Discrete Event and Hybrid Systems in Robotics and Automation
Faculty
Students
- Radesh Kanniganti
- Yoon Jin Lee
An Environment and Applications for Discrete Event and Hybrid Systems in Robotics and Automation
Hybrid systems, in which digital and analogue devices and sensors interact
over time, is attracting the attention of researchers. Representation
of states and the physical system condition includes continuous and discrete
numerics, in addition to symbols and logical parameters. Most of the current
robotics, automation, and intelligent systems problems, as well as problems
in other domains, fall within
the description of hybrid systems. There are many issues that need to be
resolved, among them, definitions for observability, stability and
stabilizability, controllability in general, uncertainty of state transitions
and identification of the system.
The underlying mathematical representation of complex
computer-controlled systems is still insufficient to create a set of
models which accurately captures the dynamics of the systems over the
entire range of system operation. We remain in a situation where
we must tradeoff the accuracy of our models with the
manageability of the models. Closed-form solutions of mathematical
models are almost exclusively limited to linear system models.
Computer simulation of nonlinear and discrete-event models
provide a means for off-line design of control systems. Guarantees of
system performance are limited to those regions where the
robustness conditions apply. These conditions may not
apply during startup and shutdown or during periods of anomalous
operation.
Recently, attempts have been made to model low and high-level system changes
in automated and semi-automatic systems as discrete event dynamic systems
(DEDS). Several attempts to improve the modeling capabilities are focused on
mapping the continuous world into a discrete one. However, repeated results
are available which indicate that large interactive systems evolve into
states where minor events can lead to a catastrophe. Discrete event and hybrid
system formulations have been used in many domains to model and control
system state changes within a
process. Some of the domains include: Manufacturing, Robotics,
Autonomous Agent Modeling, Control Theory, Assembly and Planning,
Concurrency Control, Distributed Systems, Hierarchical Control,
Highway Traffic Control, Autonomous Observation Under Uncertainty,
Operating Systems, Communication Protocols, Real-Time Systems,
Scheduling, and Simulation.
A number of tools and modeling techniques are being used to model
and control discrete event systems in the above domains. Some of the modeling
strategies include: Timed, untimed and stochastic Petri Nets and State
Automata,
Markovian, Stochastic, and Perturbation models, State Machines,
Hierarchical State Machines, Hybrid Systems Modeling, Probabilistic
Modeling (Uncertainty Recovery and Representation), Queuing Theory,
and Recursive Functions.
In our project we develop a graphical environment
for simulating, analyzing, synthesizing,
monitoring, and controlling complex discrete event and hybrid systems
within the robotics, automation, and intelligent systems domain.
We also attempt to apply the discrete event and hybrid system
formulations in various problems within robotics and automation.
Some of the work in this project is done as a part of the activities of the
IEEE Robotics and Automation Society,
Technical Committee on Discrete Event Dynamic Systems, which is co-chaired
by Professor Tarek Sobh, and Professor
Beno Benhabib of the Department of Mechanical Engineering, University of Toronto.
Selected Publications:
- Books and Book Chapters:
-
- -
- T. M. Sobh, C. Jaynes, M. Dekhil, and T.
C. Henderson, ``Automated Inspection and Reverse Engineering,'' in Intelligent
Systems: Safety, Reliability, and Maintainability Issues, O. Kaynak,
G. Honderd and E. Grant (Eds.), Springer-Verlag, Berlin, pp. 95-122, 1993.
- -
- T. M. Sobh and R. Bajcsy, ``Visual Observation of a Moving Agent,'' in
Engineering Systems with Intelligence; Concepts, Tools, and Applications,
Book Chapter, Kluwer Academic Publishers, 1991.
- Journal Papers
-
- -
- T. M. Sobh, J. C. Owen,
K. P. Valavanis, and D. Gracanin, ``A Subject-Indexed Bibliography of Discrete
Event Dynamic Systems.'' In IEEE Magazine on Robotics and Automation,
Vol. 1, No. 2, June 1994.
- -
- T. M. Sobh, J. C. Owen,
and M. Dekhil, ``A Dynamic Recursive Approach for Autonomous Inspection
and Reverse Engineering.'' In Journal of Robotics and Autonomous Systems,
Special Issue on Discrete Event Systems in Robotics and Automation, October
1994.
- -
- T. M. Sobh, J. C. Owen,
M. Dekhil, and T. C. Henderson, ``Industrial Inspection and Reverse Engineering'',
Invited paper, Computer Vision, Graphics, and Image Processing (CVGIP),
Image Understanding Journal, Special Issue on Model-Based Vision.
- -
-
- T. M. Sobh and R. Bajcsy, ``A Discrete
Event Framework for Autonomous Observation Under Uncertainty.'' In the Journal
of Intelligent and Robotic Systems, October 1996.
- Invited Papers and Book Chapters:
-
- -
- T. M. Sobh and R. Bajcsy, ``Visual Observation as a Discrete Event Dynamic
System''. Presented at the International Joint Conference on Artificial
Intelligence (IJCAI), Workshop on Dynamic Scene Understanding, Sydney,
Australia, August 1991.
- -
- T. M. Sobh, C. Jaynes, M. Dekhil, and T.
C. Henderson, ``Automated Inspection and Reverse Engineering,'' in Intelligent
Systems: Safety, Reliability, and Maintainability Issues, O. Kaynak,
G. Honderd and E. Grant (Eds.), Springer-Verlag, Berlin, pp. 95-122, 1993.
- -
- T. M. Sobh, J. C. Owen, M. Dekhil, and T.
C. Henderson, ``Industrial Inspection and Reverse Engineering'', Invited
paper, Computer Vision, Graphics, and Image Processing (CVGIP), Image Understanding
Journal, Special Issue on Model-Based Vision.
- Conference Papers
-
- -
- T. M. Sobh, P. Sloan, and M. Dekhil,
``A Graphical Environment and Applications for Discrete Event and Hybrid
Systems in Robotics and Automation''. Submitted to the IEEE/RSJ International
Conference on Intelligent Robots and Systems (IROS 95), Pittsburgh,
August 1995.
- -
- T. M. Sobh, M. Dekhil, and J. C. Owen, ``Discrete
Event Control for Inspection and Reverse Engineering.''. In proceedings
of the IEEE International Conference on Robotics and Automation,
San Diego, May 1994.
- -
- T. M. Sobh, J. C. Owen, M. Dekhil, C. Jaynes,
and T. Henderson, ``Industrial Inspection and Reverse Engineering''. In
Proceedings of 1993 IEEE CAD-Based Vision Workshop, Pittsburgh,
February 1994.
- -
- T. M. Sobh, M. Dekhil, C. Jaynes, and T.
Henderson, ``A Perception Framework for Inspection and Reverse Engineering''.
In Proceedings of the IEEE Conference on Computer Vision and Pattern
Recognition (CVPR '93), New York City, June 1993.
- -
- T. M. Sobh, C. Jaynes, and T. Henderson,
``A Discrete Event Framework for Intelligent Inspection.''. In Proceedings
of the IEEE International Conference on Robotics and Automation, Atlanta,
May 1993.
- -
- T. M. Sobh, R. Bajcsy, and J. R. James,``Visual
Observation for Hybrid Intelligent Control Implementation''. In Proceedings
of the IEEE Conference on Decision and Control, Tucson, Arizona, December
1992. Invited Session on Hybrid Systems.
- -
- T. M. Sobh, C. Jaynes, and T. Henderson,
``Intelligent Inspection and Reverse Engineering''. NATO Advanced Research
Workshop on Intelligent Systems, Izmir, Turkey, August 1992.
sobh@bridgeport.edu