction Literature ReviewResearch MethodsExpected Results Slide 39 National Yunlin University of Science & Technology 39 Slide 40 National Yunlin University of Science & Technology 40 Expected results The expected results of this research hope that it can resolve the problems about systems resource changes by reconfiguring the manufacturing system and avoiding deadlock. Introduction Literature ReviewResearch MethodsExpected Results Slide 41 National Yunlin University of Science & Technology 41