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COB419 DYNAMICALLY COMPENSATED CAMS
Luiz Augusto Martin Gonçalves*, Pascal Degezelle & Joris de Schutter
Division of Production Engineering, Machine Design and Automation (PMA), Department of Mechanical Engineering, Katholieke Universiteit Leuven, Celestijnenlaan 300B, B-3001 Leuven, Belgium-E-mail: luiz.goncalves@mech.kuleuven.ac.be
In a cam-follower system the dynamics of the follower-train mechanism cause an actual motion which deviates from the desired one. This effect can be compensated by taking into account the inverse dynamic model of the follower-train in the design of the cam motion law. By considering a constant cam velocity, the follower-train has linear dynamics. However, due to the varying transmission ratio, and due to other nonlinear effects, the whole drive train is a nonlinear system, and nonlinear procedures should be used to fit a motion law. A theoretical analysis with only the linear feedforward compensation, supported by simulation results, has shown the potential of this approach, at least in the case of simple follower-train dynamics: a considerable reduction of the motion error, and a good robustness with respect to errors in the estimated resonance frequency and damping ratio of the follower-train. Experiments with a small driving servomotor, as expected, show different results, due to the non-constant angular velocity. The observed cam angular velocity ripple can be taken into account, in future experiments, to design a complete nonlinear feedforward motion law.
Keywords: Cams, cam vibration, tuned cams, dynamically compensated cams, feedforward compensation.
COB639 MODELAGEM AUTOMÁTICA DE SISTEMAS DINÂMICOS VIA GRAFOS DE SISTEMAS E PROCEDIMENTO SISTEMÁTICO / AUTOMATIC MODELLING OF DYNAMIC SYSTEMS USING LINEAR GRAPH AND A SYSTEMATIC PROCEDURE FOR STATE SPACE EQUATIONING
João Bosco Gonçalves & Alberto Adade Filho
Divisão de Engenharia Mecânica-Aeronáutica, Instituto Tecnológico de Aeronáutica – ITA
CEP 12228-900 São José dos Campos SP, Brasil – E-mail: adade@mec.ita.cta.br
This paper discusses an approach to automating mathematical modelling of lumped parameters dynamic systems, utilizing linear graphs as system representation, and a systematic procedure for obtaining the equations. It is presented the main characteristics of the associated developed software (acronym MASD) for automatic state space modelling in symbolic form. An application example, an hydraulic system, is presented in order to clarify, more specifically, some characteristics of MASD. A special motivation for this development is its application as an aid for teaching in the dynamic systems area.
Keywords: modelagem de sistemas/system modelling, grafos de sistemas/linear graphs, manipulação simbólica/symbolic manipulation, procedimento sistemático/systematic procedure
COB658 ANÁLISE DINÂMICA DE VIGAS ELASTO-PLÁSTICAS. UM MODELO ATRAVÉS DOS GRAFOS DE LIGAÇÃO / DYNAMIC ANALISYS OF ELASTIC-PLASTIC BEAMS. A BOND GRAPH APPROACH
Fernando Ribeiro da Silva
Instituto Militar de Engenharia
E-Mail: d4fernan@epq.ime.eb.br
Mauro Speranza Neto
Pontifícia Universidade Católica do Rio de Janeiro
E-Mail: msn@mec.puc-rio.br
In this work we show that using the physical models with lumped parameters representing the basic structural elements, we can obtain the mathematical models of the system where the effects of storage and dissipation of energy must be considered. We consider for the model the effects of the dynamic plasticity for which the modeling process depends on the plasticity mechanisms. To validate the results we show the behavior of an Euler beam.
Keywords: Structures, Bond Graphs, Dynamic Plasticity, Dynamic Simulation.
COB664 TRANSFORMADORES CINEMÁTICOS. UMA REPRESENTAÇÃO ATRAVÉS DOS GRAFOS DE LIGAÇÃO. / KINEMATIC TRANSFORMERS. A BOND GRAPH REPRESENTATION.
Mauro R. R. Melo, Mauro Speranza Neto & Clódio Alberto Pastro Sarzeto.
- Departamento de Engenharia Mecânica e de Materiais - IME, Pç. Gal. Tibúrcio, s.n0. - Praia Vermelha - CEP 22290-270 - Rio de Janeiro - RJ - Brasil, E-mail: d4sarzet@epq.ime.eb.br
- Departamento de Engenharia Mecânica - PUC-RJ, R. Marquês de São Vicente, 225 - Gávea - CEP 22453-900 - Rio de Janeiro - RJ - Brasil, E-mail: msn@mec.puc-rio.br
In this paper is presented a procedure for modeling the kinematic of closed-loop mechanisms, known as Kinematic Transformer, by Bond Graph techniques. The main advantage of Kinematic Transformer approach is the assembling of kinematical multi-loop system by means of mathematical conection of Kinematics Transformers obtained to each kinematical single-loop. Bond Graph is a recent technique that permits the modeling of several physical systems through power flow considerations and, to mechanical systems, the dynamic model can be obtained by kinematic model.
Keywords: Kinematic; Bond Graph; Kinematic Transformer.
COB877 Simulation of Helicopter Yaw Motion and Blade Rotational Speed Decrease after Tail Rotor Shaft Failure
Olympio Achilles de Faria Mello
Instituto de Aeronáutica e Espaço, Centro Técnico Aeroespacial,
12228-904 - São José dos Campos - SP, Brazil - e-mail: oamello@iconet.com.br
After a helicopter accident with typical tail rotor loss characteristics, an alternate possibility was suggested in that the accident occurred due to pilot's loss of pedal control after he suddenly increased the collective pitch near the ground and delayed applying pedals as needed. In order to investigate this hypothesis, numerical flight dynamics simulations were performed. Simple models of the aircraft yaw dynamics and tail rotor aerodynamics were used. For tail rotor aerodynamics, momentum and blade element theories, supplemented by empirical formulae for vortex ring and turbulent wake states, were used. For tail rotor loss simulations, the blade rotational equation of motion was also established. All equations of motion were time-integrated using a fourth-order Runge-Kutta scheme. Simulation results indicated that pedal control would still be available even with a three second pilot delay in applying the pedals, therefore the hypothesis of loss of pedal control was discarded and the hypothesis of loss of tail rotor was maintained.
Keywords: Helicopter, Simulation, Accident, Tail Rotor.
Manoel L. M. de Carvalho Jr.(1), B. Wayne Bequette(2) & Howard Kaufman(3) Meaem(1), Che(2), Ecse(3)
Rensselaer Polytechnic Institute,110 Eighth St., Troy, NY 12180, USA, E-mail: carvam2@rpi.edu(1), bequeb@rpi.edu(2), kaufmh@rpi.edu(3)
This paper presents the development of a lumped parameter dynamic model of a chemical vapor deposition (CVD) reactor for deposition of CdTe film on a GaAs substrate. The model contains the basic elements of the dynamics of the CVD processes, viz., transport delay, diffusion resistance and reaction kinetics. open-loop behavior of the reactor is investigated and simulation results are compared to experimental data to validate the model.
Keywords: chemical vapor deposition, CdTe, control, dynamic, model
COB963 CONJUNÇÃO DE UM CRITÉRIO UTILIZANDO O TEOREMA DE NYQUIST PARA SIMULAÇÃO DINÂMICA DE SISTEMAS MECÂNICOS / THE CRITERION CONJUNCTION UTILISING THE NYQUIST THEOREM FOR THE DYNAMICS SIMULATION OF THE MECHANICAL SYSTEMS
Natanael Victor de Oliveira
Departamento de Engenharia Mecânica, Centro de Ciência e Tecnologia, UFPB,
CEP 58109-970 Campina Grande, Brasil - E- mail:jornaljc@cct.ufpb.br
This paper examines a criterion for simulation of the mechanical systems making use of the Nyquist Theorem for the efficient sample of the displacements signals in the frequency domain. The erros and/or desviation of the displacements signals, utilizing a excitation signal (force), is obtained to part a synthesis of low - peak factor periodic signals are investigated. An exact solution - steady state utilizing this excitation signal, is then simulated. A conjunction of the search criterion using the Nyquist Theorem for making use of efficient samples of the displacements signals in the frequency domain that measurements is examinated. The efficient solution obtained to part of the exact solution utilizing this criterion is then compared with one obtained of the numerical solution considering a generalized aceleration of the Newmark method. Shows that utilizing this search of criterion, the Newmark methods is very efficient if compared with another ones from the literature.
Keywords: Simulation, Dynamic, Criterion, Nyquist Theorem, Conjunction - Simulação, Dinâmica, Critério, Teorema de Nyquist, Conjunção
COB964 AVALIAÇÃO DE MÉTODOS DE INTEGRAÇÃO NUMÉRICA APLICADA A IDENTIFICAÇÃO DE PERTURBAÇÕES EXTERNAS / NUMERICAL VALUATION INTEGRATION METHODS APPLIED TO A EXTERNAL PERTURBATIONS IDENTIFICATION
Valdemir Mariano
Departamento de Engenharia Mecânica, Centro de Ciências e Tecnologia - UFPB / ETFPE - UNED Pesqueira
Natanael Victor de Oliveira
Departamento de Engenharia Mecânica, Centro de Ciências e Tecnologia - UFPB
CEP 58109-970 - Campina Grande, Brasil - E - mail:jornaljc@cct.ufpb.br
In this work the accuracy of numerical integration methods such as: Central Difference method, Houbolt method, Wilson q and Newmark methods have been investigated. These methods were applied on a process of external perturbations (force) identification in dynamic systems using least square estimation method. The results obtained from the application of each method were compared with the results obtained by using the numerical integration Runge-Kutta method of 4th order. In this study, a MDOF system of two degree-of- freedom, which consists of an axis-plain cylindrical journal bearing system, was applied. From the results it can be conclued that the Newmark method has an accuracy closer to the Runge-Kutta method than the other methods investigated.
Keywords: Avaliação Numérica, Integração, Identificação, Força. - Numerical Valuation, Integration, Identification, Force.
COB984 OTIMIZAÇÃO DO CONSUMO DE COMBUSTÍVEL DE UM PROCESSO DE DESIDRATAÇÃO UTILIZANDO SECADOR TIPO TÚNEL CONCORRENTE / OPTIMIZATION OF FUEL CONSUMPTION OF DEHYDRATION PROCESS BY CONCURRENT TUNNEL DRYER
Virgínia Maria da Silva Santos & Ricardo Luiz Utsch de Freitas Pinto
Universidade Federal de Minas Gerais, Departamento de Engenharia Mecânica - UFMG
Av. Antônio Carlos, 6627 - Campus da Pampulha - Belo Horizonte - Minas Gerais - Brasil
CEP: 31270-901 - Email: utsch@vesper.ufmg.br
Values for inlet air temperature and truck speed in a concurrent tunnel dryer are obtained in order to minimize fuel consumption per weight of dehydrated fruit. The mathematical model is composed by non-linear ordinary differential equations numerically integrated by an adaptive method. The quality of dehydrated fruit is guaranteed by an equality constraint in the final moisture content and by an inequality constraint in the maximum temperature of the product throughout the process.
Keywords: Dryers, fuel consumption minimization, process optimization / Secadores, minimização do consumo de combustível, otimização de processos
COB987 AÇÃO DA DINÂMICA DE UMA PESSOA NUM BALANÇO/SIMULATION OF THE DYNAMIC OF A SWINGER
Hugo Mário Tavares Júnior
Departamento de Física, Instituto de Ciências Exatas-UA
Av. Gen. Rodrigo Octávio Jordão Ramos, 3000, Japiim-Manaus-AM-CEP 69.077-000 - e-mail: hugojr@fua.br
The pumping of a playground swing from the seated position is modeled as a system of particles. The model consists of four masses attached to each others in a particular fashion. One of these masses represents the legs of the swinger; the others, their body. The methods of Maggi-Kane and Lagrange are employed to get the equations of motion. Based on analysis of the Maggi-Kane's equations it is concluded that the mechanism is driven by two terms: gyroscopic coupling and generalized external torques. Numerical results are presented to simulate the movement when the motion is started up by the oscillation of the legs.
Keywords: Maggi-Kane's equations, Lagrange's equations, oscillation, gyroscopic coupling, operator split.
Palavras Chaves / Equações de Maggi-Kane, equações de Lagrange, oscilação, acoplamento giroscópico, decomposição de operadores.
COB1343 TRANSFERÊNCIAS ORBITAIS BI-IMPULSIVAS COM LIMITE DE TEMPO / BI-IMPULSIVE ORBITAL TRANSFERS WITH TIME LIMIT
Evandro M. Rocco, Antonio F. B. A. Prado & Marcelo L. O. e Souza
Instituto Nacional de Pesquisas Espaciais - INPE
Caixa Postal 515, CEP 12201-970 - São José dos Campos, SP, Brasil
E-mail: evandro@dem.inpe.br; prado@dem.inpe.br; marcelo@dem.inpe.br
In this work we consider the problem of two-impulse orbital transfer between coplanar elliptical orbits with minimum fuel consumption but with a time limit for this transfer. This time limit imposes a new characteristic to the problem that rules out the majority of transfer methods. Then, we used the equations presented by D. F. Lawden, modified and solved those equations to develop a software for orbital maneuvers. This software will be used in the next missions developed by INPE. The original method developed by Lawden considers only the case where the initial and final points of maneuver are known. The software developed here extends this method to the case where only one point is known and to the case where the two points are free. The four possible cases were tested with success.
Keywords: Astrodynamics, Orbital Transfer, Optimal Control. Astrodinâmica, Transferência Orbital, Controle Ótimo.
COB1344 MANOBRAS COM DOIS E TRÊS IMPULSOS PARA SATÉLITES ARTIFICIAIS / MANEUVERS WITH TWO AND THREE IMPULSES FOR ARTIFICIAL SATELLITES
Gislaine de Felipe & Antonio F. Bertachini A. Prado
Departamento de Mecânica de Orbital e Controle, Instituto Nacional de Pesquisas Espaciais - INPE
CEP12.201-970 São José dos Campos, Brasil - E-mail: Prado@dem.inpe.br, Xlaine@provale.com.br
This paper deals with orbital transfer maneuvers. It studies the problem of transferring a spacecraft from an initial to a coplanar final orbit. The control available to perform this task is a sequence of two or three impulses. The main goal is to study what is the best approach for a large set of initial and final orbits. Two methods available in the literature (one for a two-impulse and one for a three-impulse maneuver) are selected and used for comparison. The results show the fuel consumption for each case and produces a map of the regions of optimality for both cases.
Keywords: Astrodynamics, Orbital Transfer, Impulsive Maneuvers / Astrodinâmica, Transferência Orbital, Manobras Impulsivas
COB1345 EFFECT OF VISIBILITY CONSTRAINTS IN ARTIFICIAL SATELLITES MANEUVERS / EFEITO DE VÍNCULOS DE VISIBILIDADE EM MANOBRAS DE SATÉLITES ARTIFICIAIS
Walkíria Schulz, Antônio Fernando Bertachini de Almeida Prado & Hélio Koiti Kuga
Instituto Nacional de Pesquisas Espaciais - INPE - Caixa Postal 515 - CEP 12201-970
São José dos Campos, Brasil - E-mail: walkiria@dem.inpe.br, prado@dem.inpe.br, hkk@dem.inpe.br
In this work, the effect of visibility constraints due to the use of only one ground station control of a spacecraft during a bi-impulsive transfer between two given non coplanar elliptical orbits is analyzed from the point of view of fuel consumption. This kind of constraint requires special orbital places to apply impulsive maneuvers, where the ground station is able to track the satellite. The increment of the fuel consumption imposed by this kind of constraint is evaluated by subdividing of the true anomalies' intervals at the initial and final orbits. This research takes part on the orbital maneuvers program for the China-Brazil Earth Resources Satellite (CBERS) and should be extended for any kind of bi-impulsive orbital transfer.
Keywords: Astrodynamics, artificial satellites, numerical method, orbital maneuver / Astrodinâmica, satélites artificiais, método numérico, manobra orbital.
COB1346 DETERMINAÇÃO DE ÓRBITA EM TEMPO REAL ATRAVÉS DO GPS UTILIZANDO O FILTRO DE KALMAN / REAL TIME ORBIT DETERMINATION WITH GPS USING KALMAN FILTER
Ana Paula M. Chiaradia, Rodolpho V. de Moraes, Sandro da S. Fernandes & Hélio K. Kuga
Instituto Nacional de Pesquisas Espaciais - INPE- Av. dos Astronautas,1758, São José dos Campos
CEP 12227-010, SP, Brasil. - E-mail: chiara@dem.inpe.br
In this paper, we discuss a method of preliminary orbit determination in real time for an artificial satellite with a GPS receiver on board. Classical elements are considered as state variables and a simple dynamic model, based in the classic two-body problem, is used. The observations are formed by range and range-rate measurements with respect to four visible GPS satellites. An extended Kalman filter is used as the estimation technique. The data are simulated through numerical propagation (Cowell’s method), which considers special perturbations for the GPS satellite constellation and an user satellite.
Keywords: GPS system, Kalman filter, orbit determination. Sistema GPS, filtro de Kalman, determinação de órbita.
COB1347 UTILIZAÇÃO DA SOLUÇÃO DE NAVEGAÇÃO DO GPS PARA DETERMINAÇÃO DE ÓRBITA DE SATÉLITES A BAIXA ALTITUDE / UTILIZATION OF THE NAVIGATION SOLUTION FROM THE GPS TO DETERMINE THE ORBIT OF A SATELLITE IN A LOW ORBIT
Jorge Martins do Nascimento, Helio K. Kuga & Antonio F. Bertachini A. Prado
Depto Mecânica Espacial e Controle, Instituto Nacional de Pesquisas Espaciais INPE
Av. dos Astronautas 1758, CEP 12227010, São José dos Campos, Brasil Email: HKK@DEM.INPE.BR, PRADO@DEM.INPE.BR
In this work the orbit determination problem of an Earth artificial satellite is analyzed. This problem is solved using the GPS (Global Positioning System). It’s assumed that the target satellite will carry a GPS receiver. To perform this mission, one needs to perform the following steps: i) To simulate the motion of the GPS and the target satellites; ii) To calculate all the distances between the GPS satellites and the target satellite; iii) To determine which GPS satellites are visible; iv) To corrupt those data by adding a random error; v) To develop a software that is able to get a navigation solution on each point of the orbit, vi) To develop a new software to get the target satellite state vector (position and velocity) from the navigation solution. This work was motivated by INPE’s plans of performing this kind of mission in a near future. It must be emphasized that the goal of this work is not to provide the system maximum accuracy, but a sufficient accuracy to track and control the satellite at a low cost.
Keywords: GPS, Astrodynamics, Orbit Determination / GPS, Astrodinâmica, Determinação de Órbita
COB 1352 CHAOS IN SPACECRAFT ATTITUDE MOTION IN EARTH MAGNETIC FIELD
V.V.Beletsky 1 , M.L.Pivovarov 2 & R.V.F.Lopes 3
1 Keldysh Applied Mathematics Institute, Miusskaya 4, Moscow, Russia
E-mail: beletsky@spp.keldysh.ru
2 Space Research Institute, 117810, Profsoyuznaya 84/32, Moscow, Russia
E-mail: mpivovar@vm1.iki.rssi.ru
3 National Institute for Space Research - INPE, 12.227-010 - S.J. dos Campos - SP - Brazil
E-mail: rvfl@dem.inpe.br
The paper deals with spacecraft attitude motion on polar, circular, Keplerian orbit. It is supposed that the spacecraft is equipped by permanent magnet. The model of Earth magnetic field is the dipole aligned with the Earth rotation axis. The spacecraft rotation is considered under the action of the magnetic torque only. The model is naive, but it includes the main effect which is important for magnetically stabilized spacecraft design and attitude dynamics analysis. The motion obeys asecond-order, nonlinear, nonautonoumus equation which depends on one parameter only, namely the magnetic moment of the spacecraft. The goal of the paper is the investigation of global phase picture of the problem for a wide interval of magnetic parameter using the numerical implementation of Poincare point map method. In course of the analysis, new periodic solutions are found, the evolution of the phase picture and bifurcations of periodic solutions dependent on the magnetic parameter are studied, the values of the magnetic parameter which are dangerous'' from standpoint of spacecraft stabilization are discussed.
Keywords: Attitude motion, periodic solutions, chaos.
COB1353 SYMBOLIC MODELING AND DYNAMIC SIMULATION OF ROBOTIC MANIPULATORS WITH FLEXIBLE LINKS
Sergio Adriani David & João Maurício Rosário
Departamento de Projeto Mecânico, Faculdade de Engenharia Mecânica - UNICAMP, CEP - 13083 - 970 - Campinas - S.P. - Brasil
The need for fast and precise robots in the industrial environment, capable of attending the productivity and quality demands and that allow a high volume of work, needs the usage of manipulators with flexible links. Besides this, aeronautic applications demand the usage of long and thin arms, which leads to remarkable structural changes. Therefore, the development of manipulators with structural flexibility and its automatic control has become an important research area. The main goal of this work is to model the dynamic behavior of flexible manipulators. It is also presented a comparative study with rigid robots. It is possible to use the model for computer simulations to aid the development of efficient control.
Keywords: Robotics, Simulation, Industrial Robot, Flexible Robot - Robótica, Simulação, Robôs Industriais, Robôs Flexíveis
Nicolò Bachschmid, Andrea Curami, Andrea Vania, Riccardo Dellupi
Dipartimento di Meccanica, Politecnico di Milano, P.zza L. da Vinci, 32, 20133 Milano, Italy
Phone: ++39-2-23994718, ++39-2-23994831, Fax: ++39-2-70638377
E-mail: bachschm@hp1.mecc.polimi.it, dellupi@hp1.mecc.polimi.it
A survey of the most updated techniques for modelling rotor systems composed by rotors, bearings and supporting structures, is presented. Some benchmarking test results of several different codes for rotordynamics calculations and oil film bearing coefficients evaluation are shown. Methods for increasing reliability and accuracy in rotordynamic calculations are proposed, because a higher accuracy is needed for model based diagnostic procedures. Finally also a unified approach for fault modelling is presented, which is particularly suitable for fault identification procedures used in model based diagnostics of rotor systems.
Keywords: Rotordynamics, Model Based Diagnostics, Rotor, Bearing, Foundation.