Tesis: "Vehicle wheels"

1

Ewin, Nathan. "Traction control for electric vehicles with independently driven wheels". Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:dfc99786-fe17-4225-bd91-3ab83416981f.

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The necessity to reduce climate related emissions is driving the electrication of transportation. As well as reducing emissions Electric Vehicles (EV) have the capability of improving traction and vehicle stability. Unlike a conventional vehicle that uses a single Internal Combustion Engine (ICE) to drive one or both axles, an EV can have an electric machine driving each of the wheels independently. This opens up the possibility of using the electric machines as an actuator for traction control. In conventional vehicles the hydraulic brakes together with the ICE are used to actuate traction control. The advantages of electric machines over hydraulic brakes are precise measurable torque, higher bandwidth, bidirectional torque and kinetic energy recovery. A review of the literature shows that a wide range of control methods is used for traction control of EVs. These are mainly focused on control of an individual wheel, with only a minority being advanced to the experimental stage of verication. Integrated approaches to the control of multiple wheels are generally lacking, as well as verication that tests the vehicle's directional stability. A large body of the literature uses the slip ratio of the wheel as the key control variable. A signicant challenge for slip-based traction control is the detection of vehicle velocity together with the calculation of slip around zero vehicle velocity. A traction control method that does not depend upon vehicle velocity detection or slip ratio is Maximum Transmissible Torque Estimation (MTTE), after Yin et al. (2009). In this thesis an MTTE based method is developed for a full size electric vehicle with independently driven rear wheels. The original MTTE method for a single wheel is analysed using a simple quarter vehicle model. The simulation results of Yin et al. (2009) are in general reproducible although a lack of data in the original research prevents a quantitative comparison. A modication is proposed to the rate compensation term. Simulation results show that the proposed modication ensures that the torque demand is delivered to the wheel under normal driving conditions, this includes negative torque demand which is not possible for MTTE, Yin et al. (2009). Enabling negative torque demands means that the proposed traction control is compatible with higher level stability control such as torque vectoring. The performance of the controller is veried through a combination of simulation and vehicle based experiments. Compared with experiments, simulations are fast and inexpensive and can provide greater insight as all of the variables are observable. To simulate the controller a high delity vehicle model is required. To achieve this it is necessary to initially validate the model against experimental data. Simulation verication using a validated vehicle model is lacking in the literature. A full vehicle model is developed for this thesis using Dymola, a multi-body system software tool. The model includes the full suspension geometry of the vehicle. Pacejka's "Magic Formula" is used for the tyre model. The model is validated using Delta Motorsport's E4 coupe. The two Wheel Independent Drive (2WID) MTTE-based traction controller is derived from the equations of motion for the vehicle. This shows that the maximum transmissible torque for one driven wheel is dependent on the friction force of both driven wheels, which has not been shown before. An equal torque strategy is proposed to maintain vehicle directional stability on mixed-μ roads. For verication the 2WID-MTTE controller is simulated on the validated vehicle model described above. The proposed 2WID-MTTE controller is benchmarked against a similar method without the equal torque strategy, termed Independent MTTE, as well as a method combining Direct Yaw Control (DYC) and Independent MTTE. The three controllers are simulated for a vehicle accelerating onto a split-μ road. The results show that the proposed 2WID-MTTE controller prevents the vehicle spinning o the road when compared to Independent MTTE. 2WID-MTTE is found to be as eective as DYC+Independent MTTE but is simpler in design and requires fewer sensors. The proposed 2WID-MTTE controller is also simulated for a vehicle accelerating from a low- to high-μ road. This is done to assess the controller's ability to return to normal operation after a traction event, and because there are no simulations of this type for MTTE control on a high delity vehicle model in the literature. The results show that oscillations in the tyre-road friction force as the wheel transitions across the change in μ somewhat impede the return of the controller's output torque to the torque demand. The 2WID-MTTE controller is implemented on Delta Motorsport's E4 coupe by integrating it into the vehicle's Powertrain Control Module (PCM). This is experimentally tested for the vehicle accelerating across a range of surfaces at the MIRA proving ground. The experimental tests include high- to low-μ, low- to high-μ and split-μ roads. The results for the high- to low-μ road tests show that 2WID-MTTE control prevents the vehicle spinning when compared to no control. Similar to the simulation, the results of the low- to high-μ road experiment show that the controller output torque is also impeded from returning to the demand torque. Observation of the estimated friction force together with the on-board accelerometers conrm that this is due to tyre friction oscillating after the transition. This justies the use of a tyre model with transient dynamics. The proposed 2WID-MTTE controller uses wheel velocity and torque feedback to estimate friction torque. These signals are obtained from the vehicle's motor controllers via a Controlled Area Network (CAN) bus. The 2WID-MTTE controller is benchmarked against Independent MTTE that uses wheel velocity measured directly from the wheel hub sensors and the torque demand to estimate friction torque. The results show that the delays introduced by the CAN bus increase wheel slip for the 2WID-MTTE controller. However, the equal torque strategy means that 2WID-MTTE controller maintains greater vehicle directional stability, which is more important than the pursuit of greater acceleration.

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2

Gerrard, Douglas R. "Dynamic control of a vehicle with two independent wheels". Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA340452.

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Thesis (M.S. in Electrical Egnineering) Naval Postgraduate School, September 1997.
"September 1997." Thesis advisor(s): Xiaoping Yun. Includes bibliographical references (p. 27). Also available online.

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3

Schmitt, Peter S. M. Massachusetts Institute of Technology. "Just build it! : a fully functional concept vehicle using robotic wheels". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42342.

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Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2007.
Page 64 blank.
Includes bibliographical references (p. [62]-[63]).
Interest in electric vehicle drive units is resurging with the proliferation of hybrid and electric vehicles. Currently emerging key-technologies are: in-wheel motors, electric braking, integrated steering activators and active suspension combined with embedded sensors and real time computation. These electric vehicle drive units have the potential to go beyond current applications and lead to a novel vehicle architectures and a new vehicle culture. Building upon the research in the Smart Cities Group at the MIT Media Lab I propose to implement a novel mechanical and electric robotic wheel technology and the associated control and drive software in a fully functional concept vehicle. I will make use of a modular design for wheel robots which I developed through prior iterations at different scales combined with applied automotive technologies. This platform provides a realistic and scalable test-bed for evaluating the proposed technologies and will ultimately serve building a full scale concept vehicle.
by Peter Schmitt.
S.M.

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4

Batmanian, Saro y Pasam Naga. "Control and balancing of a small vehicle with two wheels for autonomous driving". Thesis, KTH, Fordonsdynamik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-265618.

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Control and balancing of an inverted pendulum has gained a lot of attention over the past few decades due to its unstable properties. This has become a great challenge for control engineers to verify and test the control theory. To control and balance an inverted pendulum, proportional integrated derivative (PID) method or linear quadratic regulator (LQR) method can be used through which a lot of simulations can be done using the represented theories.Since urban population is increasing at a very alarming rate, there is a need to discover new ways of transportation to meet the future challenges and demands. Scania has come up with a new conceptual bus called NXT which aims to develop a modular vehicle that should configure and re-configure themselves between different transportation tasks. NXT vehicle has front and rear drive modules which can be represented as single axle, two-wheeled vehicles which in-turn can be viewed as an inverted pendulum with a huge Center of Gravity. Controlling and balancing of the pod or drive module precisely and accurately is an interesting challenge since it is an unstable inverted pendulum with huge center of gravity (COG). This behaviour of the system has created a research question whether the module is controllable or not.Therefore this thesis focuses on the possibility of controlling the pod which is a two-wheeled inverted pendulum vehicle with a COG offset. Also, the thesis focuses on the construction, mod-elling, testing and validation of a down-scaled model, what sensors are needed to balance the pod precisely, how the sensors must be integrated with the system and how the pod can be controlled remotely from a certain distance by a human. The developed pod houses the technologies like sensors, BLDC motor controllers, hoverboard, Arduino board and Bluetooth transmitters.The Master Thesis starts by presenting an introduction to the inverted pendulum theories, Scania NXT project, information about the research methods, thesis outline and structure . It continues by describing related literature about the inverted pendulums, segways, hoverboards, motor controllers and Arduino boards. Afterwards, the process of deriving a mathematical model, together with simulation in Matlab, Simulink and Simscape is described. Later, construction of the pod is made and lot of effort is put to run the pod. Since the pod needs to be controlled remotely by a human, a remote controlled systemis implemented via mobile phone using an app and finally the thesis is finished with a conclusion and ideas for future work.
Reglering och balancering av en inverterad pendel har väckt stor uppmärksamhet över de senaste decennierna på grund av dess instabila egenskaper. Det har skapat stora utmaningar för regleringenjörer eftersom området tillåter test och verifikation av diverese lösningar. För reglering och balansering av en inverterad pendel, så kan en regulator med proportionell, integral och derivat (PID) konstanter eller en linjär kvadratisk regulator (LQR) användas tillsammans med simuleringar för att bekräfta teorin.I och med att stadsbefolkningen ökar i mycket hög takt, så uppstår behovet av att uppfinna nya transportmedel för att lösa framtida utmaningar och krav. Scania har tagit fram en ny konceptbuss som heter NXT, med målet att utveckla ett modulfordon som kommer att konfigurera och rekonfigurera sig själva mellan olika transportuppgifter. NXT-fordonet har fram- och bakdriv-moduler som kan representeras som enaxlade tvåhjuliga fordon, vilka i sin tur kan betraktas som en inverterad pendel med en stor massa. Att reglera och balansera drivmodulen på ett noggrant sätt är en utmaning eftersom det är ett mycket instabilt system med enorm massa och en okänd tyngdpunkt. Systemets beteende har skapat en forskningsfråga om modulen är reglerbar eller inte.Denna uppsats fokuserar därmed på möjligheterna att kunna reglera drivmodulen samt vilka begränsningar det finns. Uppsatsen fokuserar också på konstruktion, modellering, testning och validering av en nedskalad modell, vilka sensorer som krävs för att balansera drivmodulem, samt hur sensorerna måste integreras med systemet för att kunna fjärstyra fordonet från ett visst avstånd. Utveckingen av en sådan nedskalad modell berör olika områden såsom sensorer, BLDC-motorstyrenheter, hoverboard balanserings scootrar, Arduino kretskort och Bluetooth-sändare/mottagare.Uppsasten börjar med en introduction om olika inverterade pendel teorier, Scania NXT project, forskningsmetoder, en översikt och övergripande struktur. Vidare fortsätter beskrivining av relaterade litteratur om inverterade pendel, Segway, hoverboard, borstlösa motor styrenheter och Arduino kretskort. Senare fortsätter processen för att härleda matematiska modeller som beskirver systemet, tillsammans med simuleringar i Matlab, Simulink och Simscape. Därefter beskrivs konstruktionen av en nedskalad modell av drivmodulen och beskrivning av nödvändiga processer för att få hårdvara och mjkukvara att fungera ihop. Då fordonen ska ha möjlighet att fjärrstyras, så implementerades en bluetooth enhet tillsammans med en programmerbar mobil applikation. Slutligen avlutas uppsatsen med resultat, slutsats och diskussioner och förslag till framtida arbeten.

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5

Schultz, Christopher R. "An Autonomous Underwater Vehicle for Validating Internal Actuator Control Strategies". Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/33190.

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There are benefits to the use of internal actuators for rotational maneuvers of small-scale underwater vehicles. Internal actuators are protected from the outside environment by the external pressure hull and will not disturb the surrounding environment during inspection tasks. Additionally, internal actuators do not rely on the relative fluid motion to exert control moments, therefore they are useful at low speed and in hover. This paper describes the design, fabrication and testing of one such autonomously controlled, internally actuated underwater vehicle.

The Internally Actuated, Modular Bodied, Untethered Submersible (IAMBUS) can be used to validate non-linear control strategies using internal actuators. Vehicle attitude control is provided by three orthogonally mounted reaction wheels. The housing is a spherical glass pressure vessel, which contains all of the components, such as actuators, ballast system, power supply, on-board computer and inertial sensor. Since the housing is spherically symmetric, the hydrodynamics of IAMBUS are uncoupled (e.g. a roll maneuver does not impact pitch or yaw). This hull shape enables IAMBUS to be used as a spacecraft attitude dynamics and control simulator with full rotational freedom.
Master of Science

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6

NORMELIUS, ANTON y KARL BECKMAN. "Hand Gesture Controlled Omnidirectional Vehicle". Thesis, KTH, Skolan för industriell teknik och management (ITM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279822.

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The purpose of this project was to study how hand gesture control can be implemented on a vehicle that utilizes mecanum wheels in order to move in all directions. Furthermore, it was investigated how the steering of such a vehicle can be made wireless to increase mobility. A prototype vehicle consisting of four mecanum wheels was constructed. Mecanum wheels are such wheels that enable translation in all directions. By varying rotational direction of each wheel, the direction of the resulting force on the vehicle is altered, making it move in the desired direction. Hand gesture control was enabled by constructing another prototype, attached to the hand, consisting of an IMU (Inertial Measurement Unit) and a transceiver. With the IMU, the hand’s angle against the horizontal plane can be calculated and instructions can be sent over to the vehicle by making use of the transceiver. Those instructions contain a short message that specifies in what direction the vehicle should move. The vehicle rotates the wheels in the desired direction and move thereafter. The results show that wireless hand gesture based control of an omnidirectional vehicle works without any noticeable delay in the transmission and the signals that are sent contain the correct information about moving directions.
Syftet med detta projekt var att studera hur handstyrning kan implementeras på ett fordon som utnyttjar mecanumhjul för att röra sig i alla riktningar. Vidare undersöktes också hur styrningen av sådant fordon kan genomföras trädlöst för ökad mobilitet. En prototypfarkost bestående av fyra mecanumhjul konstruerades. Mecanumhjul är sådana hjul som möjliggör translation i alla riktningar. Genom att variera rotationsriktningen på vardera motor ändras riktningen av den resulterande kraften på farkosten, vilket gör att den kan förflytta sig i önskad riktning. Handstyrning möjliggjordes genom att konstruera en till prototyp, som fästs i anslutning till handen, bestående av en IMU och en transceiver. Med IMU:n kan handens vinkel gentemot horisontalplanet beräknas och instruktioner kan skickas över till farkosten med hjälp av transceivern. Dessa instruktioner innehåller ett kort meddelande som specificerar i vilken riktning farkosten ska röra sig i. Resultaten visar på att trädlös handstyrning av en farkost fungerar utan märkbar tidsfördröjning i signalöverföring och att signalerna som skickas till farkosten innehåller korrekta instruktioner gällande rörelseriktningar.

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7

Oslizlo, Aleš. "Vliv rotace kol na aerodynamické charakteristiky vozu". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229237.

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The diploma thesis is focused on computational examination of influence of boundary condition settings in CFD software on the final aerodynamic characteristics of a vehicle. The flow analysis is carried out around a vehicle with and without the rotation of the wheels and along with the stationary and moving road. Furthermore, there is demonstrated the method of the CFD model composition and there is described the influence of rotating wheels on vehicle aerodynamic characteristics.

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8

Öhnander, Fred. "An Attempt Towards FE-Modelling of Fracture Propagation in Railway Wheels". Thesis, KTH, Spårfordon, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-234468.

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The demand for higher velocities and heavier axle loads for freight trains leads to higher forces on the railway wheels which in turn lead to an increase in stresses on and below the surface of the wheel-rail contact. By time, this induces wear on the wheels which consequently lead to higher maintenance costs and in some cases accidents. The ability to predict the evolution of wheel profiles due to uniform wear has been demonstrated with a rather accurate precision in most operational conditions. These wear models are based on wear coefficients and since they are not usually valid for real operational conditions, the models are generally calibrated against real-life scenarios in order to adjust the coefficients from test conditions to real-life lubrication conditions. This engineering approach can be useful in prediction of wear in systems where the materials and contact conditions do not vary. However, when addressing material development focused on reducing specific damage modes, the approach is of limited use because the obtained wear coefficients are not directly related to material properties. Therefore, attempts towards developing physical fracture propagation models that relates to the contact conditions and material properties have been made. The purpose has been to retrieve vital information about where a fracture initiates and how it propagates. In the long run, it is of great interest to be able to attain information about how a material particle is removed from the contact surface. Studies for this type of model was done in the 70’s and 80’s mainly with pin-disk experiments but has not been utilized in the specific field of wheel-rail contact. The thesis is part of the FR8RAIL project arranged by the European rail initiative Shift2Rail. Literature studies have been the basis for the thesis in order to gain vital insights into fracture mechanics and other related fields. The physical fracture propagation models have been constructed in the FE software Abaqus with the implementation of the XFEM. For the 2D model, the fracture initiates at the top of the implanted inclusion when the friction coefficient is and propagates upwards a few elements. For , the fracture initiates at the right surface boundary where the pressure distribution and traction is applied. The fracture propagation angle increases relative to the surface as the friction coefficient value is increased. The fracture for the 3D model extends broader compared to the 2D model at the top of the inclusion in the case of . The fracture initiates at the same surface location as for the 2D model for . The fracture propagation is however non-existent due to convergence problems. The FE-models constructed are initial steps towards analysing the fracture propagation and closely related phenomena for a railway freight wheel in detail. At the end of the thesis, the simplified models give mainly information about the fracture initiation, propagation and its patterns. From this first phase, further adjustments and improvements can take place in order to eliminate the margins of error. In the long run, fully integrated models with further implementations such as detailed microstructure for the contact conditions, plastic behaviour for the material, and complete three-dimensional models can finally be employed.
Efterfrågan på högre hastigheter och tyngre axelbelastningar för godståg leder till högre krafter på järnvägshjulen som i sin tur leder till ökade spänningar på och under ytan vid hjul-räl-kontakten. Med tiden induceras slitage på hjulen som följaktligen leder till höga underhållskostnader och i vissa fall olyckor. Förmågan att förutse utvecklingen av hjulprofiler på grund av enhetligt slitage har visats kunna ske med en noggrann precision under de flesta driftsförhållanden. Dessa slitagemodeller bygger på slitagekoefficienter, och eftersom de vanligtvis inte är giltiga under realistiska driftsförhållanden är modellerna i allmänhet kalibrerade mot verkliga händelseförlopp för att justera koefficienterna från testförhållandena till realistiska smörjförhållanden. Detta tekniska tillvägagångssätt kan vara användbart vid prognos av slitage i system där material och kontaktförhållanden inte varierar. När man addresserar materialutveckling inriktad på att reducera specifika skadelägen är emellertid tillvägagångssättet av begränsad användning eftersom de erhållna slitagekoefficienterna inte är direkt relaterade till materialegenskaper. Därför har försök gjorts till att utveckla fysikaliska sprickbildningsmodeller som relateras till kontaktförhållanden och materialegenskaper. Syftet har varit att erhålla viktig information om var en spricka initieras och hur den fortskrider. I det långa loppet är det även av stor vikt att kunna erhålla information om hur en materialpartikel avlägsnas från kontaktytan. Studier för denna typ av modeller har gjorts på 70- och 80-talet i huvudsak med stift- och skivexperiment men har inte använts inom det specifika området för hjul-räl-kontakt. Avhandligen ingår i FR8RAIL-projektet som arrangeras av det europeiska järnvägsinitiativet Shift2Rail. Literaturstudier har varit grunden för avhandlingen för att få väsentlig insikt i frakturmekanik och andra relaterade områden. De fysiska sprickbildningsmodellerna har konstrueras i FE-mjukvaran Abaqus med XFEM som implementering. För 2D-modellen initieras sprickan överst vid den implanterade imperfektionen när friktionskoefficienten är och propagerar uppåt några få element. För initieras sprickan på högra ytgränsen där tryckfördelning och friktionskraft appliceras. Utbredningsvinkeln för sprickan ökar relativt till ytan då friktionskoefficienten ökar. Sprickan för 3D-modellen breder ut sig mer jämfört med 2D-modellen överst vid imperfektionen då . Sprickan initieras på samma ytplats som för 2D-modellen vid . Sprickbildningen är dock obefintlig på grund av konvergensproblem. De konstruerade FE-modellerna är initiala steg mot att analysera sprickutbredningen och närbesläktade fenomen för ett godstågs järnvägshjul i detalj. I slutet av avhandlingen ger de förenklade modellerna huvudsakligen information om sprickinitiering, utbredning och dess mönster. Ytterligare justeringar och förbättringar kan ske efter denna första fas i syfte att eliminera felmarginalerna. På lång sikt kan slutligen helt integrerande modeller med ytterligare implementeringar såsom detaljerad mikrostruktur för kontaktförhållandena, oelastiskt materialbeteende och kompletta tredimensionella modeller användas.
FR8RAIL

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9

Juna, Anwar Pervez. "On the characterisation and detection of rolling contact fatigue (RCF) type cracks in railway vehicle wheels using an alternating current field measurement (ACFM) technique". Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7945/.

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The development of the alternating current field measurement (ACFM) technique for high-speed inspection of railway wheels/track is important to ensure the integrity of railway assets. The stress and conditions at the wheel/rail contact patch, severity of rolling contact fatigue (RCF) damage and changes in microstructure and hardness with tread depth for railway wheels are investigated. This study employs experimental measurement of RCF defects in railway wheels to understand ACFM sensor signal - RCF defect relationships. The influence of sensor frequency and speed, sensor angle relative to crack angle, lift-off distance, crack propagation angle and inter-crack spacing distance are investigated. Low rather than high frequency sensors are better suited at sizing cracks in railway wheels and track. The optimum signal is obtained when the sensor is oriented parallel to the crack angle. The signal is reduced at higher speeds. The maximum change in the normalised Bx signal component of the sensor’s magnetic field is greater for closely spaced cracks (< 5 mm) and thus overestimates the defect. Inter-crack spacing distances of 15-20 mm yield estimates for crack pocket depths that are oversized by 20-36%. The inner cracks in a cluster with four defects yields higher Bₓ values than expected and thus significantly over sizes the defects at 15-20 mm inter-crack spacing distances, whereas, the sensor provides reasonable depth estimates for the outer cracks. Crack propagation angle affects the signal. Scans conducted with the probe oriented at 90° to the cluster of cracks consisting of a deep central crack surrounded by shallow cracks results in a distinct central sensor Bₓ signal that consists of a peak due to a flux leakage effect, thus, identifying the critical defect.

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10

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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11

Moro, Alberto y Laura Lonza. "Electricity carbon intensity in European Member States: Impacts on GHG emissions of electric vehicles". Elsevier, 2017. https://publish.fid-move.qucosa.de/id/qucosa%3A73241.

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The Well-To-Wheels (WTW) methodology is widely used for policy making in the transportation sector. In this paper updated WTW calculations are provided, relying on 2013 statistic data, for the carbon intensity (CI) of the European electricity mix; detail is provided for electricity consumed in each EU Member State (MS). An interesting aspect presented is the calculation of the GHG content of electricity traded between Countries, affecting the carbon intensity of the electricity consumed at national level. The amount and CI of imported electricity is a key aspect: a Country importing electricity from another Country with a lower CI of electricity will lower, after the trade, its electricity CI, while importing electricity from a Country with a higher CI will raise the CI of the importing Country. In average, the CI of electricity used in EU at low voltage in 2013 was 447 gCO2eq/kWh, which is the 17% less compared to 2009. Then, some examples of calculation of GHG emissions from the use of electric vehicles (EVs) compared to internal combustion engine vehicles are provided. The use of EVs instead of gasoline vehicles can save (about 60% of) GHG in all or in most of the EU MSs, depending on the estimated consumption of EVs. Compared with diesel, EVs show average GHG savings of around 50% and not savings at all in some EU MS.

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12

Velenis, Efstathios. "Analysis and Control of High-Speed Wheeled Vehicles". Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10476.

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In this work we reproduce driving techniques to mimic expert race drivers and obtain the open-loop control signals that may be used by auto-pilot agents driving autonomous ground wheeled vehicles. Race drivers operate their vehicles at the limits of the acceleration envelope. An accurate characterization of the acceleration capacity of the vehicle is required. Understanding and reproduction of such complex maneuvers also require a physics-based mathematical description of the vehicle dynamics. While most of the modeling issues of ground-vehicles/automobiles are already well established in the literature, lack of understanding of the physics associated with friction generation results in ad-hoc approaches to tire friction modeling. In this work we revisit this aspect of the overall vehicle modeling and develop a tire friction model that provides physical interpretation of the tire forces. The new model is free of those singularities at low vehicle speed and wheel angular rate that are inherent in the widely used empirical static models. In addition, the dynamic nature of the tire model proposed herein allows the study of dynamic effects such as transients and hysteresis. The trajectory-planning problem for an autonomous ground wheeled vehicle is formulated in an optimal control framework aiming to minimize the time of travel and maximize the use of the available acceleration capacity. The first approach to solve the optimal control problem is using numerical techniques. Numerical optimization allows incorporation of a vehicle model of high fidelity and generates realistic solutions. Such an optimization scheme provides an ideal platform to study the limit operation of the vehicle, which would not be possible via straightforward simulation. In this work we emphasize the importance of online applicability of the proposed methodologies. This underlines the need for optimal solutions that require little computational cost and are able to incorporate real, unpredictable environments. A semi-analytic methodology is developed to generate the optimal velocity profile for minimum time travel along a prescribed path. The semi-analytic nature ensures minimal computational cost while a receding horizon implementation allows application of the methodology in uncertain environments. Extensions to increase fidelity of the vehicle model are finally provided.

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13

Kučera, Pavel. "Konstrukce čtyřkolky (ATV) s elektrickým pohonem". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229722.

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This master's thesis describes the design of All-Terrain Vehicle (ATV) with electric drive. The design is focused on the main parts of the ATV, which are designed with modern trends ATVs. Location of electric drive and batteries in the frame of the ATV is solved for the sport version of the ATV. Steering geometry is designed using the program Adams. For models of main components are created stress analysis in Ansys Workbench. The input is 3D model, which is created in Pro/Engineer. The braking system and wheels are designed for movement and braking of the terrain.

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14

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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15

Becker, Carl Martin. "Profiling of rough terrain". Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-11262009-171410/.

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Regner, Dominik. "Studie příčného rychlostního pole v blízkosti rotujícího kola s uvažováním vlivu nucené konvekce kotoučové brzdy". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-399576.

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The master thesis deals with the influence of a local change of temperature due to advection from disc brake to axial velocity field close to the rotating wheel of a car. The second goal is to set parameters applicable to various wheel discs and study of the influence of these parameters to aerodynamical properties of car and thermodynamical properties of the disc brake. The thesis is numerically executed in StarCCM+. The first part focuses on theoretical background about the numerical solution and current status of research. There are described disc parameters, geometry input and solver settings in the second part. The final part deals with a comparison of velocity fields for isothermal and thermodynamical model and evaluates the influence of parameters to velocity field, aerodynamical drag and thermodynamical performance of the brake.

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17

Kienhöfer, Frank Werner. "Heavy vehicle wheel slip control". Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609594.

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West, Mark. "Design of omnidirectional vehicles with ball wheels". Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/10657.

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19

Wang, Yifei. "Experimental Study of Wheel-Vehicle Aerodynamic Interactions". Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2019. http://www.theses.fr/2019ESMA0002/document.

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Sur une maquette à l’échelle 2/5ième équipée d’un diffuseur et de pneus Michelin. La géométrie du véhicule, basée sur le modèle ASMO, a été modifiée précédemment à ce travail afin d’obtenir un angle d’attaque de l’écoulement sur les roues avant et un équilibre du sillage réaliste en présence de quatre roues tournantes. Cette configuration a servi de référence dans le cadre de cette étude.Il a été mis en évidence que la configuration de base avec un sillage équilibré peut facilement être modifiée d’un point de vue aérodynamique en changeant l’état des roues (en rotation ou pas) et le type de pneumatique, en particulier sur l’essieu arrière. Cela provient d’un effet global et d’une sensibilité importante de l’équilibre du sillage aux changements de débit au soubassement. A contrario, lorsque le sillage du véhicule se trouve déséquilibré, il devient plus robuste par rapport à des perturbations de soubassement comme un changement d’état des roues ou une modification des pneumatiques. Si l’on supprime les quatre roues ou uniquement les deux roues avant, le débit de quantité de mouvement au soubassement est grandement augmenté. Par contre, si l’on supprime le diffuseur (changement important de la géométrie du véhicule), celui-ci s’en trouve nettement réduit. Dans ces deux configurations, le sillage est très fortement déséquilibré vers le sol et devient indépendant aux modifications apportées sur les roues.Il a également été mis en évidence un effet plus local du sillage des roues sur la portance et la traînée du véhicule.En effet, la zone de dépression dans le sillage des roues avant a un effet sur la portance alors que le sillage des roues arrière pilote en partie la pression au culot et donc la traînée. Il a ainsi été observé une augmentation importante de la traînée du véhicule lorsque le sillage des roues arrière, non fermé, venait en interaction directe avec le sillage du véhicule
The thesis aims to provide a better understanding of the wheel-vehicle interaction, via experimental investigations on a 2/5-th scale vehicle with an underbody diffuser and 2/5-th scale wheels equipped with Michelin tires. The vehicle geometry, based on ASMO model, was modified prior to the PhD work, in order to achieve a reasonable front wheel yaw angle, and a realistic wake balance with four rotating wheels. It is the baseline configuration in the scope of this work.The findings demonstrate that the well-balanced wake of the baseline configuration can be easily modified by different wheel states or tire modifications, especially at the rear axle. This results from a global effect of the underbody momentum modifications, i.e. a high wake sensitivity to the underbody flow. On the contrary, when the vehicle mean wake develops into a non-balanced topology, it is more robust towards underbody perturbations such as different wheel states or tire modifications. By eliminating four wheels or front wheels, the underbody momentum flux is vastly increased; by eliminating the underbody diffuser, which is a vehicle geometry modification, the underbody momentum flux is significantly reduced. In these two circumstances, one can observea robust downwash from the roof, independent of the wheel states or tire modifications. Besides, there is a more local effect of the wheels near wakes on the aerodynamic lift and drag of the vehicle. Low pressure regions in the underbody downstream the front wheels have an effect on vehicle lift. The rear wheels impose pressure conditions on the vehicle base, influencing the vehicle drag. Particularly, the merging of nonclosed mean wakes of the rear wheels with the vehicle wake can give rise to strong penalty in vehicle drag

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20

Sreenivasan, S. V. "Actively coordinated wheeled vehicle systems /". The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487858106117313.

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21

Garcia, Hector y Emma Smith. "Wheel Induced Vibrations on Heavy Vehicles". Thesis, KTH, Skolan för teknikvetenskap (SCI), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-153927.

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Some of the most significant comfort disturbances in heavy vehicles can often be related to the wheels. In those cases, the vibration of the vehicle is excited by for example force variations within the tire, ovality of the tire or imbalance in the wheel. The disturbances are dependent on vehicle speed and are often perceived as most unpleasant at cruising speed on a motorway, at around 90 km/h. Truck manufacturers want to increase the robustness against this type of disturbance, since this results in an improved operator comfort. But it also makes it possible to lower the requirements on the suppliers of tires and rims, and thereby there is a financial gain for both customer and manufacturer. The aim with this project is to increase the understanding of wheel induced vibrations. In order to achieve this a literature survey has been performed on the subject. Furthermore, the phenomenon has been studied analytically by using a quarter car model which includes a brush tire model. The model is scripted in MATLAB. Simulations have been performed to analyse the effect on the chassis when forces excited by mass imbalance and radial run out are introduced. When looking at the second harmonic radial run out imperfection the unsprung mass, i.e the wheel, starts to bounce during the settling time. Also when comparing two different weights of a mass imbalance the power increase of the vibration in the sprung mass is much larger than the power increase of the unsprung mass at the specific frequency. This implies that the excitation frequency, the wheel rotation frequency in this case, is a harmonic repetition of the sprung mass undamped natural frequency. To avoid this phenomenon the undamped natural frequency of the sprung mass must change either by adding a damper or by changing the weight or the spring stiffness. The simulation is run with a damper although without it the power increase would be much larger.

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22

Yang, Sichao. "In-wheel motors for electric vehicles". Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/4054.

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The in-wheel motor technology as the source of traction for electric vehicles has been researched recently because it is compact and ease-to-integrate. The motor is housed in the wheel. Since the room for the motor is tightly defined by the size of the wheel and there is no gearing system, the motor must have a high torque density to drive the vehicle directly and a high efficiency to keep cool. The existing motor uses a surface-mounted magnet topology. To make it more cost-competitive, the magnet material needs to be reduced while maintaining the torque performance at the rated operating condition. It is the motive of this Ph.D. research. The thesis starts with a brief introduction on the background of the electric vehicle. Then the major challenges of the in-wheel motor technology are summarised. With the derived specifications, an induction machine and a switched reluctance machine are then simulated and analysed. Still, the permanent magnet synchronous machine is proved to have the highest torque density. Change from surface-mounted to interior topology, six new magnet topologies are investigated. The V-shaped interior magnet topology shows superior torque-to-magnet-mass ratio and is easy-to-manufacture. It gives 96% torque while using 56% of the magnet mass compared to the existing motor due to the assist from the additional reluctance torque and the lower magnetic circuit reluctance. The key to use less magnet mass while avoiding the demagnetisation is the front iron shielding effect. The analytical explanation on the better resistance to demagnetisation in the V-shaped motor is provided. The magnet loss mechanism is discussed for proper segmentation. Detailed design adjustments are made to compromise between the torque-to-magnet-mass ratio and the manufactural practicality. Issues regarding to lower mechanical rigidity occurred in initial assembly of the prototype and solutions are proposed. Followed by successful assembly, experimental tests were conducted and results show good agreement with the simulation. A specific form of torque ripple is found in the V-shaped motor and occurs generally in all fractional-slot concentrated-winding machines with saliency. It is explained by an analytical model. This model is also extended to explain the generally lower reluctance torque in vi fractional-slot concentrated-winding machines. Potential design improvements are suggested and simulated for future versions.

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23

Pan-Ngum, Setha. "Alternative vehicle electronic architecture for individual wheel control". Thesis, University of Warwick, 2001. http://wrap.warwick.ac.uk/59476/.

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Electronic control systems have become an integral part of the modern vehicle and their installation rate is still on a sharp rise. Their application areas range from powertrain, chassis and body control to entertainment. Each system is conventionally control led by a centralised controller with hard-wired links to sensors and actuators. As systems have become more complex, a rise in the number of system components and amount of wiring harness has followed. This leads to serious problems on safety, reliability and space limitation. Different networking and vehicle electronic architectures have been developed by others to ease these problems. The thesis proposes an alternative architecture namely Distributed Wheel Architecture, for its potential benefits in terms of vehicle dynamics, safety and ease of functional addition. The architecture would have a networked controller on each wheel to perform its dynamic control including braking, suspension and steering. The project involves conducting a preliminary study and comparing the proposed architecture with four alternative existing or high potential architectures. The areas of study are functionality, complexity, and reliability. Existing ABS, active suspension and four wheel steering systems are evaluated in this work by simulation of their operations using road test data. They are used as exemplary systems, for modelling of the new electronic architecture together with the four alternatives. A prediction technique is developed, based on the derivation of software pseudo code from system specifications, to estimate the microcontroller specifications of all the system ECUs. The estimate indicates the feasibility of implementing the architectures using current microcontrollers. Message transfer on the Controller Area Network (CAN) of each architecture is simulated to find its associated delays, and hence the feasibility of installing CAN in the architectures. Architecture component costs are estimated from the costs of wires, ECUs, sensors and actuators. The number of wires is obtained from the wiring models derived from exemplary system data. ECU peripheral component counts are estimated from their statistical plot against the number of ECU pins of collected ECUs. Architecture component reliability is estimated based on two established reliability handbooks. The results suggest that all of the five architectures could be implemented using present microcontrollers. In addition, critical data transfer via CAN is made within time limits under current levels of message load, indicating the possibility of installing CAN in these architectures. The proposed architecture is expected to· be costlier in terms of components than the rest of the architectures, while it is among the leaders for wiring weight saving. However, it is expected to suffer from a relatively higher probability of system component failure. The proposed architecture is found not economically viable at present, but shows potential in reducing vehicle wire and weight problems.

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24

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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25

Fields, Travis D. "The development and optimization of a teleoperated four-wheel drive/four-wheel steer vehicle". abstract and full text PDF (UNR users only), 2009. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1472952.

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26

Yu, Xu. "Tank-to-Wheel Energy Breakdown Analysis". Thesis, KTH, Fordonsdynamik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-280559.

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In early design phase for new hybrid electric vehicle (HEV) powertrains, simulation isused for the estimation of vehicle fuel consumption. For hybrid electric powertrains,fuel consumption is highly related to powertrain efficiency. While powertrainefficiency of hybrid electric powertrain is not a linear product of efficiencies ofcomponents, it has to be analysed as a sequence of energy conversions includingcomponent losses and energy interaction among components.This thesis is aimed at studying the energy losses and flows and present them in theform of Sankey diagram, later, an adaptive energy management system is developedbased on current rule-based control strategy. The first part involves developing energycalculation block in GT-SUITE corresponding to the vehicle model, calculating allthe energy losses and flows and presenting them in Sankey diagram. The secondpart involves optimizing energy management system control parameters according todifferent representative driving cycles. The third part involves developing adaptiveenergy management system by deploying optimal control parameter based on drivingpattern recognition with the help of SVM (support vector machine).In conclusion, a sturctured way to generate the Sankey diagram has been successfullygenerated and it turns out to be an effective tool to study HEV powertrain efficiencyand fuel economy. In addition, the combination of driving pattern recognition andoptimized control parameters also show a significant potential improvement in fuelconsumption.
Under den tidiga utvecklingsfasen av nya elektrifieradedrivlinor for hybridapplikationer (HEV) används simulering för uppskattning avfordonets bränsleförbrukning. För dess drivlinor är bränsleförbrukningen i hög gradkopplad till drivlinans verkningsgrad. Även om drivlinans verkningsgrad inte ären linjär prokukt av komponenternas verkningsgrad behöve rden analyseras somen sekvens av energiomvandlingar, inklusive förluster och energipåverkan mellankomponenter.Detta examensarbete syftar till att undersöka energiförluster och flöden samtpresentera dessa i form av sankey diagram. Senare utvecklas ett anpassningsbartenergihanteringssystem baserat på nuvarande regelbaserad kontrollstrategi. Deninledande delen involverar utvecklandet av energianalys i GT-SUITE som motsvararfordonsmodellen, beräkningar av totala energiförluster och flöden samt presentationav dessa i ett sankey diagram. Den andra delen innefattar optimering avenergihanteringssystems kontrollparametrar enligt olika representativa körcykler.Den tredje delen involverar utveckling av anpassningsbara energihanteringssystemgenom användning av optimala kontrollparameterar baserad på detektering avkörbeteende med hjälp av SVM ( stödvektormaskin).Slutligen, ett strukturerat sätt att generera sankey diagrammet har med framgånggenererats och visat sig vara ett effektivt verktyg för studier av HEV drivlinorseffektivitet och bränsleekonomi. Dessutom visar kombinationen av detektering avkörbeteende och optimerade kontrollparametrar på en markant potentiell förbättringi bränsleförbrukning.

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27

Li, Hong. "Measuring systems for active steering of railway vehicles". Thesis, Loughborough University, 2001. https://dspace.lboro.ac.uk/2134/6790.

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This thesis studies measuring systems for active steering of railway vehicles. The aim of the study is to develop state estimation techniques to provide high integrity feedback variables for the active steering of railway vehicles. Practicality and provision of high-integrity data are two important aspects of the work. To avoid the use of expensive sensors and complex instrumentation, practical techniques for estimating vehicle variables are developed where only economical measurements are used and they can be easily implemented. The conventional solid-axle wheelset and wheelset with independently-rotating wheels are studied and their mathematical models are developed. The fundamental stability problem of these two models is analysed from a control engineering viewpoint for studies of actively-controlled wheelsets. The Kalman filters are then developed for these models to estimate all state variables, particularly variables of the wheelset relative to the track such as lateral displacement and yaw angle which are needed for active control. A number of sensing options are also identified, analysed for performance and assessed in a comparative sense. Fault detection and isolation schemes are then studied for the estimation techniques developed. Finally, some applications are considered. The techniques and analysis methods developed for the single wheel pair are extended and applied to a MKII coach and a two-axle railway vehicle. The estimation of cant deficiency for tilting trains is explored, and also the possibility of state estimation for a real profiled wheel.

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28

Kasliwal, Suvansh. "Development of Active Rear Wheel Steering and Evaluation of Steering Feel". Thesis, KTH, Fordonsdesign, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-265599.

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In the last few years, with the development of sensor and actuator technology along with increased computation power available on-board of vehicles, the automotive industry is em-ploying more and more mechatronic systems for Advanced Driver Assistance Systems (ADAS) and Autonomous Driving (AD). Driver Assistance Systems are being used to increase safety (eg. Electronic stability program, lane keep assist etc.), reduce drive fatigue (eg. Electronic power steering) and of increasing vehicle performance and handling (eg. torque vectoring).‚is thesis explores one such driver assistance system, the Active Rear Wheel steering (ARWS) system, which is capable of increase the stability and handling of the vehicle at high speeds and reduce driver fatigue at very low speeds (such as parking manoeuvre). ‚e thesis starts by discussing the history and present state of art of ARWS systems and the control algorithms used for it. ‚en, e‡ort is put in to develop tests and objective metrics to evaluate the per-formance of the system compared to a passive vehicle. ‚ese metrics are of importance in situations where subjective driver feedback is either not available at all (such as computer simulations) or when data is needed to back up the driver feedback (inexperienced drivers).‚ese objective metrics can help the design engineer to evaluate and even predict vehicle’s performance during the design and tuning phase.‚e thesis then deÿnes how the ARWS system should beneÿt the handling of the vehicle along with certain undesired behaviour that may arise due to ARWS and should be avoided.‚is was done based upon feedback from experienced drivers and engineers along with inputs from various literature.‚e Sliding Mode Control (SMC) algorithm is chosen for the control of ARWS system due to it relative simplicity and robust performance. ‚e SMC theory is presented and then the con-troller is developed along with the reference model. ‚e controller is then put in a So›ware-in-Loop environment with IPG CarMaker and put through various test scenarios for tuning and evaluation purposes. ‚e results suggest that the system improves the vehicle’s handling.‚e last part of the thesis looks into the steering feel and its objectiÿcation along with how the AWRS system in…uences the steering feel compared to that of a passive vehicle.
Under de senaste åren har bilindustrin använt mer och mer mekatroniska system för avancerade förarstödsystem (ADAS) och autonom körning (AD) med utveckling av sensor- och aktuatorteknik tillsammans med ökad beräkningskraft som finns tillgänglig i fordonen. Förarstödsystem används för att öka säkerheten (t.ex. elektroniskt stabilitetsprogram, körfältassistans etc.), minska förarutmaning (t.ex. elektronisk servostyrning) och öka fordonens prestanda och köregenskaper (t.ex. vridmomentvektorering). Avhandlingen utforskar ett sådant system för förarhjälp, vilket kan öka fordonets stabilitet och hantering vid höga hastigheter och minska förarens utmätning vid mycket låga hastigheter (t.ex. parkeringsmanövrering), ARWS-systemet (Active Rear Wheel steering). Avhandlingen börjar med att diskutera ARWS-systemets historia och nuvarande teknik samt de regleralgoritmer som används för det. Därefter utvecklas test och objektiva mätvärden för att utvärdera systemets prestanda jämfört med ett passivt fordon. Dessa mätvärden är viktiga i situationer där subjektiv föraråterkoppling inte är tillgänglig alls (t.ex. datorsimuleringar) eller när data behövs för kopplingen (oerfarna). Dessa objektiva mätvärden kan hjälpa designingenjören att utvärdera och till och med förutsäga fordonets prestanda under design- och utvärderingsfasen. Avhandlingen definierar hur ARWS-systemet ska gynna hanteringen av fordonet tillsammans med vissa oönskade beteenden som kan uppstå på grund av ARWS och som bör undvikas. Detta gjordes baserat på feedback från erfarna förare och ingenjörer tillsammans med ett antal uppslag ur litteratur. Algoritmen för föraråterkoppling (SMC) väljs för styrning av ARWS-systemet på grund av den relativt enkla och robusta prestandan. SMC-teorin presenteras och sedan blir regulatorn utvecklad från början tillsammans med referensmodellen. Regulatorn körs sedan i en Software-in-Loop-miljö med IPG CarMaker och säker igenom olika testscenarier för avstämning och utvärdering. Resultaten visar på att systemet förbättrar fordonshanteringen. Den sista delen av avhandlingen undersöker styrkänslan och dess objektivering tillsammans med hur AWRS-systemet påverkar styrkänslan jämfört med hos passiva fordon.

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29

Rehnberg, Adam. "Vehicle dynamic analysis of wheel loaders with suspended axles". Licentiate thesis, Stockholm : Farkost och flyg, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4677.

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30

Robla, Sánchez Ignacio. "Wheel Wear Simulation of the Light Rail Vehicle A32". Thesis, KTH, Spårfordon, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-261228.

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During the last decade, a novel methodology for wheel wear simulation has been developed in Sweden. The practical objective of this simulation procedure is to provide an integratedengineering tool to support rail vehicle design with respect to wheel wear performance and detailed understanding of wheel-rail interaction. The tool is integrated in a vehicle dynamicssimulation environment.The wear calculation is based on a set of dynamic simulations, representing the vehicle, the network, and the operating conditions. The wheel profile evolution is simulated in an iterativeprocess by adding the contribution from each simulation case and updating the profile geometry.The method is being validated against measurements by selected pilot applications. To strengthen the confidence in simulation results the scope of application should be as wide aspossible in terms of vehicle classes. The purpose of this thesis work has been to try to extend the scope of validation of this method into the light rail area, simulating the light rail vehicleA32 operating in Stockholm commuter service on the line Tvärbanan.An exhaustive study of the wear theory and previous work on wear prediction has been necessary to understand the wear prediction method proposed by KTH. The dynamicbehaviour of rail vehicles has also been deeply studied in order to understand the factors affecting wear in the wheel-rail contact.The vehicle model has been validated against previous studies of this vehicle. Furthermore new elements have been included in the model in order to better simulate the real conditionsof the vehicle.Numerous tests have been carried out in order to calibrate the wear tool and find the settings which better match the real conditions of the vehicle.Wheel and rail wear as well as profile evolution measurements were available before this work and they are compared with those results obtained from the simulations carried out.The simulated wear at the tread and flange parts of the wheel match quite well the measurements. However, the results are not so good for the middle part, since themeasurements show quite evenly distributed wear along the profile while the results from simulations show higher difference between extremes and middle part. More tests would benecessary to obtain an optimal solution.

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31

Pálinkó, Márton. "Estimation of wheel-rail friction at vehicle certication measurements". Thesis, KTH, Spårfordon, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-203818.

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In certiﬁcation of new rail vehicles with respect to running characteristics, a wide variety of operating conditions needs to be considered. Behaviour on straight and curved tracks, including twisted tracks at various speeds, is of great importance. However, the wheel-rail friction should always be high corresponding to dry conditions. It means that the certiﬁcation tests have to be carried out during dry weather conditions and unlubricated rails. But measuring the friction at test conditions is a great challenge.Therefore, in a recent work (Petrov et al.), an algorithm was proposed for the continu-ous estimation of wheel-rail friction along both rails. The algorithm is based on wheel-rail forces in all three directions (Y, Q, X ) for both wheels in a wheelset, lateral contact po-sition on its wheels and wheelset angle of attack. The algorithm was evaluated with a ﬁctional vehicle with vehicle-track dynamics simulations on various tracks (straight and curves) and track irregularities.In cooperation with SNC Lavalin (formerly Interﬂeet Technology), an opportunity arose to get the required data from on-track tests. In this way, all nine quantities above were measured during test runs of a new vehicle, so the algorithm could be evaluated under realistic conditions. The tests in tight curves of radius 150 m are used in the present work for this purpose. The measured data and the algorithm were processed in a Matlab program to get the friction estimate. Apart from the friction, the creepages and spin are also estimated with the aim to serve as quality indicators of the estimated friction.As the vehicle measurements include noise, errors and uncertainties, a statistical tool was introduced. Moreover, a sensitivity analysis was performed. It was observed that in these tight curves, the friction estimation on the outer wheel is poor, but a phenomenon arose that with increasing spin corresponding to even higher contact angle the friction might be estimated again. However, small spin gives a good friction estimation provided the total creep is high enough. Therefore, sharp curves, traction/braking or large track irregularities are necessary to estimate the friction well.In order to continue the work deeper into the area, other tests with the above scenarios would be useful
Vid certifiering av nya spårfordon med avseende pa gångegenskaper, behöver hänsyn tas till ett stort antal driftsförhållanden. Fordonets beteende på rakt, krökt och skevt spår vid olika hastigheter har stor betydelse. Dock måste hjul-räl friktionen alltid vara hög motsvarande torra förhållanden. Detta betyder att proverna för certifieringen alltid måste ske under torra väderförhållanden med osmorda räler. Att mäta friktionen vid dessa förhållanden ar en stor utmaning. På grund av detta har, i ett tidigare arbete (Petrov m..), en algoritm föreslagits för kontinuerlig uppskattning av hjul-räl friktion längs båda rälerna. Algoritmen baseras på hjul-räl friktioner i tre riktningar (Y, Q, X) för båda hjulen i ett hjulpar, deras laterala kontaktpunkter, samt hjulparets attackvinkel. Algoritmen utvärderades med ett fiktivt fordon med fordon-/ spårdynamiska simuleringar på både rakspår och kurdspår samt med spårlägesfel. I samarbete med SNC Lavalin (tidigare Intereet Technology), uppstod en möjlighet att få data från verkliga test. På detta sätt kunde alla nio ovan nämnda kvantiteter mätas under provkörningar av ett nytt fordon, och på så sätt utvärdera algoritmen under verkliga förhållanden. I denna uppsats har test i snäva kurvor med en radie på 150 m använts i detta syfte. Uppmätta data och algoritmen behandlades i ett MATLAB-program för att få fram en uppskattning av friktionen. Förutom friktionen, har även kryp och spinn uppskattats, med målet att kunna använda dessa som kvalitetsindikatorer för den uppskattade friktionen. Eftersom att mätdata innehöll brus, fel och osäkerheter, har ett statistiskt verktyg använts. Utöver detta har även en känslighetsanalys utförts. Det observerades att den uppskattade friktionen på det yttre hjulet i så pass snäva kurvor var låg, men att ett fenomen uppstod där ökat spinn motsvarande en ännu högre kontaktvinkel gjorde att friktionen kunde uppskattas igen. Litet spinn ger god friktionsuppskattning förutsatt att det totala krypet är högt nog. Därför är snäva kurvor, drivning/bromsning eller stora spårlägesfel nödvändiga för att på ett tillfredsställande sätt kunna uppskatta friktionen. För fortsatt fördjupning inom området skulle er prov inom ovannämnda scenarier vara användbara.

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32

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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33

O'Connell, Sean Paul. "A theoretical and experimental investigation of wheel shimmy". Thesis, University of Salford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308221.

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34

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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35

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.

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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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36

Korhonen, Daniel. "Wheel alignment method feasibility study". Thesis, KTH, Fordonsdynamik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-280555.

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Throughout the history of motor vehicles, the tyres have always been consideredas one of the most important components of the vehicle due to their interactionwith the road. One important aspect is the wheel alignment, with the purposeto adjust the static wheel angles that are essential for many reasons, such assafety and fuel consumption for instance. Despite the numerous methods forwheel angle measurements, there seems to be no existing technical solutionbased on computer vision, that is suitable for residential use, regarding bothcost and size of the equipment. The study aims to investigate the feasibility ofsuch a system.The proposed system is based on planar fiducial markers called ArUco.From images or video frames of the marker, the pose of the marker can beestimated. Thus, by placing such markers on the ground, on the wheel andon the vehicle, the estimated pose of the markers can be used to measure andcalculate the wheel alignment parameters. Only toe and camber angles aremeasured within the scope of this thesis, even if the system has the potential tomeasure other wheel alignment parameters as well.After camera calibration, simplified ArUco marker tests were done by measuringthe known displacement and inclination of a marker with respect to areference marker. The mean absolute error was 030400 and 0:024mm for theinclination angle and displacement, respectively. Furthermore, the toe and camberangles of a vehicle were measured and compared to reference measurementsperformed with a commercial wheel alignment system, giving mean absoluteerrors of 0520 and 0280 for the camber and toe angles, respectively. Despitethe relatively large errors for the toe and camber angle measurements, theresults from the initial inclination and displacement tests show the potential ofthe system. In addition, several error sources and suggestions for improvementcan be identified.As a conclusion, the proposed system can be considered a working firstprototype, which after improvement and optimisation has the potential tobecome a feasible alternative, especially for residential use and for mobileworkshops due to the low cost, size and usability of the system.
Inom fordonstekniken har däcken alltid betraktats som en av fordonets viktigastekomponenter på grund av deras interaktion med vägen. En viktig aspektär hjulinställning, med syftet att justera de statiska hjulvinklarna som är viktigaav många anledningar, som exempelvis säkerhet och bränsleförbrukning.Trots flera metoder för mätning av hjulvinklar verkar det inte finnas någonbefintlig teknisk lösning baserad på datorseende, som är lämplig för privat brukbåde gällande kostnad och storlek på utrustningen. Syftet med studien är attundersöka genomförbarheten för ett sådant system.Det föreslagna systemet är baserat på plana ArUco-markörer. Från bildereller bildrutor i en video av markören kan dess läge uppskattas. Genom attplacera sådana markörer på marken, på hjulet och på fordonet, kan såledesmarkörernas uppskattade lägen användas för att mäta och beräkna hjulvinklarna.Endast toe- och cambervinklar mäts inom ramen för detta examensarbete, ävenom systemet också kan mäta andra hjulvinklar.Efter kamerakalibrering utfördes enkla ArUco-markörtester genom att mätaden kända förskjutningen och vinkeln av en markör i förhållande till en referensmarkör.De genomsnittliga absoluta felen var 030400 och 0:024mm förvinkeln respektive förskjutningen. Vidare mättes toe- och cambervinklar påett fordon och jämfördes med referensmätningar utförda med ett kommersiellthjulinställningssystem. De genomsnittliga absoluta felen var 0520 och 0280för camber- respektive toevinkeln. Trots de relativt stora felen i mätningarnaav toe- och cambervinklar visar resultaten från de första testerna systemetspotential. Dessutom kan flera felkällor och förslag till förbättringar identifieras.Som en slutsats kan det föreslagna systemet betraktas som en fungerandeförsta prototyp, som efter förbättring och optimering har potential att bli ettmöjligt alternativ, särskilt för hemmabruk och för mobila verkstäder på grundav låga kostnader, systemets ringa storlek och användbarhet.

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37

White, Darris L. "Statistical Characterization of Vehicle and Track Interaction Using Rail Vehicle Response and Track Geometry Measurements". Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36835.

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This study evaluates the dynamic interaction between rail vehicles and the track on which they travel. The measurements were analyzed in the time and frequency domain. The effects of external parameters such as the vehicle design, subgrade stiffness, and degree of curvature were analyzed and compared for both the vehicle response and the track geometry data. This study was conducted in close cooperation with the Transportation Technology Center, Inc. (TTCI) in Pueblo, Colorado. The track and vehicle response data was collected on the High Tonnage Loop at TTCI over a span of approximately ten years. For the purpose of this study, TTCI provided this data to the Advanced Vehicle Dynamics Laboratories (AVDL) at Virginia Tech. The analysis of the data was first completed for the vehicle response and track geometry measurements separately. In this manner, the effects of the subgrade stiffness, the degree of curvature, and the vehicle design could be evaluated for each of the measurements. The analysis of the track and rail vehicle response was successfully completed, and the results from this analysis are presented in the following chapters. The analysis showed that the subgrade stiffness had a significant effect on the vertical wheel loads, the track crosslevel, and the track gauge. For an increase in the degree of curvature, the variation of the crosslevel increased. The dynamic response of the vertical and lateral wheel loads showed a significant dependence on the alignment of the rails. Improvements for future studies of the interaction between the track and rail vehicles have been recommended.
Master of Science

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38

Tinker, Matthew Michael. "Wheel loader powertrain modeling for real-time vehicle dynamic simulation". Thesis, University of Iowa, 2006. http://ir.uiowa.edu/etd/75.

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39

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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40

El-Bayoumi, Mahmoud Attia M. "Wheel speed distribution control and its effect on vehicle handling". Thesis, University of Leeds, 2007. http://etheses.whiterose.ac.uk/641/.

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The current work aims at bridging the gap between the current vehicle handling characteristics and the future demands of higher vehicle handling performance, required to guarantee higher safety and facilitate the application of autonomous driving, platooning and automated highways systems. For this task a state 'of the art vehicle chassis control system known as "Wheel Speed Distribution Control" (WSDC) has been proposed. WSDC in principle relies on controlling the vehicle driven wheel speeds to enforce better vehicle handling performance. The WSDC system capacity has been investigated using numerical simulation. Tberefore, an innovative vehicle handling simulation model has been developed from first principles. It employs the Magic Formula (MF) tyre model for combined slip, has 23 degrees of freedom and includes more than 60 vehicle handling parameters. The vehicle handling model has been developed using the novel Cartesian Geometric Translation (CGf) technique which employs geometry, trigonometry, Cartesian coordinates and finite difference approximation in the time domain to facilitate development of high speed models. The model has been built using the BASIC'O programming code in the DOS'O environment and optimised to meet the novel Model Predictive Control (MPC) based feedforward WSDC yaw rate controller requirements, such as small code size (less than 35 kb) and processing speed faster than real time. The simulation results validated the WSDC principles as it showed the capacity of WSDC to enforce the desired yaw rates, with acceptable driven wheel longitudinal forces. To put WSDC into practice,an original hardware" Wheel Speed Distribution Differential" (WSDD) design has been developed and optimised for lower speed, torque, power,production and maintenance requirements.It has the capacity to precisely differentiate the driven wheels speed under the influence of a DC motor with relatively small power requirements. It has linear speed and torque characteristics which facilitate its control. It also has been developed to allow many beneficial differential modes. The simulation results of the whole WSDC system have clearly demonstrated that it can in fact achieve its development target of feasibly enhancing vehicle handling performance.

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41

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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42

Plantenberg, Detlef Holger. "Adaptive motion control for a four wheel steered mobile robot". Thesis, Nottingham Trent University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341262.

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For adaptive motion control of an autonomous vehicle, operating in a generally structured environment, position and velocity feedback are required to ascertain the vehicle location relative to a reference. Whilst the literature offers techniques for guiding vehicles along external references, autonomous vehicles should be able to navigate between despatch locations without the need to rely on external guidance systems. Considerations of the vehicle stability and manoeuvrability favour a vehicle design with four independently steered wheels. A new motion control methodology has been proposed which utilises the geometric relationship of the angular displacements and the rotations of the wheels to estimate the longitudinal and lateral motions of the vehicle. The motion controller consists of three building blocks: the motion control system comprising the position tracking and the motion command generation; the electronic system comprising a data acquisition system and proprietary power electronics; the mechanical system which includes an undercarriage enabling permanent contact of the wheels with the floor. The components have been designed not only to perform optimally in their specific functions but also to ensure full compatibility within the integrated system. For reliable deduction of the wheel rotations with a high degree of accuracy a dedicated data acquisition interface has been developed, which enables data to be captured in parallel from four optical encoders mounted directly on the wheel axles. Parallel sampling of the angular wheel position and parallel actuation of all steering motors improves the accuracy of the system state and gives a higher degree of certainty. Considering only circular motion of the vehicle, a method for calculating the steering angles and wheel speeds based on the complex notation is presented. By cumulating the displacement vectors of the vehicle motion and the location of the centre of rotation between consecutive samples of the controller, the path of the vehicle is estimated. The difference between the nominal and the deduced centre of rotation is determined to minimise deviations from the reference trajectory and to allow the controller to adapt to changes in the road/tyre interface characteristics. The individual mechanical and electronic components have been assembled and tested. Additionally, the performance of the electronic interface has been evaluated on a purpose built test-bed. For the experimental validation of the methodology, a simple method of mapping the centre of curvature with a pen mounted at the nominal centre of rotation has been proposed. Experiments have been conducted with both the steering angles fixed to their theoretical values for the nominal centre of rotation and with the proportional steering controller enabled. The results from the latter method have shown a significantly reduced deviation from the nominal centre of rotation. The data captured of the angular wheel positions and steering angle settings has been analysed off-line. Good agreement is obtained between the deduced and the actual centres of rotation for the measurements averaged over 1.5 seconds. A number of different centres of rotation have been investigated and the required steering angles to compensate for the deviation have been plotted to form a control surface for the motion controller. The deviation between the estimated and the actual centre of curvature was less than 1.6% and adequate results could be obtained with the proportional steering controller.

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43

Powell, Andrew. "On the active guidance of railway vehicles". Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/27142.

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The conflict between stability and curving has been well documented since the dawn of the railways. Advances in computer technology and deeper understanding of the complex mechanics of the wheel-rail interface have led to the study of innovative designs. This thesis outlines the need for steering systems for railway applications. A number of innovative passive solutions have been proposed to reduce the conflict between stability and curving. Comparisons of some of these solutions show that significant benefits can be obtained by using uncommon configurations.

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44

Batsios, Nicholas. "Design and construction of a multi-segment snake-like wheeled vehicle". Ohio : Ohio University, 1997. http://www.ohiolink.edu/etd/view.cgi?ohiou1177610642.

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Masouleh, Mehdi Imani. "Optimal control and stability of four-wheeled vehicles". Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:c55c3e9c-270c-4d47-b5f8-e86621608b24.

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Two vehicular optimal control problems are visited. The first relates to the minimum lap time problem, which is of interest in racing and the second the minimum fuel problem, which is of great importance in commercial road vehicles. Historically, minimum lap time problems were considered impractical due to their slow solution times compared with the quasi-steady static (QSS) simulations. However, with increasing computational power and advancement of numerical algorithms, such problems have become an invaluable tool for the racing teams. To keep the solution times reasonable, much attention still has to be paid to the problem formulation. The suspension of a Formula One car is modelled using classical mechanics and a meta-model is proposed to enable its incorporation in the optimal control problem. The interactions between the aerodynamics and the suspension are thereby studied and various related parameters are optimised. Aerodynamics plays a crucial role in the performance of Formula One cars. The influence of a locally applied perturbation to the aerodynamic balance is investigated to determine if a compromise made in design can actually lead to lap time improvements. Various issues related to minimum lap time calculations are then discussed. With the danger of climate change and the pressing need to reduce emissions, improvements in fuel consumption are presently needed more than ever. A methodology is developed for fuel performance optimisation of a hybrid vehicle equipped with an undersized engine, battery and a flywheel. Rather than using the widely used driving cycles, a three-dimensional route is chosen and the optimal driving and power management strategy is found with respect to a time of arrival constraint. The benefits of a multi-storage configuration are thereby demonstrated. Finally, the nonlinear stability of a vehicle model described by rational vector fields is investigated using region of attraction (RoA) analysis. With the aid of sum-of-squares programming techniques, Lyapunov functions are found whose level sets act as an under-approximation to the RoA. The influence of different vehicle parameters and driving conditions on the RoA is studied.

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46

YANG, SHI-HAO y 楊世豪. "Real time dynamic simulation for four wheels vehicle". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/01984015789137773940.

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碩士
大葉大學
機電自動化研究所碩士班
94
The study is going to research the ten degrees of freedom mathematic model of vehicle dynamic. It includes three different direction of vehicle movement and three Euler angle. Furthermore, it also includes the suspention of four wheels. The formula for automobile movement is ten degrees of freedom which purpose is to investigate the longitudinal and lateral forces and the yaw rate of vehicle. In addition, the automobile’s stableness is also examined while a controller is assembled afterward. As stimulating, the steering wheel was quickly turning around while vehicle without controller but in low friction on the ground. This factor of low friction conducts the longitudinal and lateral forces of tyres decreasing. Therefore, it cannot maintain the steady of vehicle and make vehicle tend to be slipping. However, after assembling vehicle with controller, the situation has been controlled. The controller would control one of the front wheels in order to increase or decrease the yaw rate. Throughout the stimulation, we understand the relationship between steering wheel and yaw rate. Moreover, after examining the angular magnitude of steering wheel we also obtained the variation between them. We applied these two message and their variation, the controller of vehicle steady was been designed. Plus, the stimulation of vehicle’s movement as well as the result were achieved.

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47

SHIH, JIAN-CHENG y 施建成. "The Mecanum Wheels Application on Automatic Guided Vehicle". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/995pnh.

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碩士
大葉大學
自行車創新產業碩士專班
106
Automated Guided Vehicle(AGV) has already being indispensable transportation system nowadays. The purpose of this paper is to develop AGV with Mecanum Wheel by using App controller. Because of Mecanum Wheel characteristic, AGV can easily spin in narrow place. Structure design utilize ANSYS Computer Aided Simulation to prediction internal stress in wheel sets and axis of motor. To investigate work principle、program design、develop App Inventor interface. In control, motor us 24V high piezoelectricity matching with 24V motor controller VNH5019. In develop process, use Arduino MEGA2560 to develop control board, combine with Breadboard to prevent the problem of not enouth pin. Make VNH5019 do positive negative switch through CD4069 inverter. Utilize Mecanum Wheel can replace traditional wheel in AGV, in addition it can work in narrow place to save space, it also can application in item transportation system of multiple industries. This article application software and development control system of AGV with Mecanum Wheel.

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48

Cheng, Pi-Lun y 鄭弼倫. "Integrating of the Front-Vehicle Shadows and the Wheels for Vehicles Detection on Freeway". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/15606964189335771683.

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碩士
國立中正大學
電機工程研究所
100
In this thesis, we follow the direction of the previous research using vehicle shadows to detect the existence of the front-vehicles. In addition to this, the symmetry of the rear wheels is adopted to confirm the above detection. Although the front-vehicles are not necessarily aligned, sometimes forming certain angles, the use of the shadows will distinguish the real span of the rear wheels. By this scheme, it may increase the recognition rate or extend the recognition distance. With this reliable design, it can be developed into a driver assistance system. It can tract the front vehicles, estimate the distances, alert the driver if the car is too near to the front-vehicle, or deviates from the current driving lane, etc. To give the driver a convenient assistance. The system development is based on the C language with a dual-core computer. It uses the OpenMP (Open Multi-Processing) multi-threaded programming techniques to allow the system to improve the overall performance speed of execution. It is sufficient to meet the highway needs of immediate and fast processing.

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49

Van, Niekerk J. O. "Acoustic wave propagation in steel rails, excited by flat vehicle wheels". Thesis, 2012. http://hdl.handle.net/10210/6461.

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The aim of Spoornet is to provide a minimise predictable service. In order to provide a predictable service, it is necessary to move trains safely and effectively from the place of departure to their destination. The keywords here are safely and effectively. Although support functions such as infrastructure and train control procedures are vital in moving the train, the train or rolling stock as it is generally known, warrants some attention. Defects on the rolling stock are very costly to Spoornet. This is mainly due to the fact that a defect on the rolling stock that goes undetected can cause damage to the rolling stock and the infrastructure. This damage can eventually lead to derailments. Considering that a derailment can cost Spoornet millions of rand and cause delays to the services, it is only logical to spend time preventing derailments. It is for this reason that a workgroup was formed to investigate and solve the problem of defects causing derailments and delays by developing an early warning system. The need for an integrated train condition monitoring system became apparent when considering an early warning system. The objectives of the integrated train condition monitoring system are to provide train condition information to different users, and alarms on detection of emergency or dangerous conditions. Various train defects that may cause damage or derailments were identified. One of them being a flat wheel on a rail vehicle. A flat wheel is characterised by the flattening of the wheel on one or more positions on its circumference, so that the wheel does not have an even and completely round profile. Flat wheels are mostly caused by the wheels of a vehicle becoming locked during braking, and sliding along the rail track. The friction created by this action grinds a flat spot on the wheel. The flat wheel leads to a decline in the riding quality of the rolling stock and a rise in the levels of vibration and noise is evident. But more importantly, the flat spot causes the wheel to roll unevenly, creating impacts on the rail on some points. It is these impacts that can cause damage to the rail and the rolling stock. Depending on the length of the flat spot, the vehicle type and speed, the stresses may be sufficient to cause final failure of the rail or initiate fatigue cracks in the rail. Severe flat wheels are a safety hazard and can in some cases, cause derailments and consequent delays to trains. Smaller flat spots contribute to track deterioration and so increase maintenance costs by damaging the rails, sleepers and ballast. Flat wheels can thus be very costly to Spoornet and its public image. In addition to safety and economic considerations, wheel flats reduce the comfort levels in the passenger coaches and the noises they make is annoying. In an attempt to restrict the damage caused by flat wheels, most railway administrations place a limit on the length of the flats that may stay in service. But to effectively find a flat wheel on rolling stock is currently a very expensive exercise. Flat wheels can be detected by an audible knocking sound when standing next to the rail. This sound is impossible for the driver to hear and therefore goes undetected. Normally flat wheels are detected by random inspection of the rolling stock or when they are brought in for a routine service. The service cycle on rolling stock can be up to 24 months in Spoornet. Considering that a flat wheel has an impact roughly every 3m, a serious flat generates roughly 160 000 impacts on a single trip on the coal heavy haul export line. It is therefore clear that a flat wheel can cause a considerable amount of damage between service cycles. The severity of the problem is however not accurately defined in Spoornet, because up to a few months ago there was no detection system in use to determine the distribution of flat wheels. The research department of the Deutsche Bundesbahn however considers rail fractures due to the flat wheels to be a serious problem with a significant annual replacement cost. There are thus sound safety and economic reasons for wishing to understand the mechanisms of flat wheels and to develop an early warning system using an automatic detector.

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50

Lin, Fu-Yang y 林福揚. "Implementation of vision-based path following for four wheels drive electric vehicle". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/288d7m.

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碩士
國立臺灣科技大學
機械工程系
105
The control architecture of this visual guided electric vehicle is consisted of a FPGA embedded system for the electric vehicle driving control and a PC for the image processing and data analyzing of laser ranger finder called driving decision making system. Two systems are communicated with a UART interfere. In this study, the vehicle visual guided driving process can be classified into three parts. Firstly, the road image ahead of vehicle is captured by using camera. The image pre-processing schemes are used to obtain multi-lane marking image coordinates information. Then, the Homography Matrix technology is used to convert the information into the world coordinate system for target trajectory tracking. Secondly, the vehicle current location is estimated by using the car kinematic model with four-wheels and steering encoders as feedback signals. Then the relative position error between target point and the vehicle current position can be founded. Finally, the pure pursuit geometric tracking control algorithm is used to calculate the steering angle correction command for closed loop trajectory tracking control purpose. If there is an obstacle in front of the vehicle-driving path, the obstacle avoidance path planning will be generated based on acquired multi-lane image information and the laser ranger finder data. These image processing schemes, lane following algorithm, driving decision making and obstacle avoidance strategy are implemented on a lab made four- wheel drive electric vehicle for campus playground driving test.

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