Linearization of CIF Through SOS

Linearization is the procedure of rewriting a process term into a linear form, which consist only of basic operators of the process language. This procedure is interesting both from a theoretical and a practical point of view. In particular, a linearization algorithm is needed for the Compositional Interchange Format (CIF), an automaton based modeling language. The problem of devising efficient linearization algorithms is not trivial, and has been already addressed in literature. However, the linearization algorithms obtained are the result of an inventive process, and the proof of correctness comes as an afterthought. Furthermore, the semantic specification of the language does not play an important role on the design of the algorithm. In this work we present a method for obtaining an efficient linearization algorithm, through a step-wise refinement of the SOS rules of CIF. As a result, we show how the semantic specification of the language can guide the implementation of such a procedure, yielding a simple proof of correctness.Comment: In Proceedings EXPRESS 2011, arXiv:1108.407

Refinement of communication and states in models of embedded systems

This thesis addresses two particular issues related to the design of embedded systems; namely, refinement of communication and refinement of states. The refinement of communication deals with the issue of implementing a synchronous system in an asynchronous way such that two systems are behaviourally equivalent. As a result, correctness of an asynchronous system can be achieved by establishing correctness on its synchronous version, which is computationally cheaper than analysing the latter. The research objective was to find conditions that ensure the addition of buffers do not modify the behaviour of a given synchronous system. We show that it is possible to obtain better desynchronisability conditions (even for finer equivalence like branching bisimulation) by changing the properties of the communication protocol. This is in contrast with the previous works where the focus was only on restricting the communicating components. The refinement of states deals with the stepwise development of hybrid systems. Such a concept was absent in the Compositional Interchange Format (CIF), a modelling language for embedded systems based on hybrid automata and some process algebraic operators. The research objective was to develop a compositional operational semantics of CIF with hierarchy (HCIF). We show that by referring only to the transition system of the substructures (not to their syntactic representation), the semantics of HCIF operators is almost unchanged with respect to their CIF versions. Furthermore, a definition to eliminate hierarchy in a HCIF model is presented. As a result, the existing simulation tools and the transformation tools to other timed or hybrid languages can be reused upon the elimination of hierarchy from a HCIF model

The Art of Engaging: Implications for Computer Music Systems

The art of engaging with computer music systems is multifaceted. This paper will provide an overview of the issues of interface between musician and computer, cognitive aspects of engagement as involvement, and metaphysical understandings of engagement as proximity. Finally, this paper will examine implications for the design of computer music systems when these issues are taken into account

Foundations of a compositional interchange format for hybrid systems

A compositional interchange format for hybrid systems is defined in terms of an interchange automaton, allowing arbitrary differential algebraic equations, including fully implicit or switched DAEs, discrete, continuous and algebraic variables, that can be internal or external, an urgency condition, and operators for parallel composition, action hiding, variable hiding and urgent actions. Its compositional semantics is formally defined in terms of a hybrid transition system. This allows development of transformations to and from other formalisms that can be proven to preserve essential properties, and it allows a clear separation between the mathematical meaning of a model and implementation aspects such as algorithms used for solving differential algebraic equations

World Automata: a compositional approach to model implicit communication in hierarchical Hybrid Systems

We propose an extension of Hybrid I/O Automata (HIOAs) to model agent systems and their implicit communication through perturbation of the environment, like localization of objects or radio signals diffusion and detection. The new object, called World Automaton (WA), is built in such a way to preserve as much as possible of the compositional properties of HIOAs and its underlying theory. From the formal point of view we enrich classical HIOAs with a set of world variables whose values are functions both of time and space. World variables are treated similarly to local variables of HIOAs, except in parallel composition, where the perturbations produced by world variables are summed. In such way, we obtain a structure able to model both agents and environments, thus inducing a hierarchy in the model and leading to the introduction of a new operator. Indeed this operator, called inplacement, is needed to represent the possibility of an object (WA) of living inside another object/environment (WA)

Model-Based Engineering of Supervisory Controllers using CIF

In the Model-Based Engineering (MBE) paradigm, models are the core elements in the design process of a system from its requirements to the actual implementation of the system. By means of Supervisory Control Theory (SCT), supervisory controllers (supervisors) can be synthesized instead of designingthem manually. In this paper, a framework based on the Compositional Interchange Format for hybrid systems (CIF) has been developed that integrates the MBE andthe SCT paradigms. To illustrate the framework, an industrial-size case study has been performed: 'synthesis of a supervisory controller for the patientsupport system of an MRI scanner'. In this case study, we address 1) modelling of the components and the control requirements; 2) synthesis of the supervisor;3) simulation of the synthesized supervisor and a hybrid model of the plant; and 4) real-time, simulation based control of the supervisor and the actual patient support system of the MRI scanner

Application of supervisory control synthesis to MRI scannes : improving evolvability

This paper presents an application of Ramadge-Wonham supervisory control theory to a patient support system for MRI scanners. The obtained controller was implemented and tested on real hardware. A distinguishing feature of the proposed application is that the evolvability of the controller is an essential requirement. By evolvability is the ability to adapt the controller to meet modified control objectives. The experiments conducted in the course of the case-study indicate that the use of supervisory control theory improves the evolvability of the controller