Littérature scientifique sur le sujet « Casted wheel centres »

When a car is cornering, its wheels usually lean away from the centre of rotation. This phenomenon decreases lateral force, limits tyre performance and eventually reduces the vehicle lateral grip capacity. This paper proposes a strategy for varying caster in the front suspension, thereby altering the wheel camber to counteract this outward inclination. The homogeneous transformation was utilised to develop the road steering wheel kinematics which includes the wheel camber with respect to the ground during a cornering manoeuvre. A variable caster scheme was proposed based on the kinematic analysis of the camber. A rollable vehicle model, along with a camber-included tyre force model, was constructed. MATLAB/Simulink was used to simulate the dynamic behaviour of the vehicle with and without the variable caster scheme. The results from step steer, ramp steer, and sinusoidal steer inputs simulations show that the outward leaning phenomenon of the steering wheels equipped with the variable caster, is reduced significantly. The corresponding lateral acceleration and yaw rate increase without compromising other handling characteristics. The actively controlled car, therefore, provides better lateral stability compared to the passive car. The tyre kinematic model and the vehicle dynamic model were validated using multibody and experimental data.

A 6 degrees of freedom shimmy model for four in-wheel motors independent drive electric vehicle with independent front suspension is established, and numerical analysis and simulation are used to study the dynamic response of vehicle shimmy. The influence of electric vehicle driving system on shimmy is studied by comparing with fuelengined vehicle, and the influence of vehicle structural parameters such as the caster angle, the inclination angle of front suspensions and the centre of gravity of vehicle on shimmy are studied too. It shows that as the in-wheel motor in drive system increases the weight of wheel, the amplitude of each degree of freedom in electric vehicle are larger than in fuel-engined vehicle when vehicle shimmies. The influence of the caster angle and the centre of gravity of vehicle on vehicle shimmy is obvious, but the inclination angle of front suspension have little influence.

The bronze deposits from Resenlund and Brøndumgård In the Late Bronze Age, bronze deposits in fields and bogs constitute a large part of the archaeological material. Huge values were deposited in the ground during this period, and the archaeological material witnesses a wide-ranging custom of sacrifice. The deposits are therefore central to the understanding of the societies, which once left their items in the ground, and new finds contribute to a more varied impression of the picture already existing of the Late Bronze Age. This article presents two hitherto unpublished deposits from the Early Bronze Age, both from Northern Jutland. These deposits contain bronze objects, which may throw new light on the ritual practice of the North Jutland society and its social identity during period IV (1100 BC - 900 BC).The composition of the Brøndumgård depot is special in that it contains part of hitherto unknown artefacts. The depot consists of a belt plate, fragments of at least two cuff-shaped bracelets, fragments of three mounts, a bronze ring, a sickle, two four-spoke wheel pendants, an eight-spoke wheel pendant, part of a neck ring with the head of a horse, and five bronze nuggets. The belt plate and fragments of a cuffshaped bracelet date the find to period IV. The decorations on the eight-spoke wheel pendant and the mounts also point towards period IV. The dating of the find is thus hardly questionable. The Brøndumgård depot was probably buried in a double- conic earthenware pot. The deposit was found at the bottom of a ridge originally marking the border of a wetland area. Several prehistoric mounds are preserved on top of the ridge. The location of the find – in a border area between firm ground and wetlands – indicates that the deposit should probably be interpreted as a wetland sacrifice; a gift to the gods at the edge of a bog, which was considered a magical gateway between the world of the humans and the supernatural during large parts of prehistory.The original use of the mounts is difficult to determine. Their form does not indicate a use as bucket mounts. Harness plates are another possibility, but so far, such horse mounts are not known from other finds. The bronze may have been fixed to the leather armour of a warrior, but no other finds support this theory. As a last suggestion, the mounts may have been fixed to the body of a carriage. The bronze ring supports this assumption. Apart from rings, the carriage mounts known from the Urnemark and Hallstatt Cultures include oblong, ornamented metal plates similar to the mounts from the Brøndumgård depot. It should be stressed that these are not imported mounts, as the decoration is very similar to the decoration occurring on the cuffshaped bracelets, which are considered a local Jutland product.Thus, cult wagons probably existed during the Late Bronze Age in Scandinavia. The question is: to what extent, and when? Already during the Early Bronze Age, the Trundholm Sun Chariot from Northern Zealand and the two-wheeled chariot from the rock carvings at Kivikgrav in South-eastern Scania indicate that the wagon had a central function in the iconography of the Early Bronze Age. We just lack finds of wagon parts in the archaeological material from the period to tell whether the pictorial representations of the Early Bronze Age reflect actual events.The use of wagons for ceremonies and cult processions can therefore probably not be compared to the Central European Urnemark Culture’s influence on Northern Europe until the Late Bronze Age. It is thus not until the emergence of the Urnemark Culture that the wagon plays a visible part in Central European cult. Here, the wagons are known from several well-preserved graves, which provide fine possibilities for reconstructing the look and function of the wagons. As a rule, the wagons have four wheels and a rather small body, which would have made them unsuitable for the transportation of large, heavy wagonloads. Furthermore, the body is decorated with metal plates. The rich ornamentation combined with the small, unpractical size and the fact that they were used as grave goods in rich graves all indicate that the wagons were used for processions connected to the Central European cult.In Denmark, we have but a few complete finds of wagon plates from the Bronze Age. In the absence of such complete metal plate finds, it is much more difficult to recognize metal plates as part of possible wagon ornaments. It is therefore necessary to intensify the attention concerning plates and other metal items, which may have been riveted onto wood. If such plates are found in connection with horse equipment, which naturally often occur in the same context as wagon parts, this may considerably strengthen their interpretation as wagon plates.Perhaps the eight-spoke wheel pendant should be interpreted as part of a horse’s equipment? Maybe as some sort of horse harness jingles attached to the bridle – although the eye for hanging seems too small compared with other finds of definite horse bridle jingles. In stead, the wheel pendant could have been attached to another part of the harness.The four-spoke type of wheel pendant has not previously been found in Scandinavia, but in a much larger version it is known from the Period II- grave from Tobøl in Western Jutland. The wheel with four spokes is also known from the Early Bronze Age iconography. As a pendant, the wheel with four spokes is a phenomena first occurring in Northern Europe at the same time as the Urnemark Culture begins to influence the form of objects in the Late Bronze Age. Probably, the four-spoke wheel – like the eight-spoke wheel – is from a horse’s harness.In Northern Europe, several deposits combining women’s jewellery and horse equipment are known from period V. The fact that these two artefact types are often found together in the deposits may reflect a fixed practice of some ceremony or cult act. Perhaps the deposits are really elements from a ceremonial procession – in which the wagon played a prominent part – sacrificed to the supreme beings. In the Brøndumgård depot, the women’s jewellery and horse equipment is even supplemented by possible wagon plates, and the find thus supports the hypothesis presented above that the ceremonial procession included women, horses, and a wagon. Women’s jewellery and the horse and wagon equipment were probably made by the same bronze caster, and perhaps the objects were meant to be a complete ceremonial outfit for a woman and a wagon. In the Bronze Age, it was not an unknown phenomenon that special jewellery sets were made as a complete whole, and it is therefore not altogether impossible that a complete set of equipment for a woman and a wagon were made by the same craftsman.Perhaps the depot is even containing the remains of a priestess’ equipment, ceremonial wagon included? In this respect, the Roman writer Tacitus’ retelling of the myth concerning the fertility cult of the goddess Nerthus is especially interesting – in spite of the fact that the myth was written down almost 1000 years later than the dating of the Brøndumgård depot. The horse-drawn chariot is central in Tacitus’ account, as each year, somewhere in the northern part of the free Germania, a procession with Nerthus in a horse-drawn ceremonial chariot passed from village to village to announce the coming of spring and fertility. The myth shows that the tradition of a ceremonial chariot was probably predominant in Northwest Europe during the Early Iron Age. It is therefore not unlikely that the ceremonial chariot, perhaps driven by a priestess, was part of the ritual practice in Jutland during the Late Bronze Age, and that it remained a strong tradition until the Early Iron Age.The Resenlund depot consists of three spiral arm rings, two sickles, a double button, three fragments of cuff-shaped bracelets, three parts of neck rings, a socketed spear head, a dress pin, a bronze celt, and part of a sword blade. All artefacts were probably of Scandinavian origin, possibly from the area around the Limfjord. It is not always possible to determine whether the depot was placed in a container, for instance a clay vessel. Several of the items were ruined prior to being deposited, whereas others were old and worn. The depot was probably deposited in the course of the Bronze Age period IV, between 1100 and 900 BC, as quite a few of the items date from this time.The depot thus comprises many different artefact types, and both weapons, women’s jewellery, and tools are represented. From the composition, the depot may be interpreted as a sacrifice representing a cult act managed by one or more wealthy peasants connected with arable land. The wear marks on the jewellery probably indicate that they were inherited items that may have been in the family’s possession for generations, before they were handed over to the ground. The depot itself may be interpreted as a sacrifice to the superior beings, perhaps to thank for success and fertility. At the same time, the sacrificial act itself may have helped support the position of the leading families in the local community.The two deposits from Resenlund and Brøndumgård were both deposited within the same area near the Limfjord between 1100 and 900 BC, and they both contain items with a form and an ornamentation specifically characteristic for this particular area. Both deposits were found in connection with water or wetlands, as is characteristic of the sacrificial practice of the Late Bronze Age culture in Scandinavia. However, the composition and context in the two deposits differ, and so the two finds tell individual stories.The composition of the Resenlund depot makes it interpretable as a sacred depot, with numerous different artefacts representing one or more peasant families. In favour of this interpretation is the fact that the depot contains items belonging to more women and at least one man, as well as a sickle, which may indicate that the sacrifice was connected to agriculture and fertility.The Brøndumgård depot may be part of a ritual procession sacrificed to the supreme beings. The women’s jewellery and horse and wagon equipment were probably made by the same bronze caster, and perhaps the items were meant as a complete ceremonial outfit for a priestess and her chariot. The Resenlund depot may reflect the cult act of one peasant family, which perhaps included people from a small neighbourhood – as opposed to the Brøndumgård depot, which may have been the remains of a ceremonial procession including a larger number of people. The deposits may thus be the result of two different ceremonies and cult acts made by different groups of society, but probably within the framework of the same fertility cult and practice of ritual sacrifice.Period IV of the Bronze Age was a very innovative era as regards the creation of new artefact types. Many new variants of women’s jewellery and other ornaments turn up in this period only to disappear again from the find material in period V. The variations within the ornaments are especially expressed within North and Central Jutland, to which a large number of artefacts are specific within period IV. They are artefact types, which were almost solely used in Jutland, and in this respect, this area differs from the rest of Scandinavia. Fig. 18 shows the artefacts that Evert Baudou considers special Jutland types, such as the specially ornamented bone buttons and pendants found in large numbers in graves in the Mid-Jutland area. To these special Jutland types, I would like to add the three wheel pendants from the Brøndumgård depot, which – with the five wheel pendants from the Sæsing depot – also constitute a special Jutland type during Period IV.The characteristics of the Jutland artefact types made Baudou suggest that judging from the unique artefact types in Jutland, we could be dealing with two tribal groups in Denmark during Period IV. A Jutland tribe mainly concentrated in North and Middle Jutland, and a tribe on the islands.The question is whether it is not too much of a simplification to divide Denmark into two tribes, as the artefacts reflect a more complicated situation. However, the idea of several regions having existed in the Danish area – individual cultural units with mutual contact – is not unlikely. The two wealth centres of Boeslunde in Western Zealand and Voldtofte on Southwest Funen may represent two independent regions in Denmark, to which the North- and Central Jutland period may be added as a third region due to its special artefacts. We thus get at least three regions in Denmark during the Late Bronze Age. In period V, we no longer have the same difference between South Scandinavian artefacts, and the distinctive character of the Jutland material seems to disappear. This does not mean that North and Central Jutland loose influence – on the contrary. However, we see a certain uniformity within the Nordic artefact material from Period V.In Period IV, North and Central Jutland was a region where people expressed their affiliation through the way they chose to decorate themselves. The area was probably inhabited by an independent people or tribe – assumed on the grounds that this is the place in Late Bronze Age Scandinavia where the find material mostly seems to reflect a region with unique artefact types expressing individual cultural traditions and a social identity.Jeanette VarbergInstitut for Antropologi, Arkæologi ogLingvistik, Aarhus UniversitetTranslated by Annette Lerche Trolle

In this thesis, a state of the art of the structural components of railway vehicles and the material used for their manufacturing is analyzed in order to find possible new applications for ADI (Austemperd Ductile Iron). The main scope of the research is therefore to demonstrate that high stressed steel components of railway vehicles can be replaced by casted ADI components. After a survey of the possible components to be produce in ADI, three possible applications were found: wheel centre for tyred wheels, bogie frame, couplers for heavy haul operation. A feasibility analysis was performed and after a preliminary design the project has been focused in the development of an optimized tyred wheel as replacement of the current wheel for an existing Diesel Multiple Unit (DMU). Prototypes of this wheel have been finally manufactured and tested in order to demonstrate the feasibility of the application of ADI to the structural components of railway vehicles.

Horror monsters such as the vampire, the zombie and Frankenstein's tragic creature have long been the subjects of in-depth cultural studies, but the werewolf has often been considered little more than the 'beast within': a psychoanalytic analogue for the bestial side of man. This book, the first comprehensive history of the werewolf in cinema, redresses the balance by exploring over 100 years of werewolf films, from The Werewolf (1913) to Wildling (2018) via The Wolf Man (1941), The Curse of the Werewolf (1961), Werewolves on Wheels (1971), The Howling (1981) and WolfCop (2014). Revealing the significance of she-wolves and wolf-men as evolving metaphors for the pervading fears and anxieties of their times, Phases of the Moon places its case studies in their immediate historical context to make clear that the hirsute horrors at the centre of the werewolf film have engaged with issues of race, class, gender, sexuality, crime, war and any number of other social and political concerns. It thus serves as a companion and a counterpoint to existing scholarship on the werewolf in popular culture, and illustrates how we can begin to understand one of our oldest mythical monsters as a rich, diverse and constantly shifting cultural metaphor.

AbstractThis chapter presents a maturity model for Data Spaces, which provides a management system with associated improvement roadmaps that guide strategies to continuously improve, develop, and manage the data space capability within their organization. It highlights the challenges with data sharing and motivates the benefit of maturity models. This chapter describes the Maturity Model for Data Spaces (MM4DS) and its use to determine an organization’s data space capability maturity. The MM4DS takes an organization’s user-centric/demand-side perspective utilizing a data space. The development process for the MM4DS is discussed, along with the role of design science in the model development process. Finally, the chapter details an illustrative case using the model to benchmark data space capabilities in five fictitious organizations. The MM4DS can be applied within organizations to better manage their data space capabilities, with assessment, providing insights into what they are doing well and where they need to improve.

Educational spaces across the world largely continue to be designed with little variance from the traditional industrial classroom model, and pedagogies seem stuck somewhere between the Sage-on-the-Stage, lecture-dominated paradigm, and the Guide-on-the-Side, in which the instructor acts primarily as an aide watching, encouraging, and monitoring students working on projects individually or in groups. Rather than “reinventing the wheel,” the authors argue for an academic environment based on the British coffee house or French café of the 18th and 19th centuries. Not only should this 21st-century classroom offer an innovative melding of space and technology but also introduce a new pedagogical model. The Meddler-in-the-Middle model repositions the teacher and students as co-facilitators in the creation and use of knowledge in an environment where bodies move seamlessly in and out of collegial collaborations filled with free-to-fail open debate.

This chapter begins with an analysis of the fraught organizational and economic circumstances of work with the target population, and the demands these place upon workers, illustrated with four extended case scenarios. After this, the chapter covers in broad terms the solutions that AMBIT seeks to offer, describing the coherent structure of AMBIT by means of its “wheel” diagram. Four main areas of activity to be held in balance make up the quadrants of the wheel: working with your client, your team, and your networks, and learning at work. These are surrounded by four sets of paired, and often mutually contradictory, elements of a principled stance for workers. Emphasis is placed on the inevitability of being out of balance, justifying attention to structures that support the restoration of balance, and longer-term sustainability. At the wheel’s center, the load-bearing “axle” is mentalizing, which Chapter 2 addresses.

The main idea of this chapter is to promote maintenance centered to safety, in accordance to adaptive fuzzy inference model, which has online adjustment to working conditions. Input data for this model are quality of service indicators of analyzed engineering system: reliability, maintainability, failure consequence, and severity and detectability. Indicators in final form are obtained with permanent monitoring of the engineering system and statistical processing. Level of safety is established by composition and ranking of indicators according to fuzzy inference engine. The problem of monitoring and processing of indicators comprising safety is solved by using the features that Industry4.0 provides. Maintenance centered to safety is important for complex, multi-hierarchy engineering systems. Sudden failures on such systems could have significant financial and environmental effect. Developed model will be tested in the final part of the chapter, in the case study of bucket wheel excavator.

The increasing complexity of modern ground vehicles is making crucial the role of control for improving energetic efficiency, comfort and performance. At the same time, the control software must be frequently updated in order to let the vehicle respond safely and efficiently within more sophisticated environments and to optimize the operations when new vehicle components are integrated. In this framework real-time hardware-in-the-loop simulations represent a fundamental tool for supporting the verification and validation processes of the control software and hardware. In this chapter a railway case study will be presented. The mathematical models of the most relevant electromechanical components of the vehicle powertrain are presented: the pantograph connected to an ideal overhead line with continuous voltage; the electrical components of a pre-charge circuit, the line filter and the braking chopper; the three-phase voltage source inverter and the induction motor; and, finally, the mechanical transmission system, including its interactions with the rail. Then the issues related to the real-time simulation of the locomotive components models are discussed, concentrating on challenges related to the stiff nature of the dynamic equations and on their numerical integration by combining field programmable gate array (FPGA) and central processing unit (CPU) boards. The usefulness of the real-time hardware-in-the-loop simulations for the analysis of railway control software will be demonstrated by considering the powertrains of two real metropolitan trains under complex scenarios, i.e., stator winding disconnection of the induction motor, pantograph missing contact, wheel-rail slipping phenomenon.

Vertical split rim (VSR) failures remain a failure mode for wheels in North America, and are of concern to wheel manufacturers and railroads alike. Both forged and cast wheels have suffered VSRs in service. Extensive testing during the last several years, using x-ray diffraction techniques, has shown the axial residual stress pattern within the railroad wheel rim is significantly different for new AAR Class C wheels vs. AAR Class C wheels that have failed due to a VSR, and non-failed AAR Class C wheels that have been operating in service. VSRs almost always begin at areas of tread damage, resulting from shelling or spalling, and cracking propagates into the rim section under load. At the rim locations tested, the as-manufactured wheels have a relatively “flat” axial residual stress profile, compressive but near neutral, caused by the rim quenching operation, while wheels that have been in service have a layer of high axial compressive stress at the tread surface, and a balancing zone of axial tensile stress underneath. The magnitude and direction of this axial tensile stress is consistent with the crack propagation of a VSR failure. When cracks from tread surface damage propagate into this subsurface axial tensile zone, a VSR can occur under sufficient additional service loading, such as loads caused by in-service wheel/rail impacts from tread damage. Further, softer Class U (untreated) wheels, removed from service and tested, were found to have a balancing axial tensile stress layer deeper below the tread surface than that found in used Class C wheels. This paper describes recent x-ray diffraction testing to measure the axial residual stress profile in wheel rims operated in the Facility for Accelerated Service Testing (FAST) train at the Transportation Technology Center (TTC), in Pueblo, CO. The goal of the testing was to determine the development rate and magnitude of wheel rim axial residual stress, as a function of known load and service mileage. Four new Class C wheelsets and four new Class U wheelsets were placed in service under the FAST train, and these wheelsets were subsequently removed at various mileage levels for evaluation. Two radial rim slices were cut from each wheel at each mileage level, and x-ray diffraction was used to measure the axial residual stress within the wheel rim section. The last two Class C wheelsets and last two Class U wheelsets were also exposed to an extended drag braking event at FAST, where wheel treads were heated by tread braking. The authors describe the testing and discuss the axial residual stress results in detail, with emphasis on implications for service.

A detailed analysis of the path traversed by the rear wheels of the bus is useful in highway design, and in the placement of curbs at intersections. In fact, when a bus turns a corner, the rear wheel could move into the path of a passing motorist or pedestrian by generating an hazard situation, as in the cases of traffic circles and changing lanes. Of course, the same problems regard long trucks, semi-trailer trucks and articulated vehicles, but also bicycles (tandem) and motorbikes. In particular, the path of the rear wheels of a bus or a long vehicle in general, is a tractrix or equi-tangential curve, which is different by that traced by the front wheels. The planar motion of the chassis of the vehicle can be represented by means of the centrodes, which are traced by the instant center of rotation on the ground (fixed centrode) and on the moving plane that is attached to the vehicle (moving centrode), respectively. Thus, the pure-rolling motion of the moving centrode that is represented by the axis of the rear wheel, on the fixed centrode (catenary) can reproduce the planar motion of the chassis. This paper deals with the formulation of a suitable algorithm for the kinematic analysis of the planar motion of vehicles that travel corners, traffic circles and changing lanes. The tractrix is considered as the involute of the fixed centrode (catenary), which takes also the rule of evolute. The inflection and the cuspidal or return circles, along with the Euler-Savary equation and the Aronhold Theorems, give other useful information on the planar motion of the chassis.

Abstract Although most wheeled robotic ground vehicles are either skid steered or differentially steered, there has been an increased interest in four independently driven all-wheel steering systems because of their torque density and maneuverability in tight turns. Controlling these vehicles requires coordination of the steering angles and wheel speeds such that the basic rigid body kinematic constraint on the instantaneous center of rotation (ICR) is satisfied. This makes them difficult to control except for simple cases where either the center of curvature for all turns is constrained to be along the perpendicular bisector to the longitudinal centerline of the vehicle or considerable wheel slippage is allowed to happen. Several efforts have been reported to address this problem, most of which tend to simplify the problem by extending the well-known bicycle model to these vehicles. This paper uses the Gibbs-Appel formulation to develop the equations of motion of a 4WD/4WS vehicle in the quasi-coordinate space while enforcing both the ICR and no slip constraints. Unlike the Lagrange-Euler and the Newton-Euler formulations that use Lagrange multipliers to handle constraints, which increases the dimension of the system, the Gibbs-Appell formulation results in a model of a relatively lower dimension. This model is not only easy to use in control design but also captures the dynamics of the vehicle by constraining the wheels to remain on the path. Simulation results using a simple feedback linearization controller showed the vehicle tracking the path more accurately without wheel slip where the wheels remained on the path all times.

Railway rolling noise is nowadays a major source of acoustic pollution in urban areas, with nearly up to 12 million people daily affected in Europe by this phenomenon [1]. Hence, the search for ways of decreasing such noise radiation has become a highly active and significant research field. Following this approach, a Genetic Algorithms-based shape optimization of the railway wheel [2] is developed with the aim of minimizing rolling noise. Different approaches are considered to address the problem, such as directly minimizing radiated Sound poWer Level (SWL) or using the maximization of the natural frequencies if computational efficiency is especially critical. A parametric Finite Element model is implemented for the wheel based on the most relevant geometric parameters in rolling noise radiation. For the acoustic calculation, the sound radiation models used in the TWINS software [3] are adopted, which also accounts for the whole dynamics of the wheel/rail system. Furthermore, for every candidate wheel proposed, a structural analysis is computed in order to check design feasibility in accordance with the corresponding standard [4]. In all cases, new geometries for the wheel cross section are achieved that reduce the radiated rolling noise. REFERENCES [1] WHO European Centre for Environment and Health, “Burden of disease from environmental noise”, WHO, Tech. Rep., 2011 [2] X. Garcia-Andrés, J. Gutiérrez-Gil, J. Martínez-Casas and F. D. Denia, “Wheel shape optimization approaches to reduce railway rolling noise”, Struct. Multidiscipl. Optim., Vol. 62, pp. 2555-2570, (2020). [3] D. J. Thompson, B. Hemsworth and N. Vincent, “Experimental validation of the TWINS prediction program for rolling noise, part 1: Description of the model and method”, J. Sound Vib., Vol. 193 (1), pp. 123–135, (1996). [4] UNE, “Railway applications. Wheelsets and bogies. Monobloc wheels. Technical approval procedure. Part 1: Forged and rolled wheels. UNE-EN-13979-1:2006”, Asociación Española de Normalización (UNE), Technical Standard, 2011.

This paper discusses a research project undertaken by Bently Nevada Corporation and TransCanada PipeLines to develop an improved machinery condition monitoring system for the Rolls-Royce Avon gas turbine engine. The project centers on the installation of internal vibration and temperature transducers in and around the engine internal wheel case housing for the center bearing. The paper outlines the current industry-accepted vibration monitoring system, why there is a need to improve the system, the design of the internal transducer mounting arrangements, and test results of the new system.

The lateral force created by a tire necessary for a vehicle to change direction is generated by slip and camber angles. Camber angle may be defined as the angle between a vertical line passing through a wheels’ center and the horizontal projection of this line onto the wheel. If the axis which the tire turns about is not parallel to the vertical axis, a change in camber will be induced as a result of the change in steer angle. This axis is called the steering axis and can be determined by the caster and lean angles relative to the wheel position in a body coordinate frame. The relation between the steer and camber angles may favor or detract from the lateral force being generated by the tire. This paper describes a method for determining the induced camber angle with respect to steer angle. In this method the wheel is defined throughout the steering range as a circle. The lowest point of the circle with respect to the global coordinate frame may then be defined via a method for determining maxima and minima. This point is then used to determine camber angle with respect to steer angle throughout the steering range. The lowest point of the tire may also be used in finding ride height and body roll due to change in steer angle. A sensitivity analysis reflects the suspension behavior for a variety of different suspension parameters. The relative difference between the induced steer angle about the steering axis and the actual steer angle with respect to the body coordinate frame are relevant in developing more accurate vehicle dynamics models.

It is shown in this paper that wheel climb can be initiated as the result of kinematic conditions that can be described using algebraic equations that do not depend explicitly on time. These algebraic kinematic conditions can lead to instantaneous wheel climb that is independent of the motion history. The analysis presented in this paper shows that if the contact is maintained at the wheel perimeter, a single kinematic constraint equation, expressed in terms of the wheel generalized coordinates, is obtained. This algebraic constraint equation clearly shows that a decrease in the lateral distance between the center of mass of the wheel and the rail, which can be the result of application of a lateral force, leads to an instantaneous wheel climb in the case of a constant angle of attack. It is shown that the ratio between the lateral and vertical reaction forces at the contact point is governed by a well-defined algebraic equation, and such a ratio does not depend on the applied forces. This ratio is given by dy/(dz sin2 α), where dy and dz are, respectively, the lateral and vertical distances of the wheel center from the contact point, and α is the angle of attack. In order to develop the governing dynamic equations, the kinematic constraint equations are used to derive a velocity transformation matrix that defines the relationship between the wheel velocities and the derivatives of the degrees of freedom. This velocity transformation matrix is used to obtain the independent wheel equations of motion which are solved numerically to determine the wheel motion in response to different lateral and friction forces. The results obtained show that wheel climb can be initiated with small lateral force, and an increase in the lateral force is not necessary for climb initiation. In order to shed light on the L/V ratio commonly used in wheel climb derailment criteria, the relationship between the external lateral force acting on the wheel and the reaction lateral force at the contact point is developed in this investigation. It is also shown that in the case of a tangent track and zero roll angle; the wheel longitudinal motion is completely decoupled from the vertical and yaw displacements. Therefore, the use of the distance to climb in tangent track wheel climb criteria needs to be reexamined.

Mobile robotic devices and other mobility related drive systems are often relegated to one of the two classes of devices available today: wheeled devices or tracked devices. Wheeled systems are more energy efficient and reliable than tracked systems, but existing designs have drawbacks related to rough-terrain driving and maneuvering in tight spaces. In this paper we describe the design and development of a drive system named the Single Motor Propelled Drive-train (SiMPl-D), which can potentially improve maneuvering over rough terrain and in tight spaces compared to traditional wheeled robots. SiMPl-D has two prominent features: a single drive motor, which provides both propulsion and turning, and is suspended under the center of mass of the device on a swingarm, which is linked through a suspension system to caster wheels; and it has reconfigurable drive wheel, which changes the turning radius of the device. Due to these features, SiMPl-D can traverse a wide range of terrain while remaining energy and cost efficient. SiMPl-D has been successfully used in an indoor/outdoor low-cost personal mobility device and is currently being implemented in other robotic mobility applications.