HYCON-EECI, Spring 2012

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Eecilogo.png Specification, Design, and Verification
of Networked Control Systems

Richard M. Murray, Ufuk Topcu, and Nok Wongpiromsarn

14-18 May 2012, L'Aquila (Italy)

Course Description

Increases in fast and inexpensive computing and communications have enabled a new generation of information-rich control systems that rely on multi-threaded networked execution, distributed optimization, sensor fusion and protocol stacks in increasingly sophisticated ways. This course will provide working knowledge of a collection of methods and tools for specifying, designing and verifying networked control systems. We combine methods from computer science (temporal logic, model checking, synthesis of control protocols) with those from dynamical systems and control (Lyapunov functions, trajectory generation, receding horizon control) to analyze and design partially asynchronous control protocols for continuous systems. In addition to introducing the mathematical techniques required to formulate problems and prove properties, we also describe a software toolbox (TuLiP) that is designed for analyzing and synthesizing hybrid control systems using linear temporal logic and robust performance specifications.

Course information

Lecture Schedule

The schedule below lists the lectures that will be given as part of the course. Each lecture will last approximately 90 minutes. The individual lecture pages give an overview of the lecture and links to additional information.

Lec Date/time Title Topics
Mon, 9:00 Introduction: Protocol-Based Control Systems
  • Introduction to networked control systems (NCS)
  • Overview of control "protocols"
  • Examples: Alice, RoboFlag
Mon, 11:00 Automata Theory
  • Finite transition systems
  • Paths, traces and composition of finite transition systems
  • Linear time properties; safety and liveness
  • Examples: traffic light
Mon, 14:00 Temporal Logic
  • Linear temporal logic
  • Omega regular properties
  • Buchi automata, representation of LTL using NBA
  • Examples: traffic light, (RoboFlag), autonomous driving
Mon, 16:00 Model Checking and Logic Synthesis
  • Basic concepts in model checking
  • Use of model checking for logic synthesis
  • Examples: traffic light, farmer puzzle
Tue, 14:00
Tue, 16:00
Computer Session: Spin
  • Introduction to Promela and Spin (statements, processes, messages)
  • Verification examples: traffic light, distributed traffic light, gcdrive
  • Synthesis examples: traffic light, farmer puzzle, robot navigation
Wed, 9:00 Deductive Verification of Hybrid Systems
  • Brief introduction to hybrid systems and verification techniques (deductive, algorithmic)
  • Deductive verification using barrier certificates
  • Guarded command languages and CCL for asynchronous control protocols
  • Examples: multi-agent systems, RoboFlag
Wed, 11:00 Algorithmic Verification of Hybrid Systems
  • Abstraction hierarchies for control systems
  • Finite state abstractions (discretization) and model checking
  • Discretization of continuous state systems
  • Approximate bi-simulation (if time)
  • Examples: gear changing (?), ???
Wed, 14:00 Synthesis of Reactive Control Protocols
  • Open system and reactive system synthesis
  • Satisfiability, realizability
  • Game structures, reachability/safety games
  • Mu-calculus (if time) and GR(1) games
  • Examples: runner-blocker
Thu, 9:00
Thu, 11:00
Computer Session: TuLiP
  • Introduction to TuLiP
  • Synthesis of protocols for discrete systems
  • Discretization of continuous systems (and protocol synthesis)
  • Examples: reactive motion planning
Fri, 9:00 Receding Horizon Temporal Logic Planning
  • Receding horizon control
  • Distributed control
  • Examples: reactive motion planning, electric power systems (distributed)
Fri, 11:00 Extensions, Applications, Open Questions
  • Review of control trends and course contents
  • Discussion of open problem areas and preliminary results
    • Optimization-based techniques
    • Probabilistic techniques
    • Others: Robustness, switching systems, timed systems
  • Examples: robot motion planning, electric power systems (timed)

Software Installation

We will make use of two programs during the lab sessions:

  • Spin - model checker for formal verification of distributed systems
  • TuLiP - python-based toolbox for temporal logic planning and controller synthesis

During the course, we will access these programs on a remote machine using ssh. For some parts of the course it will be useful to have a local installation of MATLAB that can be used for visualizing some simulation results.

If you would like to install the software on your own, here are some basic directions for installing the two packages:

  • Spin: if you are using Windows, you can download a binary installation. For Mac's, you need to compile from source. For this you will need a C compiler, such as the one that is part of the Xcode developer toolbox
  • TuLiP: you will need a python installation (2.6 or greater) with SciPy (0.9 or greater) installed. You might consider using the Enthought Python distribution. Once you have scipy installed, you will need to install several other python packages, including cvxopt and yices. A list of required package is available on the TuLiP project page.