dynamic modeling of wind turbines how to model flexibility into multibody modelling

Abstract This work is part of a research activity inserted into "Smart Optimazed Fault Tolerant WIND Turbines (SOFTWIND)" project of PRIN 2015, funded by the Italian Ministry of the University and Research (MIUR). The need to define a robust multibody modelling procedure to realistically characterize the dynamical behavior of a generic wind turbine and to have a reduced computational burden has pushed the authors to adopt a freeware software called Nrel-FAST, that is universally considered to be a reference in the field of aeroelastic wind turbine simulations. The lightness of this software is paid in terms of modelling simplicity, which makes the modelling of wind turbines with unconventional support structures (i.e. that con not directly outlined as a fixed-beam) difficult. In this paper, some methodologies to overcome this obstacle are presented, including the use of a more powerful multibody software which, on the other hand, entails higher simulation times. In particular, the authors present a methodology based on structure stiffness-matrix reconstruction that allows, under appropriate hypothesis, to reduce a complex wind turbine support frame to a simple fixed beam so that the simulations can be done directly in FAST environment, with low computational times. The results obtained from these different approaches are compared using as test-case a small wind turbine property of University of Perugia (UniPG)

Computational methods and software systems for dynamics and control of large space structures

Two key areas of crucial importance to the computer-based simulation of large space structures are discussed. The first area involves multibody dynamics (MBD) of flexible space structures, with applications directed to deployment, construction, and maneuvering. The second area deals with advanced software systems, with emphasis on parallel processing. The latest research thrust in the second area involves massively parallel computers

Dynamic considerations of heel-strike impact in human gait

Based on the impulsive-dynamics formulation, this article presents the analysis of different strategies to regulate the energy dissipation at the heel-strike event in the context of human locomotion. For this purpose, a seven-link 2D human-like multibody model based on anthropometric data is used. The model captures the most relevant dynamic and energetic aspects of the heel-strike event in the sagittal plane. The pre-impact mechanical state of the system, around which the analysis of the heel impact contribution to energy dissipation is performed, is defined based on published data. In the context of the proposed impulsive-dynamics framework, different realistic strategies that the subject can apply to modify the impact dynamics are proposed and analyzed, namely, the trailing ankle push-off, the torso configuration and the degree of joint blocking in the colliding leg. Detailed numerical analysis and discussions are presented to quantify the effects of the mentioned strategies.Postprint (author's final draft

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

MODELING AND SIMULATION OF INDUSTRIAL ROBOT ARMS USING SIMSCAPE MULTIBODY

The dynamic simulation modeling problem of industrial robot arm is solved, and the trajectory planning dynamic simulation is performed in this paper. In response to the lack of trajectory planning and motion controller interfaces in the robotic modelling study, including the lack of dynamic simulation visualization, a Simscape Multibody-based method for building a dynamic model of industrial robot arm is proposed and the effectiveness of the model is verified through dynamic simulation. The simulation model integrates the robotic arm trajectory planning, motion controller and data acquisition module. It has a clear structure and the parameters are easy to modify. It can reasonably simulate the structure and parameters of the research object and facilitate the subsequent research of related algorithms. It provides an innovative and open-source research and development platform for the dynamic simulation study of the robot arm

Activities of the Center for Space Construction

The Center for Space Construction (CSC) at the University of Colorado at Boulder is one of eight University Space Engineering Research Centers established by NASA in 1988. The mission of the center is to conduct research into space technology and to directly contribute to space engineering education. The center reports to the Department of Aerospace Engineering Sciences and resides in the College of Engineering and Applied Science. The college has a long and successful track record of cultivating multi-disciplinary research and education programs. The Center for Space Construction is prominent evidence of this record. At the inception of CSC, the center was primarily founded on the need for research on in-space construction of large space systems like space stations and interplanetary space vehicles. The scope of CSC's research has now evolved to include the design and construction of all spacecraft, large and small. Within this broadened scope, our research projects seek to impact the underlying technological basis for such spacecraft as remote sensing satellites, communication satellites, and other special purpose spacecraft, as well as the technological basis for large space platforms. The center's research focuses on three areas: spacecraft structures, spacecraft operations and control, and regolith and surface systems. In the area of spacecraft structures, our current emphasis is on concepts and modeling of deployable structures, analysis of inflatable structures, structural damage detection algorithms, and composite materials for lightweight structures. In the area of spacecraft operations and control, we are continuing our previous efforts in process control of in-orbit structural assembly. In addition, we have begun two new efforts in formal approach to spacecraft flight software systems design and adaptive attitude control systems. In the area of regolith and surface systems, we are continuing the work of characterizing the physical properties of lunar regolith, and we are at work on a project on path planning for planetary surface rovers