Dynamic Response Of Vehicle Research Articles

Research on Dynamic Response of Vehicle and Asphalt Pavement Interaction under Random Unevenness Excitation

Research on Dynamic Response of Vehicle and Asphalt Pavement Interaction under Random Unevenness Excitation

Vehicle Ride Comfort Analysis Based on Vehicle‐Bridge Coupled Vibration

The study in this paper aims to evaluate the effects of vehicle‐bridge coupled vibration on the vehicle ride comfort. The mechanical model of both vehicle and bridge subsystems and the vibration differential equations are established, respectively, based on the principle of dynamic balance and finite element method. The APDL command stream for iterative calculation is compiled on the ANSYS platform. The method to evaluate the vehicle ride comfort is established according to the criteria in ISO2631‐1‐1997. The vehicle dynamic responses and ride comfort are analyzed considering different pavement levels while multiple vehicles pass through the cable‐stayed bridge. The analysis results indicate that the dynamic responses of vehicles decrease with the improvement of pavement roughness, resulting in the vehicle ride comfort to be better; the dynamic responses of vehicles increase with the increment of vehicle speed or the decrement of vehicle gravity, resulting in the vehicle ride comfort to be worse. The present research results can provide an insight into the rational design of bridge structure so as to reduce the vehicle‐bridge coupling vibration responses and improve the ride quality of drivers and passengers.

ORES: a chassis dynamometer for off-road vehicles

Off-Road Environment Simulator (ORES) is a Real-time Hardware-in-the-Loop (RT-HIL) platform to simulate the dynamic response of off-road vehicles. This paper primarily focuses on the vehicle model development and validation using both field and rig testing using the ORES platform. Off-road vehicles are capable of operating on bumpy terrains where they are subjected to different resistive wheel torques due to non-unique ground friction conditions and wheel loads. If the powertrain torque output is not distributed in accordance with the resistive wheel torques, it may lead to transmission windup resulting in premature failure of various driveline components. In this study, the vehicle is driven over discrete bumps both in rig simulation and field trial. Different terrain enveloping models were evaluated namely the single point, radial-spring contact model and two-point follower (using circular and sinusoidal basis). These models were evaluated against the measured wheel acceleration responses. The two-point follower with sinusoidal basis strongly correlates with the measured responses and the ground excitations so obtained were used as inputs to a seven degree-of-freedom vehicle ride model. Ride model calculates the wheel loads and is eventually integrated with longitudinal dynamics, tire, driveline and test-rig models. Vehicle axle acceleration, wheel speed and drive torque responses are measured for validating the simulation results against field and rig trials. The field responses matches fairly well which validates the suitability of the proposed modeling approach.

Transition-based complexity-entropy causality diagram: A novel method to characterize complex systems

Complexity-entropy causality plane (CECP) and ordinal transition network (OTN) are both crucial tools to reveal the characteristics of time series and distinguish complex systems. However, when the parameters of the system to be distinguished have a wide range of values, the distinguishing function of CECP is weakened. Therefore, we propose a new measure called transition Fisher information (TFI) based on the probability transition matrix in OTN. The TFI is combined with conditional entropy of ordinal patterns and complexity measure to form a novel three-dimensional graph, called transition-based complexity-entropy causality diagram(TB-CECD). These three statistics depict the complex system from different angles. Through simulation experiments, we prove that even if the parameters of complex systems are wide-ranging, the systems of different properties can be assigned to different areas of the graph. Moreover, we find that the trace of the transition probability matrix can be seen as a function of time delay and used to reflect the periodic information of the system. For applications, the proposed methods are applied to vehicle dynamic response data to diagnose periodic short-wave defects such as rail corrugation. The financial time series and Electroencephalographic (EEG) time series are also researched.

Simultaneous identification of the frequencies and track irregularities of high-speed railway bridges from vehicle vibration data

Bridge frequencies and track irregularities are both the focuses of railway bridge condition assessment, which are coupled with each other in a vehicle-bridge system. Available algorithms face a great challenge when applied to simultaneously identify the natural frequencies and track irregularities of railway bridges using on-board measurement data. This paper proposes a novel algorithm for simultaneously identifying the frequencies and track irregularities of high-speed railway bridges using vehicle dynamic responses for the first time. An extended state-space model with unknown input condensation is established for time-dependent vehicle-bridge systems. We subsequently propose a new extended Kalman filter algorithm with an adaptive procedure for accelerating the convergence of estimation, which can simultaneously identify the frequencies and track irregularities of a railway bridge when a vehicle is running on it. The effectiveness of the proposed algorithm has been illustrated via numerical simulations of two real high-speed railway bridges. The proposed algorithm provides a low-cost and high-efficient approach for identifying the natural frequencies and track irregularities of high-speed railway bridges.

Lane Departure Warning Estimation Using Yaw Acceleration

Abstract Lane departure collisions have contributed to the traffic accidents that cause millions of injuries and tens of thousands of casualties per year worldwide. Due to vision-based lane departure warning limitation from environmental conditions that affecting system performance, a model-based vehicle dynamics framework is proposed for estimating the lane departure event by using vehicle dynamics responses. The model-based vehicle dynamics framework mainly consists of a mathematical representation of 9-degree of freedom system, which permitted to pitch, roll, and yaw as well as to move in lateral and longitudinal directions with each tire allowed to rotate on its axle axis. The proposed model-based vehicle dynamics framework is created with a ride model, Calspan tire model, handling model, slip angle, and longitudinal slip subsystems. The vehicle speed and steering wheel angle datasets are used as the input in vehicle dynamics simulation for predicting lane departure event. Among the simulated vehicle dynamic responses, the yaw acceleration response is observed to provide earlier insight in predicting the future lane departure event compared to other vehicle dynamics responses. The proposed model-based vehicle dynamics framework had shown the effectiveness in estimating lane departure using steering wheel angle and vehicle speed inputs.

Research on dynamics of a new high-speed maglev vehicle

The levitation bogie of the TR-series maglev vehicle is redesigned by adding an intermediate buffer layer between the levitationbogie and the levitation module to improve the curve negotiation capacity of the high-speed maglev vehicle and reduce the vertical coupleddynamic effect of the vehicle and the track beam. As the existing TR08 maglev vehicle dynamic model has been verified by experiments, anew type of dynamic model of maglev vehicle is constructed by transplanting the functional module of TR08 model. The vehicle-elastic trackbeam coupled dynamic model and the vehicle-curved track dynamic model are established. Simulation analyses of the dynamic response ofvehicles and track beams show that: the curve negotiation capacity of the new-type maglev vehicle is better than that of TR08 type maglevvehicle; the resonance effect does not occur between the vehicle and the track beam; the vertical dynamic displacement of the track beammid-span decreases by 23% compared with the TR08 type; the redesigned levitation bogie structure and the track beam have less dynamicinteraction, indicating that the working environment of the electromagnet in the new maglev vehicle has been improved, which can effectivelyreduce the burden of electrical decoupling of the control system.

Study on the Driver/Steering Wheel Interaction in Emergency Situations

Advanced driver assistance systems (ADAS) are becoming increasingly prevalent. The tuning of these systems would benefit from a deep knowledge of human behaviour, especially during emergency manoeuvres; however, this does not appear to commonly be the case. We introduced an instrumented steering wheel (ISW) to measure three components of force and three components of the moment applied by each hand, separately. Using the ISW, we studied the kick plate manoeuvre. The kick plate manoeuvre is an emergency manoeuvre to recover a lateral disturbance inducing a spin. The drivers performed the manoeuvre either keeping two hands on the steering wheel or one hand only. In both cases, a few instants after the lateral disturbance induced by the kick plate occurred, a torque peak was applied at the ISW. Such a torque appeared to be unintentional. The voluntary torque on the ISW occurred after the unintentional torque. The emergency manoeuvre performed with only one hand was quicker, since, if two hands were used, an initial fighting of the two hands against each other was present. Therefore, we propose to model the neuro-muscular activity in driver models to consider the involuntary muscular phenomena, which has a relevant effect on the vehicle dynamic response.

A Modified Numerical Substructure Method for Dynamic Analysis of Vehicle–Track–Bridge Systems

This paper presents a modified numerical substructure method for simulating the dynamic response of vehicle–track–bridge (VTB) systems. The method can be used to analyze large-scale VTB systems accurately and efficiently. Based on the principle of virtual work, the equations of motion are derived for two separate subsystems, i.e. a small-scale of finely modeled VTB substructure and a coarsely meshed large main bridge subsystem using different level of refinement. Different from the conventional dynamic substructuring approaches, the bridge spans close to the vehicle are modeled in both the main and substructure models, and the contradiction of repeatedly modeling is solved using a “nonlinear force corrector”. A special wheel–rail interaction (WRI) element is used to simulate the fast-moving interaction force between the vehicle and rail. In this way, the two models remain unchanged while the vehicle moves forward, and the computational accuracy is the same as the large-scale purely refined model, while the efficiency is significantly improved, particularly, for the large-scale long VTB systems. Two examples of realistic VTB systems with either smooth or un-smooth rails are used to verify the proposed method. The results demonstrate that the presented method has remarkable advantages of computational efficiency and accuracy, providing a practically useful tool for analysis of large-scale VTB systems.

Impact coefficient analysis of track beams due to moving suspended monorail vehicles

To study the impact coefficient of track beams due to moving suspended monorail vehicles under the bridge deck, this paper presents a vehicle-bridge dynamic model based on the rigid-flexible coupling method. Finite element method is used to establish the bridge model, and the vehicle is simulated as a multi-body dynamic model The mechanical characteristics of running tire are precisely modelled and the dynamic equations for the suspended monorail vehicle-bridge coupling system are derived. The proposed approach employs a double-line 7-span bridge with 210 m length as a numerical example, the impact performance of two track beams are studied and the results are verified by comparing with the theoretical solutions. The influences of critical system parameters, such as the train formation and double-line trains loads, on the dynamic responses of vehicles and the bridge are explored. The results show that it is feasible to study the impact effect with the proposed method. The separation phenomenon of rubber running tires jumping up on track surface occurs when vehicle speed is high, which may lead to negative impact coefficients. The impact coefficients of the track beam vary much with different locations, which can even be negative values at locations nearing the pier area.

Effects of wind-barrier parameters on dynamic responses of wind-road vehicle–bridge system

Accidents, such as deflections, side slips, and even rolls, can easily occur when road vehicles moving on the bridge deck at high speed are subjected to sudden changes owing to strong crosswinds. Wind barriers are an effective way to ensure the driving safety of vehicles on the bridge but with potential negative influences on the aerodynamic performance. Therefore, it is critical to evaluate the shielding effect of wind barriers on road vehicles by assessing the overall impact on the vehicle–bridge system. To optimize the wind-barrier scheme, a series of wind tunnel tests is conducted to evaluate the effects of barrier parameters on the aerodynamic characteristics of the wind-vehicle-bridge system. In this study, the aerodynamic force coefficients of the wind–vehicle–bridge system installed with wind barriers with four different heights and three ventilation ratios were investigated. With wind barriers installed on the bridge deck, dynamic responses of the wind–vehicle–bridge system were simulated with the proposed prediction procedures as those used in an earlier study. Results show that wind barriers on the bridge deck have significant influences on the aerodynamic force coefficients of the bridge, especially on the side-force coefficients, and on the dynamic responses of the wind–vehicle–bridge system. Additionally, the increase of the barrier height and the decrease of the barrier ventilation ratio considerably increase and decrease the lateral and torsional displacements of the bridge and the vehicles, respectively, but with only minor influence on the vertical displacements of both bridges and vehicles. Therefore, it is necessary to include the wind barrier in both experimental and numerical simulations of the wind-road vehicle-bridge system to explore the effect of different barrier parameters on the wind-vehicle-bridge system.

Pitching effect of a three-mass vehicle model for analyzing vehicle-bridge interaction

A rigid-mass vehicle model with wheels modelled as unsprung mass is newly proposed considering the pitching effect, which enables us to obtain the first three bridge frequencies from the vehicle’s spectrum even in the presence of surface irregularity and damping. As the vehicle moves along the bridge, it generally confronts a bumpy ride due to the presence of surface irregularity. To investigate the up and down of the vehicle body on the identification of frequencies, the use of rigid-mass vehicle model was introduced in the literature. Nevertheless, such a simple model cannot accurately capture the dynamic responses of vehicle and bridge. To this end, this work comes out a three-mass vehicle model by including a rigid-mass and two unsprung masses. Important factors such as unsprung mass, vehicle damping, bridge damping, and surface irregularity are discussed. The pitching effect is unveiled by considering three different locations for installing sensors in the vehicle body. The numerical simulation shows that the proposed vehicle-bridge interaction system is able to identify vehicle’s vertical and rotational frequencies if the sensor is installed in the suitable locations of vehicle body.

Critical Velocity of Short Floating Slab Track Using Alterable Element Method Considering Wheel-Rail Contact Loss

In actual line operation, the critical velocity is one of the key physical quantities of rail design owing to its great influence on the riding comfort and safety of vehicles due to the wheel-rail contact loss caused by the abrupt change of rail foundation rigidity, rail wear, or abruptness irregularities on rail. In this study, the short floating slab track (SFST) structure is regarded as a double-layer system. The Euler beam and the rigid body model are adopted for the rail and the floating slab, respectively, and the dispersion equation and the theoretical critical velocity of the rail structure under ideal conditions are deduced. Besides, this study considers the implementation of the SFST in the vehicle-structure coupling system. The alterable element method is introduced for accurately simulating the change of the wheel-rail contact state and coding a vehicle-structure dynamic analysis program (VSDAP) to calculate the critical velocity of rail structures from the dynamic response of vehicles and rail structures. The principle of its design at the beginning of the design is given on the basis of the theoretical value of the critical velocity and the simulation of the dynamic response, which can provide reference for practical engineering design.

A Vehicle Simulation Model and Automated Driving Features Validation for Low-Speed High Automation Applications

The low-speed high automation (LSHA) is foreseen as a development path for new types of mobility, improving road safety and addressing transit problems in urban infrastructures. As these automation approaches are still in the development phase, methods to improve their design and validation are required. The use of vehicle simulation models allows reducing significantly the time deployment on real test tracks, which would not consider all the scenarios or complexity related to automated driving features. However, to ensure safety and accuracy while evaluating the proper operation of LSHA features, adequate validation methodologies are mandatory. In this study a two-step validation methodology is proposed: Firstly, an open-loop test set attempts to tune the required vehicle simulation models using experimental data considering also the dynamics of the actuation devices required for vehicle automation. Secondly, a closed-loop test strives to validate the selected automated driving functionality based on test plans, also improving the vehicle dynamics response. To illustrate the methodology, a study case is proposed using an automated Renault Twizy. In the first step, the brake pedal and steering wheel actuators’ behavior is modeled, as well as its longitudinal dynamics and turning capacity. Then, in a second step, an LSHA functionality for Traffic Jam Assist based on a Model Predictive Control approach is evaluated and validated. Results demonstrate that the proposed methodology is capable not only to tune vehicle simulation models for automated driving development purposes but also to validate LSHA functionalities.

Dynamic response of vehicle–bridge–soil system using lumped-parameter models for structure–soil interaction

Prediction of vibrations generated by railway traffic experiences an increasing interest, as new lines are being constructed and planned in many countries. The paper proposes a numerical model to analyse a coupled vehicle–bridge–soil system, taking into account the most important phenomena affecting the structure, while at the same time being comparatively computationally efficient. Such model is useful in the early design phases of a project, when analysing a range of possible configurations or conducting parametric analysis is required.A simplified vehicle model, nonlinear wheel–rail interaction, a bridge structure modelled using the finite-element method and a semi-analytical model for layered soil are all introduced in the model. A pure time-domain solution procedure is used, utilizing lumped-parameter models (LPMs) for the soil–foundation system. Representation of the dynamic stiffness matrix using LPMs is investigated by analysing the cross-coupling between footings and a novel procedure necessary for computationally stable LPMs is introduced and utilized. Further, pure time-domain solution is compared with an iterative mixed-domain solution. Finally, to illustrate the capabilities of the model, analyses are carried out to determine the resulting maximum and minimum excitation limits resulting from wheel–rail interaction on a number of randomly generated uneven track profiles.

Effect and its mechanism of spatial coherence of track irregularity on dynamic responses of railway vehicles

A running vehicle is subjected to multiple stochastic excitations due to the irregular profiles of the wheels and rails. The combined wheel-rail irregularities on each wheel can be partly incoherent and partly coherent in reality. As a result, different assumptions for the coherence of such irregularities have been adopted in vibration and noise simulations so that vehicle-track dynamic analysis can be conducted. Less attention has been paid to the effects of these assumptions on dynamic responses of railway vehicles in a wide frequency range. The aim of this study is to theoretically investigate the effects of the spatial coherence of track irregularities on the dynamic behaviors of a two-dimensional vehicle. Two frequency-domain methods that have been verified using a time-domain method are presented first to calculate the dynamic responses of the vehicle. A new expression of the power spectral density (PSD) function of the excitations comprises an admittance coefficient, a coherence matrix, and a spatial PSD function of the track irregularities. The PSD functions of the responses of the vehicle are derived analytically. It is then illustrated that the periodic fluctuations of response spectra are caused by the spatial coherence of the excitations by introducing the concept of coherence scales. Finally, it is proved that the difference between the responses under coherent and incoherent excitations become insignificant when the wavelength of the irregularity is less than the critical wavelength.

A frequency domain analysis framework for assessing overturning risk of high-speed trains under crosswind

This study introduces a frequency domain analysis framework for assessing overturning risk of high-speed trains under the excitations of crosswind and track irregularities. Based on a comprehensive numerical computation, closed-form expressions are established for the power spectra and coherence of turbulence relative to a moving vehicle influenced by vehicle speed and direction. The wind turbulence at stationary positions fixed on the ground is characterized by Kaimal or von Karman spectra and Davenport coherence model or a more general coherence model. These closed-form expressions facilitate the quantification of vehicle dynamic response by the effective spectral analysis approach, and also provide essential turbulence information for wind tunnel studies of aerodynamic forces on stationary vehicle models. Closed-form formulations are also presented for computing vehicle dynamic response by focusing on two dominant modes relevant to vehicle overturning risk. The vehicle overturning risk analysis leads to a determination of characteristic wind speed curve for a given vehicle running speed with a target overturning probability. Examples are presented to illustrate analysis framework and to investigate the influence of various parameters including the vehicle model on the vehicle response characteristics.

Study on Dynamic Load Monitoring of an Enhanced Stress Absorption Layer

Asphalt pavement interlayer bonding and mechanical response have been hot topics in pavement research. In this paper, laying sensors on two kinds of stress absorption layers, the dynamic response laws of the two stress absorption layers were analyzed under different loads, speeds and temperatures. The results show that the asphalt pavement is a viscoelastic body and the measured results are consistent with the theoretical solution of layered elasticity: both stress absorbing layers are compressed. Five kinds of dynamic and static overload tests under the same conditions, the strain difference between the two sections increased from 11.6% of static load to 25.2% of dynamic load (40km/h). It indicates that the reinforced effect of geogrid is more obvious under dynamic load; By establishing the relationship between vehicle speed and dynamic response, a vehicle speed and dynamic response model for the enhanced stress absorption layer of slow crack (ESALOSC) is proposed; Based on the test data measured at four temperatures, a model of the temperature and dynamic response in the ESALOSC is proposed. The research results have important theoretical significance for improving the crack resistance of roads. At the same time, it provides technical support for the development of long-life pavement in China.

A Control Approach Integrating Electric Vehicle Charger and Dynamic Response of Demand-Side Resource Aggregators

Regardless of whether level 1, level 2, or dc fast charging, several methods are under development or available as an aftermarket option for Plug-in electric vehicles (EVs). While confining the charging behavior of EVs to low-load periods is difficult, it leads to significant and uncertain load peaks and valleys in the utility power network. Therefore, this paper proposes a new method for an electric vehicle charger. The proposed charging method involves power supervisory characteristics on the basis of the paradigm of a constant-current and a constant-voltage (CC–CV) charger so that the external commands from the demand-side resource aggregator in the smart grid can be executed. In the method, first, a feedback loop is included in the controller to formulate the relationship between battery voltage and charging power as a quadratic concave downward polynomial. The controlled output power at the beginning of constant voltage charging is then set to the maximum value of the quadratic polynomial because the charging power requirement near this point is closed to the highest. Hence, if the charging power is lower than the allowable maximum power, the proposed charger is determined to have followed the traditional CC–CV charging steps. On contrast, the proposed circuit launches the power control loop when the actual charging power is beyond the maximum power limitation of aggregator. The proposed charger can keep the power consumption inside an allowable range of aggregator. That is the power consumption at the EV charging sites becomes directly programmable by their aggregators. The proposed method is examined by conducting an interactive test of a remote energy management system and the proposed controller. The results revealed that the proposed method provide an easy method to dynamically control consumption pattern of the EV charging for demand-side power management.

Bridge modal identification using acceleration measurements within moving vehicles

Vehicles commuting over bridge structures respond dynamically to the bridge’s vibrations. An acceleration signal collected within a moving vehicle contains a trace of the bridge’s structural response, but also includes other sources such as the vehicle suspension system and surface roughness-induced vibrations. This paper introduces two general methods for the bridge system identification using data exclusively collected by a network of moving vehicles. The contributions of the vehicle suspension system are removed by deconvolving the vehicle response in frequency domain. The first approach utilizes the vehicle transfer function, and the second uses ensemble empirical modal decomposition (EEMD). Next, roughness-induced vibrations are extracted through a novel application of second-order blind identification (SOBI) method. After these two processes, the resulting signal is equivalent to the readings of mobile sensors that scan the bridge’s dynamic response. Structural modal identification using mobile sensor data has been recently made possible with the extended structural modal identification using expectation maximization (STRIDEX) algorithm. The processed mobile sensor data is analyzed using STRIDEX to identify the modal properties of the bridge. The performance of the methods are validated on numerical case studies of a long single-span bridge with a network of moving vehicles collecting data while in motion. The analyses consider three road surface roughness patterns. Results show that for long-span bridges with medium- to high-ongoing traffic volume, the proposed algorithms are successful in extracting pure bridge vibrations, and produce accurate and comprehensive modal properties of the bridge. The study shows that the proposed transfer function method can efficiently deconvolve the linear dynamics of a moving vehicle. EEMD method is able to extract vehicle dynamic response without a priori information about the vehicle. In addition, proposed identification methods provide secondary information about the roughness pattern and the vehicle. This study is the first proposed methodology for complete bridge modal identification, including operational natural frequencies, mode shapes and damping ratios using moving vehicles sensor data.