Controllability indices for structured systems

AbstractA new methodology is proposed for the characterization of the controllability indices of linear multivariable systems. Related to the state space representation, a new symbolism dealing only with numbers associated with the position of nonnull terms of matrices is proposed. This symbolism, associated with the graphical digraph representation model, allows one to highlight, from a structural point of view, a list of dimensions of controllable subspaces corresponding one to one with the list of controllability indices

Storage Device Sizing for a Hybrid Railway Traction System by Means of Bicausal Bond Graphs

In this paper, the application of bicausal bond graphs for system design in electrical engineering is emphasized. In particular, it is shown how this approach is very useful for model inversion and parameter dimensioning. To illustrate these issues, a hybrid railway traction device is considered as a case study. The synthesis of a storage device (a supercapacitor) included in this system is then discussed

Two-phase reservoir: development of a transient thermo-hydraulic model based on bond graph approach with experimental validation

The main purpose of the project FUI THERMOFLUID is to study the feasibility of a new electronic cooling system embedded on flying objects (missile, satellite, and airplane). The technology chosen consists of a pumped two-phase flow cooling loop (PTPFL). It is an innovative technology with a transport capacity of the thermal power up to 10 MW.m, exceeding in this way the performance of all other technologies. A PTPFL is a cooling loop based on the exploitation of the latent heat properties of the fluid trapped inside the loop, and moved by a pump. The components constituting a PTPFL are: a two-phase reservoir (TP-R), a mini- channels evaporator, a brazed plate condenser, a pump and pipes. The global research work is devoted to propose a dynamic model and experimental validation of the PTPFL. The present article is exclusively dedicated to the TP-R two-phase reservoir (TP-R). Indeed this element plays a key role in the functioning of PTPFL. Historically, the TP-R did not equip the first cooling loop. However, due to its advantages its introduction was essential. The developed dynamic model will be used in another work to predict the thermal hydraulic efficiency of the PTPFL from its mechanical and fluidic parameters, to conduct the study of transitional regimes and instability problems, and provides an original tool dedicated to design the TP-R in function of the thermal power levels to be evacuated and the selected refrigerant. The bond graph methodology is adopted for modeling works because of its energetic approach and multi physics character of the studied system.FUI Thermofluid-R

Construction and analysis of causally dynamic hybrid bond graphs

Engineering systems are frequently abstracted to models with discontinuous behaviour (such as a switch or contact), and a hybrid model is one which contains continuous and discontinuous behaviours. Bond graphs are an established physical modelling method, but there are several methods for constructing switched or ‘hybrid’ bond graphs, developed for either qualitative ‘structural’ analysis or efficient numerical simulation of engineering systems. This article proposes a general hybrid bond graph suitable for both. The controlled junction is adopted as an intuitive way of modelling a discontinuity in the model structure. This element gives rise to ‘dynamic causality’ that is facilitated by a new bond graph notation. From this model, the junction structure and state equations are derived and compared to those obtained by existing methods. The proposed model includes all possible modes of operation and can be represented by a single set of equations. The controlled junctions manifest as Boolean variables in the matrices of coefficients. The method is more compact and intuitive than existing methods and dispenses with the need to derive various modes of operation from a given reference representation. Hence, a method has been developed, which can reach common usage and form a platform for further study

STRUCTURAL IDENTIFIABILITY OF BOND GRAPH MODELS

The global identifiability is a structural property of models, which associates a unique set of parameters with given input/output response. The translation of this property into bond graph modelling language allows the combination of the physically meaningful language of bond graph methodology and the numerical accuracy of identified transfer function models. Based on the building mechanisms of a transfer function from a bond graph model, the paper develops and explains why a bond graph can be not identifiable. Both internal and input/output dynamics can be written with the Mason's rule, using causal loops and action chains. Then the way the combination of causal loops and action chains influences the identifiability of models is discussed. As a result a criterion is given, which decides whether a bond graph model is structurally globally identifiable or not. This is a crucial issue in order to guarantee the reliability of identification processes

Robust FDI based on LFT BG and relative activity at junction

International audienc

International Conference on Integrated Modeling and Analysis in Applied Control and Automation

N°ISBN : 2―9520712-5-xNational audienceno abstrac