Three-dimensional Vehicle Research Articles

Ride comfort and impact factor of a seven-span continuous cable-stayed bridge

This study was conducted to investigate the vibration serviceability and impact coefficient of a seven-span continuous cable-stayed bridge planned for an expressway extension using a three-dimensional vehicle–bridge coupled vibration analysis. For the bridge design, deflection under the designed live load of the continuous cable-stayed bridge did not meet the deflection limit specified in “Japanese Design Specifications for Highway Bridges.” The excessive deflection indicates the possibility of poor vibration serviceability. To clarify the bridge vibration serviceability, the dynamic responses of the bridge and passing vehicles were examined using the three-dimensional vehicle–bridge coupled vibration analysis. The three-dimensional analysis was validated by comparing the vibration response of a single-span steel cable-stayed bridge in service subjected to vehicle running tests with those numerical responses from the three-dimensional analysis. The ride comfort of vehicles on the bridge was assessed in terms of vibration serviceability according to the ISO 2613-1 international standard for evaluating whole-body vibration exposure. The observation from the simulation-based investigation demonstrated that the vehicle response does not exceed the ride comfort limit irrespective of vehicle, road, and running conditions. In other words, the findings confirmed a negligible effect of large deflections on driving safety. The impact factors were found to be less than 1.05 for the main girder, less than 1.03 for the main tower base, and less than 1.04 for the cable. The impact factor was greatest when several vehicles were running at resonant headway.

An optimized CIP-FEM to reduce the pollution errors for the Helmholtz equation on a general unstructured mesh

The continuous interior penalty finite element method (CIP-FEM) has shown promise in reducing pollution errors when numerically simulating the Helmholtz equation with high wave numbers. However, its reliance on structured meshes largely limits its applicability. To address this limitation, this paper presents a novel approach to CIP-FEM on general unstructured meshes. The interior penalty parameters of the CIP-FEM are determined in an offline phase through minimizing the residual obtained by substituting the plane waves into the CIP finite element equation. To enhance accuracy, a quasi-Newton algorithm is employed to correct the penalty parameters and minimize errors of the CIP finite element approximations to the plane waves. The calculated interior penalty parameters can be saved, enabling the online solutions of CIP-FEM to be obtained by reusing these parameters for arbitrary sources during practical computations. Numerical experiments are presented to demonstrate the significant reduction of pollution errors for both linear and higher-order CIP-FEMs on unstructured meshes. Furthermore, the proposed algorithm successfully simulates high-frequency acoustic fields in a three-dimensional vehicle cabin with greatly reduced errors within certain fixed computational time, demonstrating its practical effectiveness in real-world scenarios.

Development of a New Vertical Dynamic Model of a Rail Vehicle for the Analysis of Ride Comfort

The rail vehicle industry wants to produce vehicles with higher speeds, to maintain and increase its market share. However, when the speed of the vehicle increases, it may have an undesirable effect on ride comfort, in terms of ride dynamics. Recent developments towards lighter and faster vehicles make the problem of ride comfort at higher speeds increasingly important. Focusing on the behavior of flexible rather than rigid body behavior should not be neglected when designing long and light car bodies. There are several approaches to incorporate body flexibility in multibody simulations and they have some superiorities and weaknesses. In this study, an efficient and accurate vertical dynamic model for the ride comfort analysis is developed and implemented in a commercial object-oriented modeling (OOM) software Dymola (2015 FD01) which uses the open-source code Modelica. This model includes car body flexibility with the assembling of a rigid body approach. The developed model is compared to a three-dimensional vehicle model in the commercial Vampire software (Pro V5.50) at different velocities. For the vertical ride comfort analysis, the ISO 2631-1 standard was used for both the developed model and the three-dimensional model. The results are presented as acceleration history and awrms—weighted r.m.s (root mean square) of accelerations—as required by the standard. The developed model has shown its feasibility in terms of its efficiency and accuracy for the vertical ride comfort analysis. The accuracy of the model is evidenced by the fact that the car body vibration level at high speeds shows minor differences compared to the results of the Vampire, which is a validated commercial software in the area of rail vehicle dynamics. The approach involving the assembly of rigid bodies is applied for the first time for high-speed trains in dynamical modelling, with flexible car bodies for ride comfort analysis. Furthermore, it can be used for parametrical studies focusing on ride comfort, thereby offering a quite beneficial framework for addressing the challenges of ride comfort analysis in high-speed rail vehicles. Improvements for and analyses of other aspects are also possible, since the optimization and other useful libraries are readily available in Dymola/Modelica.

3D Vehicle Object Tracking Algorithm Based on Bounding Box Similarity Measurement

Effectively extracting features from a discrete point cloud is necessary for three-dimensional (3D) vehicle tracking. However, a point cloud data set is large and sparsely distributed, hindering the success of vehicle-tracking algorithms. To solve this problem, this paper proposes a 3D vehicle object tracking algorithm based on bounding box similarity measurement. The algorithm includes state prediction, temporal association, trajectory management, state update, and other processes. Also incorporated is a vehicle object temporal association method based on a siamese encoder. The bounding box is encoded into a high-dimensional space, the feature distance is calculated as the time series association cost, and triplet loss was introduced to urge the encoder to learn the geometric similarity of the truth matching box. A 3D Kalman filter and greedy matching are used to effectuate 3D vehicle object tracking algorithm. The experimental results using a KITTI multi-object tracking dataset show that the proposed algorithm can achieve good vehicle tracking performance. In the case of frame loss of point cloud in the frequency reduction simulation, compared with the benchmark method AB3DMOT, the average multi-object tracking accuracy ( AMOTA) and the average multi-object tracking accuracy ( AMOTP) of the improved method are increased by 2.62% and 1.41% respectively, and the performance is better in the frame loss scene.

Study on the Frontal Collision Safety of Trains Based on Collision Dynamics

The high-speed collision issue brought on by railway vehicles’ intensive and high-speed operation has become a critical concern for operational safety. Therefore, it is necessary to research the high-speed collision problem of trains. Firstly, a train collision dynamic model suitable for higher collision velocities is established. This model includes a 38-degree-of-freedom (DOF) three-dimensional vehicle model and a three-layered vibrating fixed-track model. Corresponding mathematical models are developed for nonlinear factors such as wheel–rail contact, car–end contact, and coupler overload representation in the model. Then, the Train Collision State Score (TCSS) is proposed, enabling quantitative safety evaluation under different collision conditions. Finally, the influence of the energy-absorbing device’s initial attitude and leading car parameters on collisions is studied. The results indicate that initial vertical height difference and pitching angle significantly increase TCSS. As the force level of the energy-absorbing device of the leading car increases, the effects of two intermediate coupler overload states on TCSS show opposite trends.

Simulation study on flow and response temperature of armored vehicle in low temperature environment test

In this paper, three-dimensional CFD simulation and vehicle’s environmental test were combined, according to the size and operating parameters of the actual environmental test chamber, a model of the low-temperature environmental test chamber was constructed by using 3D modeling software; by removing the structure that has little influence on the process of environmental experiment, a three-dimensional vehicle model suitable for simulation calculation is built, and by means of 3D model assembly, the combination of vehicle and environmental chamber model is realized. According to the low temperature environment test conditions, CFD numerical simulation method was used to analyze the flow velocity distribution in the test chamber and the response trend of each chamber to the low temperature environment, the results were also compared with the experimental data of low temperature environment, which provides a theoretical basis for carrying out simulation and prediction research based on digital environment test.

A comparative study of vehicle-bridge interaction dynamics with 2D and 3D vehicle models

The dynamics of vehicle-bridge interaction (VBI) involve the adoption of two-dimensional (2D) and three-dimensional (3D) vehicle models in simulations. It is worth noting that the 2D vehicle model lacks several crucial degrees of freedom and a complete road roughness compared to the 3D vehicle model. Despite the common usage of the 2D vehicle model in VBI simulations, the difference between the two models has not received sufficient attention in previous studies. Therefore, this study aims to quantitatively assess the differences in bridge response between the 2D and 3D vehicle models. To achieve this goal, the study employs a VBI modeling method based entirely on general finite element software first. Then, a series of comparisons between the 2D and 3D vehicle models are implemented through a steel composite girder bridge and a cable-stayed bridge. The results indicate that road roughness significantly contributes to the observed differences. Specifically, the 2D vehicle model generates larger bridge responses than the 3D vehicle model, primarily due to the absence of rolling and vibration cancellation effects. Furthermore, the differences between the two models increase as the road surface roughness worsens, with a maximum difference of 25.07 % in the cable-stayed bridge’s mid-span acceleration. Notably, the discrepancies in bridge acceleration are more significant than those in displacement or cable stress. Adopting the 2D vehicle model in VBI simulations may lead to more conservative engineering recommendations, resulting in higher economic costs and greater consumption of building materials. Thus, this study emphasizes the importance of considering the 3D vehicle model in VBI simulations, particularly for bridges with poor road conditions.

An integrated three-dimensional powertrain-vehicle dynamics model for tracked vehicle analysis

A tracked vehicle employs a special transmission to generate a speed difference between the inner and outer tracks for steering. In this paper, the dynamic model of one of the most widely used steering transmissions called double differential steering has been derived and integrated with a multi-body tracked vehicle model. A simplified multi-body model for tracks has been proposed to reduce the computational and numerical difficulties arising from a detailed three-dimensional multi-body model. The accuracy of the proposed model is demonstrated by extensive comparison with a detailed multi-body model developed using the Tracked Vehicle module of the commercial software ADAMS. Simulations are carried out using the integrated tracked vehicle model to demonstrate the effects of changes in three-dimensional vehicle dynamic performance with design changes in powertrain systems.

Application and Assessment of Cooperative Localization in Three-Dimensional Vehicle Networks

The trajectory planning and control of multi-agent systems requires accurate localization, which may not be possible when GPS signals and fixed features required for SLAM are not available. Cooperative Localization (CL) in multi-agent systems offers a short-term solution that may significantly improve vehicle pose estimation. CL algorithms have been mainly developed and assessed for planar mobile robot networks due to complexities and singularities in three-dimensional (3D) motion. In this paper, we develop the required singularity-free equations and apply and assess an EKF-based CL for 3D vehicle networks. We assess the performance of CL with respect to the number of simultaneous and redundant measurements. We further assess CL performance with only relative position measurements available. Finally, experiments are performed to validate the proposed algorithms. We further investigate the effect of absolute position measurements in CL. Conclusions: Cooperative localization is an effective method when applied to 3D vehicle networks. However, CL does not improve localization with only relative position measurements, and thus previously reported results for 2D vehicle models were only effective due to relative orientation measurements. Absolute measurement reduces the overall localization errors much more significantly when there has been CL with prior relative position measurements.

Generative Inverse Design of Aerodynamic Shapes Using Conditional Invertible Neural Networks

Abstract Conditional invertible neural networks (cINNs) were used for generative inverse design of aerodynamic shapes for a given aerodynamic performance target. The methodology was used to generate two-dimensional (2D) airfoil shapes for a target lift coefficient and three-dimensional (3D) vehicle shapes for a low drag vehicle given an aerodynamic drag coefficient target. Training data for both cases were generated for the forward process i.e., aerodynamic performance as a function of design variables that define the airfoil or vehicle shape, using design of experiments (DOE) and computational fluid dynamics (CFD) simulations. Due to the structure of the cINNs, the inverse process was learned implicitly, i.e., samples from latent space were transformed back to the design variables. The designs generated by the trained cINN model were simulated under identical conditions to check if they met the desired aerodynamic performance target. The distribution of design variables conditioned on a performance target learned by the cINN model was compared to the distribution in the training data. cINNs provide an easy-to-use tool to generate new designs that meet the desired aerodynamic performance, thereby, reducing the iteration time between aerodynamicists and stylists. In case of vehicle shape generation, since all generated vehicle shapes meet the aerodynamic performance target, the designer can select the shapes that do not conflict with other design constraints such as the interior volume, comfort, styling, and various safety requirements.

SSA3D: Semantic Segmentation Assisted One-Stage Three-Dimensional Vehicle Object Detection

One-stage 3D object detection using mobile light detection and ranging (LiDAR) has developed rapidly in recent years. Specifically, one-stage methods have attracted attention because of their high efficiency and light weight compared with two-stage methods. Inspired by this, we present the semantic segmentation assisted one-stage three-dimensional vehicle object detection (SSA3D), a network for the rapid detection of objects that keeps the advantages of the semantic segmentation module in the two-stage methods without increasing redundant computational load. First, we modified the sampling of the farthest point to improve the quality of the sampling points. This helps to reduce sampling outlier points and bad points that are difficult to perceive in the spatial structure information surrounding the point. Second, a neighbor attention group module is devoted to selectively add extra weight to neighbor points because of the different importance of neighbor points for the corresponding sampling point. Correctly increasing the weight is helpful to obtain richer spatial structure information. Finally, a delicate box generation module is included as a voted center point layer based on the generalized Hoff vote method and an anchor-free regression. We used the feature aggregation module as the backbone and the feature propagation module as the auxiliary network to achieve efficiency. At the same time, the auxiliary network retains the ability to extract point-wise features from the state-of-the-art semantic segmentation network. In experiments, we evaluated and tested the SSA3D on a common KITTI dataset and achieved improved performance in the class of car accuracy.

Indirect identification of bridge frequencies using a four-wheel vehicle: Theory and three-dimensional simulation

Indirect identification of bridge frequencies, which refers to identifying bridge frequencies from the dynamic response of a vehicle moving on the bridge, has the potential to fast inspect bridges in large quantities. Accurate analysis on the dynamic response of the vehicle used for sensing is crucial to the indirect frequency identification. Most published research on this topic, however, is based on a simplified two-dimensional (2D) analysis of vehicle–bridge interaction (VBI), which cannot fully reproduce the mechanism of a real three-dimensional (3D) vehicle. As a complement, this study carries out the 3D simulation of VBI and accordingly proposes a novel frequency-domain method to identify bridge natural frequencies from the vertical acceleration of a full-car model’s wheels. The wheels’ equations of motion are first transferred into the frequency domain, then the frequency responses of the front and rear wheels are subtracted with a time lag to eliminate the adverse effect of road roughness. Also proposed by this study is a new method to identify the speed of the sensing vehicle with the correlation function of wheel acceleration so that the time lag for subtraction can be calculated. In order to investigate the performance of the proposed methods, a series of numerical simulations are conducted, including sensitivity analysis on the vehicle speed, the class of road roughness, the noise level, and the vehicle frequency. Finally, this paper remarks on the accuracy and robustness of the proposed method and challenges faced by the engineering practice of the indirect bridge structural identification methodology.

Long-Term Monitoring of Local Track Irregularity and Its Influence for Simply Supported Girder Bridge of HSR

By analyzing dynamic track geometric irregularity data of high-speed railway (HSR) with ballast track in China, there is a peak of [5, 11] m wavelength for the longitudinal level at the beam joint of simply supported girder bridges. The difference between the absolute value of track longitudinal level at the beam joint and that at the midspan is one to three mm. Under annual temperature cycle, the ballast at the beam joint loosens because of the bridge–track interaction, which results in the longitudinal level at the beam joint gets larger in winter and smaller in summer, that means the longitudinal level is negatively correlated with temperature, and at the same time, the development of the track longitudinal level and Track Quality Index (TQI) with the temperature are given. In addition, the vertical acceleration of axle box and bogie, and wheel–rail vertical force are larger when the train passes the beam joint than when it passes the midspan, which threatens running safety significantly. This article established a three-dimensional vehicle–track–bridge finite element model (FEM), thus the thresholds of track longitudinal level at the beam joint for simply supported girder bridge with ballast track in 250 km/h HSR were proposed, i.e., the maximum of dynamic track longitudinal level is 14 mm, and the maximum of static value is 11 mm. Once one of the two thresholds exceeds the corresponding limit, the train speed should be reduced to 160 km/h or below.

Vehicle-SFT-current coupling vibration of multi-span submerged floating tunnel, part I: mode superposition and Galerkin hybrid method

The submerged floating tunnel (SFT), whose ends are constrained by the banks, is a traffic structure in the deep water environment. In order to analyze the vehicle-SFT-current coupling vibration of the multi-span SFT considering flexible joints under arbitrary boundary condition, the tube and cables are simplified as a multi-span continuous spatial beam on elastic supports. A twelve degrees of freedom (twelve-DOF) model is applied to simulate the three-dimensional vehicle, and the coupling vibration of current-structure is considered based on the wake oscillator model. By using the Hamilton's principle, the vehicle-SFT-current coupling spatial vibration equation is derived. Then the mode superposition and Galerkin hybrid method (MSGHM) is proposed to solve the vibration equations, and the corresponding analysis program is developed. The reliability of the proposed method and its programming are validated by comparing with the previous research using the finite difference method. The results show that the proposed MSGHM in this paper can conveniently analyze the vehicle-SFT-current coupling vibration of the multi-span SFT with arbitrary boundary condition, and improve the calculation efficiency on the premise of ensuring the accuracy.

Cooperative Localization of 3D Vehicle Networks - The Dynamic Model

Cooperative localization (CL) algorithms have mainly focused on two-dimensional (2D) vehicle models and have almost uniformly employed only the kinematic model with velocities as inputs, making these algorithms unsuitable for force control problems. We have previously extended a CL algorithm to include a three-dimensional (3D) vehicle kinematic model with the use of quaternions to avoid singularities. In this paper, we extend the algorithm to a full 3D nonlinear dynamic vehicle model, again using quaternions. We evaluate the effectiveness of a CL algorithm and assess its benefits, when the full dynamic model is employed, by running a series of Monte Carlo type simulations with multiple relative pose measurements.

A Three-Dimensional Integrated Non-Linear Coordinate Control Framework for Combined Yaw- and Roll-Stability Control during Tyre Blow-Out.

A tyre blow-out can greatly affect vehicle stability and cause serious accidents. In the literature, however, studies on comprehensive three-dimensional vehicle dynamics modelling and stability control strategies in the event of a sudden tyre blow-out are seriously lacking. In this study, a comprehensive 14 degrees-of-freedom (DOF) vehicle dynamics model is first proposed to describe the vehicle yaw-plane and roll-plane dynamics performance after a tyre blow-out. Then, based on the proposed 14 DOF dynamics model, an integrated control framework for a combined yaw plane and roll-plane stability control is presented. This integrated control framework consists of a vehicle state predictor, an upper-level control mode supervisor and a lower-level 14 DOF model predictive controller (MPC). The state predictor is designed to predict the vehicle’s future states, and the upper-level control mode supervisor can use these future states to determine a suitable control mode. After that, based on the selected control mode, the lower-level MPC can control the individual driving actuator to achieve the combined yaw plane and roll plane control. Finally, a series of simulation tests are conducted to verify the effectiveness of the proposed control strategy.

Vehicle Body and Roll Cage Assessment involving Frontal, Side and Roll-over Crash Analysis by FEA using LS-Dyna

Simulating the vehicle collision has gained importance in the automotive sector due to its accuracy, cost effectiveness and enhanced reliability. It aids in improving the safety of driver and passenger and also examine the cause of crash or collision. This numerical analysis investigates the materials capability to enhance safety. A three-dimensional vehicle model was developed along with its roll cage using solid work tool. Hypermesh work bench was employed to discretise the sensitive parts of the body and roll cage using beam 189 element having six degree of freedom at each node. The existing structural steel members were replaced with reinforced carbon fibre in all the sensitive part of the body and roll cage and its structural stability was assessed using the frontal, side and roll over crash simulation using LS Dyna. This investigation also reveals the change in internal energy, kinetic energy absorption and momentum transfer for both structural steel and carbon fiber under all the crash scenarios. The outcomes of this numerical investigation proved that the reinforced carbon fiber can be effectively replaced with the structural steel to enhance safety.

Importance of Three-Dimensional Vehicle Heat Exchanger Modeling

Abstract This article demonstrates, via a comprehensive study, the necessity of using a 3D computational fluid dynamics (CFD) approach for heat exchanger (HTX) modeling within underhood vehicle simulation. The results are presented as the difference between 1D and 3D CFD approaches with a focus on auxiliary fluid (e.g., coolant) temperature prediction as a function of primary fluid (e.g., air) inlet conditions. It has been shown that the 1D approach could significantly underpredict auxiliary fluid inlet temperature due to neglecting the spatial distribution of primary fluid velocity magnitude. The resultant difference in the auxiliary fluid flow HTX inlet temperature is presented and discussed as a function of the uniformity index (UI) of the primary fluid flow velocity magnitude. In addition, the 3D HTX model’s importance is demonstrated in an industrial example of full 3D underhood simulation.

Three-Dimensional Vehicle–Curved Track Dynamic Model Based on FEM and DEM

In this work, a systematic vehicle–curved track dynamic model is presented, in which the vehicle is modeled as a multi-rigid-body system. The track structure is modeled by finite element method with curved rail beam element considered in geometry. To obtain accurate dynamic behavior of railway ballasted track, the resistance characteristics of ballast bed are revealed by introducing the discrete element method. Besides, a two-step iterative-update method is improved to solve the multi-nonlinearity of the vehicle–curved track dynamic interaction. To improve the computational efficiency, and the improved infinite cyclic calculation method is introduced. Apart from the model validations, the application of this model in engineering practices, such as the vehicle-induced vibration of the continuously welded rail (CWR), has been revealed, and some conclusions are drawn from the numerical studies.

Scanning torsional-flexural frequencies of thin-walled box girders with rough surface from vehicles’ residual contact response: Theoretical study

This paper studies theoretically the retrieval of torsional-flexural frequencies of mono-symmetric thin-walled box girder bridges from vehicles’ residual contact response for the first time. To start, the three-dimensional vehicle–bridgeequations of motion including the lateral and torsional (coupled) and vertical (uncoupled) vibrations are derived for a moving test vehicle. Then, closed-form solutions for the vehicle and vehicle–bridge contact point are derived. The contact response is selected since it is free of vehicle frequency, which may overshadow the bridge frequencies in FFT spectra. The other disturbing factor is surface roughness, which will be resolved by the residue method, i.e., by using the residual response of two connected vehicles. Through the parametric study, the proposed approach is verified to be feasible. The conclusions include: (1) the contact response performs better than the vehicle response for all the scenarios considered; (2) the surface roughness effect can be virtually eliminated using the residual contact response even for damped bridges with not-so-good pavements; (3) a larger vehicle’s eccentricity from bridge’s centerline enables the torsional-flexural frequencies to be better identified; and (4) the first several flexural and torsional-flexural frequencies of the girder can always be identified for a wide variety of parameters considered.