Electronic Communications of the
EASST Volume 21 (2009)
Presented By:
Ayush Khandelwal
00940178
About the Authors..
• Akshay Rajhans : Working on model-based design and formal
analysis of cyber-physical systems
• Shang-Wen Cheng: Currently as Software Engineer at the
NASA Jet Propulsion Laboratory
• Bradley Schmerl: Senior Systems Scientist, School of
Computer Science Carnegie Mellon University
• David Garlan: Professor of School of Computer Science.
Research areas as formal methods, domain-specific software
architectures and programming environments.
• Bruce H. Krogh: Research Area Signals/Control
• Clarence Agbi : Secretary for PhD in Electrical and Computer
Engineering at Carnegie Mellon University
• Ajinkya Bhave: Working in The Robotics Institute at Carnegie
Mellon University
Acknowledgments:
This work was supported in part by National Science Foundation (NSF)
under grant no. CNS0834701 and by Air Force Office of Scientific
Research (AFOSR) under contract no. FA9550-06-1-0312.
CONTENT
ABSTRACT
CPS is based on….
» Disparate Mathematical Formalisms
» Dissimilar Methodologies in Engineering and
Computer Science
Goal…
To create an extensible framework within which a
comprehensive set of design tools can be created
Previous Works..
Software Architecture model:
•
Components
•
Connectors
Standardized Notations:
• UML 2.0
• SysML
• AADL
Contd..
CPS ARCHITECTURAL STYLE
• Represent systems at a higher level
• Challenge of treating cyber and physical elements
equally
• Usage of Acme ADL
• Architectural style is represented as a family
• Three families
• Cyber Family
• Physical family
• Cyber-physical interface family
Cyber Family
• Data Stores
• Computation
• IO Interfaces
• Types of Cyber Connectors
• Call-return Connector
• Publish Subscribe
Connector
Physical family:
Challenges in developing representation:
• Should not have all the details required for a full simulation
• Also, should correspond to intuitive notions of physical
dynamics
Solution:
Introduction of components and connectors in energy view of
Physical systems
Examples : Bond Graphs, Langrangian Mechanics
Physical family Contd…
Physical Component:
• Sources
• Energy storage
• Physical transducers
Physical Connector:
• Power flow
• Shared variable
• Measurement
Cyber-Physical Interface Family:
Inherits elements of cyber and physical families and adds new
elements to bridge the gap.
Simple Interfaces:
• P2C connector
• C2P connector
Complex Interfaces
•
P2C transducer
•
C2P transducer
• Example: intelligent sensor nodes
Example:
Another Example
Behavioral Annotations:
Implemented for behavioral modeling frameworks –
•
Finite State Processes
• Linear Hybrid Automata
Plugins•
Usage :generate analyzable text files from these properties
• Plug-in for FSP: Labelled Transition System Analyser
• Plug-in for LHA: Polyhedral Hybrid Automaton Verifyer
Example:
Behavioral Verification:
Goal : Maintaining Zone 1 temperature close to the thermostat set
point
Furnace States – Powered Off, Powered On and Heating
Challenge : Furnace misses the Heat On command.
Solution 1: Usage of Finite State Process and Liveliness property of
Labeled Transition System Analyzer and added shutdown notification
connector between furnace and thermostat.
Challenge: If Furnace is a Dumb Device
Solution 2:LHA analysis in PHAVer, and using Real Time Clock and Rates
of Change of Temperature
Discussion:
A new CPS architectural style is proposed with tools for annotating
CPS architectures with behavioral models such as finite state
processes and linear hybrid automata.