DSD - Dynamic Stack Decider

We present the Dynamic Stack Decider (DSD), a lightweight open-source control architecture. It combines different well-known approaches and is inspired by behavior trees as well as hierarchical state machines. The DSD allows to design and structure complex behavior of robots as well as software agents while providing easy maintainability. Challenges that often occur in robotics, i.e., a dynamic environment and situation uncertainty, remain well-manageable. Furthermore, it allows fast modifications of the control flow, while providing the state-fullness of a state machine. The approach allows developing software using a simple Domain Specific Language (DSL) which defines the control flow and two types of elements that contain the programmed parts. The framework takes care of executing the demanded portions of the code and gives, due to its stack-like internal representation, the ability to verify preconditions while maintaining a clear structure. The presented software was used in different robotic scenarios and showed great performance in terms of flexibility and structuredness.

An Evaluation of Communication Protocol Languages for Engineering Multiagent Systems

Communication protocols are central to engineering decentralized multiagent systems. Modern protocol languages are typically formal and address aspects of decentralization, such as asynchrony. However, modern languages differ in important ways in their basic abstractions and operational assumptions. This diversity makes a comparative evaluation of protocol languages a challenging task. We contribute a rich evaluation of diverse and modern protocol languages. Among the selected languages, Scribble is based on session types; Trace-C and Trace-F on trace expressions; HAPN on hierarchical state machines, and BSPL on information causality. Our contribution is four-fold. One, we contribute important criteria for evaluating protocol languages. Two, for each criterion, we compare the languages on the basis of whether they are able to specify elementary protocols that go to the heart of the criterion. Three, for each language, we map our findings to a canonical architecture style for multiagent systems, highlighting where the languages depart from the architecture. Four, we identify design principles for protocol languages as guidance for future research.

Automated analysis of Stateflow models

Stateflow is a widely used modeling framework for embedded and cyberphysical systems where control software interacts with physical processes. In this work, we present a framework and a fully automated safety verification technique for Stateflow models. Our approach is two-folded: (i) we faithfully compile Stateflow models into hierarchical state machines, and (ii) we use automated logic-based verification engine to decide the validity of safety properties. The starting point of our approach is a denotational semantics of Stateflow. We propose a compilation process using continuation-passing style (CPS) denotational semantics. Our compilation technique preserves the structural and modal behavior of the system. The overall approach is implemented as an open source toolbox that can be integrated into the existing Mathworks Simulink/Stateflow modeling framework. We present preliminary experimental evaluations that illustrate the effectiveness of our approach in code generation and safety verification of industrial scale Stateflow models.