Compositional Modeling for Refinement for Heirarchical Hybrid Systems

In this paper,we develop a theory of modular design and refinement of hierarchical hybrid systems. In particular, we present compositional trace-based semantics for the language CHARON that allows modular specification of interacting hybrid systems. For hierarchical description of the system architecture, CHARON supports building complex agents via the operations of instantiation, hiding, and parallel composition. For hierarchical description of the behavior of atomic components, CHARON supports building complex modes via the operations of instantiation, scoping, and encapsulation. We develop an observational trace semantics for agents as well as for modes, and define a notion of refinement for both, based on trace inclusion. We show this semantics to be compositional with respect to the constructs in the language

Model-Based Testing and Monitoring for Hybrid Embedded Systems

We propose an integrated framework for testing and monitoring the model-based embedded systems. The framework incorporates three components: 1) model-based test generation for hybrid system, 2) run-time verification, and 3) modular code generation for hybrid systems. To analyze the behavior of a model-based system, the model of the system is augmented with a testing automaton that represents a given test case, and with a monitoring automaton that captures the formally specified properties of the system. The augmented model allows us to perform the model-level validation. In the next step, we use the modular code generator to convert the testing and monitoring automata into code that can be linked with the system code to perform the validation tasks on the implementation level. The paper illustrates our techniques by a case study on the Sony AIBO robot platform

Unit & Dynamic Typing in Hybrid Systems Modeling with CHARON

In scientific applications, dimensional analysis forms a basis for catching errors as it introduces a type-discipline into the equations and formulae. Dimensions in physical quantities are measured via their standard units. However, many programming and modeling tools provide limited support for incorporating these units into the variables. Thus, it is quite difficult for a programmer to ensure dimensional consistency in the code. Different existing standards for units further complicates this problem and an incautious use could cause inconsistencies, often with catastrophic results. In this paper, we propose an extension of the basic type system in CHARON, a language for modeling of hybrid systems, to include Unit and Dynamic data types. Through a combination of indirect user-guided annotations and typeinference, we address the problem of ensuring both dimensional consistency, and consistency with respect to different unitsystems. Further, we also introduce dynamic data typing, that allows programmers to specify entities that bind at runtime. Such abstractions are particularly useful to program controllers for dynamic environments. We illustrate these benefits with an example on mobile robots

R-Charon, a Modeling Language for Reconfigurable Hybrid Systems

This paper describes the modeling language as an extension for architectural reconfiguration to the existing distributed hybrid system modeling language Charon. The target application domain of R-Charon includes but is not limited to modular reconfigurable robots and large-scale transportation systems. While largely leaving the Charon syntax and semantics intact, R-Charon allows dynamic creation and destruction of components (agents) as well as of links (references) between the agents. As such, R-Charon is the first formal, hybrid automata based modeling language which also addresses dynamic reconfiguration. We develop and present the syntax and operational semantics for R-Charon on three levels: behavior (modes), structure (agents) and configuration (system)

Sound Code Generation From Hybrid System Models: Some Theoretical Results

Code generation from hybrid system models, a promising approach for producing reliable embedded systems, has been our research focus for some time now. In this report, we summarize the progress made thus far and provide directions for research towards realization of this goal

MASL: a Language for Multi-Agent System

The classical approach for Multi-Agent System (MAS) Control, especially autonomous and robotic ones, deals first from a microscopic point of view: each agent embed a control program with communication/synchronization primitives that enable cooperation between agents. The emergence of a global behaviour from a macroscopic point of view can only be observed afterwards. In this context, MASL offers a macroscopic and unified approach with heterogeneous and distributed calculations over deliberative, reactive or hybrid agents. In this high level language, regardless of the runtime, each concurrent agent locally decides its participation in a collective execution block named an e-block. Each e-block is an anonymous collective program that runs over an agent network following local conditions. The orchestral mode (scalar, asynchronous, synchronous) is statically fixed by a shared block attribute. The communication use shared memory, events, synchronous messages passing, and asynchronous messages passing. Heterogeneous agents are managed with heritage and polymorphism. Permeability mechanism, dealing with agent autonomy, allows an agent to dynamically filter calls to its interface in respects to the sender position in the e-block hierarchy. In dynamic task allocation of agents, auto failover and recovery, agent replacement in a robot fleet (case of agent failure, loss of a mandatory functionality for the mission) an e-block is an entry point of a collaborative work. In the case of synchronous e-block, the programming paradigm is the data parallel model with iterative task for waves of agents. Finally, MASL offers advances in the field of MAS (dynamic belonging to groups, accuracy of the pace of actions to undertake to enable a desired cooperation) and for the management of errors

A Framework and Architecture for Multi-Robot Coordination

In this paper, we present a framework and the software architecture for the deployment of multiple autonomous robots in an unstructured and unknown environment with applications ranging from scouting and reconnaissance, to search and rescue and manipulation tasks. Our software framework provides the methodology and the tools that enable robots to exhibit deliberative and reactive behaviors in autonomous operation, to be reprogrammed by a human operator at run-time, and to learn and adapt to unstructured, dynamic environments and new tasks, while providing performance guarantees. We demonstrate the algorithms and software on an experimental testbed that involves a team of car-like robots using a single omnidirectional camera as a sensor without explicit use of odometry

Abstractions of Stochastic Hybrid Systems

In this paper we define a stochastic bisimulation concept for a very general class of stochastic hybrid systems, which subsumes most classes of stochastic hybrid systems. The definition of this bisimulation builds on the concept of zigzag morphism defined for strong Markov processes. The main result is that this stochastic bisimulation is indeed an equivalence relation. The secondary result is that this bisimulation relation for the stochastic hybrid system models used in this paper implies the same kind of bisimulation for their continuous parts and respectively for their jumping structures

Using formal methods to support testing

Formal methods and testing are two important approaches that assist in the development of high quality software. While traditionally these approaches have been seen as rivals, in recent years a new consensus has developed in which they are seen as complementary. This article reviews the state of the art regarding ways in which the presence of a formal specification can be used to assist testing

Proceedings of Monterey Workshop 2001 Engineering Automation for Sofware Intensive System Integration

The 2001 Monterey Workshop on Engineering Automation for Software Intensive System Integration was sponsored by the Office of Naval Research, Air Force Office of Scientific Research, Army Research Office and the Defense Advance Research Projects Agency. It is our pleasure to thank the workshop advisory and sponsors for their vision of a principled engineering solution for software and for their many-year tireless effort in supporting a series of workshops to bring everyone together.This workshop is the 8 in a series of International workshops. The workshop was held in Monterey Beach Hotel, Monterey, California during June 18-22, 2001. The general theme of the workshop has been to present and discuss research works that aims at increasing the practical impact of formal methods for software and systems engineering. The particular focus of this workshop was "Engineering Automation for Software Intensive System Integration". Previous workshops have been focused on issues including, "Real-time & Concurrent Systems", "Software Merging and Slicing", "Software Evolution", "Software Architecture", "Requirements Targeting Software" and "Modeling Software System Structures in a fastly moving scenario".Office of Naval ResearchAir Force Office of Scientific Research Army Research OfficeDefense Advanced Research Projects AgencyApproved for public release, distribution unlimite