Modeling Stiffness and Damping in Rotational Degrees of Freedom Using Multibond Graphs

A contribution is proposed for the modeling of mechanical systems using multibond graphs. When modeling a physical system, it may be needed to catch the dynamic behavior contribution of the joints between bodies of the system and therefore to characterize the stiffness and damping of the links between them. The visibility of where dissipative or capacitive elements need to be implemented to represent stiffness and damping in multibond graphs is not obvious and will be explained. A multibond graph architecture is then proposed to add stiffness and damping in hree rotational degrees of freedom. The resulting joint combines the spherical joint multibond graph relaxed causal constraints while physically representing three concatenated revolute joints. The mathematical foundations are presented, and then illustrated through the modeling and simulation of an inertial navigation system; in which stiffness and damping between the gimbals are taken into account. This method is particularly useful when modeling and simulating multibody systems using Newton-Euler formalism in multibond graphs. Future work will show how this method can be extended to more complex systems such as rotorcraft blades' connections with its rotor hub.Fondation Airbus Grou

Multi-physic system simplification method applied to a helicopter flight axis active control

A helicopter flight axis control, which is a complex multi-physic system, is modelled using an energetic based graphical tool: the Energetic Macroscopic Representation. Elements of the system are mainly composed of passive technologies and their number tends to increase year after year to improve the pilots comfort by adding new functions. A new methodology is proposed to transform the system into a new active one by replacing some hydro-mechanical elements by a new controllable active mechanical source. The challenge is to simplify the flight control architecture while preserving the global behaviour of the system

Adaptation de la loi de mouvement aux systemes de positionnement à dynamique élevée

L’augmentation des performances des machines de positionnement passe par l’augmentation des accélérations et donc des sollicitations transmises à la structure de la machine. Ces contraintes sont susceptibles d’engendrer des déformations et des vibrations dégradant le suivi de profil ainsi que le positionnement final. Les commandes numériques avancées disposent de différentes formes de loi de movement à jerk limité, polynomiale...) qui ont un effet notable sur le compromis entre la durée du mouvement effectif et la précision attendue. L’objectif de cet article vise à démystifier cet effet en proposant une analyse comparative de l’influence de différents types de lois de mouvement sur les vibrations, ainsi que sur la durée du mouvement d’un axe soumis à un mode de déformation prépondérant.National audienceL’augmentation des performances des machines de positionnement passe par l’augmentation des accélérations et donc des sollicitations transmises à la structure de la machine. Ces contraintes sont susceptibles d’engendrer des déformations et des vibrations dégradant le suivi de profil ainsi que le positionnement final. Les commandes numériques avancées disposent de différentes formes de loi de movement à jerk limité, polynomiale...) qui ont un effet notable sur le compromis entre la durée du mouvement effectif et la précision attendue. L’objectif de cet article vise à démystifier cet effet en proposant une analyse comparative de l’influence de différents types de lois de mouvement sur les vibrations, ainsi que sur la durée du mouvement d’un axe soumis à un mode de déformation prépondérant

Conception architecturale d’un système mécatronique d’assistance à opérateur par Bond-Graph

Les systèmes mécatroniques requièrent une forte intégration physique et fonctionnelle. Pour répondre au premier besoin, l’usage d’un outil de modélisation multi-physique tel que le Bond-Graph est nécessaire. Son extension à la modélisation fonctionnelle est possible si la description informationnelle des échanges fonctionnels peut être mise sous forme d’action-réaction. Les travaux exposés proposent une méthodologie de conception du niveau architectural d’un système mécatronique d’assistance à l’opérateur, basée sur une modélisation multi-physique et multi-domaine (physique et informationnel) de son cahier des charges.International audienceLes systèmes mécatroniques requièrent une forte intégration physique et fonctionnelle. Pour répondre au premier besoin, l’usage d’un outil de modélisation multi-physique tel que le Bond-Graph est nécessaire. Son extension à la modélisation fonctionnelle est possible si la description informationnelle des échanges fonctionnels peut être mise sous forme d’action-réaction. Les travaux exposés proposent une méthodologie de conception du niveau architectural d’un système mécatronique d’assistance à l’opérateur, basée sur une modélisation multi-physique et multi-domaine (physique et informationnel) de son cahier des charges

Multi-physic system simplification method applied to a helicopter flight axis active control

International audienceA helicopter flight axis control, which is a complex multi-physic system, is modelled using an energetic based graphical tool: the Energetic Macroscopic Representation. Elements of the system are mainly composed of passive technologies and their number tends to increase year after year to improve the pilots comfort by adding new functions. A new methodology is proposed to transform the system into a new active one by replacing some hydro-mechanical elements by a new controllable active mechanical source. The challenge is to simplify the flight control architecture while preserving the global behaviour of the system

Complementary use of BG and EMR formalisms for multiphysics systems analysis and control

In this paper, a complex multiphysics system is modeled using two different energy-based graphical techniques: Bond Graph and Energetic Macroscopic Representation. These formalisms can be used together to analyze, model and control a system. The BG is used to support physical, lumped-parameter modeling and analysis processes, and then EMR is used to facilitate definition of a control structure through inversion-based methodology. This complementarity between both of these tools is set out through a helicopter flight control subsystem

Modelling and Control of an Effort Feedback Actuator in Helicopter Flight Control Using Energetic Macroscopic Representation

In helicopter field, electromechanical devices controllers are usually designed and tuned from global analysis with transfer functions calculations. This leads to control architectures with a reduced number of controllers. Their regulating loops are usually global PID controllers where parameters are directly set up on dedicated test benches. Energetic representation tools such as Energetic Macroscopic Representation (EMR) aim at simplifying systems analysis and control providing model and control structuring method. In this paper, a simplified helicopter flight axis control is modelled with the intention of controlling the helicopter stick force feedback. Performances of both global PID and energetic model based inversion controllers are discussed through simulation results

Modelling and Control of an Effort Feedback Actuator in Helicopter Flight Control Using Energetic Macroscopic Representation

In helicopter field, electromechanical devices controllers are usually designed and tuned from global analysis with transfer functions calculations. This leads to control architectures with a reduced number of controllers. Their regulating loops are usually global PID controllers where parameters are directly set up on dedicated test benches. Energetic representation tools such as Energetic Macroscopic Representation (EMR) aim at simplifying systems analysis and control providing model and control structuring method. In this paper, a simplified helicopter flight axis control is modelled with the intention of controlling the helicopter stick force feedback. Performances of both global PID and energetic model based inversion controllers are discussed through simulation results

Inversion-based control of electromechanical systems using causal graphical descriptions

Causal Ordering Graph and Energetic Macroscopic Representation are graphical descriptions to model electromechanical systems using integral causality. Inversion rules have been defined in order to deduce control structure step-bystep from these graphical descriptions. These two modeling tools can be used together to develop a two-layer control of system with complex parts. A double-drive paper system is taken as an example. The deduced control yields good performances of tension regulation and velocity tracking

Inversion-based control of electromechanical systems using causal graphical descriptions

Causal Ordering Graph and Energetic Macroscopic Representation are graphical descriptions to model electromechanical systems using integral causality. Inversion rules have been defined in order to deduce control structure step-bystep from these graphical descriptions. These two modeling tools can be used together to develop a two-layer control of system with complex parts. A double-drive paper system is taken as an example. The deduced control yields good performances of tension regulation and velocity tracking