Dissertations / Theses on the topic 'Wheel dynamics'
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Müller, Steffen. "Linearized wheel-rail dynamics : stability and corrugation /." Düsseldorf : VDI-Verl, 1998. http://www.gbv.de/dms/bs/toc/265578795.pdf.
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Silva, Seth F. "Applied System Identification for a Four Wheel Reaction Wheel Platform." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/328.
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Applied System Identification for a Four Wheel Reaction Wheel Platform
By
Seth Franklyn Silva
At the California Polytechnic State University, San Luis Obispo there is a four-wheel reaction wheel pyramidal simulator platform supported by an air-bearing. This simulator has the current capability to measure the wheel speeds and angular velocity of the platform, and with these measurements, the system identification process was used to obtain the mass properties of this simulator. A handling algorithm was developed to allow wireless data acquisition and command to the spacecraft simulator from a “ground” computer allowing the simulator to be free of induced torques due to wiring. The system identification algorithm using a least squares estimation scheme was tested on this simulator and compared to theoretical analysis. The resultant principle inertia about the z-axis from the experimental analysis was 3.5 percent off the theoretical, while the other inertias had an error of up to 187 percent. The error is explained as noise attributed to noise in the measurement, averaging inconsistencies, low bandwidth, and derivation of accelerations from measured data.
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Shahzamanian, Sichani Matin. "Wheel-rail contact modelling in vehicle dynamics simulation." Licentiate thesis, KTH, Spårfordon, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-127949.
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The wheel-rail contact is at the core of all research related to vehicle-track interaction. This tiny interface governs the dynamic performance of rail vehicles through the loads it transmits and, like any high stress concentration zone, it is subjected to serious damage phenomena. Thus, a clear understanding of the rolling contact between wheel and rail is key to realistic vehicle dynamic simulation and damage analyses. In a multi-body-system simulation package, the essentially demanding contact problem should be evaluated in about every millisecond. Hence, a rigorous treatment of the contact is highly time consuming. Simplifying assumptions are, therefore, made to accelerate the simulation process. This gives rise to a trade-off between accuracy and computational efficiency of the contact models in use. Historically, Hertz contact solution is used since it is of closed-form. However, some of its underlying assumptions may be violated quite often in wheel-rail contact. The assumption of constant relative curvature which leads to an elliptic contact patch is of this kind. Fast non-elliptic contact models are proposed by others to lift this assumption while avoiding the tedious numerical procedures. These models are accompanied by a simplified approach to treat tangential tractions arising from creepages and spin. In this thesis, in addition to a literature survey presented, three of these fast non-elliptic contact models are evaluated and compared to each other in terms of contact patch, pressure and traction distributions as well as the creep forces. Based on the conclusions drawn from this evaluation, a new method is proposed which results in more accurate contact patch and pressure distribution estimation while maintaining the same computational efficiency. The experience gained through this Licentiate work illuminates future research directions among which, improving tangential contact results and treating conformal contacts are given higher priority.QC 20130911
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Logan, Jeffery Jay. "Control and Sensor Development on a Four-Wheel Pyramidal Reaction Wheel Platform." DigitalCommons@CalPoly, 2008. https://digitalcommons.calpoly.edu/theses/27.
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The Pyramidal Reaction Wheel Platform, or PRWP, is used to simulate three-axis controls in a torque free space-like environment. The primary purpose of the system will be to evaluate the effects of conjoining sensors to maximize pointing accuracy. Furthermore, the system will incorporate a star tracker in conjunction with a Simulated Star Field (SSF) to better estimate the PRWP orientation. For the sake of this document, however, the goal is to implement a gyroscope, wheel rate sensors, and a make-shift accelerometer—to the PRWP—and integrate a controls algorithm such that three-axis controls are achieved for the PRWP. Three sensors were either better integrated into the system or added altogether. Tachometers were created as a form of hardware circuitry to measure each wheel rate with an accuracy of approximately 2.5 Hz (nearly 15 radians per second). The TAC board circuitry converted each motors encoder output into a speed by use of a frequency to voltage converter. Additionally, although three gyroscopes had been implemented previously, the system was better incorporated into the model such that it was directly transformed via a ROBOSTIX ADC converter before being relayed to SIMULINK via a Bluetooth link. The MEMS gyroscopes allowed for very accurate rate measurements—with a minimum resolution of approximately 0.25 radians per second. Finally, a makeshift accelerometer was incorporated into the system for the purpose of system identification. The accelerometer was incorporated into the system by utilizing a discrete time derivative of the gyroscope readings. However, thankfully a system of two accelerometers can be later utilized to achieve an accuracy of approximately 6 degrees per second-second in the x-axis and 2-3 degrees per second-second in the y- and z-axes. A controls test was performed where the starting location was qo=[0, 0, sqrt(2)/2, sqrt(2)/2] and the target location was qc=[0, 0, 0, 1]. At 80 seconds, the pointing accuracy was 70 degrees around the target and the system was unable to settle during the 80 second trial. The inaccuracy was because of the low frequency of operation of the system—1 Hz. Additionally, the platform reacts slowly to sensor readings and commands. The coupling of these issues causes the pointing accuracy to high. Furthermore, through experimental testing, the maximum wheel rate was found to be approximately 6400 RPM at a duty cycle of 50% at an 8000Hz PWM application due to the Pololu MD01B design limitations: low voltage range (up to 16V), low limit current limiter (5A), and high susceptibility to overheating for large currents.
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Hossein, Nia Saeed. "On Heavy-Haul Wheel Damages using Vehicle Dynamics Simulation." Doctoral thesis, KTH, Spårfordon, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-220344.
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Maintenance cost is one of the important issues in railway heavy-haul operations. In most of the cases, these costs are majorly referring to reprofiling and changing the wheels of the locomotives and the wagons. The main reason of the wheel damages is usually severe wear and/or surface initiated rolling contact fatigue (RCF).This work tries to enhance and improve the knowledge of the wheel wear and RCF prediction models using dynamic simulations. While most of the contents of this study can be generalised to other operational networks, this study is focused on the locomotives and wagons of the Swedish iron-ore company LKAB. The trains are operating on the approximately 500 km long IORE line from Luleå to Narvik in the north of Sweden and Norway respectively.Firstly, a literature survey of dynamic modelling of the wagons with various three-piece bogie types is presented. Then, with concentrating on the standard three-piece bogies, parameter studies are carried out to find out what the most important reasons of wheel damages are. Moreover, the long-term stability of wheel profiles of the IORE wagons is analysed. This is done by visualising the wear and RCF evolution on the wheel profiles over 150,000km of simulated running distance.Most of the calculations for the wagons are repeated for the locomotives. However, traction and braking are also considered in the simulation model and their effects on wheel damages are briefly studied. To improve the accuracy of the wheel damage analysis, a newly developed algorithm called FaStrip is used to solve the tangential contact problem instead of FASTSIM. The damage prediction model developed in the thesis is used to study the effects of increasing axle load, correcting the track gauge, limiting the electro-dynamic braking and using a harder wheel material on the wheel life. Furthermore, a new method is developed to predict the running distance between two consecutive reprofilings due to severe surface initiated fatigue. The method is based on shakedown analysis and laboratory tests.Most of the research works in wear calculation are limited to two approaches known as wear number and Archard methods. The correlation between these two methods is studied. The possibility of using the relation between the two methods for the wear calculation process is investigated mainly to reduce the calculation time for wheel profile optimisation models.QC 20171219
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Varnhagen, Scott Julian. "Development of Vehicle Dynamics Control for Wheel-Motored Vehicles." Thesis, University of California, Davis, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3685305.
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This dissertation describes a methodology for the vehicle dynamics control of a wheel motored vehicle. All theory is developed assuming that the driver has control of the front wheel steering angle, and that wheel torque is solely generated by independent wheel motors at each corner of the vehicle. Theoretical work is presented for the general case with four independent wheel motors, but can be easily reduced to a situation with only two wheel motors. Indeed, all theory developed in this work is evaluated experimentally on a production automobile converted to be driven by two independent rear wheel motors.
As opposed to directly allocating wheel torques, the proposed philosophy operates in the slip-ratio domain. Doing so helps to prevent excessive tire saturation and allows the system to adapt to changing road surfaces. To that end, this dissertation first proposes a method of estimating slip-ratio utilizing only sensors currently available on modern automobiles. A slip-ratio controller is then developed approximating the disturbance observer structure. This allows the controller to be robust to changing road surface and as a byproduct provide an accurate estimate of longitudinal tire force. Combining the estimated longitudinal tire force with the estimated slip-ratio it is then possible to ascertain some degree of tire saturation. With this in mind, an optimal control allocation problem is proposed which attempts to achieve the desired vehicle dynamics while at the same time minimizing tire saturation.
It is shown experimentally that the proposed control methodology effectively achieves desired vehicle dynamics. In addition, the system adapts its behavior to changing road surfaces resulting in optimal performance regardless of operating conditions.
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Hosseini, SayedMohammad. "A Statistical Approach to Modeling Wheel-Rail Contact Dynamics." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/101864.
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The wheel-rail contact mechanics and dynamics that are of great importance to the railroad industry are evaluated by applying statistical methods to the large volume of data that is collected on the VT-FRA state-of-the-art roller rig. The intent is to use the statistical principles to highlight the relative importance of various factors that exist in practice to longitudinal and lateral tractions and to develop parametric models that can be used for predicting traction in conditions beyond those tested on the rig. The experiment-based models are intended to be an alternative to the classical traction-creepage models that have been available for decades. Various experiments are conducted in different settings on the VT-FRA Roller Rig at the Center for Vehicle Systems and Safety at Virginia Tech to study the relationship between the traction forces and the wheel-rail contact variables. The experimental data is used to entertain parametric and non-parametric statistical models that efficiently capture this relationship. The study starts with single regression models and investigates the main effects of wheel load, creepage, and the angle of attack on the longitudinal and lateral traction forces. The assumptions of the classical linear regression model are carefully assessed and, in the case of non-linearities, different transformations are applied to the explanatory variables to find the closest functional form that captures the relationship between the response and the explanatory variables. The analysis is then extended to multiple models in which interaction among the explanatory variables is evaluated using model selection approaches. The developed models are then compared with their non-parametric counterparts, such as support vector regression, in terms of "goodness of fit," out-of-sample performance, and the distribution of predictions.Master of Science
The interaction between the wheel and rail plays an important role in the dynamic behavior of railway vehicles. The wheel-rail contact has been extensively studied through analytical models, and measuring the contact forces is among the most important outcomes of such models. However, these models typically fall short when it comes to addressing the practical problems at hand. With the development of a high-precision test rig—called the VT-FRA Roller Rig, at the Center for Vehicle Systems and Safety (CVeSS)—there is an increased opportunity to tackle the same problems from an entirely different perspective, i.e. through statistical modeling of experimental data. Various experiments are conducted in different settings that represent railroad operating conditions on the VT-FRA Roller Rig, in order to study the relationship between wheel-rail traction and the variables affecting such forces. The experimental data is used to develop parametric and non-parametric statistical models that efficiently capture this relationship. The study starts with single regression models and investigates the main effects of wheel load, creepage, and the angle of attack on the longitudinal and lateral traction forces. The analysis is then extended to multiple models, and the existence of interactions among the explanatory variables is examined using model selection approaches. The developed models are then compared with their non-parametric counterparts, such as support vector regression, in terms of "goodness of fit," out-of-sample performance, and the distribution of the predictions. The study develops regression models that are able to accurately explain the relationship between traction forces, wheel load, creepage, and the angle of attack.
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Villella, Matthew G. "Nonlinear Modeling and Control of Automobiles with Dynamic Wheel-Road Friction and Wheel Torque Inputs." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5198.
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This thesis presents a new nonlinear automobile dynamical model and investigates the possibility of automobile dynamic control with wheel torque utilizing this model. The model has been developed from first principles by applying classical mechanics. Inputs to the model are the four independent wheel torques, while the steer angles at each wheel are specified as independent time-varying signals. In this way, consideration of a variety of steering system architectures, including rear-wheel steer, is possible, and steering introduces time-varying structure into the vehicle model.
The frictional contact at the wheel-road interface is modeled by use of the LuGre dynamic friction model. Extensions to the existing two-dimensional LuGre friction model are derived and the steady-state of the friction model is compared to existing static friction models. Simulation results are presented to validate the model mathematics and to explore automobile behavior in a variety of scenarios.
Vehicle control with wheel torque is explored using the theory of input-output linearization for multi-input multi-output systems. System relative degree is analyzed and use of steady-state LuGre friction in a control design model is shown to give rise to relative degree singularities when no wheel slip occurs. Dynamic LuGre friction does not cause such singularities, but instead has an ill-defined nature under the same no-slip condition. A method for treating this ill-defined condition is developed, leading to the potential for the system to have relative degree.
Longitudinal velocity control and combined longitudinal and angular vehicle velocity control are demonstrated in simulation using input-output linearization, and are shown to produce improved vehicle response as compared to the open-loop behavior of the automobile. Robustness of the longitudinal velocity control to friction model parameter variation is explored and little impact to the controller's ability to track the desired trajectory is observed.
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Shakleton, Philip Andrew. "An optimised wheel-rail contact model for vehicle dynamics simulation." Thesis, Manchester Metropolitan University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.515184.
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The wheel-rail interface is a complex component of the dynamic railway vehicle-track system. The wheel-rail interface governs the motion of a railway vehicle and is responsible for wheel and track damage such as wear and rolling contact fatigue. Wheelrail contact models are used extensively in railway engineering to calculate contact forces and stresses, in order to evaluate dynamic vehicle behaviour or assess track damage. Due to the complexity of the wheel-rail interaction, and computational limitations, all wheel-rail contact models make simplifying assumptions so that solutions may be obtained in an acceptable time. This thesis presents a survey of current wheel-rail contact models and theories, and associated literature, focussing on the various simplifications made by the different approaches. In order to allow an informative comparison of contact model performance a wheel-rail contact benchmark has been established, detailing carefully defined, challenging contact conditions. Interested parties were invited to submit solutions for the contact benchmark cases, and results from ten contributors were received and compared. From the analysis of current contact models and the contact benchmark results, a new wheel-rail contact model has been developed. The model is based on a novel relationship between the normal contact force and the intersecting volume found from virtually penetrating two, three dimensional contacting bodies. Results from the new contact model, named the 'Rectified Interpenetration method', were compared favourably to the recognised methods of Hertz and Kalker. To aid future validation of wheel-rail contact model and understanding of the wheel. rail interaction, a feasibility study of a new wheel-rail contact measurement technique has been undertaken. The technique is based on an established ultrasound method capable of measuring the normal contact pressure distribution for machined wheel and rail samples in laboratory conditions. The new technique aims to advance the state of the art to allow wheel-rail contact measurements under rolling conditions. The study concluded that there is scope for further development of the technique, and discusses the transitional difficulties in advancing the static method to rolling contacts.
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ZHU, JING. "Host-rotaxanes as binding agents: the effects of wheel dynamics." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1214400642.
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Zhu, Jing. "Host-rotaxanes as binding agents the effects of wheel dynamics/." Cincinnati, Ohio : University of Cincinnati, 2008. http://rave.ohiolink.edu/etdc/view.cgi?acc_num=ucin1214400642.
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Thesis (Ph. D. )--University of Cincinnati, 2008.Advisors: David B. Smithrud PhD (Committee Chair), Allan R. Pinhas PhD (Committee Member), Apryll Stalcup PhD (Committee Member) Title from electronic thesis title page (viewed Oct. 4, 2008). Includes abstract. Keywords: rotaxane Includes bibliographical references.
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Zhan, Yun, and 詹云. "Finite element analysis of vibration excited by rail-wheel interaction." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/208053.
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Shahzamanian, Sichani Matin. "On Efficient Modelling of Wheel-Rail Contact in Vehicle Dynamics Simulation." Doctoral thesis, KTH, Spårfordon, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-181691.
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The wheel-rail contact is at the core of all research related to vehicletrackinteraction. This tiny interface governs the dynamic performanceof rail vehicles through the forces it transmits and, like any high stressconcentration zone, it is subjected to serious damage phenomena. Thus,a clear understanding of the rolling contact between wheel and rail is keyto realistic vehicle dynamics simulation and damage analysis. In a multi-body dynamics simulation, the demanding contact problemshould be evaluated at about every millisecond for several wheel-rail pairs.Hence, a rigorous treatment of the contact is highly time-consuming.Simplifying assumptions are therefore made to accelerate the simulationprocess. This gives rise to a trade-o between the accuracy and computationaleciency of the contact model in use. Conventionally, Hertz+FASTSIM is used for calculation of the contactforces thanks to its low computational cost. However, the elliptic patchand pressure distribution obtained by Hertz' theory is often not realisticin wheel-rail contact. Moreover, the use of parabolic traction bound inFASTSIM causes considerable error in the tangential stress estimation.This combination leads to inaccurate damage predictions. Fast non-elliptic contact models are proposed by others to tacklethis issue while avoiding the tedious numerical procedures. The studiesconducted in the present work show that the accuracy of these models iscase-dependent. To improve the accuracy of non-elliptic patch and pressure estimation,a new method is proposed. The method is implemented in an algorithmnamed ANALYN. Comparisons show improvements in patch and, particularly,pressure estimations using ANALYN. In addition, an alternative to the widely-used FASTSIM is developed, named FaStrip. Unlike FASTSIM, it employs an elliptic traction boundand is able to estimate the non-linear characteristic of tangential stressdistribution. Comparisons show more accurate estimation of tangentialstress and slip velocity distribution as well as creep forces with FaStrip. Ultimately, an ecient non-elliptic wheel-rail contact model consistingof ANALYN and FaStrip is proposed. The reasonable computationalcost of the model enables it to be used on-line in dynamics simulationand its accuracy can improve the damage predictions.QC 20160202
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Abbott, Michael Shawn. "Kinematics, Dynamics and Control of Single-Axle, Two-Wheel Vehicles (Biplanar Bicycles)." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/31702.
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A two-wheeled, single-axle, differentially driven vehicle possesses many salient advantages when compared to traditional vehicle designs. In particular, high traction factor, zero turn radius, and inherent static and dynamic stability are characteristics of this configuration. Drive torque is provided via a swinging reaction mass hanging below the axle. While mechanically simple, the resulting nonlinear vehicle dynamics can be quite complex. Additional design challenges arise if non-pendulating platforms or hardware mounts are required. Ultimately, this vehicle class has great potential in autonomous robotic applications such as mine clearance, planetary exploration, and autonomous remote inspection. This thesis discusses the kinematic and dynamic analyses of this vehicle class and develops design tools including performance envelopes and control strategies. Further, it confronts the stable platform problem and provides one solution while suggesting alternative design concepts for other applications.Master of Science
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Hossein, Nia Saeed. "An Investigation of the Iron-Ore Wheel Damages using Vehicle Dynamics Simulation." Licentiate thesis, KTH, Spårfordon, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-159733.
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Maintenance cost is one of the important issues in railway heavy haul operations. For the iron-ore company LKAB, these costs are mainly associated with the reprofiling and changing of the wheels of the locomotives and wagons. The main reason for the wheel damages is usually surface initiated rolling contact fatigue (RCF) on the wheels.The present work tries to enhance and improve the knowledge of the vehicle-track interaction of the Swedish iron-ore freight wagons and locomotives used at Malmbanan. The study is divided into two parts. Firstly, it is tried to get into the roots of RCF using the simulation model of the iron ore wagon (Paper A). Secondly, the study is focused on predicting wear and RCF on the locomotive wheels also via a dynamic simulation model (Paper B).In the first paper, some key issues of the dynamic modelling of the wagons with three piece bogies are first discussed and then parameter studies are carried out to find the most important reasons of wheel damages. These parameter studies include track design geometry, track irregularities, wheel-rail friction level, cant deficiency and track stiffness. The results show a significant effect of the friction level on the amount of RCF risk.As the locomotive wheel life is much shorter than that of the wagons, LKAB has decided to change the locomotive wheel profile. Two final wheel profiles are proposed; however, one had to be approved for the field tests. In the second paper, the long term evolution of the two profiles is compared via wear simulation analysis. Also, the RCF evolution on the wheel profiles as a function of running distance is discussed. The process is first carried out for the current locomotive wheel profiles and the results are compared with the measurements. Good agreement is achieved. Finally, one of the proposed profiles is suggested for the field test because of the mild wear and RCF propagation.QC 20150210
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Jonasson, Mats. "Exploiting individual wheel actuators to enhance vehicle dynamics and safety in electric vehicles." Doctoral thesis, KTH, Fordonsdynamik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11005.
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This thesis is focused on individual wheel actuators in road vehicles intended for vehicle motion control. Particular attention is paid to electro-mechanical actuators and how they can contribute to improving vehicle dynamics and safety. The employment of individual wheel actuators at the vehicle's four corner results in a large degree of over-actuation. Over-actuation has a potential of exploiting the vehicle's force constraints at a high level and of controlling the vehicle more freely. One important reason for using over-actuated vehicles is their capability to assist the driver to experience the vehicle as desired. This thesis demonstrates that critical situations close to the limits can be handled more efficiently by over-actuation. To maximise the vehicle performance, all the available actuators are systematically exploited within their force constraints. Therefore, force constraints for the individually controlled wheel are formulated, along with important restrictions that follow as soon as a reduction in the degrees of freedom of the wheel occurs. Particular focus is directed at non-convex force constraints arising from combined tyre slip characteristics. To evaluate the differently actuated vehicles, constrained control allocation is employed to control the vehicle. The allocation problem is formulated as an optimisation problem, which is solved by non-linear programming. To emulate realistic safety critical scenarios, highly over-actuated vehicles are controlled and evaluated by the use of a driver model and a validated complex strongly non-linear vehicle model. it is shown that, owing to the actuator redundancy, over-actuated vehicles possess an inherent capacity to handle actuator faults, with less need for extra hardware or case-specific fault-handling strategies.QC 20100722
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Chu, Tzyy-Wen. "Eigenstructure analysis of automobile steering dynamics with application to robust four wheel steering control." Thesis, University of Warwick, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246817.
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Sharaf, Al-Hossein Mostafa. "Investigation of all-wheel-drive off-road vehicle dynamics augmented by visco-lock devices." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/34904.
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A peculiarity of AWD off-road vehicles is that their behaviour depends not only on the total power, provided by the engine, but also on its distribution among the drive axles/wheels. In turn, this distribution is largely regulated by the drivetrain layout and its torque distribution devices. At the output of the drivetrain system, the torque is constrained by the interaction between the wheels and the soft soil. For off-road automotive applications, the design of drivetrain systems has usually been largely dominated by the mobility requirements. With the growing demand to have a multipurpose on/off road vehicle with improved manoeuvrability over deformable soil, particularly at higher speed, the challenges confronting vehicle designers have become more complex. The thesis presents a novel integrated numerical approach to assess the dynamic behaviour of all-wheel-drive vehicles whilst operating over deformable soil terrain.
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GRAU, CESAR A. "A PARAMETRIC STUDY OF THE LATERAL DYNAMICS OF A NONLINEAR FOUR-WHEEL ROAD-VEHICLE MODEL." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1054134618.
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Lee, Hyunwook. "A Polynomial Chaos Approach for Stochastic Modeling of Dynamic Wheel-Rail Friction." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77195.
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Accurate estimation of the coefficient of friction (CoF) is essential to accurately modeling railroad dynamics, reducing maintenance costs, and increasing safety factors in rail operations. The assumption of a constant CoF is popularly used in simulation studies for ease of implementation, however many evidences demonstrated that CoF depends on various dynamic parameters and instantaneous conditions. In the real world, accurately estimating the CoF is difficult due to effects of various uncertain parameters, such as wheel and rail materials, rail roughness, contact patch, and so on. In this study, the newly developed 3-D nonlinear CoF model for the dry rail condition is introduced and the CoF variation is tested using this model with dynamic parameters estimated from the wheel-rail simulation model. In order to account for uncertain parameters, a stochastic analysis using the polynomial chaos (poly-chaos) theory is performed using the CoF and wheel-rail dynamics models.
The wheel-rail system at a right traction wheel is modeled as a mass-spring-damper system to simulate the basic wheel-rail dynamics and the CoF variation. The wheel-rail model accounts for wheel-rail contact, creepage effect, and creep force, among others. Simulations are performed at train speed of 20 m/s for 4 sec using rail roughness as a unique excitation source. The dynamic simulation has been performed for the deterministic model and for the stochastic model. The dynamics results of the deterministic model provide the starting point for the uncertainty analysis. Six uncertain parameters have been studied with an assumption of 50% uncertainty, intentionally imposed for testing extreme conditions. These parameters are: the maximum amplitude of rail roughness (MARR), the wheel lateral displacement, the track stiffness and damping coefficient, the sleeper distance, and semi-elliptical contact lengths. A symmetric beta distribution is assumed for these six uncertain parameters. The PDF of the CoF has been obtained for each uncertain parameter study, for combinations of two different uncertain parameters, and also for combinations of three different uncertain parameters.
The results from the deterministic model show acceptable vibration results for the body, the wheel, and the rail. The introduced CoF model demonstrates the nonlinear variation of the total CoF, the stick component, and the slip component. In addition, it captures the maximum CoF value (initial peak) successfully. The stochastic analysis results show that the total CoF PDF before 1 sec is dominantly affected by the stick phenomenon, while the slip dominantly influences the total CoF PDF after 1 sec. Although a symmetric distribution has been used for the uncertain parameters considered, the uncertainty in the response obtained displayed a skewed distribution for some of the situations investigated. The CoF PDFs obtained from simulations with combinations of two and three uncertain parameters have wider PDF ranges than those obtained for only one uncertain parameter.
FFT analysis using the rail displacement has been performed for the qualitative validation of the stochastic simulation result due to the absence of the experimental data. The FFT analysis of the deterministic rail displacement and of the stochastic rail displacement with uncertainties demonstrates consistent trends commensurate with loss of tractive efficiency, such as the bandwidth broadening, peak frequency shifts, and side band occurrence. Thus, the FFT analysis validates qualitatively that the stochastic modeling with various uncertainties is well executed and is reflecting observable, real-world results.
In conclusions, the development of an effective model which helps to understand the nonlinear nature of wheel-rail friction is critical to the progress of railroad component technology and rail safety. In the real world, accurate estimation of the CoF at the wheel-rail interface is very difficult since it is influenced by several uncertain parameters as illustrated in this study. Using the deterministic CoF value can cause underestimation or overestimation of CoF values leading to inaccurate decisions in the design of the wheel-rail system. Thus, the possible PDF ranges of the CoF according to key uncertain parameters must be considered in the design of the wheel-rail system.Ph. D.
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Brooks, Douglas Antwonne. "Control of reconfigurability and navigation of a wheel-legged robot based on active vision." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26545.
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Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.Committee Chair: Howard, Ayanna; Committee Member: Egerstedt, Magnus; Committee Member: Vela, Patricio. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Refvem, Charles T. "Design, Modeling and Control of a Two-wheel Balancing Robot Driven by BLDC Motors." DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2110.
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The focus of this document is on the design, modeling, and control of a self-balancing two wheel robot, hereafter referred to as the balance bot, driven by independent brushless DC (BLDC) motors. The balance bot frame is composed of stacked layers allowing a lightweight, modular, and rigid mechanical design. The robot is actuated by a pair of brushless DC motors equipped with Hall effect sensors and encoders allowing determination of the angle and angular velocity of each wheel. Absolute orientation measurement is accomplished using a full 9-axis IMU consisting of a 3-axis gyroscope, a 3-axis accelerometer, and a 3-axis magnetometer.
The control algorithm is designed to minimize deviations from a set point specified by an external radio remote control, which allows the remote operator to steer and drive the bot wirelessly while it remains balanced. Multiple dynamic models are proposed in this analysis, and the selected model is used to develop a linear-quadratic regulator based state-feedback controller to perform reference tracking. Controller tracking performance is improved by incorporating a prefilter stage between the setpoint command from the remote control and the state-feedback controller.
Modeling of the actuator dynamics is considered brie y and is discussed in relation to the control algorithm used to balance the robot. Electrical and software design implementations are also presented with a focus on effective implementation of the proposed control algorithms.
Simulated and physical testing results show that the proposed balance bot and controller design are not only feasible but effective as a means of achieving robust performance under dynamic tracking profiles provided by the remote control.
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Meymand, Sajjad Zeinoddini. "State of the Art Roller Rig for Precise Evaluation of Wheel-Rail Contact Mechanics and Dynamics." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/64920.
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The focus of this study is on the development of a state-of-the-art single-wheel roller rig for studying contact mechanics and dynamics in railroad applications. The use of indoor-based simulation tools has become a mainstay in vehicle testing for the automotive and railroad industries. In contrast to field-testing, roller rigs offer a controlled laboratory environment that can provide a successful path for obtaining data on the mechanics and dynamics of railway systems for a variety of operating conditions. The idea to develop a laboratory test rig started from the observation that there is a need for better-developed testing fixtures capable of accurately explaining the complex physics of wheel-rail contact toward designing faster, safer, and more efficient railway systems. A review of current roller rigs indicated that many desired functional requirements for studying contact mechanics currently are not available. Thus, the Virginia Tech Railway Technologies Laboratory (RTL) has embarked on a mission to develop a state-of-the-art testing facility that will allow experimental testing of contact mechanics in a dynamic, controlled, and consistent manner. VT roller rig will allow for closely replicating the boundary conditions of railroad wheel-rail contact via actively controlling all the wheel-rail interface degrees of freedom: cant angle, angle of attack, and lateral displacement. Two sophisticated independent drivelines are configured to precisely control the rotational speed of the wheels, and therefore their relative slip or creepage. A novel force measurement system, suitable for steel on steel contact, is configured to precisely measure the contact forces and moments at the contact patch. The control architecture is developed based on the SynqNet data acquisition system offered by Kollmorgen, the motors supplier. SynqNet provides a unified communication protocol between actuators, drives, and data acquisition system, hence eliminating data conversion among them. Various design analysis indicates that the rig successfully meets the set requirements: additional accuracy in measurements, and better control on the design of experiments. The test results show that the rig is capable of conducting various contact mechanics studies aimed for advancing the existing art. Beyond developing the experimental testing fixture for studying contact mechanics, this study provides a comprehensive review of the contact models. It discusses the simplifying assumptions for developing the models, compares the models functionality, and highlights the open areas that require further experimental and theoretical research. In addition, a multi-body dynamic model of the entire rig, using software package SIMPACK, is developed for conducting modal analysis of the rig and evaluating the performance of the rig's components. A MATLAB routine is also developed that provides a benchmark for developing creep curves from measurements of the rig and comparing them with existing creep curves.Ph. D.
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Knobel, Christian. "Optimal control allocation for road vehicle dynamics using wheel steer angles, brake, drive torques camber angles." Düsseldorf VDI-Verl, 2009. http://d-nb.info/992593425/04.
Full text
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Seegmiller, Neal A. "Dynamic Model Formulation and Calibration for Wheeled Mobile Robots." Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/460.
Full textAbstract:
Advances in hardware design have made wheeled mobile robots (WMRs) exceptionally mobile. To fully exploit this mobility, WMR planning, control, and estimation systems require motion models that are fast and accurate. Much of the published theory on WMR modeling is limited to 2D or kinematics, but 3D dynamic (or force-driven) models are required when traversing challenging terrain, executing aggressive maneuvers, and manipulating heavy payloads. This thesis advances the state of the art in both the formulation and calibration of WMR models We present novel WMR model formulations that are high-fidelity, general, modular, and fast. We provide a general method to derive 3D velocity kinematics for any WMR joint configuration. Using this method, we obtain constraints on wheel ground contact point velocities for our differential algebraic equation (DAE)-based models. Our “stabilized DAE” kinematics formulation enables constrained, drift free motion prediction on rough terrain. We also enhance the kinematics to predict nonzero wheel slip in a principled way based on gravitational, inertial, and dissipative forces. Unlike ordinary differential equation (ODE)-based dynamic models which can be very stiff, our constrained dynamics formulation permits large integration steps without compromising stability. Some alternatives like Open Dynamics Engine also use constraints, but can only approximate Coulomb friction at contacts. In contrast, we can enforce realistic, nonlinear models of wheel-terrain interaction (e.g. empirical models for pneumatic tires, terramechanics-based models) using a novel force-balance optimization technique. Simulation tests show our kinematic and dynamic models to be more functional, stable, and efficient than common alternatives. Simulations run 1K-10K faster than real time on an ordinary PC, even while predicting articulated motion on rough terrain and enforcing realistic wheel-terrain interaction models. In addition, we present a novel Integrated Prediction Error Minimization (IPEM) method to calibrate model parameters that is general, convenient, online, and evaluative. Ordinarily system dynamics are calibrated by minimizing the error of instantaneous output predictions. IPEM instead forms predictions by integrating the system dynamics over an interval; benefits include reduced sensing requirements, better observability, and accuracy over a longer horizon. In addition to calibrating out systematic errors, we simultaneously calibrate a model of stochastic error propagation to quantify the uncertainty of motion predictions. Experimental results on multiple platforms and terrain types show that parameter estimates converge quickly during online calibration, and uncertainty is well characterized. Under normal conditions, our enhanced kinematic model can predict nonzero wheel slip as accurately as a full dynamic model for a fraction of the computation cost. Finally, odometry is greatly improved when using IPEM vs. manual calibration, and when using 3D vs. 2D kinematics. To facilitate their use, we have released open source MATLAB and C++ libraries implementing the model formulation and calibration methods in this thesis.
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Andersson, Emil. "Optimization and re-design of a wheel hub to reduce unsprung mass of a rallycross car." Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-15721.
Full textAbstract:
The Wheel Hub of a rallycross car is analysed to reduce the unsprung mass of the car. The problem statement is to mainly focus on the unsprung mass related to the suspension, and more specifically on the Wheel Hub. One of the objectives of the suspension system of a car is to damping the movement of the car. This is an important area when designing a vehicle, and especially a race car due to the extreme conditions that may result in reduced traction and loose of confidence for the driver. A theoretical model is performed to demonstrate the importance of a low unsprung mass and to illustrate how it affects the vehicle-handling. A process to evaluate the current Wheel Hub and decision to re-design the Wheel Hub is performed, and the parts are analysed using the Finite Element Method to verify the design and material selection. Vehicle dynamics of the car is analysed to calculate the acting forces. Optimization of the design is performed by using Computer Aided Engineering. The re-designed Wheel Hub presented as the result of this project with a Brake Disk Adapter integrated in Hub. This design reduces the number of parts, and the unsprung mass up to 25% without any effects on suspension geometry or other parts of the car.
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Jayakumar, Gautham. "Modeling And Analysis Of Fault Conditions In Avehicle With Four In-Wheel Motors." Thesis, KTH, Fordonsdynamik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-121475.
Full textAbstract:
A vast expansion is found in the field of automotive electronic systems. The expansion iscoupled with a related increase in the demands of power and design. Now, this is goodarena of engineering opportunities and challenges. One of the challenges faced, isdeveloping fault tolerant systems, which increases the overall automotive and passengersafety. The development in the field of automotive electronics has led to the innovationof some very sophisticated technology. However, with increasing sophistication intechnology also rises the requirement to develop fault tolerant solutions.As one of many steps towards developing a fault tolerant system, this thesis presents anexhaustive fault analysis. The modeling and fault analysis is carried out for a vehicle withfour in-wheel motors. The primary goal is to collect as many of the possible failuremodes that could occur in a vehicle. A database of possible failure modes is retrievedfrom the Vehicle Dynamics research group at KTH. Now with further inputs to thisdatabase the individual faults are factored with respect to change in parameters of vehicleperformance. The factored faults are grouped with respect to similar outputcharacterization.The fault groups are modeled and integrated into a vehicle model developed earlier inMatlab/Simulink. All the fault groups are simulated under specific conditions and theresults are obtained. The dynamic behavior of the vehicle under such fault conditions isanalyzed. Further, in particular the behavior of the vehicle with electronic stabilitycontrol (ESC) under the fault conditions is tested. The deviation in the vital vehicleperformance parameters from nominal is computed.Finally based on the results obtained, a ranking system termed Severity Ranking System(SeRS) is presented. The severity ranking is presented based on three essential vehicleperformance parameters, such as longitudinal acceleration ( ), lateral acceleration ( )and yaw rate ( ̇ ). The ranking of the faults are classified as low severity S1, mediumseverity S2, high severity S3 and very high severity S4. A fault tolerant system must beable to successfully detect the fault condition, isolate the fault and provide correctiveaction. Hence, this database would serve as an effective input in developing fault tolerantsystems.
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Moas, Eduardo. "Investigation of the finite element method for computing wheel/rail contact forces in steady curving." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/50064.
Full textAbstract:
The understanding of rail vehicle steady-state and dynamic curving has increased
substantially in the last few years. Contemporary curving models include such nonlinear
effects as two-point contact, creep force saturation, and rail flexibility. The
usual approximation concerning the contact geometry is that the Iocalized wheel and
rail curvatures at the center of the contact patch are constant throughout the contact
patch. This approximation allows computation of contact stresses using Hertzian
theory, and it allows the computation of contact patch forces using one of Kalker’s
theories.
ln vehicle curving, contact usually occurs at or near the wheel flange, where the
wheel/rail contact geometry is non·Hertzian. Furthermore, after being in service for
some time, the wheel and rail profiles provide non·Hertzian geometry due to wear.
Both of these effects tend to invalidate the assumption of Hertzian contact geometry
in the contact region.
This work uses a generic wheelset model which is the basic component of any rail
vehicle model. The wheel/rail interaction is modelled using the finite element
method. The wheel is generated as a surface of revolution of its tread profile, and the
rail is generated as an extrusion of the rail head profile. Three—dimensional contact
elements are used to characterize the wheel/rail interface. A simple stick/slip friction
model is used wherein relative motion is permitted if the tangential force exceeds the
adhesion limit, and no relative motion occurs otherwise.
The results show that the finite element method was successfully used to solve the
static contact problem. Both Hertzian and non-Hertzian contact problems were ana-
Iyzed correctly. However, the application of the finite element method to the rolling
contact problem was not completely successful. The finite element method results
for tangential contact forces were about 25 percent lower than forces predicted by
Kalker’s theory. Recommendations for extending the analysis to solve the rolling
contact problem are made. The report includes a derivation of the wheelset steadystate
equations of motion, as well as a solution algorithm for the nonlinear, algebraic
equations.Master of Science
incomplete_metadata
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Hosseinipour, Milad. "Electromechanical Design and Development of the Virginia Tech Roller Rig Testing Facility for Wheel-rail Contact Mechanics and Dynamics." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/82542.
Full textAbstract:
The electromechanical design and development of a sophisticated roller rig testing facility at the Railway Technologies Laboratory (RTL) of Virginia Polytechnic and State University (VT) is presented. The VT Roller Rig is intended for studying the complex dynamics and mechanics at the wheel-rail interface of railway vehicles in a controlled laboratory environment. Such measurements require excellent powering and driving architecture, high-performance motion control, accurate measurements, and relatively noise-free data acquisition systems. It is critical to accurately control the relative dynamics and positioning of rotating bodies to emulate field conditions. To measure the contact forces and moments, special care must be taken to ensure any noise, such as mechanical vibration, electrical crosstalk, and electromagnetic interference (EMI) are kept to a minimum. This document describes the steps towards design and development of all electromechanical subsystems of the VT Roller Rig, including the powertrain, power electronics, motion control systems, sensors, data acquisition units, safety and monitoring circuits, and general practices followed for satisfying the local and international codes of practice.
The VT Roller Rig is comprised of a wheel and a roller in a vertical configuration that simulate the single-wheel/rail interaction in one-fourth scale. The roller is five times larger than the scaled wheel to keep the contact patch distortion that is inevitable with a roller rig to a minimum. This setup is driven by two independent AC servo motors that control the velocity of the wheel and roller using state-of-the-art motion control technologies. Six linear actuators allow for adjusting the simulated load, wheel angle of attack, rail cant, and lateral position of the wheel on the rail. All motion controls are performed using digital servo drives, manufactured by Kollmorgen, VA, USA.
A number of sensors measure the contact patch parameters including force, torque, displacement, rotation, speed, acceleration, and contact patch geometry. A unified communication protocol between the actuators and sensors minimizes data conversion time, which allows for servo update rates of up to 48kHz. This provides an unmatched bandwidth for performing various dynamics, vibrations, and transient tests, as well as static steady-state conditions.
The VT Roller Rig has been debugged and commissioned successfully. The hardware and software components are tested both individually and within the system. The VT Roller Rig can control the creepage within 0.3RPM of the commanded value, while actively controlling the relative position of the rotating bodies with an unprecedented level of accuracy, no more than 16nm of the target location. The contact force measurement dynamometers can dynamically capture the contact forces to within 13.6N accuracy, for up to 10kN. The instantaneous torque in each driveline can be measured with better than 6.1Nm resolution. The VT Roller Rig Motion Programming Interface (MPI) is highly flexible for both programmers and non-programmers. All common motion control algorithms in the servo motion industry have been successfully implemented on the Rig. The VT Roller Rig MPI accepts third party motion algorithms in C, C++, and any .Net language. It successfully communicates with other design and analytics software such as Matlab, Simulink, and LabVIEW for performing custom-designed routines. It also provides the infrastructure for linking the Rig's hardware with commercial multibody dynamics software such as Simpack, NUCARS, and Vampire, which is a milestone for hardware-in-the-loop testing of railroad systems.Ph. D.
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Duan, FangFang. "Numerical tribology of the wheel-rail contact : Application to corrugation defect." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0019/document.
Full textAbstract:
Depuis plus d'un siècle, l’usure ondulatoire représente un des problèmes de maintenance les plus important pour les réseaux ferroviaires. Celle-ci est à l’origine d’émissions sonores incommodantes pour le voisinage et de vibrations structurelles pouvant réduire la durée de vie des infrastructures et matériels ferroviaires. Ce phénomène périodique présent à la surface des rails est intimement lié à la dynamique du contact roue-rail qui résulte des paramètres régissant le frottement, la dynamique du train et de la voie… Afin de mieux appréhender les conditions menant à l’apparition de l’usure ondulation, un modèle numérique a été proposé pour compenser l’impossibilité d’instrumenter localement et de façon fiable un contact roue-rail dynamiquement. Tout d'abord, un outil approprié a été choisi pour modéliser la dynamique du contact roue-rail afin de reproduire numérique de l’usure ondulatoire des voies rectilignes. Le code d'éléments finis dynamique implicite Abaqus a été choisi pour instrumenter numériquement localement le contact roue-rail. Ainsi, tant l'origine que l'évolution de l’usure ondulatoire dans des phases transitoires (accélération / décélération) sont étudiées. Une étude de sensibilité a été menée pour mettre en évidence la sensibilité de l’usure ondulatoire apparaissant dans des conditions transitoires au passage d’une ou plusieurs roues ainsi que d’un défaut géométrique présent à la surface du rail. Des conditions dynamiques locales d’adhérence-glissement (stick-slip), liées à la dynamique de la roue et du rail couplés par le contact, est identifié comme origine de l’usure ondulatoire des voies rectilignes dans des conditions transitoires. Deuxièmement, les résultats obtenues avec le modèles précédent ont mis en évidence une décroissance de l’amplitude de l’usure ondulatoire reproduire numérique en fonction du nombre de roue passant sur le rail. Ce résultat semble être en contradiction avec les observations de rails réels. Ce problème est lié à la difficulté de gérer la dynamique de contact, et tout particulièrement dans le cas où il y a des impacts locaux, dans les modèles éléments finis classiques tels que ceux implémentés dans Abaqus. Pour palier ce problème, une méthode de masser redistribuée a été implémentée dans Abaqus et utilisée sur le cas précédent. Les résultats montrent un accroissement plus réaliste de l’usure ondulatoire en fonction du nombre de rouesFor more than a century, rail corrugation has been exposed as one of the most serious problems experienced in railway networks. It also comes with a series of problems for maintenance, such as rolling noises and structural vibrations that can reduce lifetime of both train and track. This periodical phenomenon on rail surface is closely linked to wheel-rail contact dynamic, which depends on friction, train dynamics… To better understand corrugation birth conditions, a numerical model is suggested to complement the experimental limitations and to instrument a wheel-rail contact both locally and dynamically. At first, an appropriate tool was chosen to create the dynamic wheel-rail contact model to reproduce straight-track corrugation, also called “short-pitch” corrugation. The implicit dynamic finite element code Abaqus was chosen to investigate the dynamic local contact conditions. Both the origin and the evolution of straight-track corrugation under transient conditions (acceleration / deceleration) are studied. The parametrical sensibility of corrugation is thus investigated both with single/multiple wheel passing(s) and with geometric defect. A stick-slip phenomenon, linked to both wheel and rail dynamics coupled through the contact, is identified as the root of straight-track corrugation under transient conditions. Secondly, results obtained with the previous model have highlighted a quick decrease of corrugation amplitude with the increase of wheel passings over the rail. This last result seems to be in contradiction with reality. This problem comes from the difficulty to reliably manage contact dynamics, and particularly with local impacts, with the use of classical finite element models such as the one implemented in Abaqus. To compensate for this lack, a mass redistribution method is implemented in Abaqus and used with the previous case. The results show a more realistic corrugation growth according to the number of wheel passings
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Elias, Laila Mireille 1977. "Dynamics of multi-body space interferometers including reaction wheel gyroscopic stiffening effects : structurally connected and electromagnetic formation of flying architectures." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/17795.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2004.Includes bibliographical references (p. 181-184).
Space telescopes have the potential to revolutionize astronomy and our search for life-supporting planets beyond our Solar System. Free of atmospheric distortions, they are able to provide a much "clearer" view of the universe than ground-based telescopes. A developing technology that appears promising is space-based interferometry, which uses multiple apertures separated at great distances to act as a large virtual aperture. In this way, interferometers will achieve angular resolutions far greater than those achievable by monolithic telescopes. In this thesis, we investigate the dynamics and control of two proposed architectures for spaceborne interferometers: structurally connected interferometers and electromagnetic formation flying interferometers. For structurally connected interferometers, we develop a coupled disturbance analysis method that accurately predicts a space telescope's optical performance in the presence of reaction wheel vibrational disturbances. This method "couples" a reaction wheel to a structure using estimates of the accelerances (or mobilities) of both bodies. This coupled analysis method is validated on the Micro-Precision Interferometer testbed at NASA's Jet Propulsion Laboratory. The predictions show great improvement over a simplified "decoupled" analysis method when compared to experimental data. For formation flying interferometers, we consider the use of electromagnets as relative position actuators. A high fidelity, nonlinear dynamic model of a deep-space electromagnetic formation flight (EMFF) array is derived from first principles. The nonlinear dynamics are linearized for a two-vehicle array about a nominal trajectory, and the linearzed model is shown to be unstable,
(cont.) but controllable, and therefore stabilizable. A linear optimal controller is designed for the system and implemented to form the closed-loop dynamics. Time simulations of the closed-loop nonlinear dynamics demonstrate that EMFF using linear control proves very effective, despite the nonlinearities of the system's dynamics and the electromagnetic actuators.
by Laila Mireille Elias.
Ph.D.
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Currie, Blake J. "Control of a Spacecraft Using Mixed Momentum Exchange Devices." DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1313.
Full textAbstract:
Hardware configurations, a control law, and a steering law are developed for a mixed hardware spacecraft that uses both control moment gyros and reaction wheels. Replacing one or more gyros in a spacecraft with a reaction wheel has potential for cost savings while still achieving much greater performance than using reaction wheels alone. Several simulated tests are run to compare the performance to a traditional all reaction wheel or all control moment gyro spacecraft, including analysis of failure modes and singular configurations. The mixed system performed similarly to all gyro systems, responding within 6% of the gyro system’s time for all nominal cases. It far exceeds the performance of reaction wheel systems, taking only a fourth of the time. It also handles failures better than reduced size gyro systems. As such, it can be an effective cost saving measure for certain satellite missions.
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Papp, Tomáš. "Konstrukční návrh měřicího volantu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231766.
Full textAbstract:
This diploma thesis describes construction design of a measuring steering wheel. This mechanism replaces the original steering wheel in the tested vehicle. Connection is made via steering shaft through an adapter. Measured parameters are steering torque and angular position of steering while driving. Measurements obtained during test-ride show some of the dynamic aspects of the tested vehicle.
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Ahmad, Husain Abdulrahman. "Dynamic Braking Control for Accurate Train Braking Distance Estimation under Different Operating Conditions." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/19322.
Full textAbstract:
The application of Model Reference Adaptive Control (MRAC) for train dynamic braking is investigated in order to control dynamic braking forces while remaining within the allowable adhesion and coupler forces. This control method can accurately determine the train braking distance. One of the critical factors in Positive Train Control (PTC) is accurately estimating train braking distance under different operating conditions. Accurate estimation of the braking distance will allow trains to be spaced closer together, with reasonable confidence that they will stop without causing a collision. This study develops a dynamic model of a train consist based on a multibody formulation of railcars, trucks (bogies), and suspensions. The study includes the derivation of the mathematical model and the results of a numerical study in Matlab. A three-railcar model is used for performing a parametric study to evaluate how various elements will affect the train stopping distance from an initial speed. Parameters that can be varied in the model include initial train speed, railcar weight, wheel-rail interface condition, and dynamic braking force. Other parameters included in the model are aerodynamic drag forces and air brake forces. An MRAC system is developed to control the amount of current through traction motors under various wheel/rail adhesion conditions while braking. Minimizing the braking distance of a train requires the dynamic braking forces to be maximized within the available wheel/rail adhesion. Excessively large dynamic braking can cause wheel lockup that can damage the wheels and rail. Excessive braking forces can also cause large buff loads at the couplers. For DC traction motors, an MRAC system is used to control the current supplied to the traction motors. This motor current is directly proportional to the dynamic braking force. In addition, the MRAC system is also used to control the train speed by controlling the synchronous speed of the AC traction motors. The goal of both control systems for DC and AC traction motors is to apply maximum available dynamic braking while avoiding wheel lockup and high coupler forces. The results of the study indicate that the MRAC system significantly improves braking distance while maintaining better wheel/rail adhesion and coupler dynamics during braking. Furthermore, according to this study, the braking distance can be accurately estimated when MRAC is used. The robustness of the MRAC system with respect to different parameters is investigated, and the results show an acceptable robust response behavior.
Ph. D.
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Downs, Matthew C. "Adaptive Control Applied to the Cal Poly Spacecraft Attitude Dynamics Simulator." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/231.
Full textAbstract:
The goal of this thesis is to use the Cal Poly Spacecraft Attitude Dynamics Simulator to provide proof of concept of two adaptive control theories developed by former Cal Poly students: Nonlinear Direct Model Reference Adaptive Control and Adaptive Output Feedback Control. The Spacecraft Attitude Dynamics Simulator is a student-built air bearing spacecraft simulator controlled by four reaction wheels in a pyramidal arrangement. Tests were performed to determine the effectiveness of the two adaptive control theories under nominal operating conditions, a “plug-and-play” spacecraft scenario, and under simulated actuator damage. Proof of concept of the adaptive control theories applied to attitude control of a spacecraft is provided. The adaptive control theories are shown to attain similar or improved performance over a Full State Feedback controller. However, the measurement capabilities of the simulator need to be improved before strong comparisons between the adaptive controllers and Full State Feedback can be achieved.
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Nelkov, Nyagolov Dimitar, Bashir Abbas, and Genovski Filip Valentinov. "Simulation of the Geometry Influence on Curvic Coupled Engagement." Thesis, Linnéuniversitetet, Institutionen för teknik, TEK, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-27291.
Full textAbstract:
The thesis is performed in order to improve the curvic coupled engagement of a dog clutch situated in the transfer case of a truck. The dog clutch is used to engage the so called all-wheel-drive system of the truck. If the driver tries to engage the all-wheel-drive when truck’s rear wheels already skid, due to a slippery surface a relative rotational speed in the dog clutch will occur. This relative rotational speed will cause the dog clutch to bounce back of itself before engagement, or to not engage at all. The dog clutch has been redesigned to prevent this. Dynamic simulations using MD Adams have been made for the existing model, for the models created in previous works, and for the new model in order to figure out which of them will show the most stable engagement, at high relative rotational speed. The implemented simulations show that better results can be obtained. Separation into two parts of the disc pushed by the fork, shows that dog clutch’s engagement is faster and more stable, comparing to the original model and the other created models. The new model shows better coupling in the whole range of the relative rotational speed from 50 up to 120rpm.
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de, Leeuw Bente. "Improving the validation of a railway vehicle model in the virtual certification process." Thesis, KTH, Spårfordon, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302262.
Full textAbstract:
Before vehicles can be placed in service it has to complete an authorisation process. At the moment,this process is largely depended on tests. This is, however, an expensive and long process. With new technologies and improved simulations this process can be shortened and the costs can be lowered. The validation of a vehicle model, however, is often limited by the available data. Often the measured rail profiles are not available and thus a new UIC60 profile is used for the simulations. The railway track often has been used and showssigns of wear and damages, therefore research has been done to investigate the influence of the rail profiles on the validation of a railway vehicle model. The current methods of validation in the European norm are used to compare simulated values with forces and accelerations available from vehicle measurements. In the first step,25 track sections with different curve radii have beensimulated with a measured rail profile every 100 meters. In the next step, the same sections have been simulated by using the standard UIC60 rail profile. The results show that the use of measured rail profiles does have a positive influence on the outcome of simulation. In the final step, one single narrow curve has been simulated to show the effect of standard and worn rail profiles. Four different wear stages of the rail profile are simulated and compared to the available vehicle measurements available. These simulations show that the use of a medium worn rail profile gives the most accurate value.Innan ett fordon kan tas i bruk måste det genomgå en tillståndsprocess. För närvarande är denna process till stor del beroende av provningar. Detta är dock en dyr och lång process. Med hjälp av ny teknik och förbättrade simuleringar kan denna process förkortas och kostnaderna sänkas. Valideringen av en fordonsmodell begränsas dock ofta av de tillgängliga uppgifterna. Ofta finns inte de uppmätta rälsprofilerna tillgängliga och därför används en ny UIC60-profil för simuleringarna. Järnvägsspåret har ofta använts och visarDärför har forskning gjorts för att undersöka hur rälsprofilerna påverkar valideringen av en modell av ett järnvägsfordon. De nuvarande valideringsmetoderna i den europeiska normen används för att jämföra simulerade värden med de krafter och accelerationer som finns tillgängliga från fordonsmätningar. I det första steget har 25 spårsektioner med olika kurvradier använts.simulerats med en uppmätt rälsprofil var 100:e meter. I nästa steg har samma sektioner simulerats med hjälp av standardprofilen UIC60. Resultaten visar att användningen av uppmätta rälsprofiler har en positiv inverkan på simuleringsresultatet. I det sista steget har en enda smal kurva simulerats för att visa effekten av standard- och slitna rälsprofiler. Fyra olika slitningsstadier av rälsprofilen simuleras och jämförs med tillgängliga fordonsmätningar. Simuleringarna visar att användningen av en mediumsliten rälsprofil ger det mest exakta värdet.
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Jandora, Radek. "Výpočtové modelování dynamických projevů v kontaktu kola a kolejnice s obecnou geometrií kontaktních povrchů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-234020.
Full textAbstract:
During life of railway vehicles, shape irregularities develop on wheels and rails because of wear. The shape irregularities then affect forces in wheel-rail contact and cause further damage of contact surfaces, vibrations and noise and increase risk of derailment. A numerical simulation of railway vehicle motion with more details on contact surfaces geometry was created to investigate dynamic contact loads in wheel-rail contact. A variety of methods can be used to evaluate forces in rolling contact, the method chosen for this study was algorithm CONTACT based on boundary element method. Four studies are presented in this papers: contact loads from a wheel with a flat and with a wavy tread pattern, loads on wavy rail and load in a curve. The first three studies investigated effects of existing wear patterns, the last one looked for cause of common wear pattern developing on rails. Results of the studies with worn components used showed that the worst kind of shape irregularities is a flat present on wheel. This type of shape cause loss of contact and following impacts. The study of ride in curve showed that cause of high wear in curves, especially those with small radii, is caused by vibration of wheelset. This vibration is then caused by different length of inner and outer rail and wheels travelling along a different path.
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Eriksson, Fredrik, Joseph Linu Kuttikkal, and Amanuel Mehari. "Parametric study of a dog clutch used in a transfer case for trucks." Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-27107.
Full textAbstract:
Normally the trucks with four wheel drive option will be running in rear wheel drives and the front wheels will be rotating freely. In extreme tough driving conditions, the risk for getting stopped or slipping the rear wheels in mud is high. When the driver tries to engage the four wheel drive option and due to the difference in relative rotational speed of the dog clutch parts, there is a risk for slipping off or bouncing back of the dog clutch. After studying the importance of gear geometry and a few parameters, the team ended up with a new design and the performance of the design found satisfactory when simulated in MSC ADAMS.
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Silva, Ludmila Corrêa Alkmin e. "Principios basicos de um laboratorio virtual para veiculos : aplicação em acessibilidade." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264385.
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Orientador: Franco Giuseppe DediniDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Neste trabalho foi desenvolvido um laboratório virtual para dinâmica veicular e modelagem do contato roda-piso que foi usado para a visualização do comportamento dinâmico de uma cadeira de rodas em diversas situações. Utilizando o ambiente Working Model 2Dâ para a integração das equações de movimento e visualização dos deslocamentos e movimentos associados, implementou-se modelos do contato roda-piso a partir da literatura de referência. Foram propostos sucessivamente quatro diferentes modelos do contato roda-piso, um modelo próprio para o controle da velocidade e aceleração, o modelo de Huston, a fórmula mágica e por último o modelo de Raheman. Todos esses modelos foram implementados, simulados e comparados entre si, por meio de imagens e gráficos obtidos. Todos os modelos se mostraram bastante confiáveis e suficientemente simples. No entanto, não existem dados confiáveis para os coeficientes destes modelos quando usados para a modelagem de rodas e ambientes inteiros como acontece em uma cadeira de rodas. Assim levou-se ao desenvolvimento de uma bancada experimental para a obtenção desses parâmetros
Abstract: In this work it was developed a virtual laboratory to vehicular dynamics and the modeling of the contact between ground and wheel that was used to visualize the dynamic behavior of the wheelchair in diverse situations. Using the Working Model 2D for the integration of the equations of motion and visualization of the displacements, the model of the contact between the ground and wheel had been implemented from the reference literature. Four different models of the contact between ground and wheel had been considered successively, a proper model for control of the speed and acceleration, the Huston model, the Magic Formula and then the Raheman model. All these models had been implemented simulated and compared each other by figures and graphs. All the models developed was sufficiently trustworthy and enough simple. However, trustworthy parameters do not exist for the coefficient of these models when used for the modeling of the wheelchair. So was developed an experiment to raise these parameters
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica
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Luu, Quang Khanh [Verfasser], Dirk [Akademischer Betreuer] Söffker, and Tamara [Akademischer Betreuer] Nestorovic. "Stability-Oriented Dynamics and Control of Complex Rigid-Flexible Mechanical Systems Using the Example of a Bucket-Wheel Excavator / Quang Khanh Luu. Gutachter: Tamara Nestorovic. Betreuer: Dirk Söffker." Duisburg, 2015. http://d-nb.info/1066206376/34.
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Luu, Quang Khanh Verfasser], Dirk [Akademischer Betreuer] [Söffker, and Tamara [Akademischer Betreuer] Nestorovic. "Stability-Oriented Dynamics and Control of Complex Rigid-Flexible Mechanical Systems Using the Example of a Bucket-Wheel Excavator / Quang Khanh Luu. Gutachter: Tamara Nestorovic. Betreuer: Dirk Söffker." Duisburg, 2015. http://d-nb.info/1066206376/34.
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Huttenlocher, Luciana de Moraes Gamba. "Estudo do esterçamento nas quatro rodas de um veículo automotivo baseado em duas estratégias de controle da literatura." Universidade de São Paulo, 2000. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-11072018-103217/.
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O comportamento da dinâmica lateral de veículos automotivos com esterçamento nas quatro rodas é estudado com o auxílio de uma ferramenta computacional de modelagem e simulação de sistemas multicorpos. São utilizadas duas estratégias de controle do esterçamento das rodas traseiras para a avaliação de suas principais características. Uma das estratégias esterça as rodas traseiras em função do ângulo de esterçamento do volante, e a outra esterça as rodas traseiras em função do ângulo de esterçamento do volante e da velocidade longitudinal do veículo. O teste utilizado para as análises é a entrada degrau de esterçamento, onde é avaliada a resposta transitória e de regime da aceleração lateral, da velocidade de guinada e do ângulo de rolagem dos veículos. Os resultados das simulações mostram que os veículos com esterçamento nas quatro rodas têm o tempo de resposta da velocidade de guinada maior, e da aceleração lateral e do ângulo de rolagem menores que o veículo convencional. Também apresentam uma diminuição no ganho da aceleração lateral, da velocidade de guinada e do ângulo de rolagem. Além disso apresentam uma característica subesterçante mais acentuada. Essas características são mais evidentes no veículo com estratégia de controle função do esterçamento do volante. Os resultados obtidos correspondem ao comportamento dos veículos com esterçamento nas quatro rodas apresentado na literatura.The lateral dynamic behavior of the automotive vehicles is studied with the aid of a computational tool for multibody systems modeling and simulation. Two rear wheel steering control strategies are used for evaluation of the main four wheel steering characteristics. One strategy steer the rear wheels as a function of the steering wheel angle, and the other one, steer the rear wheels as a function of the steering wheel angle and the speed. The steer step input is the test used, where the lateral acceleration, the yaw rate and the roll angle transient and stead state response are evaluated. The simulation results show that the four wheel steering vehicles have a slower yaw rate time response, and a fast lateral acceleration and roll angle time response than the conventional vehicle. Also four wheel vehicles show a reduction in lateral acceleration, yaw rate a.nd roll angle gain. Moreover they are more understeer than the conventional vehicle. These characteristics are particularly more evident on the vehicle with steer dependent system. The obtained results correspond with four wheel steering vehicles behavior founded in literature.
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Wanner, Daniel. "Controlling over-actuated road vehicles during failure conditions." Doctoral thesis, KTH, Fordonsdynamik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-166819.
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The aim of electrification of chassis and driveline systems in road vehicles is to reduce the global emissions and their impact on the environment. The electrification of such systems in vehicles is enabling a whole new set of functionalities improving safety, handling and comfort for the user. This trend is leading to an increased number of elements in road vehicles such as additional sensors, actuators and software codes. As a result, the complexity of vehicle components and subsystems is rising and has to be handled during operation. Hence, the probability of potential faults that can lead to component or subsystem failures deteriorating the dynamic behaviour of road vehicles is becoming higher. Mechanical, electric, electronic or software faults can cause these failures independently or by mutually influencing each other, thereby leading to potentially critical traffic situations or even accidents. There is a need to analyse faults regarding their influence on the dynamic behaviour of road vehicles and to investigate their effect on the driver-vehicle interaction and to find new control strategies for fault handling. A structured method for the classification of faults regarding their influence on the longitudinal, lateral and yaw motion of a road vehicle is proposed. To evaluate this method, a broad failure mode and effect analysis was performed to identify and model relevant faults that have an effect on the vehicle dynamic behaviour. This fault classification method identifies the level of controllability, i.e. how easy or difficult it is for the driver and the vehicle control system to correct the disturbance on the vehicle behaviour caused by the fault. Fault-tolerant control strategies are suggested which can handle faults with a critical controllability level in order to maintain the directional stability of the vehicle. Based on the principle of control allocation, three fault-tolerant control strategies are proposed and have been evaluated in an electric vehicle with typical faults. It is shown that the control allocation strategies give a less critical trajectory deviation compared to an uncontrolled vehicle and a regular electronic stability control algorithm. An experimental validation confirmed the potential of this type of fault handling using one of the proposed control allocation strategies. Driver-vehicle interaction has been experimentally analysed during various failure conditions with typical faults of an electric driveline both at urban and motorway speeds. The driver reactions to the failure conditions were analysed and the extent to which the drivers could handle a fault were investigated. The drivers as such proved to be capable controllers by compensating for the occurring failures in time when they were prepared for the eventuality of a failure. Based on the experimental data, a failure-sensitive driver model has been developed and evaluated for different failure conditions. The suggested fault classification method was further verified with the conducted experimental studies. The interaction between drivers and a fault-tolerant control system with the occurrence of a fault that affects the vehicle dynamic stability was investigated further. The control allocation strategy has a positive influence on maintaining the intended path and the vehicle stability, and supports the driver by reducing the necessary corrective steering effort. This fault-tolerant control strategy has shown promising results and its potential for improving traffic safety.QC 20150520
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Sureka, Arihant. "Improvement of an existing Integrated Vehicle Dynamics Control System influencing an urban electric car." Thesis, KTH, Flygdynamik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-284446.
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The Integrated Vehicle Dynamics Control (IVDC) concept can influence the vehicle behaviour both longitudinally and laterally with just one upper level control concept and further lower level controllers. This demands for state estimation of the vehicle which also includes estimating parameters of interest for the vehicle dynamicist. The approach to this research is firstly in developing a robust unscented Kalman filter (UKF) estimator for the vehicle side slip tracking and also for cornering stiffness estimation which is then fed to the existing model predictive control allocation (MPCA) controller to enhance the lateral stability of the vehicle for the different manoeuvres studied. Based on these developments, two types of filters are created. One with adaption of distance between center of gravity (COG) and roll center height and another without adaption. The key factor in the estimator development is the time adaptive process covariance matrix for the cornering stiffnesses, with which only the initial values have to be parameterised. Combining this research encompasses effective and adaptive method for a better quality of estimation with a kinematic vehicle model which behaves like a real world vehicle, at least virtually.This study is carried out with the understanding of various optimal estimators, parametric sensitivity analysis and statistical inferences, facilitating a base for robust estimation. Keywords: kalametric, state estimation, design matrix, aliasing, kalman filter, projection algorithm, resolutionKonceptet Integrated Vehicle Dynamics Control (IVDC) kan påverka fordonets beteende både longitudinellt och lateralt med bara ett regler koncept iett övre lager och ytterligare regulatorer på lägre nivåer. Detta kräver tillståndsuppskattning av fordonet som också inkluderar uppskattning av parametrar av intresse för en fordonsdynamiker. Tillvägagångssättet för denna studie är för det första att utveckla en robust tillståndsestimering med hjälp av ett Unscented Kalman Filter (UKF) för att uppskatta ett fordons avdriftsvinkel och även för uppskattning av ett däcks sidkraftskoefficient, vilket sedan används i den befintliga modell-prediktiva regleralgoritmen (MPCA) för att förbättra lateralstabiliteten hos fordonet för de olika studerade manövrarna. Baserat på denna utveckling skapades två typer av filter, ett med anpassning av avståndet mellan tyngdpunkten (COG) och krängcentrumhöjden och ett annat utan anpassning. Nyckelfaktorn i estimeringsutvecklingen är den tidsberoende adaptiva inställningenav processkovariansmatrisen för sidkraftskoefficienterna, med vilken endast de initiala värdena behöver parametriseras. Efter filterutvecklingen identifieras parametrar baserade på en förväntad kundanvändning och en statistisk variansanalys (ANOVA) utförs för att bestämma de mest inflytelserika faktorerna i gruppen. En parameteroptimering utförs för att förbättra uppskattningskvaliteten. Kombinationen av detta arbete omfattar en effektiv och anpassningsbar metod för en bättre uppskattningskvalitet med en kinematisk fordonsmodell som har en fordonsrespons som ett verkligt fordon, åtminstone praktiskt taget. Denna studie har genomförts med förståelse för olika optimala estimatorer, parametrisk känslighetsanalys och statistiska slutsatser, vilket underlättaren bas för robust uppskattning. Nyckelord: kalametric, tillståndsestimering, designmatris, vikningsdistorsion, kalmanfilter,projection algorithm, upplösning
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Elsayed, Abdel Hameed Amer Shaltout Ramy. "MULTIBODY APPROACH FOR RAILWAY DYNAMIC ANALYSIS." Doctoral thesis, Universitat Politècnica de València, 2013. http://hdl.handle.net/10251/27622.
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En este trabajo se ha llevado a cabo el desarrollo de una herramienta computacional para la simulación dinámica de vehículos ferroviarios. El modelo está basado en técnicas multicuerpo debidas a Shabana. Con respecto a otras metodologías existentes, la propuesta hace uso de un conjunto de sistemas de referencia que permite el empleo de coordenadas independientes sin la posibilidad de configuraciones singulares debidas a grandes giros. El conjunto de sistemas de referencia sirve de base para formular de manera precisa el problema de contacto rueda-carril. El programa está diseñado para considerar de forma flexible distintas configuraciones de vehículo así como diversas geometrías de trazado. La estructura del programa está abierta a cambios orientados a la mejora del modelo de contacto rueda-carril o a la implementación de la dinámica estructural de la vía. Se ha implementado un modelo eficiente que permite detectar con precisión las coordenadas de los puntos en contacto localizados en la interfase entre la rueda y el carril. La herramienta de simulación desarrollada en esta tesis se ha aplicado para diferentes casos-estudio con el objetivo de validar la idoneidad de la metodología propuesta en el análisis del sistema ferroviario. Se ha realizado una comparación entre los resultados obtenidos por la herramienta de simulación presentada y los resultados ofrecidos por varios programas comerciales de simulación dinámica en el análisis del vehículo de Manchester Benchmark. Además, la herramienta se ha empleado para desarrollar un análisis dinámico del vehículo de la locomotora TGV y los resultados obtenidos se han comparado con los ofrecidos por el programa comercial SIMPACK para el mismos modelo de vehículo, bajo las mismas condiciones de operación. Finalmente, sobre la base de la calidad de los resultados, se puede concluir que la herramienta de simulación es fiable y eficiente para emplearse en el análisis dinámico de los diferentes sistemas ferroviarios.Elsayed Abdel Hameed Amer Shaltout, R. (2013). MULTIBODY APPROACH FOR RAILWAY DYNAMIC ANALYSIS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/27622
TESIS
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Štěnička, Petr. "Stend pro analýzu přístroje k mazání okolků kolejových vozidel." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229383.
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This work deals with construction of an experimental measuring stand. This stand will be used for research focused on wheel flange lubrication improvement. The construction is based on wheel flange lubrication system Tribotec OK-02. First part treats of rail vehicle dynamics and wheel flange lubrication problematics, second part describes construction itself.
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Gunduz, Aydin. "Multi-Dimensional Stiffness Characteristics of Double Row Angular Contact Ball Bearings and Their Role in Influencing Vibration Modes." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1326397623.
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Gérardin, Fabien. "Étude expérimentale et numérique de la dispersion d'aérosols dans le sillage d'une roue de véhicule." Thesis, Vandoeuvre-les-Nancy, INPL, 2009. http://www.theses.fr/2009INPL015N/document.
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S’il est admis que la pollution particulaire observée sur les sites industriels est issue des étapes de production et de fabrication, il est en revanche peu fréquent de considérer le phénomène d’aérosolisation de particules provoqué par le passage du véhicule. Qu’il s’agisse de routes goudronnées ou de voies industrielles, la circulation de véhicule est à l’origine de l’envol de particules présentes naturellement à leur surface. Anecdotique dans certaines situations urbaines, cette source d’émission peut se révéler très préoccupante dans un contexte industriel. L’exposition des travailleurs aux particules dans des secteurs d’activités tels que les carrières, les chantiers BTP, les cimenteries, etc. constitue une préoccupation majeure pour les hygiénistes industriels. Sur la base d’une recherche bibliographique, les travaux présentés dans ce manuscrit sont consacrés à la caractérisation de la source d’émission principale. Ils visent une description aérodynamique détaillée du sillage d’une roue de véhicule et l’illustration, pour les différentes configurations expérimentales, de la répartition spatiale des particules aérosolisées en aval du point de contact de la roue avec le sol. Ce travail de recherche s’inscrit dans un cadre expérimental élargi à la simulation. Adossé à une étude numérique, l’ensemble de l’expérimentation s’est déroulé en laboratoire dans des conditions opératoires maîtrisées. A terme, cette investigation scientifique posera les fondements d’une réflexion sur les moyens technologiques qui pourront être déployés pour garantir une atténuation significative des émissions de poussières provoquées par la circulation de véhicules en situation industrielleWhilst it is common knowledge that fuel combustion in a motorised vehicle generates gaseous and particulate pollution, particles emission caused by a travelling vehicle is accounted for to a much lesser extent. Whether a vehicle is moving on motorways, roads, unpaved roads or industrial soils, it projects particles that are naturally present on the ground. This case represents a significant diffuse emission source, depending principally on the speed of the vehicle, on the load and on the humidity of the road surface material. Studying the aerodynamic behaviour of air in the vicinity of wheels under real conditions is not easy from an experimental point of view and numerical models are difficult to validate. Insufficient knowledge of this issue and the complexity of this type of aerodynamic behaviour support the preferred option of studying a simple case, such as an isolated wheel The goal of this work is to provide background information on the aerosol spreading in the field close to a vehicle rotating wheel. From a state of the art on this issue, this study was to assess the airflow and particles experimental behaviour around a wheel integrating the presence of patterns on the surface of the tire. While not claim a comparative study between different pattern geometries, this work is to highlight the differences between flow around a smooth wheel and patterned wheel. This research is based on the experimentation extended to the simulation. It will be the bases for a reflection on the possibilities of devices development to reduce dust emissions caused by the movement of industrial vehicles
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Velasquez, Andres Eduardo Baquero. "helvis III - Desenvolvimento e caracterização da plataforma robótica." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18149/tde-05052015-101452/.
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O principal propósito deste trabalho é desenvolver e caracterizar o veículo robótico ℏelvis III, para ser usado no desenvolvimento de pesquisas na área de controle e navegação de robôs móveis. O sistema de propulsão foi caracterizado para determinar a velocidade real do veículo em quatro tipos diferentes de terrenos (Asfalto, grama, grama-terra e terra). Também foi caracterizado o sistema de esterçamento mediante o modelo cinemático da bicicleta, onde se obteve a relação entre a posição do servo motor encarregado do esterçamento do veículo e o valor do ângulo de esterçamento de uma bicicleta. Foram determinados os valores dos erros CEP (Circular Error Probability) e SEP (Spherical Error Probability) do GPS (Global Positioning System) embarcado no veículo mediante dois testes: um em São Carlos – SP (Brasil) e outro em Villavicencio – Meta (Colômbia). Nesses testes foi caracterizada a IMU (Inertial Measurement Unit) embarcada no veículo, além de verificado o efeito da luz solar no funcionamento do sensor tipo LIDAR (Laser Imaging Detection and Ranging) embarcado no helvis III. Por último, pode-se definir a dinâmica do veículo à frente, com a determinação seu centro de massa, e é apresentado o comportamento das forças sob as rodas quando o veículo fica parado ou em movimento sobre terrenos que geram uma inclinação em algum dos eixos cartesianos.The main objective of this work is the development and characterization of a robotic vehicle ℏelvis III in order to use it in the development of researches focused on the fields of mobile robotics control and navigation. Initially the propulsion system was characterized in order to determine the real velocity of vehicle in real conditions (four different kinds of grounds were used). In addition to this, the steering system was also characterized by applying the well-known bicycle kinematic model. During these experimental tests we could find the relation between the position of the servo-motor and the value of steering angle of the bicycle model. The real values of CEP (Circular Error Probability) and SEP (Spherical Error Probability) errors of the vehicle embedded GPS (Global Positioning System) were determined based on two experiments: the first one was carried out in São Carlos – SP (Brazil) and the second one in Villavicencio – Meta (Colombia). During the GPS experiments we could also characterize the vehicle embedded IMU (Inertial Measurement Unit). Then we could observe and measure the effect of solar light on the LIDAR sensor (Laser Imaging Detection and Ranging) performance. Finally, the forward vehicle dynamics is described, with the determination of the center of mass of the vehicle and the observation of the normal forces behavior in the vehicle wheels when it is stopped or moved on an inclined floor.