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Showing papers in "Vehicle System Dynamics in 2014"


Journal ArticleDOI
TL;DR: In this article, the authors investigated the vehicle lateral dynamics stabilisation problem to enhance vehicle handling by considering time-varying longitudinal velocity and proposed a novel technique to reduce the number of vertices.
Abstract: In this paper, we investigate the vehicle lateral dynamics stabilisation problem to enhance vehicle handling by considering time-varying longitudinal velocity. The longitudinal velocity is described by a polytope with finite vertices and a novel technique is proposed to reduce the number of vertices. Since the tyre dynamics is nonlinear, the cornering stiffness is represented via the norm-bounded uncertainty. Concerning the time-varying velocity and the nonlinear tyre model, a linear parameter-varying vehicle model is obtained. As the velocity and the states are measurable, a gain-scheduling state-feedback controller is introduced. In the lateral control, the sideslip angle is required to be as small as possible and the yaw rate is constrained to a certain level. Thus, the control objective is to minimise the sideslip angle while the yaw rate is under a prescribed level or constrain both the sideslip angle and the yaw rate to prescribed levels. To consider the transient response of the closed-loop system,...

255 citations


Journal ArticleDOI
TL;DR: In this paper, an automated steering strategy based on nonlinear model predictive control is proposed to cope with the longitudinal speed tracking problem, and a simultaneous longitudinal and lateral control strategy helps to improve the combined control performance.
Abstract: This paper deals with the longitudinal and lateral control of an automotive vehicle within the framework of fully automated guidance. The automotive vehicle is a complex system characterised by highly nonlinear longitudinal and lateral coupled dynamics. Consequently, automated guidance must be simultaneously performed with longitudinal and lateral control. This work presents an automated steering strategy based on nonlinear model predictive control. A nonlinear longitudinal control strategy considering powertrain dynamics is also proposed to cope with the longitudinal speed tracking problem. Finally, a simultaneous longitudinal and lateral control strategy helps to improve the combined control performance. This whole control strategy is tested through simulations showing the effectiveness of the present approach.

210 citations


Journal ArticleDOI
TL;DR: In this article, a robust nonlinear model predictive controller (RNMPC) is used to help the driver navigating the vehicle in order to avoid obstacles and track the road centre line, and a robust invariant set is used in the RNMPC design to guarantee that state and input constraints are satisfied in the presence of disturbances and model error.
Abstract: This paper proposes a robust control framework for lane-keeping and obstacle avoidance of semiautonomous ground vehicles. It presents a systematic way of enforcing robustness during the MPC design stage. A robust nonlinear model predictive controller (RNMPC) is used to help the driver navigating the vehicle in order to avoid obstacles and track the road centre line. A force-input nonlinear bicycle vehicle model is developed and used in the RNMPC control design. A robust invariant set is used in the RNMPC design to guarantee that state and input constraints are satisfied in the presence of disturbances and model error. Simulations and experiments on a vehicle show the effectiveness of the proposed framework.

181 citations


Journal ArticleDOI
Liang Li1, Gang Jia1, Xu Ran1, Jian Song1, Kaihui Wu1 
TL;DR: In this article, a variable structure extended Kalman filter integrated with the sidelip angle rate feedback algorithm and damping item is proposed to compensate the model error caused by road friction estimation inaccuracy.
Abstract: Sideslip angle plays an important role in vehicle stability control. However, it is difficult to measure directly unless some complex and expensive devices are employed. Thus, sideslip angle estimated by vehicle states such as lateral acceleration, yaw rate and so on is required in real-time vehicle stability control. A new variable structure extended Kalman filter integrated with the sideslip angle rate feedback algorithm and damping item is proposed in this paper. The main idea of the sideslip angle rate feedback algorithm is to compensate the model error caused by road friction estimation inaccuracy while that of the damping item is to suppress the error accumulation. The estimated results are compared with the real values obtained by the differential global position system on a low friction road and it shows that the proposed methodology can provide accurate sideslip angle to some extent for vehicle stability control.

129 citations


Journal ArticleDOI
TL;DR: In this article, the minimum-lap-time optimal control problem for a Formula One race car is solved using direct transcription and nonlinear programming, which results in significantly reduced full-lap solution times and the simultaneous optimization of the driven line, the driver controls and multiple car set-up parameters.
Abstract: The minimum-lap-time optimal control problem for a Formula One race car is solved using direct transcription and nonlinear programming. Features of this work include significantly reduced full-lap solution times and the simultaneous optimisation of the driven line, the driver controls and multiple car set-up parameters. It is shown that significant reductions in the driven lap time can be obtained from track-specific set-up parameter optimisation. Reduced computing times are achieved using a combination of a track description based on curvilinear coordinates, analytical derivatives and model non-dimensionalisation. The curvature of the track centre line is found by solving an auxiliary optimal control problem that negates the difficulties associated with integration drift and trajectory closure.

114 citations


Journal ArticleDOI
TL;DR: In this paper, feed-forward types of tyre force distribution control with some norms for motion control of a full drive-by-wire electric vehicle are presented. And the effects of the distribution control on improving vehicle stability and reducing the tyre energy dissipation caused by tyre slip are investigated.
Abstract: Feed-forward types of tyre force distribution controls with some norms for motion controls of a full drive-by-wire electric vehicle are presented. One of the norms for the distribution control introduced is minimising tyre workload and another one is minimising tyre dissipation energy due to tyre slip during vehicle motion. The effects of the distribution controls are substantiated using an experimental vehicle on a proving ground. Especially the effects of the tyre force distribution norms on improving vehicle stability and on reducing the tyre energy dissipation caused by tyre slip are investigated.

97 citations


Journal ArticleDOI
TL;DR: In this article, a platform for investigation of these aspects is developed based on a state-of-the-art optimisation tool together with adoption of existing vehicle chassis and tyre models, with the overall aim of finding improved fundamental principles for future active safety systems.
Abstract: There is currently a strongly growing interest in obtaining optimal control solutions for vehicle manoeuvres, both in order to understand optimal vehicle behaviour and, perhaps more importantly, to devise improved safety systems, either by direct deployment of the solutions or by including mimicked driving techniques of professional drivers. However, it is non-trivial to find the right combination of models, optimisation criteria, and optimisation tools to get useful results for the above purposes. Here, a platform for investigation of these aspects is developed based on a state-of-the-art optimisation tool together with adoption of existing vehicle chassis and tyre models. A minimum-time optimisation criterion is chosen for the purpose of gaining an insight into at-the-limit manoeuvres, with the overall aim of finding improved fundamental principles for future active safety systems. The proposed method to trajectory generation is evaluated in time-manoeuvres using vehicle models established in the literature. We determine the optimal control solutions for three manoeuvres using tyre and chassis models of different complexities. The results are extensively analysed and discussed. Our main conclusion is that the tyre model has a fundamental influence on the resulting control inputs. Also, for some combinations of chassis and tyre models, inherently different behaviour is obtained. However, certain variables important in vehicle safety-systems, such as the yaw moment and the body-slip angle, are similar for several of the considered model configurations in aggressive manoeuvring situations.

87 citations


Journal ArticleDOI
TL;DR: In this article, the authors review current techniques in dynamics modelling of friction draft gears to provide a starting point that can be used to improve existing or develop new models to achieve more accurate force amplitude and pattern predictions.
Abstract: Longer and heavier trains mean larger in-train forces and more complicated force patterns. Practical experience indicates that the development of fatigue failure of coupling systems in long heavy trains may differ from conventional understanding. The friction-type draft gears are the most widely used draft gears. The ever developing heavy haul transport environment requires further or new understanding of friction draft gear behaviour and its implications for train dynamics as well as fatigue damage of rolling stock. However, modelling of friction draft gears is a highly nonlinear question. Especially the poor predictability, repeatability and the discontinuity of friction make this task more challenging. This article reviews current techniques in dynamics modelling of friction draft gears to provide a starting point that can be used to improve existing or develop new models to achieve more accurate force amplitude and pattern predictions.

79 citations


Journal ArticleDOI
TL;DR: In this paper, the authors developed a model of the powertrain system of an electric car equipped with an axle motor and analyzed the transfer characteristics of the motor torque in the driveline and its effect on blended braking control performance.
Abstract: Because of the damping and elastic properties of an electrified powertrain, the regenerative brake of an electric vehicle (EV) is very different from a conventional friction brake with respect to the system dynamics. The flexibility of an electric drivetrain would have a negative effect on the blended brake control performance. In this study, models of the powertrain system of an electric car equipped with an axle motor are developed. Based on these models, the transfer characteristics of the motor torque in the driveline and its effect on blended braking control performance are analysed. To further enhance a vehicle's brake performance and energy efficiency, blended braking control algorithms with compensation for the powertrain flexibility are proposed using an extended Kalman filter. These algorithms are simulated under normal deceleration braking. The results show that the brake performance and blended braking control accuracy of the vehicle are significantly enhanced by the newly proposed algorithms.

76 citations


Journal ArticleDOI
TL;DR: In this paper, an approximate analytical method is proposed for calculating the contact patch and pressure distribution in the wheel-rail interface, where the deformation of the surfaces in contact is approximated using the separation between them.
Abstract: An approximate analytical method is proposed for calculating the contact patch and pressure distribution in the wheel-rail interface. The deformation of the surfaces in contact is approximated using the separation between them. This makes it possible to estimate the contact patch analytically. The contact pressure distribution in the rolling direction is assumed to be elliptic with its maximum calculated by applying Hertz' solution locally. The results are identical to Hertz's for elliptic cases. In non-elliptic cases good agreement is achieved in comparison to the more accurate but computationally expensive Kalker's variational method (CONTACT code). Compared to simplified non-elliptic contact methods based on virtual penetration, the calculated contact patch and pressure distribution are markedly improved. The computational cost of the proposed method is significantly lower than the more detailed methods, making it worthwhile to be applied to rolling contact in rail vehicle dynamics simulation. Such fast and accurate estimation of contact patch and pressure paves the way for on-line modelling of damage phenomena in dynamics simulation packages.

74 citations


Journal ArticleDOI
TL;DR: In this article, a single-track car model coupled with an extended Kalman filter was used to estimate the vehicle slip angle, and a tuning procedure was proposed that takes into account both nonlinear and saturation characteristics typical of vehicle lateral dynamics.
Abstract: It is well known that vehicle slip angle is one of the most difficult parameters to measure on a vehicle during testing or racing activities. Moreover, the appropriate sensor is very expensive and it is often difficult to fit to a car, especially on race cars. We propose here a strategy to eliminate the need for this sensor by using a mathematical tool which gives a good estimation of the vehicle slip angle. A single-track car model, coupled with an extended Kalman filter, was used in order to achieve the result. Moreover, a tuning procedure is proposed that takes into consideration both nonlinear and saturation characteristics typical of vehicle lateral dynamics. The effectiveness of the proposed algorithm has been proven by both simulation results and real-world data.

Journal ArticleDOI
TL;DR: In this article, a Kalman Filter (KF) was applied to estimate the track geometry of Shinkansen tracks using car-body motions only to solve the problem of track irregularity estimation in vertical direction.
Abstract: Track maintenance works based on track geometry recordings are essential to enhance the safety and comfort of railway transportation. The track condition monitoring system is mainly used for the choice of area needing track tamping works for the purpose of the good riding comfort. An advantage of car-body acceleration measurement devices is their simple structures, which make it easier to carry out maintenance. However, the car-body acceleration waveform is considerably different from track geometry. This paper demonstrates the possibility to estimate the track geometry of Shinkansen tracks using car-body motions only. In an inverse problem to estimate track irregularity from car-body motions, a Kalman Filter (KF) was applied to solve the problem. Estimation results showed that track irregularity estimation in vertical direction is possible with acceptable accuracy for real use.

Journal ArticleDOI
TL;DR: In this article, a vehicle adaptive sliding-mode control (SMC) algorithm is presented with the estimated vehicle velocity, the tyre/road friction coefficients and the optimal slip ratios.
Abstract: A sliding-mode observer is designed to estimate the vehicle velocity with the measured vehicle acceleration, the wheel speeds and the braking torques. Based on the Burckhardt tyre model, the extended Kalman filter is designed to estimate the parameters of the Burckhardt model with the estimated vehicle velocity, the measured wheel speeds and the vehicle acceleration. According to the estimated parameters of the Burckhardt tyre model, the tyre/road friction coefficients and the optimal slip ratios are calculated. A vehicle adaptive sliding-mode control (SMC) algorithm is presented with the estimated vehicle velocity, the tyre/road friction coefficients and the optimal slip ratios. And the adjustment method of the sliding-mode gain factors is discussed. Based on the adaptive SMC algorithm, a vehicle's antilock braking system (ABS) control system model is built with the Simulink Toolbox. Under the single-road condition as well as the different road conditions, the performance of the vehicle ABS system is sim...

Journal ArticleDOI
TL;DR: In this article, a detailed investigation of the effects of rail corrugation on the dynamic behavior of metro rail fastenings is presented, obtained from extensive experiments conducted on site and from simulations of train-track dynamics.
Abstract: This paper presents the results of a detailed investigation of the effects of rail corrugation on the dynamic behaviour of metro rail fastenings, obtained from extensive experiments conducted on site and from simulations of train–track dynamics. The results of tests conducted with a metro train operating on corrugated tracks are presented and discussed first. A three-dimensional (3D) model of the metro train and a slab track was developed using multi-body dynamics modelling and the finite element method to simulate the effect of rail corrugation on the dynamic behaviour of rail fastenings. In the model, the metro train is modelled as a multi-rigid body system, and the slab track is modelled as a discrete elastic support system consisting of two Timoshenko beams for the rails, a 3D solid finite element (FE) model for the slabs, periodic discrete viscoelastic elements for the rail fastenings that connect the rails to the slabs, and uniformly viscoelastic elements for the subgrade beneath the slabs. The prop...

Journal ArticleDOI
TL;DR: In this article, a literature survey on the validation of vehicle dynamics simulation models is presented, which presents different views on the definition of validation, and its usage in vehicle simulation models.
Abstract: In this work, a literature survey on the validation of vehicle dynamics simulation models is presented. Estimating the dynamic responses of existing or proposed vehicles has a wide array of applications in the development of vehicle technologies, e.g. active suspensions, controller design, driver assistance systems, etc. Although simulation environments, measurement tools and mathematical theories on vehicle dynamics are well established, the methodical link between the experimental test data and validity analysis of the simulation model is still lacking. This report presents different views on the definition of validation, and its usage in vehicle dynamics simulation models.

Journal ArticleDOI
TL;DR: In this paper, a numerical optimisation approach to minimize rolling contact fatigue (RCF) damage and wear in the crossing panel by varying the nose rail shape is presented in order to improve the dynamic behaviour of turnout crossings, a combined weighted objective function is used consisting of the normal contact pressure and the energy dissipation along the crossing responsible for RCF and wear.
Abstract: Proper rail geometry in the crossing part is essential for reducing damage on the nose rail. To improve the dynamic behaviour of turnout crossings, a numerical optimisation approach to minimise rolling contact fatigue (RCF) damage and wear in the crossing panel by varying the nose rail shape is presented in the paper. The rail geometry is parameterised by defining several control cross-sections along the crossing. The dynamic vehicle–turnout interaction as a function of crossing geometry is analysed using the VI-Rail package. In formulation of the optimisation problem a combined weighted objective function is used consisting of the normal contact pressure and the energy dissipation along the crossing responsible for RCF and wear, respectively. The multi-objective optimisation problem is solved by adapting the multipoint approximation method and a number of compromised solutions have been found for various sets of weight coefficients. Dynamic behaviour of the crossing has been significantly improved after ...

Journal ArticleDOI
TL;DR: Wang et al. as mentioned in this paper investigated an optimization strategy for the design of rail-grinding profiles to be used on heavy-haul railway curves, aiming to reduce the rail side wear on curves.
Abstract: This article investigates an optimisation strategy for the design of rail-grinding profiles to be used on heavy-haul railway curves, aiming to reduce the rail side wear on curves. A design methodology of rail asymmetric-grinding profiles is put forward based on the principle of low wheel–rail dynamic interaction. The implementing procedure is illustrated in detail. As a case study, the rail asymmetric-grinding profiles were designed for a curve with 600 m radius on Chinese Shuohuang heavy-haul railway. The characteristics of wheel–rail contact geometry and wheel–rail dynamic interaction were analysed and compared between the original standard rail profiles and the designed rail-grinding profiles. The rails on a test curve were ground according to the designed profiles. Before and after rail grinding, both the wheel–rail dynamics indexes and the rail side wear were measured in the field. The theoretical and experimental results show that the wheel–rail dynamic interaction is clearly improved and the rail s...

Journal ArticleDOI
TL;DR: In this paper, a 3D explicit finite element model is developed to investigate the transient wheel-rail rolling contact in the presence of rail contamination or short low adhesion zones (LAZs).
Abstract: A 3-D explicit finite element model is developed to investigate the transient wheel–rail rolling contact in the presence of rail contamination or short low adhesion zones (LAZs). A transient analysis is required because the wheel passes by a short LAZ very quickly, especially at high speeds. A surface-to-surface contact algorithm (by the penalty method) is employed to solve the frictional rolling contact between the wheel and the rail meshed by solid elements. The LAZ is simulated by a varying coefficient of friction along the rail. Different traction efforts and action of the traction control system triggered by the LAZ are simulated by applying a time-dependent driving torque to the wheel axle. Structural flexibilities of the vehicle–track system are considered properly. Analysis focuses on the contact forces, creepage, contact stresses and the derived frictional work and plastic deformation. It is found that the longitudinal contact force and the maximum surface shear stress in the contact patch become...

Journal ArticleDOI
TL;DR: In this paper, a detailed analysis of the Pantograph-catenary dynamic interaction separating phenomena due to the dynamic response of the pantographto the catenary geometry from wave propagations, reflections and transmissions that occur in the Catenary is presented.
Abstract: In railways, electrical current is generally collected by the train through a complex coupledmechanical system composed of a pantograph and a catenary. Dynamic phenomena that occur duringtheir interaction are still not fully understood. Furthermore, the system behaviour is sensitive to numerousparameters and thus highly variable. The first contribution of this thesis is a detailed analysis of thepantograph-catenary dynamic interaction separating phenomena due to the dynamic response of the pantographto the catenary geometry from wave propagations, reflections and transmissions that occur in thecatenary. The coincidence of frequencies or characteristic times is then shown to explain most variationsin the quantities of interest. Moreover, droppers surrounding the mast have been shown to be particularlyimportant in dynamic interaction. Ratio of wire impedances and sum of wave velocities also appeared tobe dimensioning quantities for catenary design. The second contribution was to reduce epistemic uncertaintylinked with model parameters such as catenary damping, contact stiffness and element size. Thefinal contribution was to use the model in a configuration with random parameters. An initial step was tostatistically characterise physical catenary parameters using available measurements. From this randommodel, ranking of uncertainties using Sobol indices on static and dynamic criteria was shown to be possible.An absence of correlation between geometric and dynamic criteria was also found, which has notableimplications for maintenance policies. The high number of sensitivity studies also gave the occasion tohighlight the maturity of simulation tool and propose directions for further work on design, maintenance orcertification of pantographs and catenaries.

Journal ArticleDOI
TL;DR: In this article, an efficient co-simulation process between finite element (FE) and multibody (MB) modelling methods is described, where FE catenary models are coupled with a full flexible MB representation with pneumatic actuation of pantograph.
Abstract: This paper presents recent developments undertaken by SNCF Innovation & Research Department on numerical modelling of pantograph catenary interaction. It aims at describing an efficient co-simulation process between finite element (FE) and multibody (MB) modelling methods. FE catenary models are coupled with a full flexible MB representation with pneumatic actuation of pantograph. These advanced functionalities allow new kind of numerical analyses such as dynamic improvements based on innovative pneumatic suspensions or assessment of crash risks crossing areas that demonstrate the powerful capabilities of this computing approach.

Journal ArticleDOI
TL;DR: In this paper, a methodology for the simulation of track settlement in railway turnouts (switches and crossings, S&C) is presented, which predicts accumulated settlement for a given set of traffic loads using an iterative and cross-disciplinary procedure.
Abstract: A methodology for the simulation of track settlement in railway turnouts (switches and crossings, S&C) is presented. The methodology predicts accumulated settlement for a given set of traffic loads using an iterative and cross-disciplinary procedure. The different modules of the procedure include (I) simulation of dynamic vehicle-track interaction in a turnout applying a validated software for multibody vehicle dynamics considering space-dependent track properties, (II) calculation of load distribution and sleeper-ballast contact pressure using a detailed finite element model of a turnout that includes all of the rails (stock rails, switch rails, closure rails, crossing nose, wing rails and check rails), rail pads, baseplates and sleepers on ballast, (III) prediction of track settlement for a given number of load cycles and (IV) calculation of accumulated track settlement at each sleeper and the resulting vertical track irregularity along the turnout which is used as input in the next step of the iteration. The iteration scheme is demonstrated by calculating the track settlement at the crossing when the studied turnout is exposed to freight traffic in the facing move of the through route.

Journal ArticleDOI
TL;DR: In this article, a number of driver models were fitted to a large data set of human truck driving, from a simulated near-crash, low-friction scenario, yielding two main insights: steering to avoid a collision was best described as an open-loop manoeuvre of predetermined duration, but with situation-adapted amplitude, and subsequent vehicle stabilisation could to be accounted for by a simple yaw rate nulling control law.
Abstract: A number of driver models were fitted to a large data set of human truck driving, from a simulated near-crash, low-friction scenario, yielding two main insights: steering to avoid a collision was best described as an open-loop manoeuvre of predetermined duration, but with situation-adapted amplitude, and subsequent vehicle stabilisation could to a large extent be accounted for by a simple yaw rate nulling control law. These two phenomena, which could be hypothesised to generalise to passenger car driving, were found to determine the ability of four driver models adopted from the literature to fit the human data. Based on the obtained results, it is argued that the concept of internal vehicle models may be less valuable when modelling driver behaviour in non-routine situations such as near-crashes, where behaviour may be better described as direct responses to salient perceptual cues. Some methodological issues in comparing and validating driver models are also discussed.

Journal ArticleDOI
TL;DR: In this paper, a high-speed camera and three accelerometers fixed to the inner linings of the tyre carcass were used to study the contact area and shape of the road surface.
Abstract: The tyre–road contact area was studied visually by means of a high-speed camera and three accelerometers fixed to the inner liner of the tyre carcass. Both methods show a distorted contact area in wet conditions, but interesting differences appeared. First, the contact area in full aquaplaning seems strongly distorted on a glass plate when subjected to visual inspection, while the accelerometers indicate a more even hydrodynamic aquaplaning contact length (CL) across the tyre width. Secondly, the acceleration sensors predict the clear shortening of the CL of the tyre before the critical aquaplaning speed. It can be concluded that the visual contact area and shape are heavily dependent on the transparency of the liquid and smoothness of the glass. Meanwhile, the tyre sensors can provide a CL estimate on any road surface imaginable.

Journal ArticleDOI
TL;DR: In this paper, the authors present a study on switched control of vehicle suspension based on motion-mode detection, which can be potentially implemented via the interconnected suspension such as hydraulically interconnected suspension by actively switching its interconnection configuration in terms of the dominant vehicle body motion mode.
Abstract: This paper presents a study on switched control of vehicle suspension based on motion-mode detection. This control strategy can be potentially implemented via the interconnected suspension such as hydraulically interconnected suspension by actively switching its interconnection configuration in terms of the dominant vehicle body motion-mode. The design of the switched control law is developed focusing on three vehicle body motion-modes: bounce, pitch, and roll. At first, an H∞ optimal controller will be designed for each motion-mode with the use of a common quadratic Lyapunov function, which guarantees the stability of the switched system under arbitrary switching functions. Then, a motion-mode detection method based on the calculation of the motion-mode energy is introduced. And then, the possible implementation of the control system in practice is discussed. Finally, numerical simulations are used to validate the proposed study.

Journal ArticleDOI
TL;DR: In this paper, the conformal wheel-rail rolling contact problem is investigated using the boundary element approach together with numerical influence coefficients, that are computed using the finite element approach, and the results indicate that the contact area is longer and narrower, with smaller area and reduced stiffness, than is predicted by the half-space approach.
Abstract: The stresses between railway wheels and rails can be computed using different types of contact models: simplified methods, half-space-based boundary element approaches and finite element models. For conformal contact situations, particularly the contact between flange root and rail gauge corner, none of these models work satisfactorily. Finite element methods are too slow, half-space approaches ignore the effects of conformality, and simplified approaches schematise the elasticity of the material even further.This paper presents a thorough investigation of the conformal wheel–rail rolling contact problem. We use CONTACT's boundary element approach together with numerical influence coefficients, that are computed using the finite element approach. The resulting method is fast and detailed and can be embedded into vehicle system dynamics simulation. The results indicate that the contact area is longer and narrower, with smaller area and reduced stiffness, than is predicted by the half-space approach. The pr...

Journal ArticleDOI
TL;DR: In this paper, the authors present a review of current techniques in dynamic modelling of friction wedge suspension with various motivations: to improve dynamic models of friction wedges so as to improve general wagon dynamics simulations; to seek better friction wedge suspensions models for wagon stability assessments in complex train systems; to improve the modelling of other friction devices, such as friction draft gear.
Abstract: Three-piece bogies with friction wedge suspensions are the most widely used bogies in heavy haul trains. Fiction wedge suspensions play a key role in these wagon systems. This article reviews current techniques in dynamic modelling of friction wedge suspension with various motivations: to improve dynamic models of friction wedge suspensions so as to improve general wagon dynamics simulations; to seek better friction wedge suspension models for wagon stability assessments in complex train systems; to improve the modelling of other friction devices, such as friction draft gear. Relevant theories and friction wedge suspension models developed by using commercial simulation packages and in-house simulation packages are reviewed.

Journal ArticleDOI
TL;DR: In this article, a self-developed six-speed dry dual-clutch transmission (DCT) with two intermediate shafts is considered, and the optimal torque-coordinated control strategy between engine and dual clutches is proposed to resolve the problem of launching with twin clutches simultaneously involved based on the minimum value principle.
Abstract: As for the self-developed six-speed dry dual-clutch transmission (DCT), the optimal torque-coordinated control strategy between engine and dual clutches is proposed to resolve the problem of launching with twin clutches simultaneously involved based on the minimum value principle. Focusing on the sliding friction phase of the launching process, dynamics equations of dry DCT with two intermediate shafts are firstly established, and then the optimal transmitting torque variation rate and the driven plate's rotating speed of dual clutches are deduced by using the minimum value principle, in which the jerk intensity and friction work are taken as the performance indexes, and the terminal constraints of state variables are determined according to the driver's launching intention. Besides, the separating conditions of non-target gear clutch and the torque distributing relations of twin clutches are derived from the launching control targets that guarantee the approximately equal friction extent of two clutches and no power cycle. After the synchronisation of driving and driven plates of on-coming clutch, the output torque of engine is smoothly switched to the driver's demand level. Furthermore, launching the simulation model of the dry DCT vehicle is set up on the Matlab/Simulink platform. Simulation results indicate that the proposed launching control strategy not only can effectively reflect the driver's intention and extend the life span of twin clutches, but also obtain an excellent launching quality. Finally, the torque control laws of two clutches obtained through the simulation are transformed into clutch position control laws for the future realisation in the real car, and the closed-loop position controls of twin clutches in the launching process are conducted on the test bench with two sets of clutch actuator, obtaining preferable tracking effects.

Journal ArticleDOI
TL;DR: In this article, the effect of the flexibility of both track and car body on the entire vehicle-track coupled dynamic response is investigated by using the Green's function method, which can determine the vibration response over a wide range of frequency without any limitations due to modal truncation.
Abstract: A vertical vehicle–track coupled dynamic model, consisting of a high-speed train on a continuously supported rail, is established in the frequency-domain The solution is obtained efficiently by use of the Green's function method, which can determine the vibration response over a wide range of frequency without any limitations due to modal truncation Moreover, real track irregularity spectra can be used conveniently as input The effect of the flexibility of both track and car body on the entire vehicle–track coupled dynamic response is investigated A multi-body model of a vehicle with either rigid or flexible car body is defined running on three kinds of track: a rigid rail, a track stiffness model and a Timoshenko beam model The results show that neglecting the track flexibility leads to an overestimation of both the contact force and the whole vehicle vibration response The car body flexibility affects the ride quality of the vehicle and the coupling through the track and can be significant in certain frequency ranges Finally, the effect of railpad and ballast stiffness on the vehicle–track coupled vibration is analysed, indicating that the stiffness of the railpad has an influence on the system in a higher frequency range than the ballast

Journal ArticleDOI
TL;DR: In this article, an estimation of vehicle speed is applied to a hybrid vehicle with an electric motor on the rear axle and a combustion engine on the front axle, where the wheel torque information, provided by electric motor, is used to early detect excessive wheel slip and improve the accuracy of the estimate.
Abstract: Vehicle speed is one of the important quantities in vehicle dynamics control. Estimation of the slope angle is in turn a necessity for correct dead reckoning from vehicle acceleration. In the present work, estimation of vehicle speed is applied to a hybrid vehicle with an electric motor on the rear axle and a combustion engine on the front axle. The wheel torque information, provided by electric motor, is used to early detect excessive wheel slip and improve the accuracy of the estimate. A best-wheel selection approach is applied as the observation variable of a Kalman filter which reduces the influence of slipping wheels as well as reducing the computational effort. The performance of the proposed algorithm is illustrated on a test data recorded at a winter test ground with excellent results, even for extreme conditions such as when all four wheels are spinning.

Journal ArticleDOI
TL;DR: In this article, a steering torque computation is presented to generate a realistic steering feel, which means that the driver should not miss the basic steering functionality of a modern conventional steering system such as an electric power steering or hydraulic power steering (HPS).
Abstract: This paper deals with the control of the hand wheel actuator in steer-by-wire (SbW) vehicles and driving simulators (DSs). A novel model for the computation of the desired steering torque is presented. The introduced steering torque computation does not only aim to generate a realistic steering feel, which means that the driver should not miss the basic steering functionality of a modern conventional steering system such as an electric power steering (EPS) or hydraulic power steering (HPS), and this in every driving situation. In addition, the modular structure of the steering torque computation combined with suitably selected tuning parameters has the objective to offer a high degree of customisability of the steering feel and thus to provide each driver with his preferred steering feel in a very intuitive manner. The task and the tuning of each module are firstly described. Then, the steering torque computation is parameterised such that the steering feel of a series EPS system is reproduced. For this purpose, experiments are conducted in a hardware-in-the-loop environment where a test EPS is mounted on a steering test bench coupled with a vehicle simulator and parameter identification techniques are applied. Subsequently, how appropriate the steering torque computation mimics the test EPS system is objectively evaluated with respect to criteria concerning the steering torque level and gradient, the feedback behaviour and the steering return ability. Finally, the intuitive tuning of the modular steering torque computation is demonstrated for deriving a sportier steering feel configuration.