Vehicle Dynamics Simulation Research Articles

Identifying vehicle characteristic target based on subjective ratings from drivers

In virtual tire development, defining vehicle characteristic target is crucial to achieving the desired vehicle performance with the equipped tires. Vehicle performance is generally evaluated through subjective ratings by skilled drivers following SAE J1441 guidelines, as well as the objective performance metrics obtained via vehicle dynamics analysis. However, due to the scarcity and bias in real-world testing dataset, the vehicle characteristic target cannot be determined definitively. To address this issue, we propose a recommendation system that searches the unexplored vehicle characteristic domains. This suggested method provides virtual subjective ratings to enrich the limited real-world dataset from the skilled drivers. Moreover, we highlight the correlation between subjective and objective data using vehicle and tire dynamics simulation software. Based on this augmented data, we predict the vehicle characteristic target according to the subjective rating requirements. The proposed approach was validated through various experiments involving skilled drivers and various vehicle-tire combinations, showing 91.26% to 96.2% consistency in generated steering parameter domains. Domains of stability parameters show that one fewer domain was generated by a conservative driver compared to more lenient driver, which confirms the robustness of the proposed approach in accommodating individual driver preferences.

Large scale multi-GPU based parallel traffic simulation for accelerated traffic assignment and propagation

Traffic simulation is a critical tool for congestion analysis, travel time estimation, and route optimization in urban planning, benefiting navigation apps, transportation network companies, and state agencies. Traditionally, traffic micro-simulation frameworks are based on road segments and can only support a limited number of main roads. Efficient traffic simulation on a regional scale remains a significant challenge due to the complexity of urban mobility and the large scale of spatiotemporal data. This paper introduces a Large Scale Multi-GPU Parallel Computing based Regional Scale Traffic Simulation Framework (LPSim), which leverages graphical processing unit (GPU) parallel computing to address these challenges. LPSim utilizes a multi-GPU architecture to simulate extensive and dynamic traffic networks with high fidelity and reduced computation time. Using the parallel processing capabilities of GPUs, LPSim can perform tens of millions of individual vehicle dynamics simulations simultaneously, significantly outperforming traditional CPU-based approaches. The framework is designed to be scalable and can easily accommodate the increasing complexity of traffic simulations. We present the theory behind GPU-based traffic simulation, the architecture of single- and multi-GPU based simulations, and the graph partition strategies that enhance computation resource load balance. Our experimental results demonstrate the effectiveness of LPSim in simulating large-scale traffic scenarios. LPSim is capable of completing simulations of 2.82 million trips in just 6.28 min on a single GPU machine equipped with 5120 CUDA cores (Tesla V100-SXM2). Furthermore, utilizing a Google Cloud instance with two NVIDIA V100 GPUs, which collectively offer 10240 CUDA cores, LPSim successfully simulates 9.01 million trips within 21.16 min. We further tested our simulator with the same demand on dual NVIDIA A100-PCIE-40GB GPUs, which finished the simulation in 0.0398 h, approximately 113 times faster than the same simulation scenario running on an Intel(R) Xeon(R) Gold 6326 CPU @ 2.90 GHz, which takes 4.49 h to complete. This performance not only demonstrates its speed and scalability advantages over traditional simulation techniques but also highlights LPSim’s unique position as the first traffic simulation framework that is scalable for both single- and multiple-GPU configurations. Consequently, LPSim provides an invaluable tool for individuals and extensive research teams alike, enabling the acquisition of large-scale traffic simulation results in a time-efficient manner. LPSim code is available at: https://github.com/Xuan-1998/LPSim

Integrated Dynamic Modeling and Simulation of Wheeled Vehicle with Outer-Rotor In-Wheel Motors and Key Units

The purpose of this paper is to accurately establish a model of a special vehicle driven by in-wheel motors (IWMs) and investigate its dynamic characteristics. This study proposes a novel integrated vehicle modeling strategy, focusing on the IWM and other key subsystems. Based on this strategy, the vehicle model is developed and simulated in ADAMS. The natural frequencies of the vehicle and transmission characteristics of key components are compared with MATLAB simulation results to validate the accuracy of the model. In the time-domain analysis, the vehicle system’s time-domain characteristics are obtained by using random road spectra of different road grades as excitations. Our simulation results demonstrate that vibration input can be reduced by between 97% and 99% after multi-stage vibration reduction. This work will provide relevant parameters for the design of special vehicles driven by IWMs.

Prediction of frequency response of sub-frame bushing and study of high-order fractional derivative viscoelastic model

This paper presents experimental and dynamic modeling research on the rubber bushings of the rear sub-frame. The Particle Swarm Optimization algorithm was utilized to optimize a Backpropagation (BP) neural network, which was separately trained and tested across two frequency ranges: 1–40 Hz and 41–50 Hz, using wideband frequency sweep dynamic stiffness test data. The testing errors at amplitudes of 0.2 mm, 0.3 mm, and 0.5 mm were found to be 1.03%, 3.05%, and 1.96%, respectively. Subsequently, the trained neural network was employed to predict data within the frequency range of 51–70 Hz. To incorporate the predicted data into simulation software, a dynamic model of the rubber bushing was established, encompassing elastic, friction, and viscoelastic elements. Additionally, a novel model, integrating high-order fractional derivatives, was proposed based on the frequency-dependent model for the viscoelastic element. An enhanced Particle Swarm Optimization algorithm was introduced to identify the model's parameters using the predicted data. In comparison to the frequency-dependent model, the new model exhibited lower fitting errors at various amplitudes, with reductions of 3.84%, 3.61%, and 5.49%, respectively. This research establishes a solid foundation for subsequent vehicle dynamic modeling and simulation.

Towards digital twin trains: implementing a cloud-based framework for railway vehicle dynamics simulation

ABSTRACT The digital twin technology holds great promise in driving the railway industry into a new era of digital intelligence. By creating a dynamic, personalized digital replica of a physical train, it has the potential to enable a range of advanced applications, including predictive maintenance, adaptive control, and early fault detection. However, substantial challenges exist that hinder the effective implementation of the digital twin concept for trains. To resolve this bottleneck issue, in this paper, these challenges are first identified and thoroughly examined, with a specific focus on those within the realm of railway vehicle dynamics simulation. A novel cloud-based simulation framework for the development of railway vehicle dynamics simulation software is then proposed to tackle the identified challenges. The framework makes use of cloud computing and cloud-based visualization technology to offer a scalable and flexible solution for railway vehicle dynamics simulation. Using the framework as its foundation, a cloud platform for constructing digital twin trains is also proposed and presented, with a detailed explanation of its architecture and functionalities. In addition, CTTSIM, a cloud computing-aided train-track system dynamics real-time simulation software, is developed as an illustrative application case of the proposed framework. An evaluation is undertaken to demonstrate the feasibility and utility of both CTTSIM and the proposed framework. This work provides a practical and effective solution for using vehicle dynamics simulation for constructing digital twin trains, representing a step towards the full implementation of the digital twin concept in the railway industry.

An Alternate Search Method and An Extended Trace Line Method for Wheel‐Rail Contact Patch Centers Detection

AbstractWheel‐rail contact is a link between the vehicle system and the rail system, and the contact processing approach affects accuracy of vehicle dynamic simulation. Contact detection is usually the start of wheel‐rail contact calculation, and detecting precision of contact patch center affect accuracy of contact force calculating results, therefore it is significant to improve detecting precision of contact patch center. An alternate search method (ASM) and an extended trace line method are proposed to improve precision and efficiency of contact patch centers detection. The proposed alternate search method applies Golden Ratio Search Method and variable intervals between grids to detect contact patch centers. To make the detected contact patch centers match rail tangential directions better, an extended trace line method is constructed based on geometrical constraints between contact points and rail tangential directions. Dynamic simulations of a bogie vehicle formed by two wheelsets and a bogie frame negotiating a rail curve are conducted to evaluate effects of the proposed methods. Calculating times of the proposed methods for finishing the simulations are compared to explain computational efficiencies of the different methods. The proposed approaches are real‐time capable and can be used for vehicle dynamics simulations.

A Study on Power Transmission Control for Applying MR Fluid Multi-Plate Clutch to Automobile Power Distribution Device

The aim of this study is to design and manufacture a multi-plate clutch system that uses magnetorheological (MR) fluid control to allow for a variable power transmission ratio in power distribution systems. MR fluid is a smart material that enables presenting a solution to the shocks and power loss that occur due to mechanical problems in power distribution systems. As such, the longitudinal and lateral dynamic properties of 4WD (four-wheel drive) vehicles were examined and analyzed to develop an algorithm to control the front/rear power distribution according to the road surface state and driving conditions. To verify the algorithm, the CarSim vehicle dynamics simulation program was adopted to perform experiments to understand the vehicle’s dynamic performance improvements and turning stability via a HILS (Hardware in the Loop) system. In this study, an MR fluid, multi-plate clutch was used that combines a dry clutch and a wet clutch using the characteristics of the MR fluid. Such a clutch was designed to enable continuous and smooth torque transmission by utilizing the strengths of each of the dry and wet clutches. The CarSim vehicle dynamics program was used to conduct the experiments, which were conducted by linking to the manufactured MR fluid clutch experimental device. The experiments investigated the dynamic performance based on the power distribution ratio by performing longitudinal flat, inclined driving and lateral DLC (double lane change) driving. In summary, this study found that it is possible to perform power transmission by applying a current to an MR fluid and forming a magnetic field to change the flow properties of the fluid to control the torque transmission ratio that occurs in an MR fluid clutch.

Pitch motion suppression of electric vehicle active suspensions based on multibody dynamics

Active suspension control strategies are proposed to suppress pitch motion and address the issue of motion sickness among electric vehicle passengers. In this work, we investigate the performance of the linear quadratic regulator (LQR), variable universe fuzzy control, adaptive-network-based fuzzy inference system (ANFIS), and fuzzy PID control under continuous acceleration and deceleration and bumpy road conditions. First, a 14-degrees-of-freedom (DOF) dynamics model of an electric vehicle is developed based on a semirecursive multibody dynamics method, which was originally proposed by Javier García de Jalón. The vehicle dynamics simulation is performed to accurately model the vehicle states and responses. Second, the LQR, variable universe fuzzy control, ANFIS, and Fuzzy PID control algorithms are tailored via vehicle states, including pitch, rate, and acceleration. Their performances are investigated and compared in detail. Finally, the robustness of the proposed control strategies is further discussed based on various speed bump parameters and initial velocities. The results indicate that the proposed control strategies are capable of suppressing the pitch motion of electric vehicles, enhancing the riding comfort under diverse operating conditions, thereby reducing the likelihood of motion sickness among passengers of electric vehicles.

Review and comparison of selected methods of calculating wheel-rail contact tangential forces on the example of riding stability analysis of a two-axle vehicle

This article presents methods currently used in railway vehicle dynamics simulations (MBS) for calculating wheel-rail contact forces. Simulation models of two-axle vehicle built in Simpack 2023 simulation environment were used to compare the selected methods. The paper focuses on the issue of riding stability of the mentioned group of vehicles. The developed research methodology consists in simulating the riding of a vehicle exhibiting instability (hunting movement) on an ideal straight track using the wheel-rail contact models available in the Simpack 2023 environment. Then the obtained results are input data for recalculation of contact forces with selected algorithms. The study is aimed at comparing the selected methods for calculating contact forces, so there is no interaction of the algorithms tested with the MBS simulation model. The results obtained were compared with Kalker's "exact theory" of contact (CONTACT) for the elliptical contact area.

Carsim-based simulation study on the performances of raised speed deceleration facilities under different profiles

Objective Studying the optimal profile shape and size of deceleration facilities suitable for low-speed environment roads under different speed control intervals. Methods Simulation modeling of deceleration facilities with various profile shapes and sizes and for vehicles in different speed intervals was performed using the vehicle dynamics simulation software Carsim. The height jumped by a vehicle’s wheels, the vertical force on the wheels, and the vertical acceleration of the vehicle were used as indicators of ride comfort and operational stability for the various deceleration facility profiles. Results stability and comfort were related to the contour of the deceleration facility. Vertical forces were positively related to vehicle jump height, but the jump heights of vehicles passing through deceleration mounds with different planes at the same speed were not significantly different with increasing height. When the vehicle is traveling slowly, the vertical impact force on the vehicle is not significantly related to the speed loss of the vehicle. Conclusions Within the speed range of 20–60 km/h and profile heights of 3–10.5 cm, the effectiveness ratings of circular high width and parabolic were basically at level 2 and level 3, but the circular high width had a more stable jump height and was the best profile form, followed by sinusoidal and parabolic, then isosceles trapezoidal, and lastly conventional speed bumps.

Braking system analysis with the aid of a dynamic vehicle simulator with nine degrees of freedom

ABSTRACT The braking system is one of the most important vehicle systems, therefore, its optimised operation is essential in the dynamic performance of the automotive project; in addition to ensuring the necessary security of the object of study. Consecutively, the in-depth study on the sizing and performance of the braking system becomes necessary and, using software to assist in the manipulation of the parameters that influence this system, the automotive industry has presented different solutions in recent years, especially due to the use of central electronics such as the brake system module (BSM). In this context, the present work simulates, via a multibody virtual model and the aid of software such as VI-CarRealTime, the dynamic behaviour of a vehicle according to the braking system efficiency loss. With this goal, the virtual model is correlated with a physical test car and the conditions proposed in the AMuS test are executed, where the friction between the pad and the brake disc is changed. Using driver-in-the-loop simulation in a vehicle dynamics simulator with nine degrees of freedom, it was noted, qualitatively, that the loss of brake efficiency through g-force in each braking results in a long time for the vehicle to react according to the driver’s assessment and by telemetry.

Towards Flight Envelope Protection for the NASA Tiltwing eVTOL Flight Mode Transition Using Hamilton???Jacobi Reachability

Innovative electric vertical take-off and landing (eVTOL) aircraft designs and operational concepts, driven by advancements in battery and electric motor technologies, seek to achieve superior safety records with increased system redundancy. Validating safe flight operations within the prescribed flight envelope for passenger flights in densely populated urban environments remains a primary challenge. This paper establishes a framework for applying Hamilton???Jacobi reachability analysis to the full six-degree-of-freedom (6-DOF) dynamics of the NASA Tiltwing vehicle, verifying the flight envelope during the flight mode transition between near-hover and cruise flight, which prevents loss of control of the vehicle and ensures recoverability to safe trim conditions. This involves first verifying the nominal flight mode transition path as a series of trim points, defining the safe flight envelope using reachability, and decomposing the system dynamics into longitudinal and lateral subsystems. Our formulation guarantees the computed envelope’s robustness against modeling errors and uncertainties, and the usage of state decomposition significantly improves the tractability of the reachability computation. The result is validated through Monte Carlo 6-DOF nonlinear simulation of vehicle dynamics, demonstrating that the vehicle states within the flight envelope can successfully recover to trim states and continue the flight mode transition safely.

Lateral safety evaluation of autonomous trucks in overtaking maneuvers and adverse weather: Exploratory comparison of different lateral control modes

As the detrimental impact of the commonly recommended centered driving mode for autonomous trucks on road longevity is gaining attention, more lateral control modes are being proposed to enhance road sustainability. However, there is currently a lack of research on the lateral safety analysis of autonomous trucks with different lateral control modes, especially in complex driving scenarios (such as overtaking) and adverse weather conditions. Therefore, this study developed a safety assessment framework to comparatively analyze the risk probability differences in lateral accidents during overtaking maneuvers by autonomous trucks with different lateral control modes under adverse weather conditions. Based on aerodynamics and vehicle dynamics simulations to capture the multifactorial influences on truck lateral deviation, the results are used for model validation and training. In the reliability approach, Support Vector Machine Regression (SVR) is introduced to establish the SVR response surface model with optimal predictive performance, and combined with Monte Carlo simulations for safety assessment, quantifying safety indices. The results indicate that trucks being overtaken during overtaking maneuvers are more prone to lateral accidents under crosswind influences. The overall impact of lateral control modes on the lateral safety trends is minor. Compared to other lateral control modes, following the centered zero-drift mode is generally safer. However, in conditions of low wind speeds (below 20 km/h) or on highly slippery road surfaces (road friction coefficient below 0.1), autonomous trucks following a uniform distribution mode can better maintain a low-risk level. This study provides crucial insights for future considerations integrating road longevity and truck safety in a collaborative manner, and the proposed methodology has broad applications.

Magnetic irregularity measurement and signal processing of permanent magnet guideway for superconducting pinning maglev train

Superconducting pinning maglev train, with the advantages of heavy self-stable levitation and super-low resistance, is expected to become a high-speed transit in the future. With the increase in speed, the more will the irregularity of the PMG (permanent magnet guideway) affects the safety and comfort of the superconducting pinning maglev train. This paper is based on the PMG of the test line for the first high-speed superconducting pinning maglev engineering prototype train in China, to measure and study the magnetic irregularity of the PMG and its characteristics. Experiments were designed to measure the irregularity with a single Dewar maglev system, which can obtain the equivalent geometric irregularity directly acting on the maglev unit of the vehicle. Firstly, the frequency response function is developed based on previous studies, which can transform the response signal of the Dewar into the irregularity signal of the PMG. Secondly, the velocity and position are measured by image recognition of ground markers. Then, the dynamic signal of the Dewar maglev system moving along the PMG is gained and conversed into equivalent geometric irregularities by the frequency response function. Finally, an equivalent geometric irregularity PSD (power spectral density) function is formed, and it can generate the geometrically random track irregularity for vehicle dynamic simulations. The dynamic simulation result suggests that the superconducting pinning maglev train has the potential for smooth operation at high-speed under the excitation of the current PMG. The studies of this paper can help to understand the irregularity of the PMG further, and the gained PSD function can provide a general reference for the dynamic study of the superconducting pinning maglev train.

Dynamic vehicle–track interaction and structural loading in a crossing panel – calibration and assessment of a model with a 3D representation of the crossing rail

A three-dimensional (3D) finite element model of a railway crossing panel for use in multibody simulation (MBS) of dynamic vehicle–track interaction is presented. It is a two-layer track model with stock rails and sleepers represented by beam elements and a crossing rail represented by 3D solid elements. The track model uses linear bushings for the rail fastenings and bi-linear bushings for the ballast to allow for potentially voided sleepers. Based on the output from the MBS, the structural loading of the crossing in terms of strains, stresses and sleeper-ballast contact pressures is extracted in a post-processing step. The model is calibrated and validated to measurement data from a comprehensively instrumented switch & crossing (S&C) demonstrator installed in the Austrian railway network as a part of the European research programme Shift2Rail. The applied procedure for the calibration and critical assessment of the crossing model is described in detail. It is based on a model parameterisation with eight parameters relating to the rail fastening and foundation stiffnesses and to a distribution of the ballast voids. The calibration method uses Latin hypercube samples to explore the parameter space in a sensitivity analysis before a parameter optimisation is performed using a gradient-based method on a response surface built from a polyharmonic spline. In a comparative study it is shown that the 3D model and a more conventional beam model of the crossing rail show similar calibration results and good agreement with the measured data. The 3D model allows for the extraction of stress concentrations in the crossing rail but has an increased computational time of about 30% compared to the beam model.

Er.autopilot 1.0: The Full Autonomous Stack for Oval Racing at High Speeds

The Indy Autonomous Challenge (IAC) brought together for the first time in history nine autonomous racing teams competing at an unprecedented speed and in a head-to-head scenario, using independently developed software on open-wheel race cars. This paper presents the complete software architecture used by the team TII EuroRacing (TII-ER), covering all the modules needed to avoid static obstacles, perform active overtakes, and reach speeds above 75 m/s (270 km/h). In addition to the most common modules related to perception, planning, and control, we discuss the approaches used for vehicle dynamics modeling, simulation, telemetry, and safety. Overall results and the performance of each module are described, as well as the lessons learned during the first two events of the competition on oval tracks, where the team placed second and third, respectively.

Integrated Vehicle Dynamics Modeling, Path Tracking, and Simulation: A MATLAB Implementation Approach

Integrated Vehicle Dynamics Modeling, Path Tracking, and Simulation: A MATLAB Implementation Approach

Assessment of influence of considering the flexibility of the front loader frame on the emerging loads in the multibody system

BACKGROUND: Dynamic models are widely used for vehicle dynamics simulation. Increase of simulation accuracy is achieved with adding flexible bodies in a model, making problem solving more complicated. Therefore, assessment of influence of considering the flexibility of the front loader frame on the emerging loads in the multibody system becomes necessary.
 AIM: Assessment of considering the flexibility of the front loader frame on the emerging loads in the multibody system becomes necessary.
 METHODS: The solution of the problem is presented with the example of a multibody model of a 14.5-ton front loader (FL) with a frame coupled with wheel movers rigidly fixed to the front half-frame and a swinging axle at the rear half-frame. This method of coupling makes it possible to assess the effect of the flexibility of the elements of the FL by comparing the vertical forces that occur in the contact patch of the wheels with the support surface. The multibody models are built in the NX Motion application of the NX 2206 software package.
 RESULTS: The comparison of vertical wheel forces in given load conditions (symmetrical and skew-symmetric) using absolutely rigid and flexible models of the frame is carried out. It is found that the forces for skew-symmetric loading modes can differ by up to 20% depending on the frame stiffness.
 CONCLUSION: As a result of the conducted research, it can be stated that taking into account the suppleness of the load-bearing system of the vehicle significantly affects the results obtained in the process of modeling.

Soft Soil, Hard Problem

With the aim of helping engineers with simulating off-road tyre applications, Mechanical Simulation Corporation has added a terramechanics-based tyre model to its CarSim and TruckSim vehicle dynamics simulation software

Experimental characterization of road roughness input for tyre dynamics simulations

In the framework of road vehicle noise and vibration assessment, the experimental evaluation and the synthesis of artificial road surfaces are typically used for vehicle dynamics simulations and for the estimation of passengers' ride comfort. Indeed, besides the tyre/road interaction and the dynamics of the specific tyre, the road input represents a fundamental aspect for the prediction of the vehicle NVH (Noise, Vibration, Harshness) performances. Moreover, to perform complete simulations of specific environmental conditions, tyre models and road surfaces must be properly combined. In this context, tyre manufactures rely extensively on Finite Element Modelling (FEM) to carry out sensitivity analyses on design parameters. To account for the tyre dynamics in the frequency ranges of interest, very refined meshes are used and, therefore, tyre footprints are modelled as interface surfaces with a significant number of nodes in contact with the ground. To properly run tyre dynamics FEM simulations, this paper proposes a methodology for the experimental evaluation of a road surfaces. Measurements are carried out by means of lasers and a dedicated linear rail system. The Power Spectral Density of the road vertical profile is estimated and, eventually, the road surface was generated by means of a dedicated algorithm.