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Sundling, Emma. "Validation toolbox for a Physics Engine." Thesis, Umeå universitet, Institutionen för fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-121972.
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Physics engines become more and more common due to the rapid development and increasing demand of simulations. With this comes a need of testing the engine, a way to measure its performance, not only its speed but also its accuracy and stability. The purpose of this thesis has been to create a set of benchmark tests. They aim to check the physical aspects, especially mechanics, of the engine. A strategy and export functions for the test results in order to automate the testing have also been developed. The resulting tests became a beam on piles which analyses constraint stability, an overdetermined system consisting of a static door on multiple hinges, a falling object investigating the accuracy of the integrator, a box on an inclined plane for testing the friction model, a single pendulum as well as a multibody pendulum checking constraint accuracy and energy conservation, the Earth orbiting around the Sun which tests the stability of the integrator and finally a cantilever beam that is a static test of a real scenario. After the tests are performed the results are presented on an HTML-page. A prototype of a Web application is also established as well as a set of scalar tests that can be performed continuously, in order to follow trends or compare the engine's performance from time to time. This thesis was initialized by Algoryx Simulation AB which also provided the engine, AgX Dynamics, with the numerical method called SPOOK. It mainly performed well on all tests. In order to build a fully general toolbox more tests need to be added such as material interactions, scalable test with thousands of bodies, torque tests as well as more complex scenarios, for example a scissor lift and robots. The work can also be extended with more developed export functions, both to the Web and to documents. Hopefully this thesis can be seen as a complement to the earlier efforts done in creating a general set of benchmarks and automation framework for continuous integration and testing.<br>Fysikmotorer blir mer och mer vanliga på grund av den snabba utvecklingen och efterfrågan på simuleringar. I och med detta ökar också behovet av att testa motorerna och ett sätt att mäta prestandan, inte bara snabbheten utan också noggrannheten och stabiliteten. Syftet med detta examensarbete har varit att skapa ett set av prestandatester. De syftar till att testa de fysikaliska aspekterna av fysikmotorn, särskilt inom mekanik. En strategi och exportfunktioner för testresultaten för att automatisera testningen har också utvecklats. De resulterande testerna blev en balk på pålar som analyserar stabiliteten hos villkoren, ett överbestämt system bestående av en statisk dörr på flera gångjärn, ett fallande objekt som granskar precisionen hos integratorn, en låda på ett lutande plan som testar friktionsmodellen, en enkel pendel samt en flerkropppspendel som kontrollerar villkorsprecisionen och energikonservering, jordens bana runt solen som testar integratorns stabilitet och slutligen en utskjutande balk som är ett statiskt test av ett verkligt fall. När testerna är genomförda presenteras resultaten på en HTML-sida. En prototyp av en webb-applikation har också utvecklats samt ett set med skalära tester som kan utföras kontinuerligt för att följa upp trender och jämföra motorns prestanda över tid. Det här examensarbetet initierades av Algoryx Simulation AB som även tillhandahållit fysikmotorn, AgX Dynamics, med den numeriska metoden SPOOK. Motorn presterade överlag bra på testerna. För att bygga en allmän verktygslåda behövs fler tester så som interaktion mellan material, skalbara tester med tusentals kroppar samt mer komplexa simuleringar, t.ex. en saxlyft och robotar. Arbetet kan också utökas med mer utvecklade exportfunktioner, både mot webben och som dokument. Förhoppningsvis kan detta ses som ett komplement till de tidigare ansträgningar som gjorts för att skapa ett generellt set av prestandatester och ett automatiskt ramverk för kontinuerlig testning.
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Fratello, John David. "Multi-body Dynamics Simulation and Analysis of Wave-adaptive Modular Vessels." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/76787.
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Catamarans provide vast deck space, high thrust efficiency, and excellent transverse stability, however, in rough conditions they can be susceptible to deck slamming from head seas or bow diving in following seas and a pitch-roll coupling effect that can lead to uncomfortable corkscrew motion under bow-quartering seas. A new class of catamaran called Wave-Adaptive Modular Vessels (WAM-V™) aims to help mitigate oceanic input from the cabin by allowing for the relative motion of components not common to classic catamaran design. This thesis presents a set of multi-body dynamics simulation models created for two active WAM-Vs™ along with analysis on their suspension characteristics. Both models provide conclusive and realistic results, with the final model being validated against on-water testing data from a 12-ft unmanned prototype WAM-V.
The first of these simulations serves primarily as a tool to evaluate WAM-V™ response characteristics with respect to a variety of parametric variations. The modeling environment is highlighted along with details of the parametric simulation and how it was created. The results fall in line with our expectations and are presented along with analysis of the sensitivity of each parameter at three longitudinal locations. The final simulation attempts to model the response of a 12-ft unmanned surface vessel (USV) prototype of the WAM-V™ configuration. Testing data is collected, processed, and applied to the model for validation of its prediction accuracy. The results of the sea tests indicate that the simulation model performs well in predicting USV motions at sea. Future considerations for testing WAM-Vs™ can include changes in suspension and mass parameters as well as limiting particular degrees-of-freedom by making their joints rigid.<br>Master of Science
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Nordberg, Anders. "Simulation of a complete truck and trailer assembly : Multi body dynamics." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-67401.
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Aghaei, Shayan. "Acoustic Radiation Of An Automotive Component Using Multi-Body Dynamics." Thesis, KTH, Fordonsdynamik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-288710.
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An important facet of creating high-quality vehicles is to create components that are quiet and smooth under operation. In reality, however, it is challenging to measure the sound that some automotive components make under load because it requires specialist facilities and equipment which are expensive to acquire. Furthermore, the motors used in testbeds drown out the noise emitted from much quieter components, such as a Power Transfer Unit (PTU). This thesis aims to solve these issues by outlining the steps required to virtually estimate the acoustic radiation of a PTU using the Transmission Error (TE) as the input excitation via multi-body dynamics (MBD). MBD is used to estimate the housing vibrations, which can then be coupled with an acoustic tool to create a radiation analysis. Thus, creating a viable method to measure the acoustic performance without incurring significant expenses. Furthermore, it enables noise and vibration analyses to be incorporated more easily into the design stage. This thesis analysed the sound radiated due to gear whine which arises due to the TE and occurs at the gear mesh frequency and its multiples. The simulations highlighted that the TE can be accurately predicted using the methods outlined in this thesis. Similarly, the method can reliably obtain the vibrations of the housing. The results from this analysis show that at 2000 rpm the PTU was sensitive to vibrations at 500, 1000 and 1500 Hz, the largest amplitude being at 1000 Hz. Furthermore, the Sound Power Level (SWL) was proportional to the vibration amplitudes in the system. Analytical calculations were conducted to verify the methods and showed a strong correlation. However, it was concluded that experiments are required to further verify the findings in this thesis.<br>En viktig aspekt i att skapa fordon av hög kvalitet är att skapa komponenter som är tysta och smidiga under drift. I verkligheten är det dock svårt att mäta ljudet som vissa fordonskompo- nenter ger under belastning eftersom det kräver specialanläggningar och utrustning, vilket är dyrt att skaffa. Dessutom maskerar motorerna som används i testbäddar ut bullret från mycket tystare komponenter, till exempel en kraftöverföringsenhet (PTU). Detta examensar- bete syftar till att lösa dessa problem genom att beskriva de steg som krävs för att virtuellt uppskatta den akustiska strålningen av en PTU med hjälp av transmissionsfelet (TE) som ingångsexcitation via flerkroppsdynamik (multi-body dynamics, MBD). MBD används för att uppskatta kåpans vibrationer, som sedan kan kopplas till ett akustiskt verktyg för att skapa en ljudutstrålningsanalys. Således skapas en genomförbar metod för att mäta den akustiska pre- standan utan att medföra betydande kostnader. Dessutom möjliggör det att lättare integrera ljud- och vibrationsanalyser i designfasen. Detta examensarbete analyserade ljudet som utstrålats på grund av kugghjulsljud, som uppstår på grund av TE och uppträder vid kuggingreppsfrekvensen och dess multiplar. Simuleringarna belyste att TE kan förutsägas exakt med de metoder som beskrivs i detta examensarbete. På samma sätt kan metoden på ett tillförlitligt sätt uppnå kåpans vibrationer. Resultaten från denna analys visar att vid 2000 rpm var PTU känslig för vibrationer vid 500, 1000 och 1500 Hz, den största amplituden var vid 1000 Hz. Dessutom var ljudeffektsnivån (SWL) proportionell mot vibrationsamplituderna i systemet. Analytiska beräkningar genomfördes för att verifiera metoderna och visade en stark korrelation. Dock drogs slutsatsen att experiment krävs för att ytterligare verifiera resultaten i detta arbete.
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Lopik, David van. "A computational model of the human head and cervical spine for dynamic impact simulation." Thesis, Loughborough University, 2004. https://dspace.lboro.ac.uk/2134/7643.
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Injury to the human neck is a frequent consequence of automobile accidents and has been a significant public health problem for many years. The term `whiplash' has been used to describe these injuries in which the sudden differential movement between the head and torso leads to abnormal motions within the neck causing damage to its soft tissue components. Although many different theories have been proposed, no definitive answer on the cause of `whiplash' injury has yet been established and the exact mechanisms of injury remain unclear. Biomechanical research is ongoing in the field of impact analysis with many different experimental and computational methods being used to try and determine the mechanisms of injury. Experimental research and mathematically based computer modelling are continually used to study the behaviour of the head and neck, particularly its response to trauma during automobile impacts. The rationale behind the research described in this thesis is that a computational model of the human head and neck, capable of simulating the dynamic response to automobile impacts, could help explain neck injury mechanisms. The objective of the research has been to develop a model that_,, can accurately predict the resulting head-neck motion in response to acceleration impacts of various directions and severities. This thesis presents the development and validation of a three-dimensional computational model of the human head and cervical spine. The novelty of the work is in the detailed representation of the various components of the neck. The model comprises nine rigid bodies with detailed geometry representing the head, seven vertebrae of the neck and the first thoracic vertebra. The rigid bodies are interconnected by spring and damper constraints representing the soft-tissues of the neck. 19 muscle groups are included in the model with the ability to curve around the cervical vertebrae during neck bending. Muscle mechanics are handled by an external application providing both passive and active muscle behaviour. The major findings of the research are: From the analysis of frontal and lateral impacts it is shown that the inclusion of active muscle behaviour is essential in predicting the head-neck response to impact. With passive properties the response of the head-neck model is analogous to the response of cadaveric specimens where the influence of active musculature is absent. Analysis of the local loads in the soft-tissue components of the model during the frontal impact with active musculature revealed a clear peak in force in the majority of ligaments and in the intervertebral discs very early in the impact before any forward rotation of the head had occurred. For the case of rear-end impact simulations it has been shown for the first time that the inclusion of active musculature has little effect on the rotation of the head and neck but significantly alters the internal loading of the soft-tissue components of the neck.
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Brown, Sean M. "Determination of Human Powered Helicopter Stability Characteristics using Multi-Body System Simulation Techniques." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/874.
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Multi-Body System Simulation combined with System Identification was developed as a method for determining the stability characteristics of a human powered helicopter(HPH) configurations. HPH stability remains a key component for meeting competition requirements, but has not been properly treated. Traditional helicopter dynamic analysis is not suited to the HPH due to its low rotation speeds and light weight. Multi-Body System Simulation is able to generate dynamic response data for any HPH configuration. System identification and linear stability theory are used to determine the stability characteristics from the dynamic response. This thesis focuses on the method development and doesn't present any HPH analysis results.
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Ramachandran, Praveen. "Modelling and Dynamic Simulation of Tracked Forwarder in Adams ATV Module." Thesis, KTH, Maskinkonstruktion (Inst.), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-182803.
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Swedish forest industry is relying on the cut-to-length method for logging and there has always been a constant quest to make it more efficient and sustainable. Reduction of forest soil damage and operator vibration dosages are crucial steps that could facilitate meeting the above stated targets. In this context Skogforsk- The Swedish Forest Research Institute has decided to explore the potential usage of caterpillar tracks on conventional wheeled forwarders. An efficient way to perform this study is to use multi body simulations to evaluate the performance of the tracked forwarder concept over different terrains. This thesis work aims to model and simulate a tracked forwarder in Adams ATV module. As part of the thesis a conventional wheeled forwarder was selected and a track unit was conceptualised to fit it. The concept was modelled and simulate with Adams ATV for various ground conditions. An effort was also made to identify the performance parameters required to improve traction, handling, and ride performance. Based on this some results were selected and studied and inferences were made. The results from the thesis work could provide a guideline on the methodology to be followed and a a deliverable is also a multi-body dynamics model for future design research.<br>Svensk skogsindustri jobbar efter kortvirkesmetoden för trädavverkning. Det finns en strävan efter att göra denna metod mer effektiv och samtidigt mer ekologiskt hållbar, exempelvis en minskad markpåverkan reduktion av de helkroppsvibrationer som operatören utsätts för. Motivet till detta examensarbete är att utforska möjligheten att ersätta dagens hjulbaserade skogsmaskiner med banddrivna. Det överordnade syftet för examensarbetet är att utveckla en modelleringsmetodik för dynamiska systemsimuleringar. Metoden för detta är att modellera och simulera en banddriven skotare med Adams ATV-modul och att beskriva ett rekommenderat tillvägagångssätt och möjliga resultat. Som en del av arbetet har en traditionell skotare valts och en konceptuell bandenhet har skapats och anpassats för att passa till skogsmaskinen. Konceptet modellerades och simulerades med Adams ATV för olika markunderlag. Ytterligare arbete lades på att identifiera de parametrar som är viktiga för grepp, fordonskontroll och framkomlighet. Baserat på några av resultaten valdes några för en fördjupad studie. Resultatet från examensarbetet kan ge riktlinjer för val av lämplig metodik för denna typ av prestandastudier. En konkret leverabel från projektet är också en dynamisk flerkroppsmodell, som kan utgöra en bas för fortsatta konstruktions- och prestandastudier.
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Strobel, Jens, Jens Sumpf, and Hagen Bankwitz. "Dynamic Studies on a Slide Chain Conveyor System." Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-231745.
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In slide chain conveyors vibrations often appear. These cause detrimental effects in conveying process and decrease the durability of chains. To study the vibrations, a multi-body simulation model has been developed, in which rheological elements are used to represent the dynamic effects. A focus was determining material values required for the model. These were identified by hysteresis experiments. Finally, the model was verified by comparing simulation results with measurements in the conveyor system<br>In Gleitkettenfördersystemen werden häufig Schwingungen der Kette beobachtet, die einen zuverlässigen Förderprozess auf diesen Anlagen beeinträchtigen können. Ziel dieser Arbeit ist die Erforschung dieser Schwingungen mit Hilfe von einem Mehrkörpersimulationsmodell. Zur Abbildung der dynamischen Effekte wurden rheologische Elemente verwendet. Ein Schwerpunkt lag bei der Ermittlung der für das Modell notwendigen Materialkennwerte. Diese wurden mit Hilfe von Hystereseversuchen herausgefunden. Zum Schluss wurde das Modell über einen Abgleich zwischen Simulation und Messung im Fördersystem verifiziert
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Bartram, Matthew. "Transient tyre modelling for the simulation of drivetrain dynamic response under low-to-zero speed traction manoeuvres." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/8489.
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The work presented in this thesis is dedicated to the study of transient tyre dynamics and how these influence the dynamic behaviour of the vehicle and its driveline, with the main focus being on low-to-zero speed manoeuvres such as pull-away events. The bulk of the work focuses on the amalgamation of the hitherto disparate fields of driveline modelling and detailed tyre modelling. Several tyre models are employed and their relative advantages and disadvantages analysed. The observed dynamic behaviour is correlated to the inherent structure of each tyre model in order for the most appropriate for driveline studies to be identified. The main simulation studies are split into two parts: the first comprises a study into isolated driveline dynamics; where the yaw, pitch and roll behaviours of the vehicle body are neglected. A relatively detailed driveline model with an open differential is used with tyre models of increasing complexity with the aim of determining when increased model detail fails to increase the accuracy of the results. The second part is concerned with the study of how the dynamics of the vehicle body and suspension affect tyre model performance and associated effects on the driveline behaviour. For this, the driveline and tyre models are incorporated into a full six degree-of-freedom vehicle model with full suspension effects. Frequency migration on low-μ surfaces is successfully explained via the decoupling of the vehicle and driveline inertias. Frequencies observed in FFT analyses of the simulation results correspond to those obtained through eigen-analysis of appropriately modified state-space models with varying degrees of coupling that reflect the vehicle travelling on uniform low- or split-μ surfaces. The main finding of the thesis is that this decoupling theory can also be applied to high-speed take-off manoeuvres, as it is the position along the tyre slip-force curve that dictates decoupling; i.e. if the curve has saturated. This leads to the effective traction stiffness being zero, which modifies the equations of motion and subsequently the system eigenvalues. A series of measurements are taken in order to verify the findings from the simulation work. Manoeuvres analogous to those simulated are carried out. It is found that only the simulation of split-μ conditions is necessary, as the results from the low-μ test show a similar pattern to those seen on the split-μ surface.
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Dye, John. "Development and application of computational dynamic and kinematic constrained multi-body system simulations in MATLAB." Thesis, Wichita State University, 2011. http://hdl.handle.net/10057/3951.
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Historically machine and mechanism design relied heavily upon analytical and graphical means to evaluate the performance a system. With increasing complexity, these methods have been modified for use with computational tools. General purpose solvers have been created such as Adams, DADS and Dap3d to analyze different machines and mechanisms. Although these tools are available, they allow limited access to source code or utilize a language that is not readily taught in academics.
This thesis will focus on the creation of a general-purpose simulation enviroment using the currently used programming language Matlab. Four simulation programs have been created allowing simulation of kinematics and dynamics for planar and spatial mechanical systems. Discussed along with the program operation is the mathematics behind normal computational dynamics. A section is dedicated to the solution and its implementation of purely kinematic methods allowing the solution of planar and spatial systems. Constraints are heavily utilized in the formation of multi-body systems and their equations and formulations are detailed. For spatial kinematic simulations, Euler parameters are discussed in detail, and the related equations needed for multibody system simulations have been provided. The mathematics of the dynamic simulations is also discussed, along with addition of non-rigid elements such as springs and dampers.
Example simulations of specific systems have also been included, showing the results of interest utilizing the graphical user interfaces that have been created. Along with these examples is a simulation that includes two dimensional beam elements injected into the dynamic solver, which illustrates how multiple fields of engineering can be included in the simulations<br>Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.
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Kraft, Sönke. "Parameter identification for a TGV model." Phd thesis, Ecole Centrale Paris, 2012. http://tel.archives-ouvertes.fr/tel-00731143.
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This work investigates the applicability of identification methods to the suspension parameters of a TGV multi-body model. The aim is to adjust the model to the real system by estimating the suspension parameters from measured vehicle response data. Due to the nonlinear behavior of the system the time-domain based model updating has been chosen. It requires the definition and minimization of a misfit function in the time domain describing the distance between model and measurement. The fastest convergence is obtained by the use of gradient methods requiring the calculation of the derivatives of the misfit function relative to every parameter. Since the calculation from finite differences is time consuming and less accurate the gradients are calculated from the adjoint method. The application to a simplified bogie model with known mathematical description allows the identification of its suspension parameters. The presence of local minima in the misfit function of the TGV model requires the use of global optimization methods. The simulated annealing and the genetic algorithm method give important reductions of the misfit function and improved parameter estimations. In following work this information could be used for further applications like the condition monitoring.
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Kosaraju, Nikhil Maharshi. "Dynamic Analysis of an Automotive Power Transfer unit : Towards prediction of TE and housing vibrations." Thesis, KTH, Maskinkonstruktion (Avd.), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259683.
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This work describes the use of Multi-Body Simulation (MBS) to create a virtual prototype of a geared drive called Power transfer unit (PTU). PTU is a subsystem of the all-wheel drive driveline responsible for transfer of power between front and rear axles in an Automobile. The objective of the developing the prototype is to simulate the dynamic behavior of the PTU. Focus is on predicting the gear transmission error(TE) and gearbox housing vibration level. A Hypoid gear set, bearings, tubular shaft and housing are the major components in the PTU. This work is carried out at GKN Automotive which specializes in development of Automotive All wheel drive systems. When developing such geared systems one important characteristic analyzed is the noise and vibration it generates. And for companies like GKN it is desirable to predict these characteristics as early as possible for two reasons, to avoid late design changes and to speed up the product development cycle. To achieve this, a validated virtual model which is computationally efficient is desired. The methodology followed contains of two facets, development of the MBS model and validation of the developed model with physical testing. An integrated MBS-FEM approach is used, an FE modal reduction technique is used to create flexible components with which a virtual prototype is built and simulated in an MBS tool MSC ADAMS c . Gear contact and bearings are defined using an analytical approach which considers the nonlinear stiffness and damping. A dynamic analysis and system level modal analysis is performed to predict the TE, housing vibrations and PTU modal parameters. Experimental modal analysis and physical testing on test rig are performed to measure the actual values of the above predicted outputs. Parameters like damping, contact stiffness of the model are then tuned to achieve correlation. When comparing test and prediction, close correlation is seen in the TE and for housing vibration a similar trend is observed with some deviations. Predicted TE is heavily dependent on gear contact parameters. On the modal parameter comparison, a correlation of five modes and mode shapes below 2500Hz is seen which shows the validity of the MBS model. Parameter studies are performed to study the effect of bearing damping and preload on housing vibrations and TE. It is observed that an optimum value of preload and damping is essential to avoid unnecessary vibrations. In conclusion, the model with some fine tuning of damping parameters can be used for virtual noise and vibration analysis of the PTU.<br>Detta arbete beskriver anv¨andningen av beräkningsmetoden Multi-Body Simulation (MBS) för att skapa en virtuell prototyp av en vinkelväxel (Power Transfer Unit, PTU ). PTU är ett delsystem för fyrhjulsdrift som har funktionen att överföra kraft mellan fram- och bakaxlar i en bil. Målet med att utveckla modellen är att simulera PTUns dynamiska beteende. Fokus ligger på att beräkna vinkelväxelns transmissionsfel och vibrationsnivåer på växellådans hus. De vikitgaste komponenterna i PTUn är hypoidväxeln med kronhjul och pinjong, röraxel, lager och hus. Detta arbete har utförts på GKN Automotive som är specialiserade på utveckling av drivsystem för fyhjulsdrivna bilar. Ljud och vibrationer är viktiga egenskaper att ta hänsyn till under utvecklingen. För företag som GKN är det önskvärt att kunna beräkna dessa egenskaper så tidigt i projektet av två skäl: dels för att undvika sena konstruktionsförändringar och dels att påskynda produktutvecklingscykeln. För att uppnå detta behövs en validerad virtuell modell som är beräkningseffektiv. Den metod som använts innehåller två delar: utveckling av MBS-modellen och validering av den utvecklade modellen med fysisk testning. En integrerad MBS-FEM -mettod har använts. Det innebär att en FE-modal reduktionsteknik andvänds för att skapa flexibla komponenter med vilka en virtuell prototyp byggs och simuleras i ett MBS-verktyg (MSC ADAMS (c) ). Lager och kuggkontakt i växeln definieras med hjälp av en analytisk metod som beaktar den olinjära styvheten och dämpningen. En dynamisk analys och modalanalys på systemnivå har utförts för att beräkna TE, husvibrationer och PTUns modala parametrar. Experimentell modalanalys och testning i rigg gjorts för att mäta motsvarande värden som har beräknats. Parametrar som dämpning och kontaktstyvhet har sedan justerats för att uppnå korrelation. Vid jämförelse av test och förutsägelse ses en god korrelation i TE och för husvibrationer observeras en liknande trend, med vissa avvikelser. Beräknat TE är starkt beroende på parametrar för kuggkontakten i växeln. Vid jämförelse av modala parametrar ses en god korrelation under 2500 Hz mellan fem moder i mätning och beräkning vad gäller frekvens och modform, vilket visar MBS-modellens giltighet. Parameterstudier har utförts för att studera effekten av lagerdämpning och förbelastning på TE och husvibrationer. Ett optimalt värde på förbelastning och dämpning är viktigt för att undvika onödiga vibrationer. Sammanfattningsvis kan modellen med viss finjustering av dämpningsparametrar användas i virtuell ljud- och vibrationsanalys av PTU.
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Tobiáš, Martin. "Analýza měřených dynamických stavů motocyklů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400514.
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This thesis, within a long-term project at the Institute of automotive engineering at FME BUT, aspires to prepare a motorcycle for analysis of its dynamic riding behavior. A multi-body model of a motorcycle is created based on the measured parameters and a system for measuring driving conditions is designed. The necessary motorcycle parameters were measured using a 3D scanner and through experiments aided by computer technology and CAD software. This laid the foundation for the follow-up research and development work.
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Lečbych, Jiří. "Fotogrammetrické snímaní polohy jezdce na motocyklu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-445157.
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This Master’s thesis deals with designing a measuring device that would record driver’s movements during dynamic riding states known as localization, and based on the recorded data creating a simulation in multi-body software. The first part reviews the current state of knowledge in the field of photogrammetry, sensors, and motorcycles’ characteristics. Moreover, the second part focuses on constructing the measuring device, practical aspects of data collection, processing, and evaluation in multi-body software.
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Aravindababu, Sumanth Ram. "Investigation of sources of wheel-rail impact force deviation through dynamic simulations." Thesis, KTH, Fordonsdynamik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302783.
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Due to the increase in demand on freight transportation it becomes necessary to avoid delays to ensure that the goods reach its destination on time. The main factors causing disturbances in the traffic on the mainline is the breakdown of vehicles mainly due to damaged wheels. The damaged wheels are identified through the wheel-rail impact force measurements provided by the wheel impact load detectors (WILD). This calls for the optimal schedule of maintenance of wheelsets and wagons in general. During the maintenance, the officials manually check for defective wheels and the exchange of wheelsets is performed based on the type of damage. The classification of wheel damages plays a vital role in providing ease of damage identification and insights to deduce a strategy for wheelset exchange. In this study, an attempt to classify the damaged wheelsets is done by analysing the wheel-rail impact force data from the wayside detectors. The data from the detectors are acquired from PredgeAB, a Luleå based startup pioneering in providing decision support on optimal maintenance schedules and predictive maintenance of rail wheels. Through their detection and prediction solutions it was observed that of all the wheels marked as damaged by the detectors 10% were undamaged. The source of the deviation in the impact force readings could help Predge make better estimations in damage detection and prediction. In this study, the sources contributing to the deviation is studied using multi-body simulations in GENSYS. A new method for modelling wheel damage is developed to overcome the shortcomings of the software. The findings of this study can then be used appropriately to make classifications of wheel damages.<br>På grund av den ökade efterfrågan på godstransporter är det nödvändigt attundvika förseningar för att säkerställa att varorna når sin destination i tid. Deviktigaste faktorerna som orsakar störningar i trafiken på huvudlinjen är stopp ispår av fordon, främst på grund av skadade hjul. De skadade hjulen identifierasmed hjälp av mätningar av slagkraft mellan hjul och spår som tillhandahållsav hjulbelastningsdetektorer (WILD). Detta kräver ett optimerat schema förunderhåll av hjulsatser och vagnar i allmänhet. Under underhållet kontrollerartjänstemännen manuellt för defekta hjul och utbytet av hjulsatser utförs baserat på typen av skada. Klassificeringen av hjulskador spelar en viktig roll närdet gäller att underlätta identifiering av skador och ge insikt för att bedöma enstrategi för hjulbyte. I den här studien görs ett försök att klassificera de skadade hjulsatserna genom att analysera data från slagkraften mellan spår ochhjul från detektorer. Uppgifterna från detektorerna hämtas från PredgeAB, enLuleå-baserad uppstartsbolag som är pionjärer för att ge beslutsstöd om optimala underhållsscheman och prediktivt underhåll av järnvägshjul. Genom sinadetekterings- och prediktiva lösningar observerades att 10% av alla hjul märktasom skadade av detektorerna var oskadade. Källan till avvikelsen i slagkraftavläsningarna kan hjälpa Predge att göra bättre uppskattningar när det gällerupptäckning och förutsägelse av skador. I den här studien studeras de källorsom bidrar till avvikelsen med simuleringar av flera kroppar i GENSYS. En nymetod för modellering av hjulskador har utvecklats för att övervinna programvarans brister. Resultaten av denna studie skulle kunna användas på lämpligtsätt för att göra klassificeringar av hjulskador.
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Karis, Tomas. "Correlation between Track Irregularities and Vehicle Dynamic Response Based on Measurements and Simulations." Licentiate thesis, KTH, Farkost och flyg, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-228056.
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Deviations from the design track geometry are called track irregularities, which are a main excitation mechanism in the track–vehicle dynamic system, and very important to monitor and maintain to have trac on a line run safely and comfortably. Especially during vehicle acceptance testing, it is important that a new vehicle behaves close to design predictions and within limit values, thus it is important to be able to describe track irregularities in a consistent way. There are several methods which quantify the eects track irregularities have on a vehicle while running along the track. Most common is analyse standard deviations and percentiles and maximum values over sections with pre-defined length. However, these quantities do not correlate well with the vehicle dynamic response, e.g. two track sections with similar maxima and standard deviations can result in very dierent response of the vehicle. To improve the correlation between track irregularities and vehicle re- sponse measures, it is recommended by past research to use multiple regres- sion analysis to take e.g. vehicle speed and track curvature into account as well. Other methods range from derivatives of track irregularities, via trans- fer functions and vehicle filters to neural networks. Common for all these methods are that there is either still slight inconsistencies in the results or that they are tailored for certain vehicle types on specific lines. As a result, the preferred method to evaluate track irregularities is still to use standard deviations. In this thesis, data from three vehicles in two measurement campaigns is evaluated using a single degree of freedom model as inspiration to break down the path from track to vehicle into several steps. A weak link in these steps is identified, which shows significantly lower correlation coecients than the other steps. The weak link is the step from vertical track irregularity second spatial derivative to vertical axle box acceleration divided by the squared vehicle speed. A variable wavelength range Dx is introduced, as an alternative to the common D1 (3–25 m), D2 (25–70 m) and D3 (70–150 m) wavelength ranges. Its wavelength range corresponds to the vehicle response band-pass filter frequencies and is thus speed dependent. Simulations are also carried out to investigate the weak link and for the possibility to vary parameters that cannot be changed during on-track mea- surements. A multi-body system model of the passenger coach Bim 547.5 is used, together with recorded track data and vehicle speed from the on-track measurements. The varied parameters have rather low sensitivity and aect results to a small extent. Most impact has the randomly varying vertical track stiness which aects the vertical wheel–rail forces and axle box accelerations. In future work, it should be explored if it is possible – and in such case how – to separate the eects of varying track stiness from the track irreg- ularities. This to better understand when a vehicle response is linked more to the track irregularities or to the track flexibility. The weak link identified in the steps from track to vehicle should also be further explored, perhaps by extending the underlying model or evaluate a dierent set of measurements.<br>Spårlägesfel är avvikelser från den nominella spårgeometrin. De är en vik- tig excitationsmekanism i det dynamiska system som bana och fordon utgör och är viktiga att övervaka och åtgärda för att trafiken ska kunna flyta sä- kert och komfortabelt. Eftersom det vid mätningar för typgodkännande av fordon är viktigt att fordonet beter sig som förväntat och inom gränsvärden, är det viktigt att kunna beskriva spårlägesfel på ett sätt som är konsekvent och motsvarar hur fordonet ”känner av” dem. Det finns ett flertal olika metoder som kvantifierar de eekter spårläges- fel har på ett fordon som rör sig längs ett spår. Vanligast är att använda standardavvikelser, percentiler och maxvärden från spårsektioner med för- definierad längd. Dessa storheter korrelerar dock inte väl med den dynamiska fordonsresponsen, till exempel kan två spårsektioner med liknande maxvärden och standardavvikelse resultera i väldigt olika fordonsrespons. För att förbättra korrelationen mellan storheter för spårlägesfel och for- donsrespons rekommenderar tidigare forskning att använda multipel regres- sionsanalys för att även ta hänsyn till till exempel fordonets hastighet eller spårets kurvatur. Det finns flera alternativa metoder, till exempel derivator av spårlägesfel, överföringsfunktioner och fordonsfilter eller neurala nätverk. Generellt ger dock dessa metoder antingen fortfarande en viss osäkerhet i resultaten, eller så är de anpassade för vissa fordonstyper på enstaka järn- vägslinjer. Sammantaget är resultatet att den metod som föredras för att utvärdera spårlägesfel, fortfarande baseras på standardavvikelser. I den här avhandlingen används en enfrihetsgradsmodell som inspiration för att bryta ner excitationsvägen från spår till fordon i ett antal steg, som sedan undersöks genom att utvärdera mätdata från tre fordon i två forsk- ningsprojekt. En svag länk bland stegen identifieras, vilken visar signifikant lägre korrelationsvärde än övriga steg. Den svaga länken är steget från spatial andraderivata av spårlägesfel till axelboxacceleration dividerat med fordons- hastigheten i kvadrat. Ett variabelt våglängdsområde Dx introduceras som ett alternativ till de vanligt förekommande D1 (3–25 m), D2 (25–70 m) och D3 (70–150 m). Det variabla våglängdsområdet motsvarar de frekvenser som används för utvärdering av fordonsrespons och är därmed hastighetsberoende. Vidare används simuleringar för att undersöka den svaga länken och för möjligheten till parametervariationer. En flerkroppsmodell (MBS-modell) av passagerarvagnen Bim 547.5 används tillsammans med uppmätta data för spår och fordonshastighet. De parametrar som varieras visar sig ha låg käns- lighet och påverkar resultaten i liten utsträckning. Störst inverkan har den slumpmässigt varierande vertikala spårstyvheten, vilken påverkar de vertikala hjul–rälkrafterna och axelboxaccelerationerna. Fortsatt forskning bör undersöka om det är möjligt att – och i så fall hur – separera eekten av varierande spårstyvhet och spårlägesfel. Detta kan ge bättre förståelse för om fordonsrespons kopplar mer till spårlägesfelen eller till spårflexibiliteten. Den svaga länken som identifierats bör också undersö- kas ytterligare, förslagsvis genom att utöka den bakomliggande modellen eller analysera annan mätdata.<br><p>QC 20180517</p>
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Miri, Amin. "Mitigating severity of longitudinal interaction of rail-track-bridge system in transition zones for safer trains." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/236242/1/Amin%2BMiri%2BThesis%282%29.pdf.
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Extreme heat and temperature fluctuation in Queensland result in buckling of railway tracks which jeopardize the safety of train operation and cost huge sums to repair. This thesis carried out an elaborate investigation on the issue of track buckling and provided several approaches to mitigate the risks of track buckling to enable safer trains and lower maintenance costs for railway operators in Australia.
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Ostiguy, Matthew James. "Experiment and Simulation of the Acoustic Signature of Fatigued-Cracked Gears in a Two-Stage Gearbox." DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1328.
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This thesis focuses on the development of a health monitoring system for gearbox transmissions. This was accomplished by developing and understanding a two-stage gearbox computer model that emulates an actual gearbox test rig. The computer model contains actual gearbox geometry, flexible shafts, bearings, gear contact forces, input motor torque, output brake torque, and realistic gearbox imbalance. The gear contact force of each gear stage and the input bearing translational acceleration were the main outputs compared between a healthy gearbox and damaged gearbox computer model. The damage of focus was a fatigue crack on the input pinion gear. A sideband energy ratio comparison yielded the computer simulation accurately modeled the difference between a healthy and damaged gearbox. The next step in this study involved the development of a repeatable procedure to initiate and propagate a fatigue crack at the tooth root in an actual spur gear. A damaged spur gear allows for a future comparison of an actual healthy and damaged gearbox system in the lab. A custom fatigue fixture was designed and manufactured for a Martin S1224BS 1 spur gear. The fatigue crack was initiated by position control fatigue testing which deflects the gear tooth a set amplitude for a number of cycles. Over the length of the test, the load that the tooth can withstand in bending decreases as damage begins to occur. Once the max load on the gear has dropped by a significant percentage (5-15%) a crack has initiated and begun to propagate across the tooth face. The use of a scanning electron microscope confirmed the presence a fatigue crack.
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Makkonen, Petri. "On multi body systems simulation in product design." Doctoral thesis, Stockholm, 1999. http://www.lib.kth.se/abs99/makk0525.pdf.
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Křepela, Jan. "Dynamické vlastnosti osy C pro multifunkční soustružnické centrum." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-233982.
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his Disertation thesis involves the creating of the simulation model of the C axis drive over mentioned machine and them verification on the prototype of this machine. C axis is controlled with position feedback. Simulation model was created before the realisation of the machine prototype for the preliminary identification of the dynamic behaviours in the working cycles and them opportunity of the realisation this conception. C axis is constructed with worm gear and is controlled with help of Master-Slave drive. This torque drive eliminates the production backlash in the worm gear. The multifunction turning center, where is used this C axis, is determinate for heavy duty roughing cutting of the forged peaces, where is problem with dynamic stability of the cutting process. Simulation model includes the problems with multi-body mass system, friction on the worm gear, self locking, damping on the worm gear and the optimization of the parametrs for many regulators. Simulation model was verified on the prototype of the machine. Achieved results bring the new knowledge, which are used for simulation complicated machine nodes and this knowledge is used for research and developing of the similar mechatronics system.
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Fiala, Dusan. "Dynamic simulation of human heat transfer and thermal comfort." Thesis, Online version, 1998. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.340123.
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Chapman, D. A. "Theory for three dimensional dynamic simulation of towed cable-body systems." Thesis, University of Bath, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378147.
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Taghipour, Reza. "Efficient Prediction of Dynamic Response for Flexible and Multi- Body Marine Structures." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2321.
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Astaraky, Davood. "A Simulation Based Approximate Dynamic Programming Approach to Multi-class, Multi-resource Surgical Scheduling." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/23622.
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The thesis focuses on a model that seeks to address patient scheduling step of the surgical scheduling process to determine the number of surgeries to perform in a given day. Specifically, provided a master schedule that provides a cyclic breakdown of total OR availability into specific daily allocations to each surgical specialty, we look to provide a scheduling policy for all surgeries that minimizes a combination of the lead time between patient request and surgery date, overtime in the ORs and congestion in the wards. We cast the problem of generating optimal control strategies into the framework of Markov Decision Process (MDP). The Approximate Dynamic Programming (ADP) approach has been employed to solving the model which would otherwise be intractable due to the size of the state space. We assess performance of resulting policy and quality of the driven policy through simulation and we provide our policy insights and conclusions.
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Pant, Gaurav, I. Felician Campean, Aleksandrs Korsunovs, Daniel Neagu, and Oscar Garcia-Afonso. "Hybrid Dynamic Modelling of Engine Emissions on Multi-Physics Simulation Platform." SAE, 2020. http://hdl.handle.net/10454/18376.
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Yes<br>This paper introduces a hybrid dynamic modelling approach for the prediction of NOx emissions for a Diesel engine, based on a multi-physics simulation platform coupling a 1-D air path model (GT-Suite) with in-cylinder combustion model (CMCL Stochastic Reactor Model Engine Suite). The key motivation for this research was the requirement to establish a real time stochastic simulation capability for emissions predictions early in engine development, which required the replacement of the slow combustion chemistry solver (SRM) with an appropriate surrogate model. The novelty of the approach in this research is the introduction of a hybrid approach to metamodeling that combines dynamic experiments for the gas path model with a zonal optimal space-filling design of experiments (DoEs) for the combustion model. The dynamic experiments run on the virtual Diesel engine model (GT- Suite) was used to fit a dynamic model for the parameters required as input to the SRM. Optimal Latin Hypercubes (OLH) DoE run on the SRM model was used to fit a response surface model for the NOx emissions. This surrogate NOx model was then used to replace the computationally expensive SRM simulation, enabling real time simulations of transient drive cycles to be executed. The performance of the proposed approach was validated on a simulated NEDC drive cycle against experimental data collected for the engine case study, which proved the capability of methodology to capture the transient trends for the NOx emissions. The significance of this work is that it provided an efficient approach to the development of a global model with real time transient modelling capability based on the integration of dynamic and local DoE metamodeling experiments.<br>The full-text of this article will be released for public view at the end of the publisher embargo on 12 Aug 2021.
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Quadrelli, Bruno Marco. "Dynamic analysis of multi-flexible body systems with spatial beams and finite rotations." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/12052.
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Gonzalez, Hernán. "Complex dynamic scene analysis through multi-body motion segmentation : application to intelligent vehicles." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS519.
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Dans le contexte applicatif des Systèmes d'Aide à la Conduite et des Véhicules Autonomes (anglais ADAS), l'analyse de scène est un processus fondamental d'inférence duquel dépendent multiples fonctions d'asservissement et de prise de décision. Le résultat issu de l'analyse de scène permet une description fiable de l'environnement aux alentours du véhicule composée des objets statiques et dynamiques ainsi que des éléments de structure de la scène (e.g. route, espace navigable, marquage routier) et de la localisation du véhicule observateur (e.g. odométrie). Ces informations supportent les décisions et l'engagement d'actions des systèmes automatiques dans la navigation autonome et les manœuvres d'assistance à la conduite. Pour ce faire, les systèmes de perception sont conçus afin de fournir des observations de la scène redondantes et fiables. Dans le cadre de cette thèse nous nous intéressons à la segmentation d'une scène dynamique en utilisant des images issues d'un système de vision monoculaire. Dans un premier temps, une étude bibliographique des approches de l'état de l'art est présentée en contrastant les avantages et les limites des méthodes suivant des indicateurs de performance et de temps de calcul. Cela a permis la sélection d'une méthodologie récente basée vision servant de référence pour la segmentation de mouvement. Parallèlement, une étude approfondie des pré-traitements nécessaires à l'estimation du flot optique a aussi été menée. Cette première étape est clore par une implantation algorithmique pour la l'identification et la formalisation des contributions adressant les limites de l'état de l'art. Dans la deuxième étape de ce travail, nous proposons un algorithme de segmentation de mouvement basée image. Les notions et les méthodes introduites font appel à la technique du Suivi-avant-Detection (anglais Track-before-Detect) en couplage serré aux méthodes de calcul de la structure et du mouvement (anglais Structure from Motion). La méthode dénommée TbD-SfM a pour objectif la réduction de la complexité dans l'analyse de la scène intégrant un modèle de mouvement générique à 6 dégrées de liberté. Et cela en préservant la densité de caractéristiques suivies sur les mouvements observés. Plus tard, nous proposons une variante accélérée de l'algorithme TbD-SfM dénommée ETbD-SfM qui limite efficacement la complexité de la segmentation par rapport au nombre de mouvements observés dans la scène. L'ensemble des contributions a été évalué en utilisant différentes bases de données publiques reconnues dans le domaine des Transports Intelligents. Nous avons étudié les algorithmes TbD-SfM et ETbD-SfM avec le dataset Hopkins dans de conditions idéales : sans erreurs de suivi de caractéristiques et faible vitesse. Le dataset KITTI permit de vérifier la robustesse de l'approche et d'évaluer leur performance dans des scénarios incluant multiples objets en mouvement. Pour conclure, les résultats expérimentaux démontrent que les méthodes TbD-SfM et ETbD-SfM effectuent la segmentation d'une scène dynamique en utilisant un modèle à 6 dégrés de liberté obtenant une faible erreur de ré-projection tout en préservant la densité de caractéristiques essentiel au suivi de mouvement. La géométrie de la scène 3D calculée en estimant le facteur d'échelle est comparée et analysée aux trajectoires 3D des objets référencés dans la scène<br>In the context of Advanced Driver Assistance Systems (ADAS) and Autonomous Vehicles, scene understanding is a fundamental inference process in which several servoing and decision making functions depends on. Such a process is intended to retrieve reliable information about the vehicle's surroundings including static and dynamic objects (e.g. obstacles, pedestrians, vehicles), the scene structure (e.g. road, navigable space, lane markings) and ego-localization (e.g. odometry). All this information is essential to make crucial decisions in autonomous navigation and assistance maneuvers. To this end, single or multiple perception systems are designed to provide redundant and reliable observations of the scene. This thesis is devoted and focused on image-based multi-body motion segmentation of dynamic scenes using monocular vision systems. The conducted research starts by surveying methods of the state-of-the-art and contrasting their advantages and drawbacks in terms of performance indicators and computation time. After identifying a recent vision-based methodology, sparse optical flow required pre-processes are studied. As a concept-proof, an algorithm implementation shows, in practice, limits of the addressed approach leading to envision and formalize our contributions. Detecting and tracking objects in a classic processing chain may lead to low-performance and time-consuming solutions. Instead of segmenting moving objects and tracking them independently, a Track-before-Detect framework for a multi-body motion segmentation (namely TbD-SfM) was proposed. This method relies detection and tracking on a tightly coupled strategy intended to reduce the complexity of an existing Multi-body Structure from Motion approach. Efforts were also devoted for reducing the computational cost without introducing any kinematic model constraints and for preserving features density on observed motions. Further, an accelerated implementation variant of TbD (namely ETbD-SfM) was also proposed in order to limit the complexity increasing with respect to the number of observed motions. The proposed methods were extensively tested with different publicly available datasets such as Hopkins155 and KITTI. Hopkins dataset allows a comparison under feature-tracking ideal conditions since the dataset includes referenced optical flow. KITTI provides image sequences under real conditions in order to evaluate robustness of the method. Results on scenarios including the presence of multiple and simultaneous moving objects observed from a moving camera are analyzed and discussed. In conclusion, the obtained results show that TbD-SfM and ETbD-SfM methods can segment dynamic objects using a 6DoF motion model, achieving a low image segmentation error without increasing of computational cost and preserving the density of the feature points. Additionally, the 3D scene geometry and trajectories are provided by estimating scale on the monocular system and comparing these results to referenced object trajectories
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Conger, Michael Anthony. "Validation of CFD-MBD FSI for high-gidelity simulations of full-scale WAM-V sea-trials with suspended payload." Thesis, University of Iowa, 2015. https://ir.uiowa.edu/etd/1960.
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High-fidelity CFD-MBD FSI (Computational Fluid Dynamics - Multi Body Dynamics Fluid-Structure Interaction) code development and validation by full-scale experiments is presented, for a novel hull form, WAM-V (Wave Adaptive Modular Vessel). FSI validation experiments include cylinder drop with suspended mass and 33 ft WAM-V sea-trials. Calm water and single-wave sea-trails were with the original suspension, while the rough-water testing was with a second generation suspension. CFDShip-Iowa is used as CFD solver, and is coupled to Matlab Simulink MBD models for cylinder drop and second generation WAM-V suspension. For 1DOF cylinder drop, CFD verification and validation (V&V) studies are carried out including grid and time-step convergence. CFD-MBD results for 2DOF cylinder drop show that 2-way coupling is required to capture coupled physics. Overall, 2-way results are validated with an overall average error value of E=5.6%DR for 2DOF cylinder drop. For WAM-V in calm water, CFD-MBD 2-way results for relative pod angle are validated with E=14.2%DR. For single-wave, CFD-MBD results show that 2-way coupling significantly improves the prediction of the peak amplitude in pontoon motions, while the trough amplitudes in suspension motions are under-predicted. The current CFD-MBD 2-way results for single-wave are validated with E=17%DR. For rough-water, simulations are carried out in regular head waves representative of the irregular seas. CFD-MBD 2-way results are validation with E=23%D for statistical values and the Fourier analysis results, which is reasonable given the differences between simulation waves and experiments.
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Ham, Franklin Edward. "Flow simulation using the finite analytic method with multi-block body-fitted grids." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0014/MQ31580.pdf.
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Peng, Tao. "Coupled Multi-body Dynamic and Vibration Analysis of Hypoid and Bevel Geared Rotor System." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1282931782.
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PREMKUMAR, SRIDHAR. "A UNIFIED SIMULATOR FOR MULTI-DOMAIN SIMULATION OF SYSTEMS USING DYNAMIC INTERPRETATION." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1172859432.
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Sagal, Ellen Jean 1954. "An object oriented approach to finite element analysis and multi-body dynamic analysis program designs." Thesis, The University of Arizona, 1993. http://hdl.handle.net/10150/278289.
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Procedurally-oriented computer programs used to perform finite element and multibody dynamics analyses are difficult to understand, use, and modify. A new approach, object-oriented programming, was used to develop a finite element code that is easier to apply, understand, and modify. Object-oriented code is easier to understand, as the characteristics and operations associated with a physical phenomena are grouped in a class whose structure closely parallels the modeled entity. Elements, bodies, joints, and mechanisms are modeled as classes. Program application is facilitated by a hierarchy of class structure. Manipulation of higher level body and mechanism class types direct the complicated, lower level code of element calculations. Lower level code is hidden in an object library resulting in a shorter, simpler driver program for an analysis. Modification and expansion of programs is easily accomplished through object-oriented language features such as modularization of code into classes and overloaded functions. Body and element abstract base classes provide "templates" for creation of new type classes used to develop additional analyses.
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Bediz, Mehmet. "A computer simulation study of a single rigid body dynamic model for biped postural control." Thesis, Monterey, California. Naval Postgraduate School, 1997. http://hdl.handle.net/10945/8136.
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Approved for public release; distribution is unlimited<br>Existing kinematics models for humans cannot simulate movement beyond geometric constraints. On the other hand, complex dynamics models are computationally expensive for real time computer graphics applications in Virtual Environments(VE). To be able to create a more realistic, real time, and computationally efficient human model, a simple dynamic model needs to be developed. The approach taken in this thesis was to develop a single rigid body dynamic human model with massless legs. Instead of a Lagrangian model, which complicates the calculations exponentially as the complexity of the system increases, the Newton-Euler method was chosen to derive system differential equations. Linear state feedback was used for postural control. As part of this research, a previous realistic looking human model is further developed. The major conclusion of this thesis is that a single rigid body dynamic model can be used for simulation of postural control. The simulation results contained in this thesis show that such a modeling technique could be used to cause a detailed kinematic representation of a human figure to move in a smooth and realistic way without resorting to complexity of a multi-link dynamic model
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Au, Lai Piu. "A simulation study of dynamic customer flow control in multi-site service system /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?IEEM%202002%20AU.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.<br>Includes bibliographical references (leaves 106-108). Also available in electronic version. Access restricted to campus users.
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Rao, Dhananjai M. "Study of Dynamic Component Substitutions." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1060366173.
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Kanarat, Amnart. "Modeling and Simulation of a Multi-Unit Tracked Vehicle." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/9755.
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A multi-unit tracked vehicle such as a continuous haulage system is widely used in underground mining applications due to its high mobility and payload capacity on rugged and soft terrain. To automate such a system, a high fidelity model of a tracked vehicle is essential in designing a controller for each tracked vehicle in the system, and a system model is required to simulate its response to input commands.
This thesis presents the 2-D mathematical models of a tracked vehicle and a multi-unit tracked vehicle. All existing track-terrain interaction models are investigated and modified. By employing the modified track-terrain interaction model and applying Newton's second law of motion, the equations of motion of both single and multi-unit tracked vehicles can be derived. Computer programs for simulating the motions of these tracked vehicles on level ground have been implemented on a digital computer based on the derived system of differential equations. The fourth-order Runge-Kutta and Keun's methods are adopted to numerically integrate these differential equations.
The simulation results clearly show that the programs can accurately predict the motion of a tracked vehicle maneuvered on horizontal plane, and closely predict the response of a multi-unit tracked vehicle operated on level ground its command inputs.<br>Master of Science
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Lee, Jung-Hoon. "The modelling and simulation of dynamic supply chain networks : a multi-agent systems approach." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411233.
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Bergs, Christoph [Verfasser], and M. [Akademischer Betreuer] Heizmann. "Multi-Fidelity Modeling of Dynamic Systems for Operation-Parallel Simulation / Christoph Bergs ; Betreuer: M. Heizmann." Karlsruhe : KIT-Bibliothek, 2020. http://d-nb.info/1218599782/34.
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Nailah, Firdausiyah. "MULTI-AGENT SIMULATION USING ADAPTIVE DYNAMIC PROGRAMMING BASED REINFORCEMENT LEARNING FOR EVALUATING JOINT DELIVERY SYSTEMS." Kyoto University, 2018. http://hdl.handle.net/2433/235076.
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Czechowicz, Maciej P. "Analysis of vehicle rollover using a high fidelity multi-body model and statistical methods." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/18106.
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The work presented in this thesis is dedicated to the study of vehicle rollover and the tyre and suspension characteristics influencing it. Recent data shows that 35.4% of recorded fatal crashes in Sports Utility Vehicles (SUVs) included vehicle rollover. The effect of rollover on an SUV tends to be more severe than for other types of passenger vehicle. Additionally, the number of SUVs on the roads is rising. Therefore, a thorough understanding of factors affecting the rollover resistance of SUVs is needed. The majority of previous research work on rollover dynamics has been based on low fidelity models. However, vehicle rollover is a highly non-linear event due to the large angles in vehicle body motion, extreme suspension travel, tyre non-linearities and large forces acting on the wheel, resulting in suspension spring-aids, rebound stops and bushings operating in the non-linear region. This work investigates vehicle rollover using a complex and highly non-linear multi-body validated model with 165 degrees of freedom. The vehicle model is complemented by a Magic Formula tyre model. Design of experiment methodology is used to identify tyre properties affecting vehicle rollover. A novel, statistical approach is used to systematically identify the sensitivity of rollover propensity to suspension kinematic and compliance characteristics. In this process, several rollover metrics are examined together with stability considerations and an appropriate rollover metric is devised. Research so far reveals that the tyre properties having the greatest influence on vehicle rollover are friction coefficient, friction variation with load, camber stiffness, and tyre vertical stiffness. Key kinematic and compliance characteristics affecting rollover propensity are front and rear suspension rate, front roll stiffness, front camber gain, front and rear camber compliance and rear jacking force. The study of suspension and tyre parameters affecting rollover is supplemented by an investigation of a novel anti-rollover control scheme based on a reaction wheel actuator. The simulations performed so far show promising results. Even with a very simple and conservative control scheme the reaction wheel, with actuator torque limited to 100Nm, power limited to 5kW and total energy consumption of less than 3kJ, increases the critical manoeuvre velocity by over 9%. The main advantage of the proposed control scheme, as opposed to other known anti-rollover control schemes, is that it prevents rollover whilst allowing the driver to maintain the desired vehicle path.
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Venkateswaran, Jayendran. "PRODUCTION AND DISTRIBUTION PLANNING FOR DYNAMIC SUPPLY CHAINS USING MULTI-RESOLUTION HYBRID MODELS." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1185%5F1%5Fm.pdf&type=application/pdf.
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Yuan, Peng. "MODELING, SIMULATION AND ANALYSIS OF MULTI-BARGE FLOTILLAS IMPACTING BRIDGE PIERS." UKnowledge, 2005. http://uknowledge.uky.edu/gradschool_diss/310.
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The current design code governing bridge structure resistance to vessel impact loads in the U.S. is the American Association of State Highway and Transportation Officials' (AASHTO) Guide Specification and Commentary for Vessel Collision Design of Highway Bridges. The code stipulated method, based on Meir-Dornberg's equivalent static load method, is usually not warranted because of insufficient data on the impact load histories and wide scatter of the impact force values. The AASHTO load equations ignore certain fundamental factors that affect the determination of impact forces and bridge dynamic responses. Some examples of factors that are omitted during standard impact force analysis are: impact duration, pier geometry, barge-barge and barge-pier interactions, and structural characteristics of bridges.
The purpose of this research is to develop new methods and models for predicting barge impact forces on piers. In order to generate research information and produce more realistic flotilla impact data, extensive finite element simulations are conducted. A set of regression formulas to calculate the impact force and time duration are derived from the simulation results. Also, a parametric study is performed systematically to reveal the dynamic features of barge-bridge collisions. A method to determine the quasi upper bound of the average impact force under any given scenarios is preposed. Based on the upper bounds of the average impact forces, an impact spectrum procedure to determine the dynamic response of piers is developed. These analytical techniques transform the complex dynamics of barge-pier impact into simple problems that can be solved through hand calculations or design charts. Furthermore, the dependency of the impact forces on barge-barge and barge-pier interactions are discussed in detail. An elastoplastic model for the analysis of multi-barge flotillas impacting on bridge piers is presented. The barge flotilla impact model generates impact force time-histories for various simulation cases in a matter of minutes. The results from the proposed model are compatible with the respective impact time-histories produced by an exhuaustive finite element simulation.
All of the proposed methods and loading functions in this study are illustrated through design examples. Accordingly, the research results may help engineers to enhance bridge resistance to barge impacts and also lead to economic savings in bridge protection design.
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Lantoine, Gregory. "A methodology for robust optimization of low-thrust trajectories in multi-body environments." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37081.
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Future ambitious solar system exploration missions are likely to require ever larger propulsion capabilities and involve innovative interplanetary trajectories in order to accommodate the increasingly complex mission scenarios. Two recent advances in trajectory design can be exploited to meet those new requirements: the use of low-thrust propulsion which enables larger cumulative momentum exchange relative to chemical propulsion; and the consideration of low-energy transfers relying on full multi-body dynamics. Yet the resulting optimal control problems are hypersensitive, time-consuming and extremely difficult to tackle with current optimization tools.
Therefore, the goal of the thesis is to develop a methodology that facilitates and simplifies the solution finding process of low-thrust optimization problems in multi-body environments. Emphasis is placed on robust techniques to produce good solutions for a wide range of cases despite the strong nonlinearities of the problems. The complete trajectory is broken down into different component phases, which facilitates the modeling of the effects of multiple bodies and makes the process less sensitive to the initial guess.
A unified optimization framework is created to solve the resulting multi-phase optimal control problems. Interfaces to state-of-the-art solvers SNOPT and IPOPT are included. In addition, a new, robust Hybrid Differential Dynamic Programming (HDDP) algorithm is developed. HDDP is based on differential dynamic programming, a proven robust second-order technique that relies on Bellman's Principle of Optimality and successive minimization of quadratic approximations. HDDP also incorporates nonlinear mathematical programming techniques to increase efficiency, and decouples the optimization from the dynamics using first- and second-order state transition matrices.
Crucial to this optimization procedure is the generation of the sensitivities with respect to the variables of the system. In the context of trajectory optimization, these derivatives are often tedious and cumbersome to estimate analytically, especially when complex multi-body dynamics are considered. To produce a solution with minimal effort, an new approach is derived that computes automatically first- and high-order derivatives via multicomplex numbers.
Another important aspect of the methodology is the representation of low-thrust trajectories by different dynamical models with varying degrees of fidelity. Emphasis is given on analytical expressions to speed up the optimization process. In particular, one novelty of the framework is the derivation and implementation of analytic expressions for motion subjected to Newtonian gravitation plus an additional constant inertial force.
Example applications include low-thrust asteroid tour design, multiple flyby trajectories, and planetary inter-moon transfers. In the latter case, we generate good initial guesses using dynamical systems theory to exploit the chaotic nature of these multi-body systems. The developed optimization framework is then used to generate low-energy, inter-moon trajectories with multiple resonant gravity assists.
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Almesallmy, Mohammed. "Experimental and analytical investigation of inertial propulsion mechanisms and motion simulation of rigid-multi-body mechanical systems /." View online ; access limited to URI, 2006. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/3239899.
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Saxena, Sanchit. "Exploration of Cancellation Strategies for Parallel Simulation on Multi-Core Beowulf Clusters." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1352403477.
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Huynh, Quang-Nghi. "CoModels, engineering dynamic compositions of coupled models to support the simulation of complex systems." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066565/document.
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L'objectif initial de cette thèse est d'apporter une solution à ce problème en proposant, premièrement, une approche cognitive basée sur le paradigme appelé Belief-Desire-Intention (BDI) pour représenter les processus de prise de décision des acteurs humains, et deuxièmement, une validation de cette approche dans le contexte d'un modèle complet de changement d'usage des sols dans lequel la plupart des facteurs cités ci-dessus sont également simulés. Le résultat de ce travail est une approche générique qui a été validée sur un modèle intégrant le changement d'usage des sols d'une région située dans le Delta du Mékong au Vietnam. Nos contributions principales sont les suivantes : Intégration d'une architecture BDI au sein d'une plateforme de modélisation à base d'agents (GAMA) ; Conception d'un cadre générique baptisé " Multi-Agent Based Land-Use Change " (MAB-LUC) permettant de modéliser et de simuler les changements d'usage des sols en prenant en compte les décisions des agriculteurs ; Proposition d'une solution permettant d'intégrer et d'évaluer les facteurs socio-économiques et environnementaux dans le cadre de la planification agraire et d'intégrer MAB-LUC dans le processus existant proposé par la FAO. Ce travail, au-delà du cas d'étude concernant le Delta du Mékong, a enfin été conçu de façon générique afin que la méthodologie utilisée puisse être généralisée à la modélisation de systèmes socio-écologiques où les facteurs humains doivent être représentés avec précision<br>Integrated modeling approaches (multi-simulation, multimodeling, etc.) have proven challenging in practice. The first challenge deals with the technical aspects of coupling different computational or mathematical components. The second challenge lies in the alignment of the semantics of these components so that their integration does make sense, which is particularly critical in pluridisciplinary models. A number of approaches have been proposed in the last 20 years but none of them is really suitable to our context . We propose in this thesis an alternate approach, called co-modeling, which borrows concepts and tools from agent-based modeling, agent-oriented software engineering and multimodel ecologies. Simply speaking, a co-model can be defined as a multi-agent system of models and datasets. Each model or dataset is represented by one or several agents interacting with one another within the context of a larger representation of their — potentially dynamic — environment. The proposed approach does not aim at providing a general solution to the two challenges above, but at providing a framework in which modelers can easily implement their solution or test different coupling solutions. The proposed approach is fully implemented within the GAMA agent-based modeling platform. Its advantages are shown in terms of flexibility, composability and reusability in a number of case studies. The first case study is the dynamic coupling of equation-based and agent-based models to obtain “switching” models dynamically. The second one is the design of a complex integrated model where three formalisms and four modeling approaches have been successfully coupled
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Trapp, Peter. "Performance improvements using dynamic performance stubs." Thesis, De Montfort University, 2011. http://hdl.handle.net/2086/5335.
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This thesis proposes a new methodology to extend the software performance engineering process. Common performance measurement and tuning principles mainly target to improve the software function itself. Hereby, the application source code is studied and improved independently of the overall system performance behavior. Moreover, the optimization of the software function has to be done without an estimation of the expected optimization gain. This often leads to an under- or overoptimization, and hence, does not utilize the system sufficiently. The proposed performance improvement methodology and framework, called dynamic performance stubs, improves the before mentioned insufficiencies by evaluating the overall system performance improvement. This is achieved by simulating the performance behavior of the original software functionality depending on an adjustable optimization level prior to the real optimization. So, it enables the software performance analyst to determine the systems’ overall performance behavior considering possible outcomes of different improvement approaches. Moreover, by using the dynamic performance stubs methodology, a cost-benefit analysis of different optimizations regarding the performance behavior can be done. The approach of the dynamic performance stubs is to replace the software bottleneck by a stub. This stub combines the simulation of the software functionality with the possibility to adjust the performance behavior depending on one or more different performance aspects of the replaced software function. A general methodology for using dynamic performance stubs as well as several methodologies for simulating different performance aspects is discussed. Finally, several case studies to show the application and usability of the dynamic performance stubs approach are presented.
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Azarnasab, Ehsan. "Robot-in-the-loop simulation to support multi-robot system development a dynamic team formation example /." unrestricted, 2006. http://etd.gsu.edu/theses/available/etd-04012007-142947/.
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Thesis (M.S.)--Georgia State University, 2007.<br>Title from file title page. Xiaolin Hu, committee chair; Michael Weeks, Yanqing Zhang, committee members. Electronic text (108 p. : ill. (some col.)) : digital, PDF file. Description based on contents viewed May 20, 2008. Includes bibliographical references (p. 103-108).
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Azarnasab, Ehsan. "Robot-In-The-Loop Simulation to Support Multi-Robot System Development: A Dynamic Team Formation Example." Digital Archive @ GSU, 2007. http://digitalarchive.gsu.edu/cs_theses/39.
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Modeling and simulation provides a powerful technology for engineers and managers to understand, design, and evaluate a system under development. Traditionally, simulation is only used in early stages of a system design. However, with the advances of hardware and software technology, it is now possible to extend simulation to late stages for supporting a full life cycle simulation-based development. Robot-in-the-loop simulation, where real robots work together with virtual ones, has been developed to support such a development process to bridge the gap between simulation and reality.
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Neugebauer, R., P. Klimant, and M. Witt. "Realistic Machine Simulation with Virtual Reality." Universitätsbibliothek Chemnitz, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-151993.
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Today highly complex components are manufactured on NC-controlled machine tools. The NC programs, controlling these machines, are usually automatically generated by CAM software. This automatic processing is often erroneous. The VR-based realistic machine simulation, presented in this paper, extends the usual content of a machine simulation, like material removal and collision detection, by various new aspects. The coupling of a real NC unit allows the recognition and elimination of all process- as well as controller-caused errors. The integration of the multi-body simulation enables the consideration of inertia, machine rigidity and milling cutter deflection.