Modelbased Code Generation for Hybrid Systems

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Model-based Code Generation for Hybrid Systems

• Rajeev Alur
• Franjo Ivancic
• Jesung Kim
• Insup Lee
• Oleg Sokolsky

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Goal

• Automatic transition from abstract models to
  concrete implementations
• Model hybrid automata (continuousdiscrete)
• Implementation programming language (C/C)
• Formal correspondence between models and
  implementations
• Making formal verification done at the level of
  models also meaningful in implementations

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Methodology

• To design a software tool that generates
  platform-specific executable code from a
  platform-independent CHARON model
• Input CHARON model Platform description
• Output Executable code

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Motivational Example Walking Dog Model
Walk
tokenMYTOKEN
UpDown(-1)
OnGround
x
y lt y_lift
token (token1)4
L1
j1
ground
Forward
UpDown(1)
L2
g_stop
j3
(x, y)
y
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Code Generation Framework
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Challenges

• Discretization of the continuous model
• Fixed step-size simulation
• Validation
• Transition error
• ?-lookahead agent
• Numerical error
• Instrumented Hybrid Automata
• Code quality
• Modular C code
• Platform dependency
• Makefile-like script

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Semantics of Models

• CHARON
• Hybrid System with continuous time semantics
• Fixed step-size simulator
• Read, write, and transitions occur
  instantaneously at a time multiple of the step
  size
• Generated code

Read Write Transition
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Validation of Generated Code

• Given a step size ? and a CHARON model, check
  whether for all pairs of invariants I and guards
  g of outgoing transitions
• If so, the generated code will produce a valid
  execution trace on hypothetic fixed step size
  simulator.
• Otherwise, even for the fixed step size simulator
  we cannot guarantee a valid execution trace.

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Current Status Future Works

• Formal semantics
• ?-lookahead agent
• Suitable for formal reasoning of correctness
• Modular code generation
• Modularized C code
• Suitable for distributed systems
• Consideration of numerical errors
• Instrumentation
• Consideration of computational / IO delays
• Comparison with other tools