Dominique Federici

BEHAVIORAL FAULT SIMULATION

Due to the ever-increasing complexity of VLSI circuits, the use of VHDL [Vhd87] behavioral descriptions in the fields of test generation and fault simulation becomes advised. In order to understand this evolution and the context in which it is efficient, the increasing complexity of VLSI circuits must be considered. To better cope with the complexity of existing and future systems, higher abstraction levels must be taken into account. Furthermore, the only knowledge about the device being tested may come from data sheets or signal measurements. In this case the only way to generate test patterns is behavioral testing. Today, such a task is done manually and one of the main interests in Behavioral Test Pattern Generation (BTPG) is to automate it. Another point to consider is that the test generation process is an integral part of the design process and its implementation must begin during the behavioral design phase.

BFS-DEVS: A General DEVS-Based Formalism For Behavioral Fault Simulation

Discrete event modeling allows designing an easy-to-handle and reusable representation of a system but, in its classical form, only permits one simulation at a time for a system. Concurrent and Comparative Simulation (CCS) with Multi-List Propagation (MLP) appears to be an adapted solution, by providing a way to perform several simulations in a single execution run. Concurrent Fault Simulation (CFS) has been one of the first applications of the CCS. The main obstacles to a wide use of this technique are the high complexity of the concurrent simulation algorithms, along with the difficulty to integrate them in a simulation kernel. We focus in this paper on the CFS with MLP of systems described in the new BFS-DEVS formalism, which is an evolution of the original DEVS Simulator that integrates the CCS algorithm. The appli- cation is performed in the behavioral digital domain of systems described in the VHDL language.

Comparative study of two modelling implementation methods of a wound-rotor induction machine: Simulation, fault diagnosis and validation

The aim of this paper is to compare two modeling methods for a wound-rotor induction machine in order to simulate it in both healthy and faulty modes. The circuit-oriented approach which represents the machine model as a rotating transformer will be compared to the discrete event method. First, the wound-rotor induction machine model will be described using the classical equations in the abc reference frame. In fact, the circuit oriented method is based on a representation with only resistances, inductances and controlled voltage sources. It has been implemented by using the MATLAB/Simulink© software. With the discrete event method, the classical abc reference frame model is based on ordinary differential equations which are translated in block-scheme to be interpreted as a coupling of basic models based on a discrete event system specification. Finally, the performances of the two methods have been verified by comparison between simulation and experiments on a 5.5kW-220V/380V-50Hz-8 poles wound-rotor induction machine working in both healthy and faulty modes at different load conditions.

Simulation of AC Electrical Machines Behaviour Using Discrete Event System Simulator

This paper deals with the adaptation of AC electrical machine models for discrete event system simulator. The formalism chosen is DEVS (Discrete Event system Specification) which has been adapted recently for hybrid system simulation. The software PowerDEVS is close to MATLAB/Simulink(C) but without any toolbox adapted to power systems. As always, the model which is basically based on system of nonlinear differential equations has to be integrated to compute the output variables corresponding to any deterministic or stochastic inputs. In this way, the integrator atomic model has been optimized to perform many simulations with realistic CPU time. Results obtained with PowerDEVS and optimized graphical model have been validated by the same simulations using MATLAB/Simulink(C) as found in the classical literature.

Asymmetrical behavior of a double-fed induction generator: Modeling, discrete event simulation and validation

The aim of this paper is to present a discrete event simulation of a three-phase wound-rotor induction machine in order to show the efficiency of the proposed method to take into account the different winding unbalances. In fact, these machines are used in large power wind turbine generators in which the fault detection becomes more and more a serious issue. Early fault detection in the machine windings could be of great use for protection and predictive maintenance design. Therefore the classical abc reference frame model of the induction machine is translated in block-scheme to be interpreted by the discrete-event system simulator. The time-domain analysis is transformed in frequency-domain by interpolation to translate the discrete event magnitude in fixed sampling frequency and then application of normalized FFT to obtain the machine current spectrum. The technique is applied to a 5.5 kW wound-rotor induction machine in normal operation and with winding (stator, rotor, stator+rotor) unbalances. The simulation results are compared to experiments to evaluate the accuracy of the proposed simulation technique.

New trends and solutions for the simulation of electrical circuits using a discrete event approach

It is well known that a model of any electrical circuit can be translated into a system of ordinary differential equations. Usually, the simulation is performed in the timedomain using classical discrete approaches convenient for both linear and non-linear systems. An other method consists in the quantization on the variable magnitude which is based on discrete events. The discrete event system specification formalism is adapted to simulate any electrical circuit described with a system of ordinary differential equations using the system state quantification. In this paper, a solution to make more efficient the magnitude quantification for a system of linear ordinary differential equations is given. The proposed technique is used to simulate a simple three phase coupled power systems and it is compared to other solutions given by the explicit integration using formal language and the time-domain discretization using fixed-step fifth order Runge-Kutta integration method.

Computer aided design of polyphonic songs

Our works presented in this paper are part of a university project of inventory and enhancement of the Corsican cultural heritage. More precisely we work on design a software to enhance and learn the Corsican polyphonic songs. An association of Corsica has developed a method of teaching of polyphonic songs: the mimophony. The mimophony is a gestural language that enable the main singer to guide the other (Corsican polyphonies are made up of three singers). Our work is to include synthesized sung voices in these gestures. To do this, with the IRCAM (Institute for music/acoustic research and coordination), we have designed two data gloves (one for each hand) in order to capture the mimophonic gestures. The gloves are connected with the MAX/MSP software and generate values in real time. MAX/MSP is used to synthesize sung vowels too. The goal of our works is to make the link between mimophonic gestures and synthesized voices so that one singer may create a polyphonic singing.

Transformation of VHDL descriptions into DEVS models for fault modeling

We propose in this article an approach for the transformation of VHDL descriptions into DEVS models for an easy and fast fault simulation. VHDL allows description of the structure of a design, that is how it is decomposed into sub-designs, and how those designs are interconnected. The specification of the function of designs are performed using familiar programming language forms. One of the main problems is that today tools are unable to quickly and easily create and simulate fault models directly from the VHDL descriptions. A way to solve this problem is to encapsulate these descriptions in easily simulating and evolutive models. We propose to use the DEVS formalism to achieve this encapsulation.

Petri Net Modeling and Behavioral Fault Modeling Scheme for VHDL Descriptions

This paper deals with the modeling of VHDL behavioral descriptions and the development of an efficient behavioral fault modeling scheme. A set of behavioral test pattern generation methods have been proposed in the recent past. One constraint having to be pointing out is the fact that circuits under test (CUT) are expressed using a high level behavioral VHDL description. We propose to define a behavioral fault simulation method own to (i) a behavioral modeling of CUT using Petri Nets and (ii) an efficient behavioral fault modeling scheme. In this paper, the emphasis is put on the modeling aspects.

Localization method according to collect data from an acoustic wireless sensor network: Example of Homarus Gammarus in natural area

The platform STELLA MARE (Sustainable TEchnologies for LittoraL Aquaculture and MArine REsearch) has for objective to bring responses in the management of the sea in relation with the professional fishing. In this paper, we introduce an experiment on the monitoring of Homarus Gammarus. Using a passive tracking methodology using an acoustic wireless sensor network (AWSN), we try to follow some individuals, to define movement. The main objective is to build a lobster path according to the collected signal according a classical localization method to test our tracking method. Using a smoothing method and some resolution algorithms we are able to deduct a behaviour of tagged lobsters in an experimental area. This paper describes our methodology to estimate lobsters position according to data collected by an AWSN. This work represent a first step before the building a lobster model to simulate its behaviour in Corsican Mediterranean conditions.