NASA Technical Reports Server (NTRS) 19930007536: TokenPasser: A petri net specification tool. Thesis

206 Pages·4.4 MB·English

by  NASA Technical Reports Server (NTRS)

TOKENPASSER
A PETRI NET SPECIFICATION TOOL
by
Michael Mittmann
Rensselaer Polytechnic Institute
Electrical, Computer, and Systems Engineering
Troy, New York 12180-3590
January 1991
CIRSSE REPORT #81

CONTENTS
LIST OF FIGURES ................................ v
ACKNOWLEDGMENT .............................. vi
ABSTRACT .................................... vii
i. INTRODUCTION ............................... I
i.i Motivation ................................. i
i.i.I System Specification ....................... i
1.1.2 Distributed Hierarchical Systems ................ 1
1.2 Petri Nets for Analysis of Distributed Systems ............. 2
1.3 Goals of This Project ........................... 2
1.4 Application: The CIRSSE Platform .................... 3
1.5 Thesis Outline ............................... 4
2. LITERATURE REVIEW ........................... 5
2.1 Petri Net Theory ............................. 5
2.1.1 Petri nets ............................. 5
2.I.2 Petri Net Transducers ...................... 8
2.1.3 Coordination Structures ..................... 10
2.2 Current Tools ............................... 10
2.'2.1 Petri Net Tools .......................... 10
2.'2.2 Distributed System Tools .................... 13
PROBLEM STATEMENT ........................... 17
,
3.1 Project Specification ........................... 17
3.2 Project Design .............................. 17
3.2.1 Communication .......................... 17
3.2.2 Data Structures .......................... 18
3.2.3 Flow of Control .......................... 20
3.2.4 User Interface ........................... 22
CASE STUDY ................................. 24
4°
4.1 CII_SSE System Overview ........................ 24
4.1.1 Goals ................................ 24
4.1.2 System Components ....................... 25
4.2 System Command Language and Task Grammar ............ 29
4.3 Coordination Structures ......................... 30
4.3.1 The Petri Net Transducer for the Dispatcher .......... 30
4.3.2 Petri Net Transducer for the Vision Coordinator ........ 35
4.3.3 Petri Net Transducer for the Gripper Coordinator ....... 40
4.3.4 The Petri Net transducer for the Arm Coordinator ...... 42
4.4 Analysis .................................. 45
4.4.1 Structural Analysis ........................ 45
4.4.2 Simulation ............................. 46
5. CONCLUSIONS AND FUTURE RESEARCH ................ 51
5.1 Summary and Conclusions ........................ 51
5.2 Future Research and Modifications ................... 52
LITERATURE CITED .............................. 54
APPENDICES ................................... 56
A. THE TokenPasser CODE ............................ 56
A.I Compiling Instructions .......................... 56
A.2 main.c ................................... 58
A.3 draw.c ................................... 66
A.4 makepet.c ................................. 78
A.5 menu.c ................................... 90
A.6 petLib.c .................................. 94
A.7 petri.c ................................... 104
A.8 postn.c ................................... 108
A.9 read_socket.c ................................ 110
A.10 sock_connect.c ............................... 115
A.ll sock_open.c ................................ 118
'4.
111
A.12 tr_nsform.c ................................ 122
A.13 window..manager.c ............................ 132
B. NET DESCRIPTIONS ............................. 137
B.I setup_disp.c ................................. 137
B.2 setup..axm.c ................................ 148
B,3 setup.grip.c ................................ 152
B.4 setup_vision.c ............................... 155
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LIST OF FIGURES
Figure 2.1 A Petri net with tokens .....................
Figure 2.2 The configuration of PNTs .................... 9
Figure 2.3 An Olympus Implementation .................. 16
Figure 3.i The Data Structures of the TokenPasser Program ....... 21
Figure 4.1 The Simplified Dispatcher Architecture ............. 31
Figure 4.2 The Dispatcher Architecture ................... 33
Figure 4.3 The Vision Petri Net Transducer ................ 36
Figure 4.4 The Gripper Petri Net Transducer ............... 40
Figure 4.5 The Arm Petri Net Transducer ................. 43
Figure 4.6 Variations in Transmission time with Distance and Data Size . 47
Figure 4.7 Delay increases when sockets are used to communicate on a
single machine ........................... 48
Figure 4.8 There is no particular benefit to placing the Dispatcher on the
file server .............................. 49

ACKNOWLEDGMENT
I would like to thank Professor George Saridis the guidance and support given to me
during my research. I would also like to thank Dr. Fei-Yue Wang for the tremendous
amount of help developing and clarifying this thesis. Finally I would like to thank
Mr. Krishnamoorthy for his help with displaying Petri nets on Xwindows.
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ABSTRACT
In computer program design it is essential to know the effectiveness of different
design options in improving performance, and dependability. This paper provides a
description of a CAD tool for distributed hierarchical Petri nets.
After a. brief review of Petri nets, Petri net languages, and Petri net trans-
ducers, and descriptions of several current Petri net tools, the specifications and
design of the TokenPasser tool are presented. TokenPasser is a tool to allow design
of distributed hierarchical systems based oa Petri nets.
A case study for an intelligent robotic system is conducted, a Coordination
structure with one dispatcher controlling three coordinators is built to mode[ a
proposed robotic assembly system. The system is implemented using TokenPasser,
and the results are analyzed to allow judgment of the tool.
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