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Fault detection and isolation (FDI) is an essential task that allows avoiding the fault consequence on the performance of the system. The bond graph, as a modelling tool, provides through its structural and causal properties, an automatic generation of analytical redundancy relations (ARRs). These relations are used for diagnosis applications, they constitute the mathematical constraints that are used to verify the coherence between the process measurements and the reference of the system behaviour represented by the model. The classical ARR diagnosis approach allows to both detect and isolate the defective component in the system. In this work, the main goal is to increase the number of isolable faults by increasing the number of ARRs, using the output of the bond graph model along with the measured output of the real system. The innovative interest in this work is that the number of the isolated faults can be improved without the addition of more sensors. Following the general discussion of the proposed method, a robotic subsystem (traction of an omnidirectional mobile robot) is considered to validate the proposed procedure. Two faulty scenarios are then presented and discussed using both the classical and the proposed approach.The proposed method is able to isolate 3 faults that can not be isolated using classical ARR.

This paper presents a scheme of evolutionary design optimization, which integrates modeling with bond graphs and optimization using genetic programming for multi-domain engineering systems, particularly mechatronic systems. The performance of the developed system is studied using both experimentation and simulation. During the evolutionary optimization, in addition to the desired response error, system complexity is also taken into account. For the experimental study, the method is implemented in an industrial fish processing machine at the Industrial Automation Laboratory of the University of British Columbia, and the obtained results for suggested design modifications are studied and tested. The drawbacks of the fitness calculation methodologies that are presented in literature are identified and improved fitness functions are developed for evolutionary design in the present work. While previous work has investigated the integration of bond graphs and genetic programming for designing an engineering system, the present work specifically addresses the application of the developed method for the design improvement of an industrial machine. The proposed method is applicable particularly to existing engineering systems, first because the initial model can be tested by comparing its simulated results with the corresponding results from the actual physical system, and second because the design improvements as suggested by the evolutionary design framework, which is developed in the present work, may be implemented and tested against the behavior of the corresponding model.

The causally dynamic hybrid bond graph is extended to the case of mode-switching behaviour. Mode-switching 'trees' of switches and elements are historically used by bond graph practitioners to represent elements with piecewise-continuous functions. This case is defined as 'parametric switching' for the purposes of the hybrid bond graph, since the switching is internal to the element, as opposed to 'structural switching' which alters the model structure. This mode-switching 'tree' is concatenated into a new controlled element which features Boolean switching parameters in the constitutive equation, removing unnecessary complexity from the model. Mixed-Boolean state equations can be derived from the model, which are nonlinear and/or time-varying (and hence not in the familiar Linear Time Invariant Form). It can be seen that controlled elements often have a static causality assignment and leave the model structure unchanged. The result is a concise method for representing nonlinear behaviour as a piecewise-continuous function in the bond graph modelling framework.

The aim of this work is to show how the modeling of an electromechanical system can be addressed using the energy-based graphical modeling technique named “Power-Oriented Graphs” (POG). Differences and analogies of POG against Bond Graphs modeling technique are discussed. The paper presents the POG dynamic model of an automatic corking machine for threaded plastic caps: the system is composed by two electric motors moving a ball screw/spline that realizes the linear/rotary motion necessary to screw a plastic cap on a bottle. First an extended POG model is presented, together with the equivalent Bond Graph model, then some proper congruent state space transformations and a POG-based graphical method are introduced to transform and reduce the system dynamic model. Simulation and experimental results are finally presented and compared.

This paper outlines an alternative modeling scheme for mechatronic systems, as a basis for their concurrent design. The approach divides a mechatronic system into three generic subsystems, namely generalized executive, sensory and control, and links them together utilizing a combination of bond graphs and block diagrams. It considers the underlying principles of a multidisciplinary system, and studies the flow of energy and information throughout its different constituents. The first and second laws of thermodynamics are reformulated for mechatronic systems, and as a result three holistic design criteria, namely energy, entropy and agility, are defined. These criteria are formulated using the bond graph representation of a mechatronic system. As a case study, the three criteria are employed separately for concurrent design of a five degree-of-freedom industrial robot manipulator.

Piezoelectric actuators are becoming very popular in applications such as nanopositioning, active vibration control or noise reduction, sometimes as part of so called smart structures. The possibility of accurately moving big loads on a micrometric scale and over a wide range of frequencies has resulted in an intense growth of this technology. This interest has prompted the development of a wide variety of mathematical models available for describing their behaviour, whose suitability depends on the specific application involved. This work overcomes this limitation by unifying the different modelization options for stack and stack-based actuators in a general Bond Graph model structure capable of handling the most important physical phenomena observed in these actuators, both linear, such as direct and indirect piezoelectric effects or rate dependence, and nonlinear, such as hysteresis. This model structure represents a basis for specific applications, and can be used for control or simulation purposes thanks to its high generality and adjustment capabilities. The proposed Bond Graph structure graphically shows the power flow between the electrical and mechanical frameworks of the piezoelectric actuator, and uses a modular structure for separately representing the electrical polarization of the material and its macroscopic electrical and mechanical effects. Finally, the model is successfully applied to describe the rate dependent behaviour of the Cedrat Groupe APA-120ML actuator. In this connection, an experimental identification method is described and adapted for implementing hysteresis descriptions based on simple operators or in differential equations in the model structure (O-based and DE-based models). These two typologies cover the majority of the models available, proving the generality of the proposed piezoelectric model for implementing less general or specific phenomenon descriptions into its structure. In consequence, the main contribution of this work is the development of a general framework for modelling piezoelectric actuators, comprising a graphical Bond Graph model and an adjustment procedure, which is flexible enough to embody different representations of the phenomena present in these actuators, and with a modular structure that admits different levels of complexity depending on the phenomena incorporated in the model.

Piezoelectric tubes exhibit a highly resonant mode of vibration which, if uncontrolled, limits the maximum scan rate in nano-scale positioning applications. Highly resonant systems with collocated sensor/actuator are often controlled using resonant shunt dampers. Unfortunately, in the configuration used here, this approach is not possible due the non-minimum phase property arising from the presence of a right-half plane zero. This problem is solved by: (i) interpreting the resonant shunt damper in the context of physical-model-based control (PMBC) and (ii) extending the PMBC approach to handle non-minimum phase systems. The resultant controller combines the physical insight of the resonant shunt damper with the ability to control the non-minimum phase piezoelectric tube. A digital implementation of the controller was experimentally evaluated and found to successfully eliminate the resonant mode of vibration during an accurate and fast scan using a piezoelectric tube actuator. � 2009 Elsevier Ltd. All rights reserved.

Causality, in the bond graph sense, is shown to provide a conceptual framework for the design of real-time dynamic substructure testing experiments. In particular, known stability problems with split-inertia substructured systems are reinterpreted as causality issues within the new conceptual framework. As an example, causality analysis is used to provide a practical solution to a split-inertia substructuring problem and the solution is experimentally verified.

A control strategy for a solid oxide fuel cell (SOFC) is developed in this paper to maintain required cell operating conditions while ensuring good fuel efficiency and satisfying the constraints on the transient performance. To verify the controller performance, a zero-dimensional true bond graph model of an SOFC system is developed which makes use of a C-field for two gas species in order to model the cathode and anode channel gases. Moreover, an existing R-field model has been extended for modeling of forced convection of a mixture of two gas species. The coupling between the chemical, thermal, mechanical and the hydraulic domains, which is encountered in a fuel cell system, is represented in a unified manner by using true bond graphs. The fuel utilization (FU) and the air utilization (AU) are interpreted in terms of the partial pressures of the gases. The static characteristics of the fuel cell obtained are in good agreement with the data from the literature. The dynamic response of the fuel cell to step changes in load current is obtained. From the simulations it is shown that all the control objectives are achieved by the proposed control system.

Tire–road interface dynamics is due to the interaction of several physical phenomena (mechanical, thermal, hydrodynamic, etc.). Modelling of such a system needs a unified approach to represent the nonlinear behavior model in a generic and systematic way. Bond graph modelling is well suited for this task. The developed model allows to estimate the longitudinal impact forces at tire–road contact in interaction with its environment. A simulation model in modular and hierarchical form is developed in Symbols 2000 software and used for model integration and validation. Finally, comparison with experimental results are presented.

This paper suggests a unified and automated design methodology for synthesizing designs for multi-domain systems, such as mechatronic systems. A multi-domain dynamic system includes a mixture of electrical, mechanical, hydraulic, pneumatic, and/or thermal components, making it difficult use a single design tool to design a system to meet specified performance goals. The multi-domain design approach is not only efficient for mixed-domain problems, but is also useful for addressing separate single-domain design problems with a single tool. Bond graphs (BGs) are domain independent, allow free composition, and are efficient for classification and analysis of models, allowing rapid determination of various types of acceptability or feasibility of candidate designs. This can sharply reduce the time needed for analysis of designs that are infeasible or otherwise unattractive. Genetic programming is well recognized as a powerful tool for open-ended search. The combination of these two powerful methods is therefore an appropriate target for a better system for synthesis of complex multi-domain systems. The approach described here will evolve new designs (represented as BGs) with ever-improving performance, in an iterative loop of synthesis, analysis, and feedback to the synthesis process. The suggested design methodology has been applied here to three design examples. The first is a domain-independent eigenvalue placement design problem that is tested for some sample target sets of eigenvalues. The second is in the electrical domain––design of analog filters to achieve specified performance over a given frequency range. The third is in the electromechanical domain––redesign of a printer drive system to obtain desirable steady-state position of a rotational load.

One of the main and most challenging steps in the design and analysis of a mechatronics system is to generate a computer model. This paper explores the fundamental theory, the methodology and the process from conceptual ideas to practical realization. Using a multienergetic approach that allows the modeling of interdisciplinary models, it explores the theory and method to automate the process of the generation of the differential equations and how to automate the derivation of transfer functions. The approach is discussed for linear and non-linear systems. The generation of a computer model takes new dimensions when that model contains mixed energy domains such as electromechanical, electrohydraulic, thermo-fluid, and electronic control systems all together. These are typical of mechatronics applications. This paper explores the bond graph technique as a modeling tool to generate state space models or non-linear models together with software tools. CAMP-G (Computer Aided Modeling Program with Graphical input) has been developed in order to generate computer models automatically and have them integrated with MATLAB–SIMULINK as simulation tools. Several aspects of mechatronics systems design have been investigated in order to focus on which areas the bond graph modeling technique can help engineers in the process of creating mechatronics systems from scratch. Towards this end, the paper deals with computer-generated models of sensors, actuators, and multidisciplinary complex physical systems.

A software tool based on bond graphs is presented together with a hardware-in-the-loop experimental rig. These are designed to be used as aids in the planning, simulation, implementation and testing of control systems containing multiple actuators with sensory feedback. The windows-based, object-orientated (OO) development tool ACE (Adaptive Control Environment) enables the user to build up a graphical representation of the system by selecting objects from a library of system elements and/or mini systems. Each of these objects, although viewed as a graphical drawing of the selected element on this level, contains data representing an acausal bond graph. As the model is built up containing several of these objects, ACE has a view of the overall interconnecting acausal bond graph of the system. For hardware-in-the-loop simulation, ACE divides the core system model into three parts, representing: • the hardware-in-the-loop objects — that is the hardware under test (e.g. an electrical motor and sensors); • the controller — whose function it is to control the afore mentioned hardware; • an applied loading. It is from the last two of these sub-systems that control code may be generated for operation and testing on a specially developed DAP (Data Acquisition Processor) controlled test-rig.

In the field of robotic control, impedance control is seen as an efficient method of position and force control during operations where there is a dynamic interaction between the robot and the environment. An impedance control strategy using an electrohydraulic servosystem for such tasks is described. The impedance of the robotic manipulator is varied by varying the damping in the hydraulic servosystem appended to the manipulator, which acts as a controller in the physical domain. Theoretical and experimental investigations carried out on a typical system are described. Bond graph as well as block diagram approaches are used for analysis of the system. Copyright ? 1996 Elsevier Science Ltd.

A tutorial introduction to the use of bond graphs in modelling mechatronic systems is given. Four illustrative examples of increasing complexity are given, culminating in a two link robotic arm with flexible drives. The role of symbolic algebra techniques in this context is emphasized and it is suggested that the marriage of bond graphs and symbolic techniques provides the basis of computer-based support tools for the analysis and design of mechatronic systems.