Bond Graphs

The context of this PhD thesis is the modelling and design of mechatronic systems. The study is positioned in the early design stage of the conception cycle (V-Cycle), where the main efforts have to be produced in terms of methodology, to enhance the quality and the functionality of the products, and based on virtual prototyping (modelling and simulation). One of the possible methodology is to reformulate the design problem as an inverse problem, in order to directly use the design specification of the product, usually given in terms of the system outputs, and then solve the design problem. In this context, the Ampere laboratory of INSA Lyon has developed a conception and design methodology, based on inverse approach and using the bond graph formalism, to propose a step-by-step method based on dynamic and energetic criteria, with a structural analysis phase that allows hierarchical analysis steps, depending on the structural physical layout of the model (topological, phenomenological, parameter set). The aim of the present works is to contribute to the development of this methodology, by enhancing it to the class of descriptor systems. This choice is led by the aim to apply the methodology in the context of chassis design and vehicle dynamics, where, among other, multi-body models represented as a differential-algebraic equation (DAE) system could occur. The contributions are proposed at the level of the topology of the model, as well as at the level of the phenomenological / behavioral aspects. A preliminary step is to enhance the existing algebraic framework to support graphical extension (in term of digraph and bond graph). The overall methodological extensions allow, firstly, a generalization of the approach to the class of descriptor systems, and, secondly, to reach a standardization of the procedures, previously dedicated to direct or inverse models, so as no mandatory differences between those models have to be done anymore.

This research paper is built on recent work in synthesizing and analyzing tree-structured transfer functions which have the form of a continued fraction. A useful feature of this transfer function is the manner in which it allows state variables to be easily removed from a model. Two components: a means to readily synthesize tree-structured transfer functions and the possibility of using the same transfer function to examine the effects on system performance of eliminating state variables provide the foundation to a novel physically-based approach of model order reduction for physical system. In the research work this approach is developed and compared to conventional techniques. The research work addresses the problem of determining which physical state variables should be retained in a reduced order model that belongs to a class of lumped physical system models, the class is defined by SISO variable pair of systems that are passive and free of internal loops. The models synthesized in the work are intended primarily for controller design, and are expressed using bond graphs. An error term that describes the reduced order model frequency response uncertainty over a given frequency range of interest is also provided

Advanced myoelectric hand prostheses aim to reproduce as much of the human hand's functionality as possible. Development of the control system of such a prosthesis is strongly connected to its mechanical design; the control system requires accurate information on the prosthesis' structure and the surrounding environment, which can make development difficult without a finalized mechanical prototype. This paper presents a new framework for the development of electromyographic hand control systems, consisting of a prosthesis model based on the biomechanical structure of the human hand. The model's dynamic structure uses an ellipsoidal representation of the phalanges. Other features include underactuation in the fingers and thumb modeled with bond graphs, and a viscoelastic contact model. The model's functions are demonstrated by the execution of lateral and tripod grasps, and evaluated with regard to joint dynamics and applied forces. Finally, future work is suggested w...

In this paper, bond graphs are employed to develop a novel mathematical model of conventional switched-mode DC-DC converters valid for both continuous and discontinuous conduction modes. A unique causality bond graph model of hybrid models is suggested with the operation of the switch and the diode to be represented by a modulated transformer with a binary input and a resistor with fixed conductance causality. The operation of the diode is controlled using an if-then function within the model. The extracted hybrid model is implemented on a boost and buck converter with their operations to change from CCM to DCM and to return to CCM. The vector fields of the models show validity in a wide operational area and comparison with the simulation of the converters using PSPICE reveals high accuracy of the proposed model, with the normalised root means square error and the maximum absolute error remaining adequately low. The model is also experimentally tested on a buck topology.

The bond graph (BG) is a modeling and simulation tool, providing many possibilities which are used in mechatronics. Mechatronics is a multidisciplinary engineering field necessitating a unified method for the monitoring. This paper deals with a model based real-time simulator for CNC machines in order to detect eventual failures. A versatile methodology based on bond graph analysis to build a dynamic icon model library which is successful implemented for the Fault Detection and Isolation (FDI). The developed approach is investigated using SYMBOLS2000 software.

Graphical methods provide useful tools to study the structure of systems. The bond-graph approach is used in modelling process of dynamical systems. The matroid theory offers a powerful tool if we are interested in combinatorial aspects of causality assignment. This paper is organized as follows: after an introduction, Section 2 introduces some matroid background, and Section 3 presents some matroid definitions about structural properties. In Section 4, the main result of this paper is the proposal of a procedure that constructs cycle and co-cycle graphs from graphical matroids defined in the previous section. Validity of this procedure and some examples are shown in Sections 5 and 6, respectively, and concluding remarks are given in Section 7.

Traction control system and Antilock Braking System (ABS) are used extensively in vehicles to control and enhance their performance. This is achieved by continuous monitoring of vehicle parameters and using on-off control to activate the system, so as to maintain the tyre slip ratio between the desired limits. As this is a continuous system, there is always a need to reduce the calculation time for cycle and to increase the overall cycle frequency. One of the approaches for achieving this is to identify the physical parameters which do not add much to the dynamics of the system. Hence, these elements if removed from the mathematical model do not disturb the results but can reduce the time of calculation and therefore the simulation time. This paper deals with discussion of such a technique using the bond graph modeling, obtaining the reduced system model of ABS and the comparison of the result of the full system with the reduced system.

This paper develops a new and efficient hybrid qualitative–quantitative system identification methodology for structures using the bond graph approach. Bond graphs provide a modeling framework that includes parametric models of both the physical system and the sensors. Structural damage is modeled as reductions in the parameter values of the structural components. Sensor faults are modeled as biases or drifts from true responses. The damage detection uses a statistical method to identify significant deviations of measurements from nominal healthy behavior of the structure. Damage isolation is carried out by comparing the predicted signatures of various damage scenarios with the observed behavior of the structure. The damage signatures are derived off-line before sensor data collection. Quantitative identification of the damage amount uses the least-squares method, analyzing only the sub-structure containing the damaged component. Numerical illustrations of damage identification of f...

The method presented aims at supporting the development of control software for embedded control systems. The method considers the implementation process as a stepwise refinement from physical system models and control laws to efficient control computer code, and that all phases are verified by simulation. Simulation is also used as a verification tool during physical system modeling and control law

To realize design automation of mechatronic systems, there are two major issues to be dealt with: opentopology generation of mechatronic systems and simulation or analysis of those models. For the first issue, we exploit the strong topology exploration capability of genetic programming to create and evolve structures representing mechatronic systems. With the use of ERCs (ephemeral random constants) in genetic programming, we can evolve the sizing of mechatronic system components together with the system structures simultaneously. The second issue, simulation and analysis of those system models, is made more complex when the systems are mixed-energy-domain systems. We take advantage of bond graphs as a tool for multi- or mixed-domain modeling and simulation of mechatronic systems. Because there are many considerations in mechatronic system design that are not completely captured by a bond graph, it is beneficial to generate multiple solutions, allowing the designer more latitude in ...

To support the concurrent design processes of mechatronic subsystems, unified mechatronics modeling and cooperative body–brain coevolutionary synthesis are developed. In this paper, both body-passive physical systems and brain-active control systems can be represented using the bond graph paradigm. Bond graphs are combined with genetic programming to evolve low-level building blocks into systems with high-level functionalities including both topological configurations and parameter settings. Design spaces of coadapted mechatronic subsystems are automatically explored in parallel for overall design optimality. A quarter-car suspension system case study is provided. Compared with conventional design methods, semiactive suspension designs with more creativity and flexibility are achieved through this approach.

ABSTRACT In this paper, a methodology to approximate a class of in3nite dimensional models by a bond graph model is investigated. This procedure is designed to preserve the passivity of the initial model. Through interconnections of passive elementary blocks (passivity is stable under interconnections), a 3nite dimensional passive approximate model is constructed. This 3nite dimensional model, if need be, is reduced thanks to a Krylov-Lanczos process. Finally, a bondgraph realization of this reduced-order model is given. An example (a fractional power pole model) and an application (the CRONE suspension) demonstrate the usefulness of the whole approximation procedure. The paper ends with the discussion of the reduced-order model initial conditions determination problem in the non-integer order case. ? 2003 Publishedby Elsevier B.V.

The aim of this article is to present an overview of the fractional operators such as integrators and differentiators based on resistive, inductive and capacitive components. Four different configurations of RLC based circuits that may produce a fractional behavior will be introduced. First, we will present these operators in the electrical domain than generalize our results in the bond graph representation. The results of the bond graph approach will be presented in state-space matrices where the main factors of power used are the flow and the effort. After that, we will show the main steps required to synthesis and realize these controllers starting from the four high-level parameters required (low and high frequencies of the phase locking, the non-integer order of derivation and the gain at the unit frequency). The number of cells is also important because we can't get a phase locking without using a minimum value as this property doesn't appear for a reduced cells' size. An application for the hydropneumatic suspension will emphasize, in more details, the way to synthesize and realize fractional operators and the compare the behavior between the ideal fractional integrator and the implemented one.

ABSTRACT This paper presents a characterization of the axial vibrational behavior of a common hand-driller coupled to a three DOF HAS (Hand-Arm-System) model. The different components are represented as lumped masses and the connections between them with a spring and a damper. The elastic constant for the structural elements are determined using FEA (Finite Element Analysis) simulations, while the damping constant values used are the recommended by the Software 20-SIM for structural damping. Once the Bond-Graph model is developed, the equations that describe the vibrational behavior of the HandTool system can be obtained. The software 20-SIM is used to simulate the developed Bond-Graph model and to determine the Hand-Arm system vibrational response for a specific excitation force.

This article proposes a new modeling approach for traffic flow using bond graphs. The objective is to provide a new description of the dynamic phenomena which govern traffic flows starting from a phenomenological representation of vehicle flow transfers in a traffic network. Among the attractions of using a bond graph approach are, the underlying graphical vision which contributes to crystallizing the analysis, the systematic formulation of the analytical models of traffic flow and its broad applicability across all engineering's fields. As such, bond graphs enormously facilitate the integration task of road activity in the supply chain.

Many models for fault detection and isolation (FDI) will contain multi-port energy storage and flow-dependencies due to convection. Converting these models into qualitative ones leads to ambiguities that can be eliminated by analysis of boundary conditions. In this study the example of an automotive cooling system is used to demonstrate how these issues can be handled. Furthermore, time constants in the models need to correspond to the bandwidth of the data acquisition system. In order to achieve this, parameters leading to irrelevant time constants can be eliminated by assigning relatively small and large parameters to be zero or infinite respectively. However, this may result in (i) discontinuities and (ii) zero order causal paths ("algebraic loops"). Compensation of qualitative e#ects instead of reversal is shown to be an adequate solution for these problems.