intro 005 slides

8/13/2019 Intro 005 Slides

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Electronic Communications of the

EASST Volume 21 (2009)

Presented By:

Ayush Khandelwal

00940178


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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


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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.


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CONTENT


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ABSTRACT


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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


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Previous Works..

Software Architecture model:

Components

Connectors

Standardized Notations:

UML 2.0

SysML

AADL


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Contd..


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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


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Cyber Family

Data Stores

Computation

IO Interfaces

Types of Cyber Connectors

Call-return Connector

Publish Subscribe

Connector


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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


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Physical family Contd

Physical Component:

Sources

Energy storage

Physical transducers

Physical Connector:

Power flow

Shared variable

Measurement


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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


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Example:


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Another Example


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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


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Example:


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Behavioral Verification:

Goal: Maintaining Zone 1 temperature close to the thermostat set

point

Furnace StatesPowered 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

Solution2:LHA analysis in PHAVer, and using Real Time Clock and Rates

of Change of Temperature


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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.

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