MODELING AND SIMULATION OF ARRAY PROCESS WITH HYBRID PETRI NETS
MODELING AND SIMULATION OF ARRAY PROCESS WITH HYBRID PETRI NETS
- 주제(키워드) HYBRID PETRI NETS
- 주제(KDC) 569
- 주제(DDC) 621
- 발행기관 아주대학교
- 지도교수 왕지남
- 발행년도 2007
- 학위수여년월 2007. 8
- 학위명 박사
- 학과 및 전공 일반대학원 전자공학과
- 본문언어 영어
초록/요약
Petri Nets are widely used to model discrete event dynamic systems such as computer systems, manufacturing systems, communication systems, etc. A general analysis method using Petri nets is to compute the set of reachable states and deduce the different properties of the system. But when a Petri net contains a large number of tokens, the number of reachable states explodes and this is the major limitation of the application of Petri nets to complex system. Array process in TFT-LCD manufacturing system is such a system that is features of the capacity-oriented productions emphasizing high utilization of machines, and reduction of loss of capacity. Due to equipment uncertainty, product diversity, process intricacy, and ever-improving technologies, it is far more complicated than other conventional manufacturing process. Considering the limitation of the ordinary Petri nets, in this research, hybrid Petri nets, a hybrid model that combines fluid and discrete event dynamics, is taken as the basis for modeling the dynamic concurrent activities of a complex manufacturing systems, in particular, the array process in TFT-LCD production lines. The entire FOHPN model of array process is constructed from several sub-modules such as machine and buffer models in a bottom-up way. The net complexity is also analyzed in terms of the number of nodes in the net model. Due to the fluid approximation characteristics of FOHPNs, the considered system can also be efficiently simulated. To facilitate the simulation, a simulation framework has been designed and an algorithm based on a unified linear dynamic model is implemented as the core of the simulator. Extensive simulation have been conducted using different system operation parameters. According to some given performance indices such as maximal throughput and machine utilizations, one might choose the optimal working configurations of the system. Results show the applicability of the proposed methodology and demonstrate the modeling power of hybrid Petri nets. Furthermore, a hierarchical framework for monitoring and control of given system is proposed. Since the hybrid Petri net model of the system is constructed via continuous approximation of discrete event dynamic, which might results in a slight difference between the expected optimal behavior described by the FOHPN model and the actual behavior of the process observed. It is necessary to adjust the system operation parameters according to the feedback from the actual process behavior at the beginning of the macro-period by using such framework.
more목차
Abstract iv
Acknowledgements vi
Table of Contents vii
List of Tables x
List of Figures xi
1 INTRODUCTION 1
1.1 Background and Motivation 1
1.2 Objectives of the Dissertation 4
1.3 Organization of the Dissertation 5
2 LITERATURE REVIEW 8
2.1 Hybrid Petri Nets 8
2.1.1 Continuous and Hybrid Petri Nets 9
2.1.2 First-Order Hybrid Petri Nets 10
2.1.3 Fluid Stochastic Petri Net 11
2.1.4 Differential Petri Nets 12
2.1.5 Batch Petri Nets 13
2.1.6 Hybrid Flow Nets 14
2.1.7 High-Level Hybrid Petri Nets 15
2.2 Application of PNs in Manufacturing Systems 15
2.2.1 Petri Nets in Manufacturing Systems 15
2.2.2 CPNs and HPNs in Manufacturing Systems 17
3 FOHPN AND A UNIFIED LINEAR DYNAMIC MODEL 20
3.1 FOHPN Structure 20
3.2 Marking and Enabling 22
3.3 Net Dynamics 23
3.3.1 Instantaneous Firing Speed 23
3.3.2 Macro-behavior of an FOHPN 24
3.3.3 Micro-behavior of FOHPN 26
3.4 Optimal IFS Vector 28
3.4.1 Admissible IFS Vector 29
3.4.2 Optimal IFS Vector 30
3.5 A Unified Linear Dynamic Model for FOHPN 32
4 MODELING ARRAY PROCESS WITH FOHPN 37
4.1 FOHPN Elementary Modules 37
4.1.1 Machine Operation Model 37
4.1.2 Machine Failure Model 38
4.1.3 Buffer Model 41
4.2 FOHPN Model of Array Process 43
4.2.1 Array Process Description 43
4.2.2 Production layout 44
4.2.3 FOHPN Model 46
4.2.4 Analysis of Model Complexity 48
5 SIMULATION AND PERFORMANCE EVALUATION 50
5.1 Implementation 50
5.2 A Simulation Algorithm 52
5.3 An Example for the Simulation Algorithm 54
5.4 Simulation Parameters and Results 60
5.4.1 Parameters setting 60
5.4.2 Simulation Results 61
5.5 Comparison of Models 86
6 A Hierarchical Control Framework Based on FOHPN 90
6.1 Monitoring and Control 90
6.2 Hierarchical Control Framework 91
7 CONCLUSIONS AND FUTURE RESEARCH 95
7.1 Original Contributions 95
7.2 Future Research 96
Bibliography 98
