Search

The suspension systems are designed to provide good performance in terms of comfort and maneuverability and to satisfy other requirements such as fatigue strength. This study focuses on the leaf springs, a classic mechanism; leaf springs are still being extensively used in several types of vehicles because of their high load capacity and low manufacturing and maintenance costs. Its dynamic behavior assesses stationary nonlinear preload state components to provide considerable added value to this suspension type. This assessment considers the contact condition of the suspension's components and the large deflections and tightening torques observed in the whole assembly. Furthermore, the components of the non-suspended mass subsystems, such as tires, shock absorbers, and stabilizer bars, are characterized according to the simplified models for reducing their computational cost. In addition, a commercial test vehicle is used for simulating the complete system using three-dimensional modeling for describing its most relevant components in terms of their mass and rigid connection. The vehicle is additionally analyzed using multibody system simulations (MBS) coupled with the finite element method (FEM) in an implicit nonlinear transient environment using the ANSYS APDL solver. This dynamic simulation is parameterdriven for obtaining the experimental design and determining the optimal suspension stiffness and damping features required for transporting suitable load sizes. [ABSTRACT FROM AUTHOR]

This paper presents the usage of additional tire information in the form of cornering stiffness to enhance vehicle handling and stability with an adaptive rear-wheel steering control (RWS). The influence of varying cornering stiffness on driving behavior is discussed in advance with a single-track model. On the basis of an enhanced single-track model, a RWS feedforward control is presented with a provided tuning parameter adapting the desired rear axle cornering stiffness for the vehicle. In the following, this paper proposes an adaption law that is derived in order to enhance handling performance and safety of a vehicle, taking into account conflicting goals. Finally, simulation results and driving experiments with the adaptive RWS feedforward control are evaluated in both steady-state and transient conditions. In order to examine the full potential of the approach, the controller is adapted to a wide spreading of the cornering stiffness. Therefore, identified cornering stiffnesses of winter-, summer- and ultra-high performance tires are used as a basis for the adaption. [ABSTRACT FROM AUTHOR]

Tire force distribution with the consideration of practical constraints is a key part of automatic driving. This paper is intended to improve the operational capability of the vehicle under low friction coefficient. The speed and front wheel angle are restricted within a specific range caused by the limitation of executable drive space, which is defined as an input constrained problem of the nonlinear system. The hierarchical design concept is adopted in this paper, including algorithms of both control and allocation to determine the driving performance cooperatively. The methodology of multi-input and multi-output sliding mode control (MIMO SMC) is applied in the high-level controller to guarantee the vehicle system stable. Confronted with circumstances that the vehicle may be seriously unstable due to longitudinal forces and lateral forces beyond the feasible region in the friction circle, the scheme of dynamic adjustment of control target is provided owing to there is no reasonable solution for tire force distribution in the low-level controller. The coefficients of reconstruction and attenuation are introduced to reconstruct the optimized controller and weaken inputs of the closed loop system, respectively. The simulation results verify that the proposed design can redistribute generalized forces and moments between the wheels especially for the poor road condition. [ABSTRACT FROM AUTHOR]

A 4-independent wheel driving (4-IWD) electric vehicle has distinctive advantages with both enhanced dynamic and energy efficiency performances since this configuration provides more flexibilities from both the design and control aspects. However, it is difficult to achieve the optimal performances of a 4-IWD electric vehicle with conventional design and control approaches. This paper is dedicated to investigating the vehicular optimal design and control approaches, with a 4-IWD electric race car aiming at minimizing the lap time on a given circuit as a case study. A 14-DOF vehicle model that can fully evaluate the influences of the unsprung mass is developed based on Lagrangian dynamics. The 14-DOF vehicle model implemented with the reprogrammed Magic Formula tire model and a time-efficient suspension model supports metric operations and parallel computing, which can dramatically improve the computational efficiency. The optimal design and control problems with design parameters of the motor, transmission, mass center, anti-roll bar and the suspension of the race car are successively formulated. The formulated problems are subsequently solved by directly transcribing the original problems into large-scale nonlinear optimization problems based on trapezoidal approach. The influences of the mounting positions of the propulsion system, the mass and inertia of the unsprung masses, the anti-roll bars, and suspensions on the lap time are analyzed and compared quantitatively for the first time. Some interesting findings that are different from the ‘already known facts’ are presented. [ABSTRACT FROM AUTHOR]

Electric ground vehicles driven by in-wheel-motors (IWMs) have control flexibility of easily generating external yaw moment, which is effective for vehicle lateral motion control without interfering driver steering maneuvers. However, IWMs small torque variation may introduce undesired yaw moment that causes vehicle trajectory drifts and affects lateral motion. This paper proposes a driver-assistance lateral motion control method specifically considering IWMs small torque variation. In driving conditions where a driver steering maneuver is not expected, the controller compensates for small torque variation to reduce the driver workload. However, for driving conditions that require steering input from the driver, the controller assists the driver to maintain the path when there is a tendency of lane departure. A gain-scheduling robust controller is designed to deal with a time-varying parameter and system uncertainty. The weighted ${H_\infty }$ performance and eigenvalue placement technique are employed to derive a suitable feedback gain. CarSim simulations are conducted to illustrate the control effectiveness for compensating small torque variation and prevent lane departure. Furthermore, human-in-the-loop tests are conducted to verify the effectiveness of the designed controller for human drivers. Both simulation results and human driving simulator tests show that the proposed controller can assist drivers with vehicle lateral motion control under different driving conditions subject to IWMs small torque variation. [ABSTRACT FROM AUTHOR]

In vehicle dynamics studies, the tire behaviour plays an important role in planar motion of the vehicle. Therefore, a correct representation of tire is a necessity. This paper describes a mathematical model for wheelchair tire based on the Magic Formula model. This model is widely used to represent forces and moments between the tire and the ground; however some experimental parameters must be determined. The purpose of this work is to identify the tire parameters for the wheelchair tire model, implementing them in a dynamic model of the wheelchair. For this, we developed an experimental test rig to measure the tires parameters for the lateral dynamics of a wheelchair. This dynamic model was made using a multi-body software and the wheelchair behaviour was analysed and discussed according to the tire parameters. The result of this work is one step further towards the understanding of wheelchair dynamics. [ABSTRACT FROM AUTHOR]

A novel method of all-wheel braking force allocation during a braking-in-turn maneuver is proposed for vehicles with the brake-by-wire (BBW) system. The concept of stability priority is applied in distributing the braking force to each wheel, which means that the stability performance has priority over the braking demand during a braking-in-turn maneuver. Based on this principle, I-curves for braking-in-turn maneuvers with respect to three parameters are developed using the graphics of a single-track vehicle model, defining the force allocation between the front and rear axles. Then, the distributed braking force of the front and rear axles is allocated between the inner and outer wheels based on the load transfer. The simulation and hardware-in-the-loop (HIL) experimental results show that the proposed allocation strategy makes good use of adhesion and ensures vehicle stability during a braking-in-turn maneuver. The proposed method provides theoretical guidelines on independent braking force control in the BBW system, which enhances vehicle stability and braking performance. [ABSTRACT FROM PUBLISHER]

The accurate estimation of the tire–road friction coefficient plays a significant role in the vehicle dynamics control. The estimation method should be timely and reliable for the controlling requirements, which means the contact friction characteristics between the tire and the road should be recognized before the interference to ensure the safety of the driver and passengers from drifting and losing control. In addition, the estimation method should be stable and feasible for complex maneuvering operations to guarantee the control performance as well. A signal fusion method combining the available signals to estimate the road friction is suggested in this paper on the basis of the estimated ones of braking, driving and steering conditions individually. Through the input characteristics and the states of the vehicle and tires from sensors the maneuvering condition may be recognized, by which the certainty factors of the friction of the three conditions mentioned above may be obtained correspondingly, and then the comprehensive road friction may be calculated. Experimental vehicle tests validate the effectiveness of the proposed method through complex maneuvering operations; the estimated road friction coefficient based on the signal fusion method is relatively timely and accurate to satisfy the control demands. [ABSTRACT FROM AUTHOR]

In this paper, a real-time center of gravity (CG) position estimator, which is based on a combined adaptive Kalman filter–extended Kalman filter (AKF–EKF) approach, for lightweight vehicles (LWVs) is proposed. Accurate knowledge of the CG longitudinal location and the CG height in the vehicle frame is helpful to the control of vehicle motions, particularly for LWVs, whose CG positions can be substantially varied by the payloads on board. The proposed estimation method, taking advantage of the separate front/rear torque control capability available in numerous LWV prototypes, only requires that the vehicle be excited longitudinally and/or vertically, thus avoiding potentially dangerous excitation of the vehicle lateral/yaw/roll motions. Moreover, additional parameters, such as vehicle moments of inertia, suspension parameters, and the tire/road friction coefficient (TRFC), are not necessary. A three-degree-of-freedom (3-DOF) vehicle dynamics model, taking the vehicle longitudinal velocity, the front-wheel angular speed, and the rear-wheel angular speed as states, is employed in the filter formulation. The designed estimator consists of two parts: an AKF for filtering noisy states and an EKF for estimating parameters. To minimize the effects of undesirable oscillation and bias in the filtered states, the optimization-based AKF judiciously tunes the suboptimal process noise covariance matrix in real time. Meanwhile, the EKF utilizes the filtered states from the AKF and takes the parameters as random walks. Simulation results exhibit the advantages of the AKF over the standard KF with fixed covariance matrices. Experimental results obtained from vehicle road tests show that the proposed estimator is capable of estimating the CG position with acceptable accuracy. Moreover, an investigation of the two-layer persistent excitation (PE) condition reveals that, although the CG height estimation largely depends on the excitation level in the maneuver, the CG longitudinal location can be always estimated via the input torque injections. [ABSTRACT FROM AUTHOR]

A methodology is presented in this work that employs the active inverted wings to enhance the road holding by increasing the downward force on the tyres. In the proposed active system, the angles of attack of the vehicle's wings are adjusted by using a real-time controller to increase the road holding and hence improve the vehicle handling. The handling of the race car and safety of the driver are two important concerns in the design of race cars. The handling of a vehicle depends on the dynamic capabilities of the vehicle and also the pneumatic tyres’ limitations. The vehicle side-slip angle, as a measure of the vehicle dynamic safety, should be narrowed into an acceptable range. This paper demonstrates that active inverted wings can provide noteworthy dynamic capabilities and enhance the safety features of race cars. Detailed analytical study and formulations of the race car nonlinear model with the airfoils are presented. Computer simulations are carried out to evaluate the performance of the proposed active aerodynamic system. [ABSTRACT FROM AUTHOR]

This paper develops a novel form of a well-known signal processing technique, so as to be applicable to the interaction between a heavy truck and a supporting bridge structure. Motivated by the problem of structural health monitoring of bridges, a newmodal coherencyfunction is defined. This relates the input action of moving wheel loads to the dynamic response of the bridge, including the effects of unevenness of the road surface and the vertical dynamics of the truck suspension. The analysis here is specifically aimed at future experimental testing – the validation of axle load estimators obtained from sensors on the truck. It is applicable even when no independent ‘ground truth’ for the dynamic loads is available. The approach can be more widely used in the analysis of dynamic interactions involving suspended moving loads on deformable structures, e.g. for structural vibrations due to high-speed trains. [ABSTRACT FROM AUTHOR]

A new adaptive vehicle suspension control method is presented that adjusts the controller parametrization to the current driving state and thereby enables to significantly enhance ride comfort while the dynamic wheel load and the suspension deflection remain within safety critical bounds. To this end, the adaptive controller structure dynamically interpolates between differently tuned linear quadratic regulators governed by the dynamic wheel load and the suspension deflection. The stability of the adaptive controller structure is analyzed by means of a common Lyapunov function approach taking into account the nonlinear damper characteristic of the suspension system. In order to provide a realistic framework for the controller design and the performance analysis, a quarter-car test rig based on an all-terrain vehicle suspension that has been equipped with an electrical linear motor to realize an active suspension system, is employed as testbed for the study. On this test rig, the significant performance of the adaptive control concept is successfully validated in a comparison to benchmark suspension controllers. [ABSTRACT FROM AUTHOR]

In the field of vehicle dynamics, commercial software can aid the designer during the conceptual and detailed design phases. Simulations using these tools can quickly provide specific design metrics, such as yaw and lateral velocity, for standard maneuvers. However, it remains challenging to correlate these metrics with empirical quantities that depend on many external parameters and design specifications. This scenario is the case with tire wear, which depends on the frictional work developed by the tire-road contact. In this study, an approach is proposed to estimate the tire-road friction during steady-state longitudinal and cornering maneuvers. Using this approach, a qualitative formula for tire wear evaluation is developed, and conceptual design analyses of cornering maneuvers are performed using simplified vehicle models. The influence of some design parameters such as cornering stiffness, the distance between the axles, and the steer angle ratio between the steering axles for vehicles with two steering axles is evaluated. The proposed methodology allows the designer to predict tire wear using simplified vehicle models during the conceptual design phase. [ABSTRACT FROM AUTHOR]

This paper proposes a method to evaluate vehicle rollover propensity based on a frequency-domain representation of the zero-moment point (ZMP). Unlike other rollover metrics such as the static stability factor, which is based on the steady-state behaviour, and the load transfer ratio, which requires the calculation of tyre forces, the ZMP is based on a simplified kinematic model of the vehicle and the analysis of the contact point of the vehicle relative to the edge of the support polygon. Previous work has validated the use of the ZMP experimentally in its ability to predict wheel lift in the time domain. This work explores the use of the ZMP in the frequency domain to allow a chassis designer to understand how operating conditions and vehicle parameters affect rollover propensity. The ZMP analysis is then extended to calculate worst-case sinusoidal manoeuvres that lead to untripped wheel lift, and the analysis is tested across several vehicle configurations and compared with that of the standard Toyota J manoeuvre. [ABSTRACT FROM AUTHOR]

This article presents models for wheels and tyres in the application field of real-time multi-body systems. For this rather broad class of applications it is difficult to foresee the right level of model complexity that is affordable in a specific simulation. Therefore we developed a tyre model that is adjustable in its degree of complexity. It consists of a list of stepwise developed sub-models, each at a higher level of complexity. These models include semi-empirical equations. The stepwise development process is also reflected in the corresponding implementation with the modelling language Modelica. The final wheel model represents a supermodel and enables users to select the right level of complexity in an unambiguous way. [ABSTRACT FROM AUTHOR]

This paper presents the experiences using Michelin's thermo-mechanical TaMeTirE tyre model for real-time handling applications in the field of advanced passenger car simulation. Passenger car handling simulations were performed using the tyre model in a full-vehicle real-time environment in order to assess TaMeTirE's level of consistency with real on-track handling behaviour. To achieve this goal, a first offline comparison with a state-of-the-art handling tyre model was carried out on three handling manoeuvres. Then, online real-time simulations of steering wheel steps and slaloms in straight line were run on Daimler's driving simulator by skilled and unskilled drivers. Two analytical tyre temperature effects and two inflation pressure effects were carried out in order to feel their impact on the handling behaviour of the vehicle. This paper underlines the realism of the handling simulation results performed with TaMeTirE, and shows the significant impact of a pressure or a temperature effect on the handling behaviour of a car. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a process for the estimation of tire–road forces, vehicle sideslip angle and wheel cornering stiffness. The method uses measurements (yaw rate, longitudinal/lateral accelerations, steering angle and angular wheel velocities) only from sensors which can be integrated or have already been integrated in modern cars. The estimation process is based on two blocks in series: the first block contains a sliding-mode observer whose principal role is to calculate tire–road forces, while in the second block an extended Kalman filter estimates sideslip angle and cornering stiffness. More specifically, this study proposes an adaptive tire-force model that takes variations in road friction into account. The paper also presents a study of convergence for the sliding-mode observer. The estimation process was applied and compared to real experimental data, in particular wheel force measurements. The vehicle mass is assumed to be known. Experimental results show the accuracy and potential of the estimation process. [Copyright &y& Elsevier]

Nowadays, many researches exist in the automotive field aimed at improving vehicle active control. Recently, the possibility to exploit sensors fixed inside the tyre (particularly on the liner) has been presented by the authors of this paper [F. Braghin, M. Brusarosco, F. Cheli, A. Cigada, S. Manzoni, and F. Mancosu, Measurement of contact forces and patch features by means of accelerometers fixed inside the tyre to improve future car active control, Vehicle Syst. Dyn. 44(1) (2006), pp. 3-13]. These sensors allow measurements to be obtained from the closest point to the contact patch, making possible the best description of contact phenomena (with respect to the actual situation in which sensors are usually placed on the hub); these data can be sent to the vehicle controller, processed and therefore used for active control. However, there is still a tyre layer between the sensors and the road, therefore a specific study of the transfer functions between tyre input and sensor signals is needed to understand how to correlate signal trends to physical events, taking into account tyre behaviour. This also means that signal features have to be analysed to find how they depend on physical parameters (such as vertical load, camber angle, etc.). A dedicated test facility has been designed and built to perform this task; this is the object of the present paper, which first of all focuses on the choices for this particular design solution. Different tyres have been tested by means of this test bench (the study has been carried out up to 2 kHz and this threshold comes from road test results), looking for eventual differences among their behaviours; in particular, the effects of tyre tread block presence have been investigated. [ABSTRACT FROM AUTHOR]

The dynamic model was developed to evaluate vibration accelerations and ride comforts during the running of the Korean-standardised rubber-tired light rail vehicle. Ride comfort indexes were analysed and tested in accordance with UIC 513R by using the dynamic model and the actual vehicle in the test track. Based on the comparisons between analysis results and test results, the validity of the developed dynamic model was evaluated. It was verified whether or not the developed Korean-standardised rubber-tired light rail vehicle met the specified target specification on ride comfort. In addition, the influence of the wearing of guide wheels on ride comfort was estimated. [ABSTRACT FROM AUTHOR]

Based on the Fourier heat equation, an analytical model to determine the tyre temperature distribution, during its employment, is described. The model, called ThermoTyre, analyses the tyre thermodynamic behaviour. The model is in one-dimensional form and is characterised by a low computational load. Therefore, it lends to be easily integrated with interaction models in order to execute handling analyses. The work takes advantage of the cooperation with the Bridgestone Technical Center Europe that produces expertise and experimental data. After an analytical model description, simplifying hypothesis and boundary conditions are illustrated. Finally, the comparison between experimental data and theoretical results are shown. [ABSTRACT FROM AUTHOR]

Modeling of tire friction is one of the central problems for vehicle control systems design. LuGre-type dynamic tire model has been proposed and well discussed in previous studies, because it offers a compact form of dynamic model that is convenient in advanced control studies. It has been successfully used in tire slip control design and vehicle state estimation problems. In this article, a concept of time-constrained Stribeck effect is introduced to interpret the mechanism of the LuGre friction model in predicting tire friction characteristics. A modified two-dimensional (2D) dynamic LuGre friction model is introduced to make it compatible with the governing theorem in the steady state. An analytical 2D modified LuGre-type dynamic tire model is developed, in which some fundamental limitations of classical LuGre models are eliminated. The main modifications involve a change in the structure of the 2D LuGre friction model, introduction of load-dependent parameters in 1D and 2D tire models, and a changed structure in the distributed parameter model. The proposed model is compared, in the steady state, to both the Magic Formula and the classical LuGre model. It improves model accuracy in the steady state and gives a physically reasonable distribution of the bristle deflection. A first-order lumped parameter (LP) nonlinear model, which has simpler structure than the distributed parameter model and the classical LP LuGre model, is then derived. Numerical simulations show that the proposed LP model has a good estimation for tire transient dynamics. Thus, the proposed model retains the merits of LuGre-type models and improves the agreement with observation and experimental data on friction force distribution along the patch and on the steady-state friction prediction. [ABSTRACT FROM AUTHOR]

The recently developed LuGre model describes the three-dimensional tyre friction dynamics given in the brush representation. The model has a three-state lumped-parameter form and an analytical solution for tyre static curves. It is simplified using the assumption of a constant slip speed along the contact patch length. This assumption is abandoned in this paper in order to extend the model with several secondary but potentially important effects such as camber, carcass compliance, conicity, ply steer and rolling resistance. Two approaches to the introduction of a variable-slip-speed effect are considered. The first is based on stepwise approximation of the slip speed along the contact patch length, and the second includes a specific, spatially distributed additive deflection term. Both approaches preserve the three-state lumped-parameter model form and an analytical steady-state solution. Qualitative and quantitative validation results point to consistency and benefits of the proposed model extensions. [ABSTRACT FROM AUTHOR]

External tyre dynamics means the rolling of a membrane-type elastic body with a small bending disturbance. Internal tyre dynamics is the coupling between belt and carcass by rubber shear forces and between belt cord layers by the shear of rubber coatings. One has to take into account that cord stresses in the belt in reality are smaller than they are prescribed by the membrane kinematic. The first approximation is to reduce the belt cord stiffness at belt shoulders near the sidewalls. A further approach is to introduce more degrees of freedom for describing the shear deformation in a separate computer program. To avoid extensive computations, a 2D tyre model for rolling on road and in soil was used for cars and tractors. In the case of a 2D tyre model, the longitudinal stiffness of the belt (a mean value) can be computed by using the measured expansion of tyre during the inflating process. Out of the plane, the body behaves as a rigid ring on elastic foundation. Within the sidewalls, the cords are radially orientated; the rubber is only a coating. This model is much faster in computation and can also be used for crash simulation and for tyre noise computing. To compare rolling on deformable soil with rolling on road, a 3D tyre model was used. Several examples, also landing of an airplane on a grass field, are given. [ABSTRACT FROM AUTHOR]

A test vehicle has been used to collect experimental data related to abrupt engine throttle tip-in transients. The data point to a significant dynamic potential of the longitudinal tyre frictional force on an ice surface. Such a behaviour cannot be predicted by using the available brash-type dynamic tyre friction models. Based on the results of experimental and simulation analyses, the LuGre tyre friction model is extended to predict the dynamic friction potential. The extended model is validated against the experimental data. [ABSTRACT FROM AUTHOR]

The main objective of this paper is the development of enhanced tyre models reran adequate description of tyre-ground interaction on the basis of shell and three-dimensional theories. Investigations are aimed at applications in off-road vehicle dynamics, in tyre design and for soil protection in agriculture. It seems to be necessary to take into account the results of internal tyre mechanics. The soil under the tyre is described by different rheological models of ground surface behaviour in the normal and tangential directions. Soil models were tested with simple one-dimensional tyre models. Results are used for the determination of and improvement in the exactness of stiffness parameters in external tyre models and in the Böhm mass-points approach for transient loading of a rolling tyre. The model is modified for the real structure of agricultural tyres with lugs. The numerical results are compared with experimental data gained by a multipoint measurement technique for displacements in the inner part of the rolling tyre. [ABSTRACT FROM AUTHOR]

A set of scaling factors has been introduced by Pacejka into his ‘magic formula’ tyre model to take into account the influence of a number of external overall parameters such as road roughness, weather conditions and suspension characteristics. These scaling factors are important for a correct prediction of tyre-road contact forces but are not a function of the tyre itself. From a different point of view, one could say that scaling factors should remain constant for different tyres on the same circuit, with the same weather conditions and with the same car. After having characterized different tyros through indoor tests (which do not consider external overall parameters) and after having identified Pacejka's coefficients with scaling factors assumed to be one, several outdoor experimental tests have been carried out to determine the influence of vehicle and road surface conditions on scaling factors. These experimental data allowed us to identify, through a minimization approach, the ‘best’ set of Pacejka's scaling factors for that vehicle and that tyre on that track. Scaling factors for the same track and vehicle but for different tyros were compared to check whether their values remained constant. All experimental data shown in this paper comes from tests carried out within the VERTEC project (vehicle, road, tyre and electronic control systems interaction: increasing active vehicle safety by means of a fully integrated model for behaviour prediction in potentially dangerous situations) (official contract G3RD-CT-2002-00805), a European funded research project that puts together knowledge from vehicle manufacturers (Volvo, Porsche and (CRF)), tyre manufacturers (Pirelli and Nokian Tyres ), control logic manufacturers (Lucas Varity GmbH), road maintenance experts (CETE), transport research organizations (TRL) and (VTI) and universities (HUT) and (UNIFI)). The results shown in this paper arc obtained by tests performed during tasks 2a (Reference tyre characterizations and tests) and 2b (Development and validation of tyre-pavement interaction model) of VERTEC project. The partners involved in these tasks are Pirelli, Nokian, Porsche, CRF, CETE, VTI, HUT and UNIFI. [ABSTRACT FROM AUTHOR]

The main objective of this paper deals with appropriate modelling (of a vehicle and the tyre-road contact) for online estimation of contact forces. This model will be helpful for trajectory monitoring, for steering control and also for diagnosis to avoid accidents or detection of oversteering or understeering situations. A robust observer is developed for adaptive estimation of the contact forces. [ABSTRACT FROM AUTHOR]

This paper describes the simulation procedure of a ply steer residual aligning torque (PRAT) using a stationary global rolling finite-clement method (FEM) tyre model combined with a detailed local FEM tread pattern model. The simulated results of the PRAT for eight tread pattern variants are compared with measured values of experimental tyres and do show a high correlation. Additionally, simulated local contact stress distributions of the tread blocks on a rolling tyre show a high degree of similarity compared with measured distributions generated with a specific in-house test drum. Finally, the local contact stresses are mechanically interpreted to obtain a basic understanding of how the PRAT is generated by the tread pattern. The application of the prescribed simulation procedure to realistic serial patterns is planned for the future. Thus tyre body and pattern PRAT effects can be balanced and the car manufacturers' requirements will be met in an early stage of product development. [ABSTRACT FROM AUTHOR]

This article proposes a tyre evaluation system by using a driving simulator with a tyre testing machine. The dynamic characteristics of the tyre are important in the vehicle dynamics, hence the combination of tyre testing machine with driving simulator is examined to create virtual proving ground proposed by the authors. By applying measurement data from the tyre testing machine in real time instead of calculations by the tyre model, it is possible to get accurate tyre characteristics on a driving simulator. The actual prototype system was made and the dynamic tyre characteristics were evaluated. The experimental results were compared with the Magic Formula model and it was found that the proposed system has several features. [ABSTRACT FROM AUTHOR]

In cooperation with the Ford Research Center Aachen the new tyre-soil interaction model AS²TM for MATLAB/Simulink was developed by Automotive Engineering, Software and Consulting (AESCO). The model is based on the principles introduced by Bekker [Bekker, M.G., 1956, Theory of Land Locomotion: The Mechanics of Vehicle Mobility (Ann Arbor, Michigan: University of Michigan Press); Bekker, M.G., 1960, Off the Road Locomotion (Ann Arbor, Michigan: University of Michigan Press), Bekker, M.G., 1960, Introduction to Terrain-Vehicle Systems (Ann Arbor, Michigan: University of Michigan Press).] and by Janosi and Hanamoto [Janosi, Z. and Hanamoto, B., 1961 Analytical determination of draw bar pull as a function of slip for tracked vehicles in deformable soils. Proceedings of the 1st International Conference of the International Society for Terrain-Vehicles System, Turin, Italy.] and takes advantage of more than a decade of research work in the field of terra-mechanics at the former Institut für Kraftfahrwesen und Kolbenmaschinen of the University of the Federal Armed Forces Hamburg under the charge of Professor I.C. Schmid. In this paper, firstly, the theoretical approach of AS²TM is discussed and the implementation of significant soft soil-elastic tyre interaction effects described and, secondly, the stand-alone model has been investigated and validated for steady-state conditions by using a virtual tyre test environment. Furthermore AS2TM is implemented as an S function into veDYNA applying the TYDEX standard tyre interface. The vehicle dynamic behaviour on deformable ground in a full vehicle simulation is highlighted and a comparison of the predicted vehicle performances on various terrains is presented. [ABSTRACT FROM AUTHOR]

This paper discusses the parameter identification procedure for the LMS comfort and durability tyre (LMS CDTire) model. CDTire is a family of three models (namely CDTire 20. CDTire 30 and CDTire 40) based on a macroscopic physical description of tyres, which is a compromise between scope of applicability and speed. The ‘macroscopic description’ implies that the actual model contains elements representing, for example, the ‘belt’, but not individual cords of the belt layers. Therefore, model parameters such as the belt bending stiffness essentially have to be determined by testing the whole tyre in a number of different ways instead of assembling mechanical properties of all the individual elements of a tyre such as cord stiffness. The considered tests are standard tyre tests that can be performed by most tyre test facilities. The parameter identification process is explained in a genetic way with exemplary focus on one specific identification subtask, as the complete process description would go beyond the scope of this article. Furthermore, some of the strategic decisions made in the build-up of the parameter identification process are highlighted. Together with a more involved discussion on some numerical aspects of the tyre test rig simulations, the choice of optimization algorithms is explained. The technical discussion is complemented with some results obtained with this parameter identification procedure on a 205/55 R16 non-commercial passenger car tyre. [ABSTRACT FROM AUTHOR]

The UniTire model is a nonlinear and non-steady-state tyre model for vehicle dynamics simulation and control under complex wheel motion inputs involving large lateral slip, longitudinal slip, turn slip and camber. The model is now installed in the driving simulator in the Automobile Dynamic Simulation Laboratory at Jilin University for studying vehicle dynamics and their control systems. Firstly, the nonlinear semiphysical steady-state tyre model, which compiles with analytical boundary conditions up to the third order of the simplified physical model, is presented. Special attention has been paid to the expression for the dynamic friction coefficient between the tyre and the road surface and to the modification of the direction of the resultant force under combined-slip conditions. Based on the analytical non-steady-state tyre model, the effective slip ratios and quasi-steady-state concept are introduced to represent the non-steady-state nonlinear dynamic tyre properties in transient and large-slip-ratio cases. Non-steady-state tyre models of first-order approximation and of high-order approximation are developed on the basis of contact stress propagation processes. The UniTire model has been verified by different pure and combined test data and its simulation covered various complex wheel motion inputs, such as large lateral slip, longitudinal slip, turn slip and camber. [ABSTRACT FROM AUTHOR]

A number of experimental activities designed and undertaken for deriving the characteristics of farm tractor tyres are presented. By means of a proprietary measuring hub the three forces and the three moments acting at the hub of a farm tractor wheel have been measured, for different combinations of lateral and longitudinal tyre slips. Tyre steady-state characteristics have been derived both on hard asphalt road and on soft soil. Validation of the measurements of tyre characteristics has been performed indirectly by introducing the data referring to tyre characteristics into a detailed mathematical model of a farm tractor. A number of actual manoeuvres have been simulated. The satisfactory agreement between simulated and measured results has provided the necessary condition for validation of the tyre characteristic measurement process. [ABSTRACT FROM AUTHOR]

The results of vehicle performance tests often vary depending on the season or with differences in the road surface temperature. It is believed that these changes can partially be attributed to the effect of the tyre surface temperature. The aim of this study is to develop a tyre force model that incorporates the influence of the tyre surface temperature. The newly developed tyre force model incorporates a thermodynamic model that allows us to consider changes in the tyre surface temperature and a force model that allows for the effects of the tyre surface temperature. The tyre model parameters were identified using the results of an indoor test facility. The surface temperature and the force values predicted using this model agreed well with actual measurements, proving the validity of the developed model. [ABSTRACT FROM AUTHOR]

This paper presents a method for estimating the loads on the wheels using road profiles. Regarding road profiles, a new method based on sliding mode observers has been developed and is compared with longitudinal profile analyser measurements. Experimental results are shown and discussed to evaluate the robustness of our approach. [ABSTRACT FROM AUTHOR]

This article presents the addition of camber to a previously published semi-empirical tyre model by the same authors. The model combines empirical models for pure braking, cornering and cambering with a model for simultaneous braking, cornering and cambering. It is based on brush-model tyre mechanics and aims to offer an easy-to-use accurate model for vehicle-handling simulations. The proposed model is a method to extract and rescale the adhesion and sliding forces from empirical pure-slip tyre models to account for the combined-slip condition. The combined-slip self-aligning torque is described likewise. Cambering affects the natural path of the tyre carcass on the road surface and deforms the threads to produce an additional force in the lateral direction. Thereby, the proportions of the sliding and adhesive forces changes. The model is computationally sound and efficient and does not rely on any additional parameters that depend on combined-slip data for calibration. It can be used in combination with virtually any empirical pure-slip model. [ABSTRACT FROM AUTHOR]

An EU-funded project entitled ‘Apollo’ aims at the development and prototyping of an intelligent tyre, which is able to detect the current state of adhesion contact between the tyre and the road. The data can be supplied to superior vehicle dynamics control systems in order to increase traffic safety. Different sensor approaches are developed and tested. A highly demanding topic is the design of evaluation algorithms for the sensor data. For this purpose, simplified, physically based tyre models have been developed, which cover local tyre tread deformations for pure longitudinal and lateral slip conditions as well as for combined slip. A brush-type tyre model is used for this purpose. The integration of the forces and moments is achieved by adding the areas of two triangles and a rectangle to reduce the effort of considering single tread lugs. The global tyre deformations, that is the lateral and the longitudinal stiffnesses of the tyre contact patch relative to the rim, is modelled by simple approaches such as a function of the inflation pressure. [ABSTRACT FROM AUTHOR]

The tyre models FTire and LMS CDTire for multibody simulation have been developed for use in the field of vehicle system dynamics. These tyre models are expected to enable us to predict the forces on the wheel spindle in ride comfort and durability simulations. In this paper, the performance of FTire and LMS CDTire in predicting durability loads is evaluated using a new test setup termed a ‘suspension on a drum’. Both tyre models demonstrated a sufficient level of performance to enable practical application in predicting durability performance. [ABSTRACT FROM AUTHOR]

A well-tuned tyre-vehicle vibration interaction strongly supports a pleasant road noise. Continental has developed efficient tools and procedures to achieve that. In the frequency range up to 300 Hz, modal tyre models turned out to be very helpful. In this paper we describe the method of simulation and its experimental validation. Using application examples, benefits and limits are shown. [ABSTRACT FROM AUTHOR]

Nowadays, obtaining results on the forces and torques in a tyre, in controllable and repetitive working conditions in a laboratory, is fundamental for research groups in vehicle dynamics simulations. There is a need, more than a convenience, to own a facility to test tyres of a wide range of dimensions and with versatile and non-restricted operating conditions of functioning. In this paper a group of experimental data obtained from tests on a tyre in the IMMa tyre test bench is presented. With the goals of determining the accuracy of these experimental test data and also the operating performance of the test bench in the steady state, the analytical model of pneumatic tyres for vehicle dynamics simulations reported by Gim and Nikravesh is employed. [ABSTRACT FROM AUTHOR]

Modeling of tire cornering properties using experimental modal parameters is studied. With tire lateral experimental modal parameters, the distribution of side force and lateral deformation under total adhesive and sliding conditions are obtained. Side force, self-aligning, cornering stiffness and relaxation length under different loads and friction coefficients are also calculated. The calculated results are in correspondence to experimental results in the references qualitatively. The non-dimensional side force obtained from the calculated results is compared with the Fiala model, its modified expression by experiments and also the widely used empirical Magic Formula model. The calculated results tally well with the fitted results obtained using Magic Formula model. It can be seen that the tire steady state cornering model using experimental modal parameters proposed in this paper is better for an in-depth study of tire natural characteristics, and the labored experimental work can be avoided. [ABSTRACT FROM AUTHOR]