Teaching kinematics and dynamics of multibody mechanical systems using the object oriented language modelica

A new modeling language, called Modelica, for physical modeling is being developed in an international effort. The main objective is to make it easy to exchange models and model libraries for different domains, such as, mechanical, pneumatics, electrical, hydraulics, and others. The design approach builds on non-causal modeling with true ordinary differential and algebraic equations and the use of object-oriented constructs stemming from modern software development, (hierarchy, encapsulation) to facilitate reuse of models and model parts. This paper gives an overview of the use of the object oriented language Modelica with the mechanical Multibody Library to model and simulate three-dimensional mechanical systems

Beyond Simulation: Computer Aided Control System Design Using Equation-Based Object Oriented Modelling for the Next Decade

After 20 years since their birth, equation-oriented and object-oriented modelling techniques and tools are now mature, as far as solving simulation problems is concerned. Conversely, there is still much to be done in order to provide more direct support for the design of advanced, model-based control systems, starting from object-oriented plant models. Following a brief review of the current state of the art in this field, the paper presents some proposals for future developments: open model exchange formats, automatic model-order reduction techniques, automatic derivation of simplified transfer functions, automatic derivation of LFT models, automatic generation of inverse models for robotic systems, and support for nonlinear model predictive control

Développement d’une méthode d’apprentissage par projet pour l’enseignement de la modélisation multicorps appliquée au corps humain

RÉSUMÉ La modélisation multicorps est un outil d’ingénierie très utilisé à travers le monde pour résoudre des problèmes de cinématique et de dynamique de divers mécanismes. Son application au corps humain a vécu une grande révolution au cours des dernières décennies dans le milieu de la recherche, permettant notamment d’estimer les forces musculaires et les couples articulaires de manière non invasive. Le recours à des modèles humains est donc devenu de plus en plus populaire et pertinent pour l’industrie des produits de santé et les applications cliniques. En outre, la modélisation multicorps s’intègre de plus en plus dans les processus de décision pour la conception de produits tels que les exosquelettes, les prothèses, les orthèses ou encore l’évaluation fonctionnelle du corps humain. En particulier, beaucoup d’efforts ont été effectués dans les dernières années pour combiner cet outil avec d’autres outils tels que les logiciels de conception assistée par ordinateur et d’éléments finis afin de pouvoir faire des études plus complètes de conception et d’analyse. Or, malgré le fait que la modélisation multicorps est très complexe, cette matière est relativement peu enseignée de manière systématique, et généralement apprise sur le tas en recherche ou en industrie, limitant grandement les capacités d’utilisation et de développement des ingénieurs. Par conséquent, il est nécessaire de mettre en place une méthodologie d’apprentissage permettant d’intégrer cette matière dans la formation des ingénieurs en biomédical et en mécanique. Ainsi, le but de cette thèse de maitrise est de proposer une méthodologie d’apprentissage par projet pour faciliter l’enseignement des bases de la modélisation multicorps appliquée au corps humain, afin que les étudiants puissent ensuite envisager des développements plus avancés sur base d’un socle de compétences solide et standardisé. La méthode générale a consisté à identifier le matériel, les méthodologies et les défis des milieux professionnels de la modélisation multicorps. Ensuite, un projet pilote a été proposé à une classe de cycles supérieurs de génie biomédical, suivi d’une étape d’identification des difficultés et des défis de l’apprentissage de la modélisation multicorps dans la littérature et par le biais d’entrevues. Enfin, une méthodologie d’apprentissage par projet a été construite en se basant sur les méthodologies et matériels identifiés dans le milieu professionnel et répondant aux difficultés identifiées. Les résultats principaux de cette étude permettent (1) d’identifier les difficultés principales relatives à l’apprentissage et à l’utilisation de la modélisation multicorps appliquée au corps humain (2) de conclure que la méthodologie de projet ne doit pas seulement utiliser de la simulation mais doit s’accompagner d’un dispositif physique. En particulier, les résultats montrent que l’utilisation de prototypage rapide permet de proposer un projet simplifié tout en restant concret et en répondant aux difficultés identifiées.Les perspectives de cette étude sont de développer une méthodologie avancée augmentant la complexité du projet et du dispositif physique pour atteindre des modèles d’une sophistication semblable aux modèles utilisés dans l’industrie et la clinique.----------ABSTRACT Multibody modeling is an engineering tool widely used to solve kinematics and dynamics problems for various mechanisms. Its application to the human body modeling by the research community has gone through a revolution in the last decades, enabling to estimate muscle forces and joint torques in a non-invasive way. Therefore, the use of human-like models has become increasingly popular and very relevant to the health industry and for clinical applications. In addition, multibody modeling is more and more involved in the decision-making process for the design of products interacting closely with the human body such as exoskeletons or prosthetics. Particularly, many efforts have been made recently to combine this tool with other tools such as computer-aided design software packages and finite elements analysis in order to make more thorough design and analysis studies. However, despite the complexity inherent to learning of multibody modeling, it is rarely taught in a systematic way, and is usually learned in ad-hoc manner in both research and or industry, thus limiting greatly the capacity of cooperation and development for engineers. Therefore, it is necessary to develop a learning methodology allowing one to incorporate this material in the training of engineers and more particularly biomedical and mechanical engineers. Therefore, the aim of this Masters thesis is to provide a project based learning methodology to facilitate the teaching of the basics of multibody modeling applied to the human body, so that students could then consider more advanced developments on the basis of stronger and better standardized skills. The general approach proposed in this master thesis is to build on the methodology of real-world project development in the field of biomedical and mechanical engineering involving multibody modeling steps, to offer a project using professional tools and techniques. Then a step of identification of the difficulties and challenges for learning multibody modeling is carried out using data collected from literature and from semi-structured interviews leading to a proposed project-based learning methodology meeting the identified challenges. The main results of this master project allow (1) to identify the main difficulties in learning and using multibody modeling applied to the human body (2) to conclude that the proposed methodology should not only use simulation but must be accompanied by a physical prototype. In particular, the results show that the use of rapid prototyping enables one to offer a simplified project while still addressing the identified challenges. The prospects of this study are to develop a methodology increasing both the project and the physical device complexity to reach a similar sophistication compared with models used in the industry and by clinicians

MUSME 2011 4 th International Symposium on Multibody Systems and Mechatronics

El libro de actas recoge las aportaciones de los autores a través de los correspondientes artículos a la Dinámica de Sistemas Multicuerpo y la Mecatrónica (Musme). Estas disciplinas se han convertido en una importante herramienta para diseñar máquinas, analizar prototipos virtuales y realizar análisis CAD sobre complejos sistemas mecánicos articulados multicuerpo. La dinámica de sistemas multicuerpo comprende un gran número de aspectos que incluyen la mecánica, dinámica estructural, matemáticas aplicadas, métodos de control, ciencia de los ordenadores y mecatrónica. Los artículos recogidos en el libro de actas están relacionados con alguno de los siguientes tópicos del congreso: Análisis y síntesis de mecanismos ; Diseño de algoritmos para sistemas mecatrónicos ; Procedimientos de simulación y resultados ; Prototipos y rendimiento ; Robots y micromáquinas ; Validaciones experimentales ; Teoría de simulación mecatrónica ; Sistemas mecatrónicos ; Control de sistemas mecatrónicosUniversitat Politècnica de València (2011). MUSME 2011 4 th International Symposium on Multibody Systems and Mechatronics. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/13224Archivo delegad

Modelling and control of aerial manipulators

Hace unos años, dentro de la robótica aérea, surgió la manipulación aérea como campo de investigación. Desde su nacimiento, su impacto ha ido incrementándose poco a poco debido, sobretodo, al gran número de aplicaciones que podrían llevarse a cabo con este tipo de sistemas. Un manipulador aéreo puede definirse como una plataforma aérea la cual ha sido equipada con uno o varios brazos robóticos. Este nuevo concepto ha abierto un mundo de posibilidades para este tipo de robots aéreos. Además, gracias a la posibilidad de este tipo de robots aéreos de interactuar con su entorno, podrían llevar a cabo inspecciones de estructuras civiles o incluso, tareas de ensamblaje de estructuras y todo ello, por supuesto, de forma autónoma. Esta tesis se centra en el estudio e implementación de sistemas de manipulación aérea y, en particular, en el diseño de estrategias de control para la plataforma aérea. Este estudio comienza con el cáculo de las ecuaciones que representan la dinámica del sistema, y que nos permite analizar su comportamiento y la influencia del movimiento de los brazos robóticos en la estabilidad de la plataforma.El análisis de estas ecuaciones nos permite diseñar de esquemas de control tales como los basados en Backstepping. Pero el objetivo de esta tesis no es solo el diseño sino también la implementación de estas técnicas de control en sistemas de manipulación aérea reales y con capacidad de llevar a cabo tareas de manipulación en escenarios al aire libre. La principales contribuciones de esta tesis son el cálculo de los modelos dinámicos para cada uno de los tipos de manipuladores aéreos estudiados he implementados durante el desarrollo de la tesis. Además del uso de estas modelos para la diseño de una estrategia de control adaptable a cada una de las plataformas. También se ha diseñado un mecanismo “compliant” que ha sido integrado en un manipulador parallevar a cabo tareas de inspección estructuras por contacto, además de un control de fuerza-posición. Cada manipulador aéreo implementado durante esta tesis, excepto el en caso del helicóptero, va unido a un estudio de las especificaciones hardware necesarias para la realización de una validación del sistema mediante experimentos de vuelo en escenarios al aire libre, y en el caso de los manipuladores aéreos para inspección de estructuras, en un puente real. Cada experimento realizado ha sido analizado en detalle para corregir errores, además de para adaptar o agregar cualquier modificación estructural o de hardware necesaria

Real-time Dynamic Simulation of Constrained Multibody Systems using Symbolic Computation

The main objective of this research is the development of a framework for the automatic generation of systems of kinematic and dynamic equations that are suitable for real-time applications. In particular, the efficient simulation of constrained multibody systems is addressed. When modelled with ideal joints, many mechanical systems of practical interest contain closed kinematic chains, or kinematic loops, and are most conveniently modelled using a set of generalized coordinates of cardinality exceeding the degrees-of-freedom of the system. Dependent generalized coordinates add nonlinear algebraic constraint equations to the ordinary differential equations of motion, thereby producing a set of differential-algebraic equations that may be difficult to solve in an efficient yet precise manner. Several methods have been proposed for simulating such systems in real time, including index reduction, model simplification, and constraint stabilization techniques. In this work, the equations of motion are formulated symbolically using linear graph theory. The embedding technique is applied to eliminate the Lagrange multipliers from the dynamic equations and obtain one ordinary differential equation for each independent acceleration. The theory of Gröbner bases is then used to triangularize the kinematic constraint equations, thereby producing recursively solvable systems for calculating the dependent generalized coordinates given values of the independent coordinates. For systems that can be fully triangularized, the kinematic constraints are always satisfied exactly and in a fixed amount of time. Where full triangularization is not possible, a block-triangular form can be obtained that still results in more efficient simulations than existing iterative and constraint stabilization techniques. The proposed approach is applied to the kinematic and dynamic simulation of several mechanical systems, including six-bar mechanisms, parallel robots, and two vehicle suspensions: a five-link and a double-wishbone. The efficient kinematic solution generated for the latter is used in the real-time simulation of a vehicle with double-wishbone suspensions on both axles, which is implemented in a hardware- and operator-in-the-loop driving simulator. The Gröbner basis approach is particularly suitable for situations requiring very efficient simulations of multibody systems whose parameters are constant, such as the plant models in model-predictive control strategies and the vehicle models in driving simulators

Proceedings of the ECCOMAS Thematic Conference on Multibody Dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: ● Formulations and Numerical Methods ● Efficient Methods and Real-Time Applications ● Flexible Multibody Dynamics ● Contact Dynamics and Constraints ● Multiphysics and Coupled Problems ● Control and Optimization ● Software Development and Computer Technology ● Aerospace and Maritime Applications ● Biomechanics ● Railroad Vehicle Dynamics ● Road Vehicle Dynamics ● Robotics ● Benchmark ProblemsPostprint (published version

An introduction to Siconos

In this document, a brief overview of the Siconos Platform is given. One of the goal is to give a flavor on a simple example of the ability of the platform to model and simulate the so-called non smooth dynamical systems (NSDS). In particular, some examples of Lagrangian mechanical systems with contact and friction or electrical circuits with ideal and piecewise linear components (diodes, MOS transistors, \ldots) are commented. Finally, the Siconos software is presented, starting from its architecture to a non exhaustive presentation of its components and functionalities. The aim of this document is not to serve as a reference guide but more as a illustrative introduction document to promote the use of the platform

Multibody dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: Formulations and Numerical Methods, Efficient Methods and Real-Time Applications, Flexible Multibody Dynamics, Contact Dynamics and Constraints, Multiphysics and Coupled Problems, Control and Optimization, Software Development and Computer Technology, Aerospace and Maritime Applications, Biomechanics, Railroad Vehicle Dynamics, Road Vehicle Dynamics, Robotics, Benchmark Problems. The conference is organized by the Department of Mechanical Engineering of the Universitat Politècnica de Catalunya (UPC) in Barcelona. The organizers would like to thank the authors for submitting their contributions, the keynote lecturers for accepting the invitation and for the quality of their talks, the awards and scientific committees for their support to the organization of the conference, and finally the topic organizers for reviewing all extended abstracts and selecting the awards nominees.Postprint (published version