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[en] ORDER REDUCTION OF LINEAR MECHANICAL MODELS: A BOND GRAPH APPROACH / [pt] REDUÇÃO DE ORDEM DE MODELOS MECÂNICOS LINEARES: UMA ABORDAGEM VIA GRAFOS DE LIGAÇÃOMAURO SPERANZA NETO 08 May 2006 (has links)
[pt] Neste trabalho descreve-se um procedimento para o
desenvolvimento de modelos reduzidos de sistemas mecânicos
lineares baseado na técnica dos Grafos de Ligação. A
partir da análise da estrutura topológica dos principais
modelos mecânicos descritos por esta técnica estabeleceu-
se uma nova formulação que possibilita a obtenção de
variadas formas de representação matemática e definiu-se
um grafo genérico, formado por hipercampos armazenadores e
dissipadores de energia, onde se encontram as matrizes que
caracterizam a dinâmica do sistema.
Sobre o grafo genérico, com algumas restrições, foi
aplicada uma metodologia de normalização e desacoplamento
dos campos armazenadores, com base nos seus modos locais,
o que permitiu a criação de um grafo particionado,
acoplado através do campo dissipador. A análise dos
coeficientes do campo de acoplamento leva ao grafo de
Ligação Reduzido do sistema. Comprova-se a validade do
procedimento através de exemplos de fácil compreensão. / [en] It is described in this work a Bond Graph based procedure
to the development of linear mechanical systems reduced
order models. From the analysis of the topological
structure of the main mechanical models represented by
this technique it was established a new formulation that
permits to obtain several mathematical representation
forms and it was defined a generic graph, formed by energy
storage and dissipative hiperfields, where the matrices
that characterizes the system dynamics are included.
On the generic graph, with some constraints, it
was applied a methodology for the normalization and
decoupling of the energy storage fields, based on its
local modes, that permits to develop a partioned graph,
couplec through the dissipative field. The analysis of the
coupling field coefficients permits to define the system
Reduced Bond Graph. The procedure was comproved by easy
comprehensive examples.
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[pt] DESENVOLVIMENTO DE PLATAFORMA PARA TESTES E SIMULAÇÃO DE SISTEMAS MULTICÓPTEROS / [en] DEVELOPMENT OF A PLATFORM FOR TESTS AND SIMULATION OF MULTICOPTER SYSTEMSRENAN DE LIMA SIMOES MONDEGO VILELA 25 February 2021 (has links)
[pt] O crescente uso de veículos aéreos não tripulados (VANTs) em diversos setores
da sociedade é fruto de avanços da tecnologia. Por sua vez, a ampliação de
aplicações de VANTs traz consigo a necessidade de aumento de robustez destes
sistemas, especialmente em ambientes compartilhados com o ser humano. A
presente dissertação aborda o desenvolvimento de uma plataforma para testes
de veículos multicópteros, com o objetivo de contribuir para o processo de desenvolvimento
e implementação de drones, permitindo sua movimentação em
torno dos seus graus de liberdade de rotação e realizando medições de atitude
e força geradas pelo sistema, sem colocar o veículo ou seu operador em
risco. Todos os dados adquiridos pela plataforma são transmitidos para um
computador, onde foi desenvolvida uma interface virtual para sua visualização
em tempo real, além de permitir armazenamento para pós-processamento
e análises futuras. Também apresenta-se e discute-se o desenvolvimento do
simulador de trajetórias proposto, que mostra o deslocamento do veículo em
função da sequência de comandos fornecida, com base nos dados adquiridos
pela plataforma. No intuito de se propiciar um melhor entendimento do funcionamento
do sistema aqui desenvolvido, é apresentado um estudo detalhado
dos subsistemas que compõem um multicóptero, bem como do processo de
modelagem dinâmica de um veículo quadricóptero, por meio da técnica de
grafos de ligação. A modelagem do veículo é complementada com a identificação
de parâmetros fundamentais para a implementação do modelo, sendo
discutidos métodos para identificação de parâmetros inerciais do veículo e
parâmetros dinâmicos do sistema motopropulsor. / [en] The growing use of unmanned aerial vehicles (UAVs) in various sectors
of society is a result of advances in technology. In turn, the expansion of
UAV applications brings with it the need to increase the robustness of these
systems, especially in environments shared with humans. and comes together
with the need for increased robustness due to its use in shared environments
with humans. This dissertation approaches the development of a platform
for testing multicopter vehicles aiming at assisting the process of developing
and implementing drones, allowing movements around their rotational degrees
of freedom and making measurements of attitude and forces generated by
the system, without putting the vehicle or its operator at risk. All data
acquired by the platform is transmitted to a computer, where a virtual
interface was developed to provide real time visualization, in addition to
allowing data storage for post-processing and future analysis. The development
of the proposed trajectory simulator is also presented and discussed, that
shows the displacement of the vehicle as a function of the sequence of
commands provided, based on the acquired data. Aiming at allowing a better
understanding of the functioning of the developed system, a detailed study
of the subsystems that compose a multicopter is presented, as well as the
process of dynamic modeling of a quadcopter vehicle, by using bond graph
technique. The modeling of the vehicle is complemented with the identification
of fundamental parameters for the model implementation, such as methods for
the identification of inertial parameters of the vehicle and dynamics of the
powertrain system.
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Bond graph modeling of hydraulic circuits on a sweet sorghum harvesterRains, Glen Christopher 02 February 2007 (has links)
A whole-stalk harvester was developed as part of a sweet sorghum-for-ethanol production system. Gathering chains grasped the stalks as they were cut at the base with a disk-cutter. These stalks were flipped onto a cross conveyor and deposited into an accumulator. Periodically the machine stopped and the accumulator was dumped. All the components on the harvester are powered hydraulically. Five pumps on the harvester supply flow to seven actuator circuits. Power is delivered to the pumps from the tractor PTO via a universal joint driveline. Each of the six existing circuits and one proposed circuit were modeled with bond graphs and implemented for computer analysis using TUTSIM. Model validation was done by comparing simulated and measured driveline torque, line pressure, and return line flow rate in each of the six existing circuits.
Data collected on the gathering chains circuit was used to analyze the effect of driveline joint angles on transmitted torque and pump output. Torque measurements at three driveline angles showed a torsional vibration with a primary harmonic at driveline rpm and a secondary at twice driveline rpm. A combination of Cardan joint characteristics, mass unbalance, the secondary couple, and non-linear driveline and V-belt stiffness was used to model the driveline. Resulting simulated torque emulated the experimental very well. Measured pressure in the gathering chains circuit showed relatively low fluctuations at the highest amplitude torsional vibration (highest driveline joint angles). It was concluded that driveline vibration would not significantly affect the gathering chains circuit performance.
The cross-conveyor motor circuit simulation showed close agreement to experimental results. Mean predicted flow, pressure, and torque were within 8.9, 7.3, and 7.7 percent of mean measured values. A simulation with a stalk load on the conveyor showed that power requirement increased only 8.0 percent.
The accumulator dump circuit was analyzed to determine if the load on the motor would become over-running and cavitate the pump or motor as the stalks were being dumped. Simulation showed that a bundle up to 300 kg could be dumped without over-running the motor, and since this was a larger bundle than the bin could hold, a design modification was not necessary.
The disk-cutter circuit was designed based on simulation results for several combinations of motor, pump, and sheave ratio. A 7.3 cm³/rad motor, 2.53 cm³/rad pump , and 2:1 sheave ratio produced the correct disk-cutter speed, and low torsional vibration when cutting the stalks, consequently this combination was selected for the design. / Ph. D.
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[en] FLUID LINES MODELS FOR TRANSIENTS ANALYSIS AND SIMULATION USING THE POWER FLOW / [pt] MODELOS DE LINHAS FLUIDAS ATRAVÉS DO FLUXO DE POTÊNCIA PARA ANÁLISE E SIMULAÇÃO DE TRANSIENTESFELIPE AUGUSTO SILVA DE ANDRADE 28 September 2007 (has links)
[pt] O estudo de fenômenos transitórios em sistemas hidráulicos
está presente
em diversos ramos da engenharia, encontra-se na área de
hidrelétricas e na
indústria do petróleo. O presente trabalho apresenta uma
análise comparativa
deste fenômeno utilizando três abordagens de modelagem
distintas: o clássico
método das características, a técnica de grafos de ligação
e o tratamento através
do fluxo de potência. No caso do método das
características emprega-se o
procedimento proposto por Streeter. Na modelagem através
de grafo de ligação
adota-se a analogia generalizada entre os sistemas fluido,
mecânico e elétrico. Na
representação pelo fluxo de potência acopla-se módulos
previamente
desenvolvidos considerando as relações de causa e efeito
entre os componentes de
um sistema. Todos os métodos foram implementados em Matlab
e foram testados
e comparados a partir de simulações em dois sistemas
simples compostos de um
reservatório, linha fluida e válvula. Os resultados
obtidos através da metodologia
de fluxo de potência aproximam-se dos encontrados pelas
abordagens
tradicionais. / [en] The study of transitory phenomena in hydraulic systems is
present in several
branches of the engineering, in the hydroelectric power
stations area and in the
petroleum industry. The present work introduce a
comparative analysis of this
phenomenon using three approaches of distinct modeling:
the classic
characteristics method, the technique of bond graphs and
the treatment through
the power flow. In the case of characteristics method is
used the procedure
proposed by Streeter. In the modeling through bond graphs
is adopted the
generalized analogy among the fluid, mechanic and electric
systems. In the
representation by power flow modules previously developed
are coupled
considering the cause and effect relationships between
components of one system.
All methods were implemented in Matlab and were tested and
compared from
simulations in two simple systems composed of a reservoir,
fluid lines and valve.
The results obtained through the methodology of power flow
are near of the
discoveries by the traditional approaches.
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Modélisation Bond Graphs en vue de l'Efficacité Énergétique du Bâtiment / Bond Graphs modeling in order to improve the energy efficiency in buildingsMerabtine, Abdelatif 19 November 2012 (has links)
L'objectif des travaux présentés dans ce mémoire concerne le développement d'un modèle global représentant le couplage de l'enveloppe du bâtiment avec les équipements énergétiques. Une approche systémique appelée les Bond Graphs, peu employée jusqu'ici dans la modélisation des systèmes thermiques, est utilisée. Le modèle global du bâtiment, regroupant sous le même environnement de simulation, les modèles de l'enveloppe du bâtiment, les apports solaires, les émetteurs de chauffage et de rafraîchissement et le système de ventilation, est développé pour reconstituer l'ensemble des articulations énergétiques entre l'enveloppe et les environnements intérieur et extérieur. A travers la modélisation d'un bâtiment multizone, le couplage systémique des modèles de l'enveloppe et des apports solaires est présenté. Par ailleurs, un système combinant un plancher chauffant et un plafond rafraîchissant est étudié à l'aide des modèles des émetteurs de chauffage et de rafraîchissement. Le renouvèlement d'air dans le bâtiment est également concerné par la modélisation Bond Graph. Enfin, des éléments de validation expérimentale sont présentés. Pour cela, la plateforme de tri-génération d'énergie ENERBAT est exploitée. L'objectif est d'étudier le couplage optimal enveloppe du bâtiment - équipements énergétiques pour lequel les modèles BG sont développés. Une étude paramétrique tenant compte des interactions entre les paramètres étudiés est menée sur un projet réel de rénovation. Finalement, une combinaison appropriée des paramètres étudiés a été retenue afin de réduire la consommation énergétique selon la réglementation thermique française (RT2012) / Our works focus on the setting of reliable tools able to analyze the interaction between the building envelope and HVAC systems. The developed approach is based on Bond Graphs methodology, a graphical modeling language which is particularly suitable for energy exchanges. A numerical model gathering, under the same simulation environment, sub-models representing the building envelope, the solar gains, the floor heating, the chilled ceiling and the ventilation system, is developed in order to predict the energy interactions between these sub-systems. The multi-zone building model is developed in order to simulate and analyze the overall building thermal behavior. Then, the solar gains model is also included to predict the solar radiation exchanges in a way close to reality. The model of the heating and cooling system, combining the floor heating and the chilled ceiling, is developed in order to improve the thermal comfort of the building. Afterwards, the ventilation system is modeled in order to represent the air exchange inside the building. The experimental validation is carried out on the tri-generation unit integrated with a thermal solar system (platform ENERBAT). Furthermore, the parametrical study was realized in order to gain a better understanding according to the impact of some factors in the energy performance of the single-family building located in Meurthe-et-Moselle region (France). Optimization of several measures, such as insulation of the building envelope, type of glazing, building orientation and ventilation system, is performed to respond to the requirements of the French thermal standard (RT2012)
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CONTRIBUTION A L'ETUDE DE LA PROPRIETE DE PLATITUDE SUR DES MODELES BOND GRAPHS NON LINEAIRESAchir, Ali 07 December 2005 (has links) (PDF)
Cette thèse a pour but l'étude de la propriété de platitude sur des modèles bond graphs (BGs) non linéaires et de contribuer à la résolution des problèmes rencontrés en pratique qui sont liés principalement à l'identification des sorties plates et le calcul de la paramétrisation différentielle. <br />Pour atteindre cet objectif, de nouveaux concepts et outils graphiques ont été introduits. En particulier, grâce à l'introduction de la notion de modèle BG tangent ou variationnel à l'aide de l'utilisation des différentielles de Kähler, il est possible de calculer les sorties plates d'un modèle BG non linéaire par intégration des bases du module qui lui est associé.<br />Par ailleurs, en définissant la notion d'anneau BG non commutatif, une nouvelle règle de gain connue sous le nom de "règle de Riegle" est introduite en BG. En montrant alors qu'un modèle BG variationnel est un cas particulier d'anneau BG non commutatif, l'obtention graphique de la paramétrisation différentielle en utilisant la règle de Riegle et la notion de bicausalité est rendue possible.<br />Enfin, pour aller plus loin dans l'introduction de l'outil d'algèbre et de modules différentiels aux BGs, le cas des modèles BGs non linéaires régis par des équations différentielles polynômiales a été abordé. Dans ce contexte, le BG permet de faire une analyse directe des propriétés principales du système telles que le choix des variables d'entrée, les dynamiques correspondant à un choix d'entrée, le calcul des degrés de transcendance (non différentiel) différentiel, etc. à partir de son modèle BG associé. Il est également montré que la règle graphique de Riegle peut être étendue à cette classe de modèles BGs.
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Modelling Of Switched Mode Power Converters : A Bond Graph ApproachUmarikar, Amod Chandrashekhar 08 1900 (has links)
Modelling and simulation are essential ingredients of the analysis and design process in power electronics. It helps a design engineer gain an increased understanding of circuit operation. Accordingly, for a set of specifications given, the designer will choose a particular topology, select component types and values, estimate circuit performance etc. Typically hierarchical modelling, analysis and simulation rather than full detailed
simulation of the system provides a crucial insight and understanding. The combination of
these insights with hardware prototyping and experiments constitutes a powerful and
effective approach to design.
Obtaining the mathematical model of the power electronic systems is a major task before any analysis or synthesis or simulation can be performed. There are circuit oriented simulators which uses inbuilt mathematical models for components. Simulation with equation solver needs mathematical models for simulation which are trimmed according to user requirement. There are various methods in the literature to obtain these mathematical models. However, the issues of multi-domain system modelling and causality of the energy variables are not sufficiently addressed. Further, specifically to power converter systems,
the issue of switching power models with fixed causality is not addressed. Therefore, our research focuses on obtaining solutions to the above using relatively untouched bond graph method to obtain models for power electronic systems. The power electronic system chosen for the present work is Switched Mode Power Converters (SMPC’s) and in particular PWM DC-DC converters.
Bond graph is a labelled and directed graphical representation of physical systems. The basis of bond graph modelling is energy/power flow in a system. As energy or power flow is the underlying principle for bond graph modelling, there is seamless integration across multiple domains. As a consequence, different domains (such as electrical, mechanical, thermal, fluid, magnetic etc.) can be represented in a unified way. The power or the energy
flow is represented by a half arrow, which is called the power bond or the energy bond.
The causality for each bond is a significant issue that is inherently addressed in bond graph modelling. As every bond involves two power variables, the decision of setting the cause variable and the effect variable is by natural laws. This has a significant bearing in the resulting state equations of the system. Proper assignment of power direction resolves the sign-placing problem when connecting sub-model structures. The causality will dictate whether a specific power variable is a cause or the effect. Using causal bars on either ends of the power bond, graphically indicate the causality for every bond. Once the causality gets assigned, bond graph displays the structure of state space equations explicitly.
The first problem we have encountered in modelling power electronic systems with bond graph is power switching. The essential part of any switched power electronic system is a switch. Switching in the power electronic circuits causes change in the structure of the system. This results in change in dynamic equations of the circuit according to position of the switch. We have proposed the switched power junctions (SPJ) to represent switching phenomena in power electronic systems. The switched power junctions are a generalization of the already existing 0-junction and 1-junction concepts of the bond graph element set. The SPJ’s models ideal switching. These elements maintain causality invariance for the whole system for any operational mode of the system. This means that the state vector of the resulting state equation of the system does not change for any operating mode. As SPJs models ideal power switching, the problem of stiff systems and associated numerical stability problems while simulating the system is eliminated. Further, it maintains one to one correspondence with the physical system displaying all the feasible modes of operation at the same time on the same graph.
Using these elements, the switched mode power converters (SMPC's) are modelled in bond graph. Bond graph of the converter is the large signal model of the converter. A graphical procedure is proposed that gives the averaged large signal, steady state and small signal ac models. The procedure is suitable for the converters operating in both Continuous Conduction Mode (CCM) and in Discontinuous Conduction Mode (DCM).
For modelling in DCM, the concept of virtual switch is used to model the converter using bond graph. Using the proposed method, converters of any complexity can be modelled incorporating all the advantages of bond graph modelling.
Magnetic components are essential part of the power electronic systems. Most common parts are the inductor, transformer and coupled inductors which contain both the electric and magnetic domains. Gyrator-Permeance approach is used to model the magnetic components. Gyrator acts as an interface between electric and magnetic domain and capacitor model the permeance of the magnetic circuits. Components like inductor, tapped inductor, transformer, and tapped transformer are modelled. Interleaved converters with coupled inductor, zero ripple phenomena in coupled inductor converters as well as integrated magnetic Cuk converter are also modelled. Modelling of integrated magnetic converters like integrated magnetic forward converter, integrated magnetic boost converter are also explored.
To carry out all the simulations of proposed bond graph models, bond graph toolbox is
developed using MATLAB/SIMULINK. The MATLAB/SIMULINK is chosen since it is general
simulation platform widely available. Therefore all the analysis and simulation can be carried out using facilities available in MATLAB/SIMULINK. Symbolic equation extraction toolbox is also developed which extracts state equations from bond graph model in SIMULINK in symbolic form.
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[en] GROUND VEHICLES SUSPENSION AND STEERING MECHANISMS MODELING AND INTEGRATION THROUGH POWER FLOW / [pt] MODELAGEM E INTEGRAÇÃO DOS MECANISMOS DE SUSPENSÃO E DIREÇÃO DE VEÍCULOS TERRESTRES ATRAVÉS DO FLUXO DE POTÊNCIARICARDO TEIXEIRA DA COSTA NETO 27 October 2008 (has links)
[pt] A sub-divisão de um veículo em módulos é muito útil quando
se quer
estudar o comportamento dinâmico de um determinado
subsistema e sua
influência nos demais componentes. Em alguns casos, devido
ao tipo de
tratamento empregado para descrever os elementos, não se
consegue perceber de
que modo as variáveis inerentes a um subsistema interagem
com as demais, e, por
conseguinte, os subsistemas entre si. A abordagem modular
baseada no fluxo de
potência permite uma melhor identificação das relações de
causa e efeito entre
subsistemas, uma vez que se pode definir, de forma clara e
consistente, quem são
as variáveis de entrada e de saída de cada componente ou
módulo, e,
conseqüentemente, seus acoplamentos. Neste tipo de
tratamento, aplicado aos
sistemas mecânicos, uma vez estabelecida a cinemática de um
subsistema, podese
obter as relações entre os esforços que seus componentes
produzem uns sobre
os outros, a partir da caracterização da potência
transmitida através dos seus
diversos elementos. Este trabalho apresenta um procedimento
semi-analítico de
equacionamento modular aplicado à modelagem e integração
dos sistemas de
suspensão e direção de veículos terrestres, no qual as
variáveis de entrada e saída
indicam o fluxo de potência entre os elementos de todo o
sistema. Tal abordagem
tem como base a técnica dos Grafos de Ligação, empregada em
sistemas
multidomínio em geral, e usa alguns conceitos da
metodologia dos
Transformadores Cinemáticos, normalmente aplicada aos
sistemas multicorpos. A
partir da definição da geometria dos mecanismos em questão,
encontram-se as
matrizes que representam os vínculos cinemáticos entre seus
elementos, das quais
o funcionamento dos sistemas integrados pode ser simulado e
analisado, e
informações necessárias aos seus projetos determinadas. As
equações (malhas)
algébricas que existem em mecanismos com estrutura
cinemática fechada são
analiticamente resolvidas, evitando deste modo modelos
matemáticos com
equações diferenciais e algébricas simultâneas. Das
relações cinemáticas, o
modelo dinâmico (matrizes de inércia, rigidez e
amortecimento, etc) é obtido, e
novamente informações essenciais à análise e síntese dos
sistemas podem ser
determinadas. O comportamento no tempo desses modelos pode
ser encontrado
por um método de integração de equações diferenciais
qualquer. Adota-se o
Simulink/MatLab® para representar o modelo assim
desenvolvido em diagrama
de blocos, e conseqüentemente simulá-lo. Através deste
tratamento, cada bloco da
implementaçao em Simulink/MatLab® contém o correspondente
modelo analítico
de um único módulo, cujo estabelecimento depende das
características dinâmicas
do sistema que se deseja analisar. A vantagem de adotar tal
representação,
baseada no fluxo de potência, consiste no fato de que um
módulo pode ser
substituído por outro, descritivo de um elemento ou
subsistema com a mesma
função, porém com configuração física distinta, e,
conseqüentemente, modelo
matemático específico, sem qualquer alteração nos demais
componentes do
sistema. Este procedimento está sendo adotado para
modelagem dos diversos
sistemas veiculares, como os de suspensão, direção,
transmissão e freios, e
também os pneus, inseridos em um chassi, incluindo os graus
de liberdade
desejados do veículo, todos descritos de forma modular semi-
analítica através da
mesma abordagem, empregando a técnica de modelagem mais
apropriada para
representá-los. / [en] The sub-division of a vehicle in modules is very useful
when we want to
study the dynamical behavior of a certain sub-system and
its influence in other
components. In some cases, due to the type of treatment
employed to describe the
dynamic behavior of the elements, we don`t get to notice
the way that inherent
variables in a sub-system interacts with the others, and,
consequently, the subsystems
amongst themselves. The modular approach based on the power
flow
allows a better identification of the causal relationships
among sub-systems, once
it can define, in clear and consistent way, what are the
input and output variables
of each component or module, and, consequently, their
couplings. In this type of
treatment applied to the mechanical systems, once
established the kinematics of a
sub-system, it can be obtained the relationships among the
efforts that their
components produce on the other ones, from the
characterization of the power
transmitted through their several elements. This paper
presents a semi-analytical
procedure of modular modeling applied to the suspension and
steering systems of
a ground vehicle, in which the input and output variables
indicate the power flow
among the elements of the whole system. Such approach has
as base the Bond
Graphs technique, used in multidomain systems in general,
and uses some
concepts of the Kinematic Transformers methodology, usually
applied to the
multibody systems. From the mechanisms geometry, the
matrices that represent
the kinematics links between its elements are found, the
operation of the
integrated systems can be simulated and analyzed, and
information about its
design can be obtained. The algebraic loops (equations)
inherent to mechanisms
with closed kinematic structure are solved analytically,
and there is not a
mathematical model with simultaneous algebraic and
differential equations. From
the kinematic relations, the dynamic model (inertial,
stiffness and damping
matrices) is obtained, and again essential information to
the systems analysis and
synthesis can be determined. The models time behavior can
be found by any
differential equations integration method. The
Simulink/Matlab is adopted to
represent the model developed by block diagrams, and
consequently to simulate it.
Through this treatment, each block in the Simulink/Matlab
implementation
contains the correspondent analytical model of a single
module, whose
establishment depends on the dynamic characteristics of the
system to be
analyzed. The advantage of adopting such representation,
based on the power
flow, consists in the fact that a module can be substituted
for other, descriptive of
an element or sub-system with the same function, however
with different physical
configuration, and, consequently, specific mathematical
model, without any
alteration in the other components of the system. This
procedure is being adopted
for modeling all vehicular systems, like the suspension,
steering, transmission and
brakes systems, and also the tires, inserted in the
chassis, including the desired
degrees of freedom of the vehicle, all described in a semi-
analytical modular way
by the same approach, using the most appropriate modeling
technique to represent
them.
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[en] DYNAMICS AND CONTROL OF PARALLEL MECHANISMS: CLOSED ANALYTICAL MODEL, INERTIAL TRANSDUCERS AND LINEAR ELECTRIC ACTUATORS INTEGRATION / [pt] DINÂMICA E CONTROLE DE MECANISMOS PARALELOS: INTEGRAÇÃO MODELO ANALÍTICO FECHADO, TRANSDUTORES INERCIAIS E ATUADORES ELÉTRICOS LINEARESALLAN NOGUEIRA DE ALBUQUERQUE 08 August 2017 (has links)
[pt] Mecanismos são essencialmente (mas não exclusivamente) compostos por vários corpos rígidos que possuem movimento relativo entre si. Cada corpo rígido está ligado através de uma junta a um ou mais corpos, sendo a sequência de corpos conectados chamada de cadeia cinemática. Cadeias cinemáticas abertas (ou em série) não têm restrições sobre uma de suas extremidades, já cadeias fechadas
(ou paralelas) têm restrições em ambas as extremidades. O foco neste trabalho será dado no estudo de mecanismos com cadeias cinemáticas fechadas ou mecanismos paralelos. Assim, este trabalho apresenta a determinação da solução analítica do modelo dinâmico de um mecanismo paralelo plano com três graus de
liberdade através da caracterização do fluxo de potência entre os seus componentes. A partir das relações geométricas associadas ao deslocamento dos seus graus de liberdade, as relações cinemáticas associadas às suas velocidades são determinadas. Considerando o fluxo de potência entre os graus de liberdade, e também entre estes e os elementos de atuação (atuadores lineares elétricos), as relações de equilíbrio das forças e torques são obtidas. Levando em consideração os efeitos inerciais dos componentes do sistema, a rigidez e efeitos de amortecimento, as equações de movimento ou as equações de estado são analiticamente determinadas e representadas em qualquer sistema de referência, local ou global. Além disso, as relações entre a cinemática inversa e a dinâmica direta são apresentadas. Esta abordagem adota os mesmos fundamentos, conceitos e elementos da técnica dos grafos de ligação, com a sua notação simbólica e representação gráfica. A metodologia proposta é generalizada e aplicável em qualquer tipo de mecanismo (aberto ou fechado, plano ou espacial). O modelo cinemático inverso do mecanismo de cadeia fechada, que tem uma solução fácil quando comparado com o modelo direto, pode ser desenvolvido por qualquer metodologia conhecida. Neste trabalho, a técnica da cadeia vetorial é usada para determinar o modelo geométrico inverso, e com a sua derivação, as relações cinemáticas são obtidas, e, portanto, a matriz Jacobiana inversa. Desse modo, é construída a estrutura em grafos de ligação da cinemática inversa e, a partir das relações de causa e efeito, encontra-se o modelo dinâmico direto do mecanismo. Assim, esta metodologia (grafos de ligação ou fluxo de potência) é mais eficiente e segura para determinar os modelos dinâmicos analíticos (fechados) de mecanismos paralelos. Um conjunto de simulações foi realizado para validar esta abordagem, usando os dados reais (geometria, inércia, amortecimento, forças de atuação, etc.) a partir de um mecanismo plano projetado e construído especialmente para a finalidade de comparar os resultados simulados e experimentais. Uma estratégia de controle de malha fechada usando a cinemática inversa e os modelos dinâmicos diretos é proposta. Finalmente, testes experimentais validam esta estratégia. As equações analíticas levam a um processo de simulação e controle em tempo real mais eficientes destes sistemas. / [en] Mechanisms are essentially (but not exclusively) made up of multiple rigid bodies that have relative motion between themselves. Each rigid body is connected through a joint to one or more bodies, wherein the sequence of connected bodies is called kinematic chain. Open (or serial) kinematic chains have no restrictions on one of their ends, as closed (or parallel) chains have restrictions on both ends. The focus in this work will be given on the study of mechanisms with closed kinematic chains or parallel mechanisms. Thus, this work presents the analytical form determination of the dynamic model of a parallel planar
mechanism with three degrees of freedom through the characterization of the power flow between its components. From the geometrical relations associated to the displacement of their degrees of freedom, the kinematic relations associated to their speeds are determined. Considering the power flow between the degrees of freedom, and also between these and the actuating elements (linear electric actuators) the equilibrium relations of the forces and torques are obtained. Accounting for inertial effects of system components, the stiffness and damping effects, the equations of motion or the state equations are analytically determined and represented in any reference frame, local or global. Besides, the relation
between the inverse kinematics and the direct dynamics is presented. This approach adopts the same fundamentals, concepts and elements of the Bond Graph Technique, with its symbolic notation and graphical representation. The proposed methodology is generalized and applicable in any type of mechanism (open or closed, planar or spatial). The inverse kinematic model of the closed chain mechanism, which has easy solution when compared to the direct model, can be developed by any known methodology. In this work, the vector loop technique is used to determine the inverse geometric model, and with its derivation, the kinematic relations are obtained, and therefore the inverse Jacobian
matrix. Thereby, the inverse kinematics bond graph is built and, from the cause and effect relations, the direct dynamic model of the mechanism is found. Thus, this methodology (bond graphs or power flow) is more efficient and secure to achieve the dynamic analytical (closed) models of parallel mechanisms. A set of simulations are performed to validate this approach, using the real data (geometry, inertia, damping, actuators forces, etc.) from a planar mechanism designed and built especially for the purpose to compare the simulated and experimental results. A closed-loop control strategy using the inverse kinematic and the direct dynamic models is proposed. Finally, experimental tests validate this strategy. The analytical equations lead to a more efficient simulation process and real-time control of these systems.
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[en] MODELING AND NON LINEAR CONTROL OF A GROUND VEHICLENULLS STEERING / [pt] MODELAGEM E CONTROLE NÃO-LINEAR DA DIREÇÃO DE UM VEÍCULO TERRESTREALEXANDRE DE LIMA SPINOLA 30 June 2004 (has links)
[pt] Modelagem e Controle Não Linear de um Veículo Terrestre
sobre Suspensão descreve um estudo em dinâmica veicular no
qual inicialmente apresenta-se um modelo analítico para
representar a geração de forças longitudinais e laterais no
contato do pneu com o solo. Em seguida é desenvolvido, para
um automóvel de passeio terrestre sobre suspensão, um
modelo não linear de 4 graus de liberdade (velocidades
longitudinal, lateral, de guinada e de rolagem), e a sua
linearização. Expande-se esse modelo para um de 8 graus de
liberdade, no qual inclui-se o movimento de rotação axial
de cada uma das quatro rodas, e consideram-se os movimentos
do veículo somente no plano, sem efeitos de pitch ou
bounce, mas apresentando alguma relação de distribuição de
cargas devido ao roll. Descrevem-se ainda modelos em Grafos
de Ligação para os três dinâmicas de um veículo terrestre
(longitudinal, lateral e vertical) e seus acoplamentos,
visando futuras análises mais detalhadas desse sistema.
Todos os modelos em malha aberta são validados através
simulações computacionais em diversas condições típicas de
operação. Na segunda parte desse trabalho é apresentada a
estratégia proposta para o tratamento do problema de
controle direcional do veículo em uma manobra qualquer,
empregando a metodologia da linearização por realimentação,
tendo como base o modelo linear de 4 graus de liberdade.
São analisados os resultados encontrados através de
simulação computacional para a malha fechada com diferentes
combinações de parâmetros, empregando os modelos não
lineares de 4 e 8 graus de liberdade. Conclui-se discutindo
a possibilidade de generalização deste procedimento para
diferentes aplicações em Dinâmica Veicular. / [en] Modeling and Non Linear Control of a Ground Vehicle's
Steering describles a study in vehicle dynamics, which
presents an analytic model representing the generation of
longitudinal and lateral forces at the contact patch
between tire and ground. Next it is developed, for a
typical passenger car, a non-linear model with four degrees
of freedom (longitudinal, lateral, yaw and roll
velocities), and its linearization. This model is then
expanded to another one with eight degrees of freedom,
which includes the axial rotation of each one of the four
wheels, and considers the vehicle's movement only at a
known plane, whithoud pitch and bounce effects, but
including some load distribution among the wheels, due to
roll. Computational simulation in varius typical operation
condition validate all open loop models. The second part of
this work presents the proposed strategy for directional
control of a vehicle at any type of manoeuvre, using the
feedback linearization methodology, directly applied to the
linear four degrees of freedom model. Theresults obtained
trhough computational simulation for a closed loop model
with different parameters are analysed using both nonlinear
four and eight degrees of freedom models. The possibility
of generalizing this procedure to distinct applications in
Vehicle Dynamics is, then, discussed.
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