CHARON

1
CHARON

• SDRL and GRASP
• University of Pennsylvania
• Funded by DARPA ITO

2
What is Charon?

• Charon is a high-level modeling language and a
  design environment for embedded systems
  reflecting the current state of the art both in
  formal and object oriented methods (UML).

3
The Hybrid Systems Group at UPenn

• Professors
• Rajeev Alur (CIS)
• Vijay Kumar (ME)
• Insup Lee (CIS)
• Max Mintz (CIS)
• George Pappas (EE)
• Harvey Rubin (Med)

• Postdocs
• Eric Aaron
• Thao Dang
• Rafael Fierro
• Hyoung Hong
• Supratik Mukhopadhyay
• Oleg Sokolsky

• Ph.D. students
• Calin Belta
• Joel Esposito
• Yerang Hur
• Franjo Ivancic
• Pradyumna Mishra
• Usa Sammapun

• Others
• Radu Grosu
• Salvatore La Torre
• Valentina Sokolskaya
• Paulo Tabuada

4
Overview

• Charon language
• Architectural Hierarchy (Agents)
• Behavioral Hierarchy (Modes)
• Charon toolkit
• Syntax-directed editor
• Parser and type checker
• Global simulator
• Plotter
• Simulation in Charon
• Conclusions

5
Language Summary

• Individual components described as agents
• Composition, instantiation, and hiding
• Individual behaviors described as modes
• Encapsulation, instantiation, and scoping
• Support for concurrency
• Shared variables as well as message passing
• Support for discrete and continuous behavior
• Well-defined formal semantics

6
Architectural Hierarchy in Charon
Agent
Robot1
Robot2
sensor
sensor
processor
processor
actuator
actuator
Input Port
Output Port
Each agent can be represented as a parallel
composition of sub-agents
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Behavioral Hierarchy in Charon
Modes
main
awayTarget
atTarget
control
sensing
Entry Port
Exit Port

• Each agent consists of modes or behaviors
• Modes can in turn consist of submodes

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Modes

• Each agent consists of modes or behaviors
• A mode describes flow of control inside an agent
• Modes contain
• Control points (entry points, exit points)
• Variables (private, input, output)
• Continuous dynamics
• Invariants
• Transitions
• Nested submodes

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Continuous Behavior in Charon

• Differential Constraints
• write Position robot_Pos
• diff diffStop d(robot_ Pos.x)0.0 d(robot_
  Pos.y)0.0
• Algebraic Equations
• write real robotEST
• alge contEST robotEST lt foo(x) bar(x)
• Invariant Constraints in Modes
• inv invTUCost lub lt x lt gub

10
Charon Toolkit

• A prototype implementation of Charon development
  environment is available
• Contains
• syntax-directed editor
• parser and type checker
• global simulator
• plotter (adapted from Ptolemy_at_Berkeley)
• Implemented in Java
• Open internal representation allows interfacing
  with other tools

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Charon Toolkit cont.
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Current Implementation Status

• Work to date
• GUI
• Syntax-directed editor
• Charon semantics
• Parser and Type-Checker
• Internal representation
• Global simulation
• Plotter
• Current work
• Graphical input language
• Modular simulation
• Distributed simulation
• Model Checker
• Qualitative reasoning

13
Simulation in Charon

• Simulation is the main analysis technique for
  hybrid systems
• Global simulation is currently implemented
• Advanced simulation techniques exploit the
  structure in Charon programs
• behavioral hierarchy is used by modular
  simulation for the computation of continuous
  behavior
• architectural hierarchy is used by distributed
  simulation to distribute the simulation workload

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Simulation in Charon cont.

• In the current approach, a program-specific
  simulator is generated from the Charon program
• Each object of the Charon program is converted
  into an executable Java object
• Together with a program-independent core, these
  objects implement behavior of the program

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Simulator Generation
simulation core
CHARON program
modes and agents
generated classes for each mode and agent
JVM
generate
external objects
I/O, mathematical libraries, etc.
map

• Note the similarity to code generation!

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?Conclusion?Final Outlook?Links?

• Not sure what to say here, other than
• More information about the Hybrid Systems Group
  at UPenn available at
• http//www.seas.upenn.edu/hybrid
• More information about Charon and download of
  current version available at
• http//www.cis.upenn.edu/mobies/charon