Vehicle Dynamic Behavior Research Articles

Effects of High-Speed Trains on Trucks Running on a Road–Rail Dual-Use Bridge Under Crosswind

The road–rail dual-use bridge can simultaneously meet the requirements of both the highway and railway transportation owing to its unique bridge type, which makes it environmentally friendly and cost-effective when compared to independent railway and road bridges. This study establishes a dynamic model of a wind-road vehicle–bridge system considering the aerodynamic sheltering effect of trains based on the coupling vibration method of wind-road vehicle–bridge systems. A container truck and a CRH2 high-speed train are considered as the research objectives, and a series of wind tunnel tests are conducted for the train and truck running simultaneously on a road–rail dual-use bridge to determine the effect of the aerodynamic interference of trains on the aerodynamic characteristics and dynamic behavior of vehicles under crosswinds. The entire process of driving the truck through the cable-stayed bridge under crosswinds and the interference of stationary trains is subsequently simulated to generate the time histories of the dynamic displacements of the truck. Consequently, the effect of the stationary trains is separately compared at different locations, such as on the track of the bridge deck and on the truck placed upwind and downwind. Furthermore, the interference effect of stationary trains on the truck placed upwind and downwind is analyzed corresponding to different wind yaw angles. The results demonstrate that the presence of trains on the bridge significantly affects the aerodynamic coefficients and dynamic responses of the truck placed downwind when compared to the truck placed upwind. Additionally, the presence of the trains on the bridge deck has a different effect on the aerodynamic coefficients and dynamic responses of the truck placed downwind. The effect of the trains on the truck at different wind yaw angles presents different patterns of change for different locations of the trains on the bridge deck.

Simultaneous Estimation of Unknown Road Roughness Input and Tire Normal Forces Based on a Long Short-Term Memory Model

This paper reports an initial study on the simultaneous estimation of unknown road roughness input and tire normal forces for automotive vehicles using a long short-term memory (LSTM) model. Active safety systems and the improvement of ride comfort using vehicle information have garnered increasing attention in the automotive industry. In particular, active safety systems rely significantly on road roughness data and the normal force of the tires. If these factors can be measured in real-time for a driving vehicle, the measured data can be used for automotive control systems for tasks, such as semi-active and active suspension control, rolling motion control, and torque vectoring. However, it is typically difficult to measure the road roughness and tire normal force directly in real-time by mounting physical sensors on the vehicle. In this study, we explore the simultaneous estimation of these factors using an LSTM model that requires only time-series data of the vehicle body. The LSTM model is implemented by using MATLAB/Simulink and includes data preprocessing, learning, and verification steps. To evaluate the estimation performance of the LSTM model, we compared it with a Kalman filter and used CarSim vehicle simulation software to simulate and interpret the dynamic behavior of vehicles.

Aquaplaning Detection Using Effect-Based Methods: An Approach Based on a Minimal Set of Sensors, Electronic Stability Control, and Drive Torques

Knowledge of actual tire-road friction potential is most relevant for safe operation of automated vehicles and for adjusting advanced driverassist systems. Aquaplaning may result in considerably reduced friction potential and unstable vehicle behavior for rear-wheel-drive vehicles; thus, awareness of risk of aquaplaning is crucial. Analysis of numerous measurements from driving on wet road surfaces, including, for example, different water levels, types of tires, tire inflation pressures, and tire wear, has revealed characteristic dynamic behavior of vehicles and their subsystems that could be related to an immediately approaching onset or the presence of aquaplaning. Thus, methods to detect such characteristic behavior are developed, and a combined detection algorithm based on effect-based criteria to detect the risk or presence of aquaplaning for rear-wheel-drive vehicles is proposed. The effectiveness and limitations of the individual methods, as well as the reliability of the presented algorithm, are shown based on measurements from test maneuvers.

Effects of geometric track irregularities on vehicle dynamic behaviour when running through a turnout

Railway vehicle dynamics is strongly affected by track irregularities, which can influence the safety and the running behaviour of the vehicle. The EN 13848-5:2017 standard provides the limits of track irregularities for standard track but does not states specific restrictions for switches and crossings. Furthermore, since turnouts have a limited length, their track geometric irregularities cannot be accurately described by stochastic functions usually adopted for railway vehicle dynamics simulations. Nevertheless, irregularities in railway turnouts, related to the non-uniform stiffness of the track support and to the variation of the rail profiles along the longitudinal direction should be considered in dynamic simulations, as they can generate large dynamic loads, strongly affecting the vehicle dynamics and running stability. The aim of the paper is to expand the Switches and Crossing benchmark exercise analysing the effect of several kinds of irregularity with different wavelengths and amplitudes on a complete turnout on the main quantities related to the vehicle dynamics. The influence of each defect on each quantity is estimated through a post-processing sensitivity analysis based on power spectral density calculation. This sensitivity analysis is hence used to combine different types of defects in order to detect irregularity combinations that could compromise running safety.

Research tools aplicable in designing of high-speed and high-power rail vehicles

The importance of the railway transport of both goods and passengers continuously grows as it is in many points of view more ecological and economical solution in comparison with road transport. Just the importance has been supporting efforts to design more powerful and faster trains reaching traction powers more than 1.6 MW per a wheel-set or service top speed much more than 300 km/h till these days. To reach design which has enabled such a kind of performances it was necessary to research dynamic behaviour of railway vehicles. Both via laboratory measurements and simulations. The laboratory experiments have been carried out on a specially designed laboratory equipment called roller rigs. A laboratory equipped by roller rig for testing of the railway vehicle dynamic behaviour has been built at the Faculty of Mechanical Engineering at CTU in Prague, also within PhD studyprograms and SGS grants. Another powerful tool within research activities is a simulation. Kind of a such simulation will be presented by this contribution with the focus on the torsion dynamics of high-power fully-suspended drive of a railway vehicle, which has been developed also by PhD students under financial support of The Faculty of Mechanical Engineering and related grants.

Dynamic Behavior of the Full-Car Model in the J-Turn Maneuver by Considering the Engine Gyroscopic Effects

This study presents a new dynamic modeling of a vehicle by considering the engine dynamics. By selecting the vehicle coordinate system as the reference frame, all the force-torque equations of the sprung mass and unsprung masses are derived in this coordinate system by using the Newton’s equations of motion. Unlike the previous researches, in this work the sprung mass of the vehicle is not considered as a rigid body. The dynamics of the sprung mass components, such as gyroscopic effects of the engine crankshaft, is considered. In order to study the vehicle's dynamic behavior, in the J-turn maneuver, the governing equations of the full-car model are evaluated and validated by the numerical simulation method and ADAMS/Car software. Based on the results, the maximum roll angle and roll rate of a vehicle reach about 8 degrees and 40 degrees per second, respectively.

Numerical and experimental investigation of the wheel/rail interaction and dynamics for a high-speed gauge-changeable railway vehicle

For a high-speed rail vehicle with gauge-changeable wheelsets, wheel/rail interactions and vehicle dynamics were numerically and experimentally studied within 600 km/h. Matching among four treads, three rail profiles, two gauges, and two rail cants are analysed by examining the wheelset conicity, contact points distribution, and stress. It shows that the conicities of the S1002 and LMA become smaller than the permitted minimum when rail cant 1/20 is used instead of 1/40 when matching with any of the three rail profiles. The conicity of S1002 decreases by up to 95% while that of LMA drops by about 30%. Whereas the RUS and LMB10 are compatible with two cants. Worn treads are more sensitive to the rail cant than new ones. Wheelback distance error leads to a conicity change, especially for worn profiles. A multi-body vehicle system dynamics analysis indicates that a 0.6 mm wheel-axle clearance leads to running instability at low speeds, but will not have an obvious effect on running safety and ride comfort. The vehicle dynamics behaviour on the standard- and broad-gauge tracks shows a slight difference. This has been validated through lab tests performed on a full-scale roller rig.

Vehicle’s Dynamic Behavior in Fishhook Maneuver by Considering the Engine Dynamics

In order to study on the vehicle’s dynamic behavior, this study presents a new dynamic modeling of the vehicle by considering the engine dynamics. The coordinate systems are considered separately for the sprung mass and unsprung masses. By using Newton’s equations of motion, the force-torque equations of the sprung mass and unsprung masses are derived in the vehicle coordinate system. In general, the sprung mass in modeling of the vehicle is considered as a rigid body. However, in this study the components rotation of the sprung mass such as the engine crankshaft is considered and its gyroscopic effects are exerted in the governing equations. The lateral and longitudinal forces of the tire are evaluated by Pacejka model. In fishhook maneuver, the vehicle's dynamic behavior is studied by the numerical simulation method under the supervision of the National Highway Traffic Safety Administration (NHTSA). The numerical simulation results are also validated by ADAMS/Car software. According to the results, the 15-DOF model in this research simulates the vehicle’s dynamic behavior with a good accuracy and the maximum roll rate of the vehicle reaches about 37 degrees per second.

On the Investigation of Energy Efficient Torque Distribution Strategies through a Comprehensive Powertrain Model

In electric vehicles with multiple motors, the torque at each wheel can be controlled independently, offering significant opportunities for enhancing vehicle dynamics behaviour and system efficiency. This paper investigates energy efficient torque distribution strategies for improving the operational efficiency of electric vehicles with multiple motors. The proposed strategies are based on the minimisation of power losses, considering the powertrain efficiency characteristics, and are easily implementable in real-time. A longitudinal dynamics vehicle model is developed in Simulink/Simscape environment, including energy models for the electrical machines, the converter, and the energy storage system. The energy efficient torque distribution strategies are compared with simple distribution schemes under different standardised driving cycles. The effect of the different strategies on the powertrain elements, such as the electric machine and the energy storage system, are analysed. Simulation results show that the optimal torque distribution strategies provide a reduction in energy consumption of up to 5.5% for the case-study vehicle compared to simple distribution strategies, also benefiting the battery state of charge.

Study of Adhesion Recovery phenomenon using a Multi-axle Roller-rig

When a railway vehicle is running on a contaminated track, the available friction is reduced, and large creep values arise at the wheel-rail interface. However, the work of the friction forces of the leading wheelsets produces a cleaning effect on both the track and the wheels, so that the contaminant layer is partially removed, and adhesion increases on the leading as well as on the trailing wheelsets. The investigation of these adhesion recovery phenomena is the key to develop new solutions aiming to improve the vehicle dynamic behaviour in degraded adhesion conditions. Since on-field tests are usually expensive and time-consuming, roller-rigs are the typical apparatus used to simulate the vehicle dynamic behaviour in laboratory conditions. The paper describes the mechanical design of an innovative roller rig specifically designed to study adhesion recovery phenomena, consisting of four wheelsets running over the same pair of rollers. Experimental tests are performed on the test bench to obtain adhesion characteristics under dry and contaminated conditions.

An energy efficient intelligent torque vectoring approach based on fuzzy logic controller and neural network tire forces estimator

In electric vehicles (EVs) with multiple motors, torque vectoring (TV) control can effectively enhance the cornering response and safety. Moreover, TV systems can also improve the overall efficiency through an optimal torque distribution that also considers the power consumption. For such a complex control system with multiple objectives, intelligent control techniques have demonstrated to be one of the best alternatives. However, the works proposed in the literature do not handle both vehicle dynamics behaviour and energy efficiency, and generally do not consider the real-time implementability of the developed controllers. To overcome the aforementioned issues, in this work, a novel torque vectoring approach is proposed, which uses a neural network-based vertical tire forces estimator and considers the regenerative braking capabilities of EVs. Moreover, the implementability of the controller in a hetereogenous (FPGA and microcontroller) automotive suitable system on chip is addressed, ensuring its real-time capabilities. For the sake of validating the proposed approach, a set of experiments have been carried out in a hardware in the loop setup. The performance of the proposed TV approach has been compared with other two TV approaches from the literature, evaluating them in several challenging manoeuvres in high and low tire-road friction coefficient scenarios. Results show that the proposed approach not only is able to enhance the vehicle dynamics behaviour but also to decrease the energy consumption about 13%.

Wheel slip ratio regulation for investigating the vehicle's dynamic behavior during braking and steering input

In this study, the vehicle's dynamic behavior during braking and steering input is investigated by considering the quarter-car model. The case study for this research is a Sport-Utility Vehicle (SUV) with the anti-lock braking system (ABS) and nonlinear dynamic equations are considered for it along with Pacejka tire model. Regulating the wheel slip ratio in the optimal value for different conditions of the road surface (dry, wet and icy) during braking is considered as the ABS control strategy. In order to regulating the wheel slip ratio in the optimal value, an intelligent adaptive fuzzy controller that can perform online parameter estimation is considered. In this regard, the proposed controller tracks the optimal wheel slip ratio with changing the condition of the road surface from dry to wet and icy. The adaptive fuzzy controller consists of linguistic base, inference engine and defuzzifier section. The wheel slip ratio and vehicle longitudinal acceleration are selected as inputs of the controller, controller adapter and detector of the road surface condition. During braking and steering input, effective parameters of the wheel that are affected on the vehicle's dynamic behavior and its stability are investigated.

Transient response analysis and synthesis of an FSAE vehicle using cornering compliance

Cornering compliance of an automobile influences the transient response of a vehicle and its handling characteristics. The cornering compliance technique provides much better information about the vehicle handling qualities than the understeer coefficient. This paper discusses about the front and rear cornering compliances for a FSAE vehicle. The relationship between the front, rear cornering compliances and the transient response as well as the vehicle dynamic behavior of a FSAE vehicle is analyzed. A bicycle model is considered for the analysis and simulation of the problem. A state space model for the handling behavior is created in MATLAB/Simulink. An in-house test rig was developed to determine the parameters constituting the cornering compliance such as roll steer, roll camber, lateral force deflection steer, etc. The front wheel compliance and rear wheel compliances are determined under static conditions. The FSAE vehicle is dynamically tested for constant radius test, step steer response tests. The experimental data obtained is compared with the simulated data from the state space model.

Dynamic Properties and Wear Analysis of a Rail Vehicle with Wheels' Self-Lubricating Coatings

The problem of wheel and rail wear in railway transport generates costs of reprofiling and availability of vehicles and infrastructure. One of the possibilities of wear minimizing is decreasing of the friction coefficient in wheel-rail contact by means of lubricants. Such a solution has drawbacks from which the most crucial are: decrease of tractive/braking forces and difficulties with the precise spreading of the lubricant. These disadvantages may be avoided by modern, innovative self-lubricating coatings, applied at the production stage on the wheel flanges. The aim of the study is to investigate the effect of self-lubricating coatings on a rail vehicle's dynamic behaviour, safety against derailment and predicted wheel wear. The numerical study was performed using the wagon multibody model with simulated self-lubricating coating on wheel flanges.

Experimental Study on the Effect of Emergency Braking without Anti-Lock Braking System to Vehicle Dynamics Behaviour

An anti-lock braking system (ABS) is a basic skid control system that can prevent the tire from locking up. In an emergency braking situation, a high possibility that the skidding phenomenon can occur without ABS. This incident become worse when an emergency braking is applied either on wet or dry surfaces. Although ABS is crucial to prevent the collision, some vehicles still do not have ABS. This study is aimed to analyse the vehicle’s dynamic behaviour during emergency braking on wet and dry surface condition. The experimental vehicle model is a Malaysian sedan car namely Proton Persona. This instrumented car is equipped with sensors,video camera and data acquisition systems to determine the vehicle’s motion. In the experiment,when the vehicle reached a maximum speed of 60 km/h, the driver push the brake pedal firmly until the car stop. From the experimental results, the effect of emergency braking without ABS is clearly seen at the wheel speed. The tire locked up can be observed when emergency braking was applied on the wet surface. However, for the emergency braking on the dry surface, the tire decreased gradually. This finding shows that without ABS, the vehicle is unsafe and accident can occur. The experimental data from this study also can be used as a guideline to a researcher and manufacturer in the development of ABS and safety system of the vehicle

Analysis of ride comfort of a continuous tracked bogie system with variable configuration

In this study, the effect of change in height of a so-called variable configuration of a continuous tracked bogie system on ride comfort performance is investigated. To this end, constraint equations among different vehicle parts are derived recursively, and equations of motion are formulated according to the Newton–Euler equations using the embedding technique. Besides, to model the track as a closed-loop chain, the penalty method has been used instead of loop-closure equations. To mathematically model the contact between tracks, wheels, and the terrain, the continuous contact force model has been employed. To validate the mathematical model, the vehicle dynamic behavior is simulated by the Runge–Kutta method in MATLAB software and compared with those obtained from the identical model, built in RecurDyn software, and the results show good agreement. Moreover, the vibrational behavior of the tracked vehicle is investigated using two different vehicle configurations. This reveals that an increase in vehicle height does not change the vehicle vibrational frequencies. However, it increases the vehicle vibration amplitude and the energy absorbed by the vehicle components and decreases the ride comfort.

Facility for Complete Characterization of Suspension Kinematic and Compliance Properties of Wheeled Military Vehicles

<div class="section abstract"><div class="htmlview paragraph">As part of their ongoing efforts to model and predict vehicle dynamics behavior, the US Army’s Ground Vehicle Systems Center procured a facility in two phases. The facility is called the Suspension Parameter Identification and Evaluation Rig (SPIdER) and has a capacity covering all of the military’s wheeled vehicles, with vehicle weights up to 100,000 lbs (45,400 kg), up to 150 inches wide, with any number of axles. The initial phase had the ability to measure bounce and roll kinematic and compliance properties. The SPIdER is the companion machine to the Vehicle Inertia Parameter Measuring Device (VIPER) which measures the inertia properties of vehicles of similar size. In 2015, the final phase of the SPIdER was completed. This phase includes ground plane wheel pad motion so that lateral, longitudinal, and aligning moment compliance and kinematic properties can be measured. These capabilities greatly enhance the SPIdER’s features, giving it the ability for making complete suspension and steering system kinematic and compliance measurements. Horizontal forces and aligning moments can be applied up to the limits of tire slip. Longitudinal forces are applied at the ground plane. The vehicle is driven onto the SPIdER and the body is restrained to a rigid T-bed. The test sequence can be performed in a few hours, and is done with the vehicle body stationary and the ground plane moving under the tires. The slight vehicle body motions are measured and this motion is accounted for in the calculations of suspension parameters. This paper describes the new capabilities of the SPIdER, including an overview of the new design features, control schemes, and measured quantities. Results from a sampling of various SPIdER tests are presented.</div></div>

Mathematical model of the vehicle initial rectilinear motion during moving uphill

In the article the mathematical model of the vehicle motion with elastic tires, which describes the phases of the initial rectilinear motion on the longitudinal slope of the road is shown. The mathematical model is valid for vehicle with two axles, one of which is driving axel and provided that the stopped vehicle on a slope is kept from rolling only by braking the non-driving axle. The aim of the study is to determine the equations to describe the process of vehicle initial rectilinear motion during moving uphill, which take into account the tires deformation energy on the stationary vehicle braking wheels. The presented equations described in the article are reflect the dynamic state of the stationary vehicle on a slope and the phase of its initial moving off uphill after brining the engine torque through the transmission to the wheels of the drive axle. The system of equations describing the vehicle dynamic behavior after brining torque to the drive wheels takes into account their false slip. The system of equations is obtained from the general dynamic equation in the form of balance of the elementary work of external forces and moments with the absence of external slipping of the driving wheels. The mathematical model of the vehicle initial rectilinear motion on a longitudinal slope of a highway described in the article can be used in theoretical basis for analyzing and synthesizing control algorithms for automatic driver assistance systems during vehicle initial motion.

Computationally Efficient Nonlinear One- and Two-Track Models for Multitrailer Road Vehicles

This paper presents nonlinear mathematical models of one- and two-track multitrailer vehicles. We derive nonlinear equations of motion in the form of a system of implicit ordinary differential equations (ODEs) by using Lagrangian mechanics. The system of ODEs has the minimum number of states and equations that enables efficient computations yet maintains the most important nonlinear vehicle dynamic behavior and allows actuator coordination and energy consumption evaluation. As examples, we build different models of a 4-unit long combination vehicle, i.e., two-track 11-axle and single-track 6-axle nonlinear models as well as a linear single-track 6-axle model. We compare the performance of these models to experimental data of different driving maneuvers. The nonlinear single-track model demonstrates close dynamic behavior to the experiment, which makes it an efficient alternative to the two-track model. The vehicle equations can be generated automatically by using the code provided in this paper and subsequently used for conducting frequency analysis, evaluating energy consumption, deriving performance measures from simulations, and facilitating optimal control applications that involve combined steering, braking and propulsion control.

How do driving modes affect the vehicle’s dynamic behaviour? Comparing Renault’s Multi-Sense sport and comfort modes during on-road naturalistic driving

Several modern vehicles provide the option to select a driving mode. However, the literature contains no empirical studies that investigate how driving modes affect the vehicle's dynamic behaviour in regular on-road driving. We examined for which CAN-bus signals the differences between Renault's Multi-Sense® comfort and sport modes are most apparent. We gathered data on a 26.3 km route containing a rural and highway section. A single person drove the route four times in comfort mode and four times in sport mode. By statistically analysing and ordering 887 CAN-bus signals, we found strong differences between the two modes for rear-wheel angle, engine torque, longitudinal acceleration, and vertical motion. Parameter identification of a quarter car model identified a 3.5 times higher damping coefficient for the sport mode compared to the comfort mode. Due to four wheel steering, compared to the comfort mode, the sport mode yielded a higher lateral acceleration and yaw rate for a given steering wheel angle and driving speed. In conclusion, this study provides quantitative insight into the extent to which the Multi-Sense driving modes impact the vehicle's lateral, longitudinal, and vertical dynamic behaviour. The results and the analysis methods help guide future driving mode designs.