Showing papers in "Vehicle System Dynamics in 2007"
TL;DR: An overview of driver models is given with respect to their application and different methodical modelling approaches and a brief look beyond is added to better complete the view on the involved task of driving and driver modelling for automobile dynamics application.
Abstract: Understanding the driver of an automobile has been attractive to researchers from many different disciplines for more than half a century. On the basis of their acquirements, models of the (human) driver have been developed to better understand, analyse and improve the combined couple of driver and automobile. Due to distinctive demands on the models in accordance with different kinds of applications, a variety of driver models is available. An overview of driver models is given with respect to their application and different methodical modelling approaches. The emphasis is put on the interest of engineers, who generally focus on the automobile (like design and optimization of vehicle components and the overall vehicle dynamics behaviour) by applying their approved (mathematical) methods. Nonetheless, a brief look beyond is added to better complete the view on the involved task of driving and driver modelling for automobile dynamics application.
313 citations
TL;DR: In this article, the authors present a survey of the application of these technologies to suspensions and running gear, focused upon the complementary issues of control and monitoring, from which they identify the key trends and conclude with a forward look at what is likely to develop over the next few years.
Abstract: Over the last twenty to thirty years, railway vehicle dynamics has changed from being an essentially mechanical engineering discipline to one that is increasingly starting to include sensors, electronics and computer processing. This paper surveys the application of these technologies to suspensions and running gear, focused upon the complementary issues of control (which has been reviewed within Vehicle System Dynamics previously) and monitoring (which has not previously been reviewed). The theory, concepts and implementation status are assessed in each case, from which the paper identifies the key trends and concludes with a forward look at what is likely to develop over the next years.
245 citations
TL;DR: In this paper, a review of the measurement, the evaluation, and the assessment of vehicle vibration felt by drivers and passengers is presented, where the authors consider human sensitivity to different magnitudes, frequencies, directions, and durations of vibration.
Abstract: Vehicle refinement should include a consideration of the discomfort likely to be caused by vibration. This paper reviews the measurement, the evaluation, and the assessment of vehicle vibration felt by drivers and passengers. The feeling of vibration that gives rise to judgements of vibration discomfort can be predicted using evaluation procedures that take into account human sensitivity to different magnitudes, frequencies, directions, and durations of vibration. The evaluation methods make it possible to optimise vehicles via dynamic modelling before the production of prototypes and they assist the testing and optimisation of prototypes and production vehicles. Vibration evaluation provides imperfect predictions of discomfort when driver or passenger opinion is influenced by factors other than the vibration that is being measured and evaluated. Vibration evaluation can detect changes that are not detectable subjectively since smaller changes can be detected by measurement and evaluation than by subjective assessment.
187 citations
TL;DR: In this article, a generic wheel-rail contact detection formulation is presented in order to determine online the contact points, even for the most general three-dimensional motion of the wheelset, which allows the study of lead and lag flange contact scenarios.
Abstract: The guidance of railway vehicles is determined by a complex interaction between the wheels and rails, which requires a detailed characterization of the contact mechanism in order to permit a correct analysis of the dynamic behavior. The kinematics of guidance of the wheelsets is based on the wheels and rails geometries. The movement of the wheelsets along the rails is characterized by a complex contact with relative motions on the longitudinal and lateral directions and relative rotations of the wheels with respect to the rails. A generic wheel–rail contact detection formulation is presented here in order to determine online the contact points, even for the most general three-dimensional motion of the wheelset. This formulation also allows the study of lead and lag flange contact scenarios, both fundamental for the analysis of potential derailments or for the study of the dynamic behavior in the presence of switches. The methodology is used in conjunction with a general geometric description of the track,...
153 citations
TL;DR: In this paper, a 14 DOF vehicle model that includes dynamics of roll center and nonlinear effects due to vehicle geometry changes is developed, and the limitations, validity of simplified equations, and various modeling assumptions are discussed by analyzing their effect on the model roll responses in various vehicle maneuvers.
Abstract: An accurate and realistic vehicle model is essential for the development of effective vehicle control systems. Many different vehicle models have been developed for use in various vehicle control systems. The complexity of these models and the assumptions made in their development depend on their application. This article looks into the development and validity of vehicle models for prediction of roll behavior and their suitability for application in roll control systems. A 14 DOF vehicle model that includes dynamics of roll center and nonlinear effects due to vehicle geometry changes is developed. The limitations, validity of simplified equations, and various modeling assumptions are discussed by analyzing their effect on the model roll responses in various vehicle maneuvers. A formulation of the popular 8 DOF vehicle model that gives good correlation with the 14 DOF model is presented. The possible limitations of the 14 DOF model compared with an actual vehicle are also discussed.
129 citations
TL;DR: The Flexible Ring Tire Model (FTire) as mentioned in this paper is one of the most widely used and generally accepted tire models for ride comfort, handling, and road load prediction in the world.
Abstract: The first version of the tire simulation software Flexible ring Tire model (FTire) had been released in December 1998. Being subject to permanent improvement and several far-reaching model extensions since then, today it is one of the most widely used and generally accepted tire models for ride comfort, handling, and road load prediction. Strength of FTire is the strictly physical background, which perfectly fits both to Multi-Body Systems (MBS) and Finite Element Method (FEM) environments. Even though certain simplifications are unavoidable, this clean mechanical, thermo-dynamical, and tribological structure of the model guarantees a consistent and plausible model behavior even in situations that are not covered by respective measurements. The modelization takes into account most of the relevant excitation sources and non-linear transfer mechanisms, up to very high frequencies and extremely short wavelengths. The model's high level of detail is accompanied by a very comfortable program interface and a nu...
118 citations
TL;DR: In this paper, a rollover index (RI)-based vehicle stability control (VSC) scheme is proposed to indicate an impending rollover by a roll dynamics phase plane analysis.
Abstract: This paper presents a rollover index (RI)-based vehicle stability control (VSC) scheme. A rollover index, which indicates an impending rollover, is developed by a roll dynamics phase plane analysis. A model-based roll estimator is designed to estimate the roll angle and roll rate of the vehicle body with lateral acceleration, yaw rate, steering angle and vehicle velocity measurements. The rollover index is computed using an estimated roll angle, estimated roll rate, measured lateral acceleration and time-to-wheel lift. A differential braking control law is designed using a direct yaw control method. The VSC threshold is determined from the rollover index. The effectiveness of the RI, the performance of the estimator and the control scheme are investigated via simulations using a validated vehicle simulator. It is shown that the proposed RI can be a good measure of the danger of rollover and the proposed RI-based VSC scheme can reduce the risk of a rollover.
112 citations
TL;DR: In this article, a fuzzy-logic procedure was implemented to identify the side-slip angle of a single-track vehicle using the information provided by the kinematic formulation during a transient manoeuvre.
Abstract: Sideslip angle could provide important information concerning vehicle's stability. Unfortunately direct measurement of sideslip angle requires a complex and expensive experimental set-up, which is not suitable for implementation on ordinary passenger cars; thus, this quantity has to be estimated starting from the measurements of vehicle lateral/longitudinal acceleration, speed, yaw rate and steer angle. According to the proposed methodology, sideslip angle is estimated as a weighted mean of the results provided by a kinematic formulation and those obtained through a state observer based on vehicle single-track model. Kinematical formula is considered reliable for a transient manoeuvre, while the state observer is used in nearly quasi-state condition. The basic idea of the work is to make use of the information provided by the kinematic formulation during a transient manoeuvre to update the single-track model parameters (tires cornering stiffnesses). A fuzzy-logic procedure was implemented to identify stea...
103 citations
TL;DR: A review of the dynamics of heavy road-vehicle systems emphasizing directional performance is presented in this paper, where the authors present information on the following topics: why are articulated vehicles used; units, hitches, and combination vehicles; multiple axle suspensions and steering systems; important performance issues; models and simulation tools; and controlling directional performance.
Abstract: This review of the dynamics of heavy road–vehicle systems emphasizes directional performance. The review presents information on the following topics: why are articulated vehicles used; units, hitches, and combination vehicles; multiple axle suspensions and steering systems; important performance issues; models and simulation tools; and controlling directional performance. The concluding section summarizes the material presented and provides ideas regarding the application of vehicle system dynamics concepts in developing controllers for road trains.
101 citations
TL;DR: UniTire as discussed by the authors is a unified nonlinear and nonsteady tire model for vehicle dynamic simulation and control under complex wheel motion inputs, involving large lateral slip, longitudinal slip, turn-slip, and camber.
Abstract: UniTire is a unified non-linear and non-steady tire model for vehicle dynamic simulation and control under complex wheel motion inputs, involving large lateral slip, longitudinal slip, turn-slip, and camber. The model is now installed in an ADSL driving simulator at Jilin University for studying vehicle dynamics and their control systems. In this paper, first, a brief history of UniTire development is introduced; then the application scope of UniTire and available interfaces to MBS software are presented; thirdly, a more detailed description of UniTire is given; fourthly, a tool aiming at parameterization of UniTire is also demonstrated; and finally, some comments on TMPT are made.
100 citations
[...]
TL;DR: In this article, the authors describe the semi-physical tire model TMeasy for vehicle dynamics and handling analyses, as it was applied in the ‘low frequency tire models’ section of the research programme tire model performance test (TMPT).
Abstract: This paper describes the semi-physical tire model TMeasy for vehicle dynamics and handling analyses, as it was applied in the ‘low frequency tire models’ section of the research programme tire model performance test (TMPT). Despite more or less weak testing input data, the effort for the application of TMeasy remains limited due to its consequent ‘easy to use’ orientation. One particular feature of TMeasy is the wide physical meaning of its smart parameter set, which allows to sustain the identification process even under uncertain conditions. After a general introduction, the modelling concept of TMeasy is compactly described in this paper. Taking the standard tire interface (STI) to multibody simulation system (MBS) software into account, the way to apply TMeasy is briefly shown. This includes three selected examples of application. The final comments of the authors on TMPT describe the experiences and earnings received during the participation in that programme.
TL;DR: In this paper, a systematic methodology is applied in an effort to select optimum values for the suspension damping and stiffness parameters of two degrees of freedom quarter-car models, subjected to road excitation.
Abstract: A systematic methodology is applied in an effort to select optimum values for the suspension damping and stiffness parameters of two degrees of freedom quarter-car models, subjected to road excitation. First, models involving passive suspension dampers with constant or dual rate characteristics are considered. In addition, models with semi-active suspensions are also examined. Moreover, special emphasis is put in modeling possible temporary separations of the wheel from the ground. For all these models, appropriate methodologies are employed for capturing the motions of the vehicle resulting from passing with a constant horizontal speed over roads involving an isolated or a distributed geometric irregularity. The optimization process is based on three suitable performance criteria, related to ride comfort, suspension travel and road holding of the vehicle and yielding the most important suspension stiffness and damping parameters. As these criteria are conflicting, a suitable multi-objective optimization ...
TL;DR: In this paper, two kinematics-based observers are proposed to estimate the vehicle roll and pitch angles by using an inertial measurement unit, and the observers are mathematically proven to be stable if the vehicle yaw rate is not zero.
Abstract: In this article, two kinematics-based observers are proposed to estimate the vehicle roll and pitch angles by using an inertial measurement unit. The observers are mathematically proven to be stable if the vehicle yaw rate is not zero. With a design variation of the observer gains, the estimated roll or pitch angle is shown to further asymptotically converge to the true value, eliminating possible errors caused by the biases of the acceleration signals. Simulation results show that accurate estimation of both pitch and roll angles can be achieved without the help of external sensors such as global positioning systems, either by using the accelerometer-based reference pitch or roll angle as the maneuver varies, or by using an observer with zero steady-state error property.
TL;DR: In this article, a joint-point locus approach is proposed to study the dynamics and stability of a vehicle planar motion system, where the difference between the front and the rear steering angles plays a key role in vehicle system dynamics.
Abstract: In this article, the problems of dynamics and stability for vehicle planar motion systems have been investigated. By introducing a so-called joint-point locus approach, equilibria of the system and their associated stability properties are given geometrically. With this method, it is discovered that the difference between the front and the rear steering angles plays a key role in vehicle system dynamics and that the topological structure of the phase portrait and the types of bifurcations are different from those published previously. In particular, the vehicle system could still be stabilized even when pushed to work in a certain severely nonlinear region, by applying extremely large steering angles. However, it is worth noticing that the attractive domain of the stable equilibrium is very narrow. These developments might prove to be important in active steering control design. Numerical experiments are carried out to illustrate the potentials of the proposed techniques.
TL;DR: The results in general suggest that the mean responses attained from dynamic fluid slosh analyses correlate well with those attained from the quasi-static analyses for a clean bore tank, and that the presence of baffles helps to suppress the peak as well as mean slosh forces and moments significantly.
Abstract: The directional dynamic analyses of partly-filled tank vehicles have been limited to quasi-static fluid motion due to computational complexities associated with dynamic fluid slosh analyses. The dynamic fluid slosh causes significantly higher magnitudes of slosh forces and moments in the transient state that cannot be characterized through quasi-static approach, which provides reasonably good estimates of the mean responses. In this study, a three-dimensional nonlinear model of a partly-filled cylindrical tank with and without baffles is developed to investigate the significance of resulting destabilizing forces and moments caused by the transient fluid slosh, and the effects of baffles. The baffles and the end caps are modeled with curved shapes. The analyses are performed under varying magnitudes of steady lateral, longitudinal and combinations of lateral and longitudinal accelerations of the tank, and two different fill volumes using the FLUENT software. The results of the study are presented in terms ...
TL;DR: In this paper, a multidisciplinary approach of railway pneumatic suspension modelling is presented, where both multibody and puneumatic aspects are taken into account, and the authors aim at obtaining a realistic model of the secondary suspension and coupling it with a multi-body model of a train.
Abstract: This article presents a multidisciplinary approach of railway pneumatic suspension modelling: both multibody and pneumatic aspects are taken into account. The work aims at obtaining a realistic model of the secondary suspension and coupling it with a multibody model of a train. Various components of the pneumatic circuit such as bellows, tanks, pipes and valves are taken into account. The article focuses on the bellow - pipe - tank subsystem for which several modelling approaches are presented and compared. Differences between differential and algebraic models are highlighted, and an application-dependent choice between them is suggested. A complete model of the pneumatic circuit is then obtained and coupled with a multibody model of the train. As a result, the behaviour of a suburban train equipped with a pneumatic secondary suspension is analysed, in particular undesired oscillating motions which affect the comfort. Topological modifications and improvements of the suspension are also investigated and discussed.
TL;DR: In this article, an active vibration reduction system using piezo-stack actuators and sensors mounted on the vehicle car body is proposed and studied in simulations, where the output signals of the sensors which are measuring the flexible deformation of the car body generate a bending moment.
Abstract: In order to improve the ride comfort of lightweight railway vehicles, an active vibration reduction system using piezo-stack actuators is proposed and studied in simulations. The system consists of actuators and sensors mounted on the vehicle car body. Via a feedback control loop, the output signals of the sensors which are measuring the flexible deformation of the car body generate a bending moment, which is directly applied to the car body by the actuators. This bending moment reduces the structural vibration of the vehicle car body. Simulations have shown that a significant reduction in the vibration level is achieved.
TL;DR: In this paper, the steering characteristics of the vehicle were modified in the course of driving, unknown to drivers, and a two-level driver model, combining a preview of vehicle dynamics and a neuromuscular steering control, reproduces these experimental results qualitatively and indicates that adaptation occurs at the haptic level rather than in the internal model of vehicle dynamic.
Abstract: When driving in curves, how do drivers use the force appearing on the steering wheel? As it carries information related to lateral acceleration, this force could be necessary for drivers to tune their internal model of vehicle dynamics; alternatively, being opposed to the drivers' efforts, it could just help them stabilize the steering wheel position. To assess these two hypotheses, we designed an experiment on a motion-based driving simulator. The steering characteristics of the vehicle were modified in the course of driving, unknown to drivers. Results obtained with standard drivers showed a surprisingly wide range of adaptation, except for exaggerated modifications of the steering force feedback. A two-level driver model, combining a preview of vehicle dynamics and a neuromuscular steering control, reproduces these experimental results qualitatively and indicates that adaptation occurs at the haptic level rather than in the internal model of vehicle dynamics. This effect is related to other theories on...
TL;DR: In this paper, a new dynamic model of a high-speed EMS maglev vehicle/guideway interaction is presented, which considers the vehicle and the guideway as an integral system and couples vertical interaction with lateral interaction.
Abstract: A new dynamic model of a high-speed EMS maglev vehicle/guideway interaction is presented. The model considers the vehicle and the guideway as an integral system and couples vertical interaction with lateral interaction. The vehicle subsystem is modeled as a multi-body system, which runs on the guideway with a constant velocity. The guideway substructure is modeled as an elastic beam. The attractive magnetic forces between vehicle and guideway are decided by controller, observer, and filter. A special simulation program is developed. Numerical results of the program are compared with test results. The results show that the coupling model is appropriate and the simulation program is credible primarily. Applications of coupling model to the investigation of the effect of irregularities on maglev system are reported at the end of the paper. The studies in this paper can be used to evaluate and optimize dynamic performances of the high-speed EMS maglev system.
TL;DR: In this article, the authors discuss the tire model performance test (TMPT) participation of the LMS International comfort and durability tire model (LMS CDTire) and the results of the TMPT validation and capability tests are discussed.
Abstract: This paper discusses the tire model performance test (TMPT) participation of the LMS International comfort and durability tire model (LMS CDTire). CDTire is a family of three models based on a macroscopic physical description of tires, which is a compromise between scope of applicability and calculation time. A short overview of the CDTire model suite, including parameter identification (PI) software and road surface models, is complemented with application examples of full vehicle simulations utilizing different sub-models and different road surface models. The PI procedure for the TMPT tire, a non-commercial 205/55 R 16 passenger car tire, is reviewed and the results of the TMPT validation and capability tests are discussed.
TL;DR: In this paper, the authors present and compare four models well adapted to tramway conditions, involving contacts on the rolling tread and on the flange with very different sliding and pressure conditions.
Abstract: One of the most important maintenance costs in tramway transport comes from wear of wheel profiles. In the highly competitive railway market, the prediction of wear is then a major concern of the constructors. In this article, we present and compare four models well adapted to tramway conditions, involving contacts on the rolling tread and on the flange with very different sliding and pressure conditions. Moreover, all models can be implemented from the natural outputs of the railway simulation packages classically used in industry for the dynamics design of the vehicles. The first one, proposed by Jendel, is based on the well-known Archard's wear model. Enblom continues Jendel's approach by taking into account the contribution of wheel deformation on the sliding velocity. The last two models, developed by Zobory, and Pearce and Sherratt, determine the wear from the energy dissipation in the contact area. The models are first compared on a theoretical basis and, for that purpose, are rewritten in a common...
TL;DR: In this article, a two-layer approach to model a driver's steering behavior is extended to higher lateral accelerations in a 2-wheel vehicle model and an analytical method to determine the driver parameters is presented, which is based on the two wheel vehicle model.
Abstract: Due to increasing demands for time and cost efficient vehicle and driver assistant systems development, numerical simulation of closed-loop manoeuvres becomes increasingly important. Thus, the driver has to be considered in the modelling. On the basis of a two-layer approach to model a driver's steering behaviour, the field of application is extended to higher lateral accelerations in this study. An analytical method to determine the driver parameters is presented, which is based on the two-wheel vehicle model. The simulation results are determined using a full vehicle model including all essential nonlinearities. Standard manoeuvres in the nonlinear range of vehicle handling behaviour are performed. A cornering manoeuvre is chosen to show the characteristics of the proposed driver model.
TL;DR: The PAC2002 tire model as discussed by the authors is a semi-empirical tire model with both the empirical (mathematical formulas) and physical modeling components, which can describe the behavior of tires traveling over relatively smooth road surfaces and its dynamical behavior is valid for frequencies up to 12 Hz.
Abstract: The history of ‘Magic Formula’ tire models is shortly described and the PAC2002 tire model is the latest generation of this type of tire models. PAC2002 is a semi-empirical tire model because it has both the empirical (mathematical formulas) and physical modeling components. The PAC2002 tire model can describe the behavior of tires traveling over relatively smooth road surfaces and its dynamical behavior is valid for frequencies up to 12 Hz. The structure of the model is explained and it is shown what the influences of the different Magic Formula-factors have on the characteristic. The classic tire model input quantities are extended with turn-slip, which is one of two components of tire spin. The functional expressions for steady-state cornering and braking/driving are given. In addition to the stretched-string (first-order relaxation effects) model to describe tire transient behavior, the newly added alternative contact-mass model is explained. The new formula set for tire spin and parking is given, whi...
TL;DR: In this paper, the effect of frame compliance and rider mobility on the scooter stability is investigated and a mathematical model is presented to describe the out-of-plane dynamics of a scooter and consists of a twelve degree-freedom linear model.
Abstract: This article investigates the effect of frame compliance and rider mobility on the scooter stability Particular attention is given to the wobble mode, because it may easily become unstable in the vehicle speed range This article includes a synthetic discussion of previous works, presents a new mathematical model, and discusses the results of both numerical and experimental analyses of the vehicle stability by varying the vehicle characteristics and motion conditions The mathematical model describes the out-of-plane dynamics of the scooter and consists of a twelve-degree-freedom linear model It describes the main scooter features and, in particular, includes the frame compliance, rider mobility, and an advanced tire model The torsion and bending compliance of both the front fork and swingarm are modelled using lumped rotational springs; similarly, the rider mobility is described by means of two soft springs which connect the rider body to the chassis The tire model describes in detail the carcass geo
TL;DR: In this article, an inverse wagon model was developed to estimate wheel-rail contact forces using only measurements of wagon body responses as inputs, including vertical and lateral translational accelerations and angular accelerations of roll, pitch, and yaw of the wagon body.
Abstract: An inverse wagon model was developed to estimate wheel–rail contact forces using only measurements of wagon body responses as inputs. The purpose of this work was to provide mathematical modelling to embed in low-cost devices that can be mounted on each freight wagon in a large wagon fleet. To minimize cost, complication, and the maintenance inconvenience of these devices, the constraint is imposed that transducers and connections are limited to locations on the wagon body. Inputs to the inverse model developed include only vertical and lateral translational accelerations and angular accelerations of roll, pitch, and yaw of the wagon body. The model combines the integration and partial modal matrix (PMM) techniques together to form an IPMM method. Besides wheel–rail contact forces some motion quantities such as the lateral and yaw displacements of wheelset are also predicted. Results from the inverse model were compared with data from full scale laboratory suspension tests for vertical suspension excitati...
TL;DR: In this paper, a combined proportional active front steering control and proportional integral active rear steering control from the yaw rate tracking error is used to assign the eigenvalues of the linearised single track steering dynamics, without lateral speed measurements, using a standard single track car model with nonlinear tire characteristics and a non-linear first-order reference model for the driver steering wheel input.
Abstract: Vehicle steering dynamics show resonances, which depend on the longitudinal speed, unstable equilibrium points and limited stability regions depending on the constant steering wheel angle, longitudinal speed and car parameters. The main contribution of this paper is to show that a combined decentralized proportional active front steering control and proportional-integral active rear steering control from the yaw rate tracking error can assign the eigenvalues of the linearised single track steering dynamics, without lateral speed measurements, using a standard single track car model with nonlinear tire characteristics and a non-linear first-order reference model for the yaw rate dynamics driven by the driver steering wheel input. By choosing a suitable nonlinear reference model it is shown that the responses to driver step inputs tend to zero (or reduced) lateral speed for any value of longitudinal speed: in this case the resulting controlled vehicle static gain from driver input to yaw rate differs from t...
TL;DR: In this paper, a robust control algorithm for an anti-lock brake system is proposed based on static-state feedback of longitudinal slip and does not involve controller scheduling with changing vehicle speed or road adhesion coefficient estimation.
Abstract: A robust control algorithm for an anti-lock brake system is proposed. The method used is based on static-state feedback of longitudinal slip and does not involve controller scheduling with changing vehicle speed or road adhesion coefficient estimation. An improvement involving scheduling of longitudinal slip reference with longitudinal acceleration measurement is included. Electromechanical braking actuators are used in simulations, and the algorithm used in this study is shown to have high performance on roads with constant and varying adhesion coefficients, displaying nice robustness properties against large vehicle speed and road adhesion coefficient variations. Guidelines are provided for tuning controller gains to cope with unknown actuator delay and measurement noise.
TL;DR: In this paper, an experimental study of driver steering control behavior in a lane-change manoeuvre was conducted, where eight test subjects were instrumented with electromyography to measure muscle activation and co-contraction.
Abstract: The article reports an experimental study of driver steering control behaviour in a lane-change manoeuvre. Eight test subjects were instrumented with electromyography to measure muscle activation and co-contraction. Each subject completed 30 lane-change manoeuvres with one vehicle on a fixed-base driving simulator. For each driver, the steering torque feedback characteristic was changed after every ten manoeuvres; the response of the vehicle to steering angle inputs was not changed. Drivers' control strategies were found to be robust to changes in steering torque feedback. Path-following errors, muscle activity and muscle co-contraction all reduce with the number of lane-changes performed by the driver, suggesting the existence of a learning process. Comparing the test subjects, there was some evidence that high levels of co-contraction were used to allow high-frequency steering inputs to be generated. The results contribute to the understanding of vehicle-driver (and more generally, human-machine) dynamic interaction.
TL;DR: In this paper, a classification of wheel flats according to the different stages of their growth is given, along with the characteristic features of the dynamic wheel-rail interaction for each category.
Abstract: A classification of wheel flats according to the different stages of their growth is given, along with the characteristic features of the dynamic wheel-rail interaction for each category. Mathematical expressions and frequency spectra of the corresponding wheel mass trajectories are derived. Difference is made between the subcritical and the transcritical speed regime. A criterion is derived for contact loss for worn flats. Simulations show that the dynamic wheel-rail interaction is governed by the track stiffness for low train speeds or long flat lengths; for high speeds and/or short flat lengths the interaction is governed by the inertial properties of the wheel and the rail. For a given flat geometry, nonlinearities in the relationship between the impact magnitude and the train speed occur in the stiffness-dominated speed domain, whereas this relationship is approximately linear in the inertia-governed domain. In the latter domain, the impact magnitude is found to be linearly dependent upon the maximum trajectorial curvature or inversely linearly dependent on the minimum circumferential wheel tread curvature. The above relationships are valid for the subcritical speed regime, in which no contact loss occurs. Different contributions from the literature are compared with respect to the established relationship between impact magnitude and speed. Significant differences are found, due to insufficiently defined parameters and conditions. Conditions are derived for a consistent application of the so-called equivalent rail indentation in experiments with wheel flats, and the indirect strain registration method for measuring dynamic wheel-rail contact forces is reviewed.
[...]
TL;DR: An overview of the TNO MF-SWIFT model is given in this article, followed by a discussion of the implementation in multibody and other simulation software, including also the available road models.
Abstract: In this paper, an overview of the TNO MF-SWIFT model is given. After an historical overview of the model development and the intended range of application, the model is described briefly. Next, the implementation in multibody and other simulation software is discussed, including also the available road models. After that, the parameterization of the tire model is described and the available identification tool is discussed. Finally, comments are given on the TMPT from the TNO point of view.