Electronic Communications of the EASST Volume 21 (2009) Presented By: Ayush Khandelwal

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. CNS and by Air Force Office of Scientific Research (AFOSR) under contract no. FA

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.