Cornering Maneuvers Research Articles

Vehicle centre of mass, roll-centre and pitch-centre height estimation

The location of a vehicle's centre of mass is an important parameter as it has a determining effect on the dynamics of a vehicle. The height of the vehicle centre of mass from the roll and pitch centres has a large influence on the load transfer which occurs between wheels during braking and cornering manoeuvres. These vehicle parameters can vary significantly especially on off-road vehicles due to the large differences in laden and unladen weight. This paper proposes an algorithm where suspension forces and inertial parameters are estimated in real time using inexpensive sensor measurements and an unscented Kalman filter. The algorithm is experimentally validated on an offroad vehicle performing various manoeuvres and driving over different terrains. The real time estimation of these parameters could contribute significantly to improving vehicle safety and control.

Effect of integrated ride and cornering dynamics of a military vehicle on the weapon responses

The present study brings out the influence of a non-linear dynamics model of military vehicle with trailing arm suspension, on the weapon dynamics responses. A 20 degrees of freedom integrated ride and cornering dynamics model has sequentially been coupled with the 7 degrees of freedom weapon dynamics model. The 20 degrees of freedom integrated model includes the bounce, pitch, roll, longitudinal, lateral and yaw motions of the sprung mass and rotational dynamics of the 14 unsprung masses. The 7 degrees of freedom weapon model comprises the coupled elevation and azimuth dynamics. The coupled weapon model includes angular rotation of the elevation drive, breech and muzzle in elevation direction, as well as, angular rotation of the azimuth drive, turret, breech and muzzle in azimuth direction. The actual physical behaviour of each of the hydro-gas trailing arm suspension units is implemented in the governing differential equations. The non-linear governing equations also incorporate the dynamic coupling between each of the axle arms and sprung mass, which is an inherent behaviour of the trailing arm suspension, unlike their equivalent vertical representation. The integrated model has been simulated for different cornering manoeuvres at specified speeds. It is observed that the sprung mass dynamics, emanating from different manoeuvres, significantly affects the coupled elevation and azimuth dynamics responses of the weapon. The weapon dynamics model coupled with the integrated ride and cornering dynamics model of the military vehicle, would be useful for implementation of a suitable robust gun control system in military vehicles.

Variable caster steering in vehicle dynamics

When a car is cornering, its wheels usually lean away from the centre of rotation. This phenomenon decreases lateral force, limits tyre performance and eventually reduces the vehicle lateral grip capacity. This paper proposes a strategy for varying caster in the front suspension, thereby altering the wheel camber to counteract this outward inclination. The homogeneous transformation was utilised to develop the road steering wheel kinematics which includes the wheel camber with respect to the ground during a cornering manoeuvre. A variable caster scheme was proposed based on the kinematic analysis of the camber. A rollable vehicle model, along with a camber-included tyre force model, was constructed. MATLAB/Simulink was used to simulate the dynamic behaviour of the vehicle with and without the variable caster scheme. The results from step steer, ramp steer, and sinusoidal steer inputs simulations show that the outward leaning phenomenon of the steering wheels equipped with the variable caster, is reduced significantly. The corresponding lateral acceleration and yaw rate increase without compromising other handling characteristics. The actively controlled car, therefore, provides better lateral stability compared to the passive car. The tyre kinematic model and the vehicle dynamic model were validated using multibody and experimental data.

Combined emergency braking and turning of articulated heavy vehicles

ABSTRACT‘Slip control’ braking has been shown to reduce the emergency stopping distance of an experimental heavy goods vehicle by up to 19%, compared to conventional electronic/anti-lock braking systems (EBS). However, little regard has been given to the impact of slip control braking on the vehicle’s directional dynamics. This paper uses validated computer models to show that slip control could severely degrade directional performance during emergency braking. A modified slip control strategy, ‘attenuated slip demand’ (ASD) control, is proposed in order to rectify this. Results from simulations of vehicle performance are presented for combined braking and cornering manoeuvres with EBS and slip control braking with and without ASD control. The ASD controller enables slip control braking to provide directional performance comparable with conventional EBS while maintaining a substantial stopping distance advantage. The controller is easily tuned to work across a wide range of different operating conditions.

Aerodynamic analysis of an active rear split spoiler for improving lateral stability of high-speed vehicles

This paper examines an active rear split spoiler designed for improving lateral stability of high-speed vehicles under high lateral acceleration (high-g) scenarios, such as a tight cornering manoeuvre at high speeds. Downforces produced by the spoiler can enhance the lateral stability of the vehicle under a high-g cornering manoeuvre. On the other hand, the spoiler may introduce additional drags on the vehicle. Aerodynamic analysis and wind tunnel testing are conducted to evaluate the dynamic effects of the active spoiler on a high-speed car. The downforce and drag, as well as their relationship, are investigated using CFD simulations of the car with the active rear split spoiler at different spoiler angles of attack and at different speeds. Then, the achieved CFD simulation results are compared with the experimental data derived from the wind tunnel on the physical car and the spoiler prototype. The observations and findings achieved from the study may provide valuable guidelines for developing active aerodynamic control systems to increase safety of high-speed vehicles.

Engineering properties and performance of asphalt mixtures incorporating steel slag

Lack of natural stone and costly expense of purchasing high-quality aggregate promote the utilization of steel slag. Asphalt mixtures incorporating basic oxygen furnace (BOF) steel slag as coarse aggregate were prepared and subsequently subjected to laboratory tests to determine the engineering properties of asphalt concrete. Results showed that the addition of steel slag into asphalt mixtures had high resistance to permanent deformation and moisture-induced damage. Steel slag included angular and rough textured particles that would enhance the interlocking mechanism and provide good mechanical properties. According to the laboratory results, a test road was constructed in 2012 by using three different types of asphalt mixtures as follows: stone mastic asphalt with BOF (SMA-BOF), dense-graded asphalt concrete with BOF (DGAC-BOF), and dense-graded asphalt concrete with natural aggregate (DGAC-NA). The rut depth of the SMA-BOF section was lowest among the three sites even though it was subject to high stress induced by braking, accelerating and turning vehicles. Surveys for pavement performance were conducted at scheduled intervals. The ride quality and the friction characteristics of both BOF sections performed as well as or better than the section constructed using natural aggregate. Field data indicated that steel slag could be used as a surface course aggregate in locations where traffic is expected to perform heavy braking and cornering maneuvers. No rutting, cracking, or other failures have been observed to any significant extent on the BOF sections since they opened to traffic throughout the three-year period. Test results suggest that the use of steel slag as coarse aggregate substitute in surface courses be technically appropriate.

A Novel Kinematic Model of a Steerable Tire for Examining Kingpin Moment during Low-Speed-Large-Steering-Angle Cornering

As long as a tire steers about a titled kingpin pivot, the point coming in contact with the road moves along its perimeter. This movement affects the determination of kingpin moments caused by the tire forces, especially for large steering angles. The movement, however, has been neglected in the literature on the steerable-tire-kinematics-related topics. In this investigation, the homogeneous transformation is employed to develop a kinematic model of a steering tire in which the instantaneous ground-contact point on the tire is considered. The moments about the kingpin axis caused by tire forces are then computed based on the kinematics. A four-wheel-car model is constructed for determining the kingpin moment of steering system during the low-speed cornering maneuver. The result shows that the displacement of the ground-contact point along the tire perimeter is significant for large steering angles. It also indicates that, at the low-speed cornering, the moment about the kingpin axis caused by vertical forces benefits self-centering while those caused by longitudinal forces, lateral forces, and 'aligning' torques facilitate the turn. A parameter study is also conducted to visualize the effects of wheel alignment parameters on the kingpin moment. It appears that an increase in kingpin offset or a decrease in caster angle affects the kingpin moment such that it supports the self-centering. The effects of kingpin inclination and caster trail on the moment, however, depend on the amplitude of steering angle. The result is compared to those derived from a multi-body model for validation.

Global modeling and simulation of vehicle to analyze the inertial parameters effects

This paper mainly studies the comparison of the global vehicle models and the effects of the inertial parameters due to the center of gravity (CG) positions when we consider that the vehicle has only one CG. This paper proposes a new nonlinear model vehicle model which considers both unsprung mass and sprung mass CG. The CG positions and inertial parameters effects are analyzed in terms of the published vehicle dynamics models. To this end, two 14 degree-of-freedom (DOF) vehicle models are developed and compared to investigate the vehicle dynamics responses due to the different CG height and inertial parameters concepts. The proposed models describe simultaneously the vehicle motion in longitudinal, lateral and vertical directions as well as roll, pitch and yaw of the vehicle about corresponding axis. The passive and active moments and the forces acting on the vehicle are also described and they are considered as a direct consequence of acceleration, braking and steering maneuvers. The proposed model [Formula: see text] takes both the CG of sprung mass, unsprung mass and total vehicle mass into account. The second model [Formula: see text] assumes that the vehicle is one solid body which has a single CG as reported in majority of literature. The two vehicle models are compared and analyzed to evaluate vehicle ride and handling dynamic responses under braking/acceleration and cornering maneuvers. Simulation results show that the proposed model [Formula: see text] could offer analytically some abilities and driving performances, as well as improved roll and pitch in a very flexible manner compared to the second model [Formula: see text].

Application of viability theory for road vehicle active safety during cornering manoeuvres

Viability theory proposes geometric metaphors in addition to classical ordinary differential equation analysis. In this paper, advantages of applying viability theory to road safety domain are presented. The exact issue is to determine if, from an initial state of a vehicle/road/driver system, a soft controls strategy is compatible with a safe driving sequence. The case of a car negotiating a curve is considered. The application of the viability theory to this issue offers the advantage to avoid classical full computing of the system. Instead of that, it consists on verifying that the states and the controls belong to a subset called the viability kernel. The construction and the use of the viability kernel for a vehicle system dynamic is proposed by using support vector machines algorithm. Then, the applicability of this theory is demonstrated through experimental tests. This innovative application of the viability theory to vehicle dynamics with road safety concerns could benefit to robust embedded warning systems.

A Study of Torque Vectoring and Traction Control for an All-Wheel Drive Electric Vehicle

Common vehicle always experience energy loss during cornering manoeuver. Thus, to ensure it did not happened especially at high speed, a study of torque vectoring and traction control need to be made since it can increase the traction control of tyres during cornering at high speed. The study of torque vectoring and traction control for an all-wheel drive electric vehicle was conducted by modelling an all-wheel drive electric vehicle (EV) in ADAMS/Car software. In addition, an optimal control algorithm will be developed for best performance to minimize energy losses using MATLAB/Simulink software. Furthermore, to prove the effectiveness of the all-wheel drive electric, the torque and traction control simulation of the all-wheel drive electric vehicle will be compared with uncontrolled electric vehicle model. According to the result, torque vectoring and traction control of in-wheel motor in all wheel drive EV can help to increase the performance of the electric vehicle during cornering manoeuver. In conclusion, this study of torque vectoring and traction control for an all-wheel drive electric vehicle will help researchers to improve the design of the future electric vehicle in term of the vehicle performance during cornering manoeuvre.

Study of Cornering Maneuvers of a Pneumatic Tire on Asphalt Pavement Surfaces Using the Finite Element Method

Field experience shows that most road accidents that occur during turning maneuvers are caused by the loss of vehicle control. The loss of vehicle control is often related to a lack of sufficient friction between the tire and the pavement surface. In experiments and analytical studies, the overall antiskidding performance of a pneumatic tire has been observed to be affected by operating conditions, road texture, and surrounding temperatures. Interactions of these parameters create a complex relationship between their combined effect and the tire's ability to combat skidding. One way to analyze the cornering maneuvers of a vehicle is by means of a validated finite element tool that can carry both the tire and the pavement properties. Few computational studies have been conducted to study the cornering performance of a rolling pneumatic tire, and none of these studies included the role of pavement surface morphologies in their analysis. In this study, a thermomechanical framework was used to analyze the influence of temperature on cornering friction. The cornering friction coefficient was found to decrease with an increase in the loads and the speeds. The cornering friction coefficient was found to increase with an increase in inflation pressure, sideslip angle, and pavement surface texture depth. The proposed study contributes to an understanding of the cornering performance of passenger car tires.

Comparison of the stress distributions of liquid gas road tankers with various configurations during braking, cornering, and vertical bump maneuvers

This paper compares the stress and displacement distributions of different head-shell junction configurations in LPG road tankers during different vehicle design maneuvers, such as braking, cornering, and vertical bumps, for the first time. Various combinations of heads (e.g., spherical and toroidal) and shell cross sections (circular and elliptical) are considered. The ABAQUS finite element software is used to model and analyze the fluid-filled tankers. The results show that the most critical maneuver affecting the fluid-filled tankers is cornering and the safest maneuver is braking. Moreover, the results reveal that the outer surface of the tanker generally behaves the most critically in all maneuvers, and cylindrical tankers with smaller cross-sections behave more acceptably compared to those with larger cross-sections. Among fluid-filled vehicle tankers with identical platform areas, tankers with elliptical cross-sections behave the most acceptably.

SUV 차량용 전동식 능동 롤 제어 시스템의 성능 평가 기술 연구

차량 선회 시 조종안정성과 주행 승차감을 향상시키기 위하여 능동적으로 차체의 롤(roll)을 줄이기 위한 연구가 진행되고 있다. 전동식 능동 롤 제어(ARC) 시스템은 전후 스테빌라이저바 중앙에 위치한 전동 모터 방식의 구동기에 의해 차량의 차체 롤을 제어한다. 본 연구에서는 이러한 전동식 ARC 시스템의 제어 성능 및 차량 동역학적 특성을 평가하고 검증하기 위한 해석, 벤치 시험, 실차 시험의 3단계 절차와 방법을 제안하였다. ARC 제어로직의 성능 및 타당성 평가를 위한 Matlab/Simulink와 CarSim간의 연동-해석 방법을 제안하였고, ARC 구동기 및 시스템의 성능을 평가하기 위한 벤치 시험 방법과 실차 시험 방법을 제안하였다.

차륜-레일 2점 접촉을 고려한 3차원 윤축 동역학 해석

윤축 동역학 해석은 철도차량 동역학 해석의 정밀도를 결정하는 핵심 요소이다. 본 연구에서는 정밀한 3차원 차륜-레일 접촉 해석을 윤축의 강체 운동 방정식에 적용하는 방법으로 3차원 윤축 동역학 해석을 수행하였다. 곡선 주행시 플랜지 접촉에 의해 차륜-레일 2점 접촉이 발생할 때 윤축의 동역학 해석이 가능한 수치해석 절차를 개발하였다. 윤축의 구속조건식과 강체 동역학 방정식을 Runge-Kutta 방법을 이용하여 수치적분을 수행하였다. 제안된 윤축 동역학 해석 결과는 VI-RAIL을 이용한 해석결과와 비교 분석하여 타당성을 검증하였다. Wheelset dynamic analysis is a key element to determine the degree of accuracy of railway vehicle dynamics. In this study, a three-dimensional wheelset dynamic analysis is presented in such a way that the precise wheel-rail contact analysis in three-dimension is implemented into the dynamic equations of a wheelset. A numerical procedure that can be used for the analysis of a wheelset dynamics when the wheel-rail two point contact occurs in a cornering maneuver is developed. Numerical solutions of the constraint equations and the dynamics equations of a wheelset are achieved by using Runge-Kutta method. The proposed wheelset dynamic analysis is validated by comparison against results obtained from VI-RAIL analysis.

Development of an electric active rollcontrol (ARC) algorithm for a SUV

Cornering maneuvers with reduced body roll and without loss in comfort are leading requirements for car manufacturers. An electric active roll control (ARC) system controls body roll angle with motor-driven actuators installed in the centers of the front and rear stabilizer bars. A vehicle analysis model developed using a CarSim S/W was validated using vehicle test data. Two ARC algorithms for a sports utility vehicle (SUV) were designed using a sliding-mode control algorithm based on a nonlinear roll model and an estimated lateral acceleration based on a linearized roll model. Co-simulation with the Matlab simulink controller model and the CarSim vehicle model were conducted to evaluate the performance of two ARC control algorithms. To validate the ARC performance in a real vehicle, vehicle tests were conducted at KATECH proving ground using a small SUV equipped with two ARC actuators, upper and lower controllers and a few subsystems. From the simulation and vehicle validation test results, the proposed ARC control algorithm for the developed ARC actuator prototypes improves the vehicle’s dynamic performance.

Handling enhancement of a sliding-mode control assisted four-wheel steer vehicle

This paper is an investigation of the role of the robust control strategy of the rear wheel steer system to improve handling. To establish an accurate model of the vehicle, a nine degree-of-freedom (DOF) model is considered. The model’s degrees of freedom consist of three angular motions (roll, pitch, and yaw) of the sprung mass, spin of the wheels, and two translational motions (forward and side travel) of the unsprung mass. Also, the environment and geometric effects, such as aerodynamic forces, tyre–ground interaction, body roll versus camber relation, steering command saturation, and roll axis inclination, are taken into account. The front and rear suspensions are assumed to be a MacPherson strut and semi-trailing arm respectively. Cornering behaviour of the vehicle is studied and compared for a manual two-wheel steer (2WS) and a sliding-mode control assisted four-wheel steer (4WS) vehicle. A 3-DOF vehicle model is used to make a fast state estimation. The yaw rate is used as the reference signal for the control system, to ensure that the desired handling is obtained. The results show that during the standard cornering manoeuvres, the sliding-mode control provides significant tracking performance and lower sensitivity to vehicle velocity, road condition, and roll axis inclination compared to the 2WS. Also lane tracking and cornering behaviour of the steering system is enhanced towards the neutral steer.

Research on New Varying Gear Ratio System

A new automotive varying gear ratio system(VGRS)is introduced in this paper. Based on the analysis of foreign advanced theory in this field, a relationship among road wheel angle, steering wheel angle and vehicle speed is derived in order to achieve the optimum steering control for cornering and emergency maneuvers, whilst retaining the high-speed stability.

Hydroplaning Behavior during Steady- State Cornering Maneuvers

Hydroplaning Behavior during Steady- State Cornering Maneuvers

A low parameter tyre model for aircraft ground dynamic simulation

The work presented in this paper describes a new low parameter mathematical model representing the force and moment components generated in an aircraft tyre for use in the computer simulation of takeoff, landing and taxiing manoeuvres of an aircraft. As such the problems addressed fall in the area of ground vehicle dynamics and the modelling of the tyre presents similar challenges to those involved in modelling automotive tyres, albeit on a much larger scale in terms of the size and the loads on the tyre.The model has been implemented in the Matlab/Simulink environment and designed to run initially with aircraft models defined by the industry standard multi-body systems program MSC.ADAMSTM.An overview is provided of current automotive and aircraft tyre models along with a critique of the application and capabilities of these existing models for aircraft simulation. The need for a model which can be used to fit the limited range of data available for aircraft tyres, compared with automotive tyres, is also discussed.The proposed low parameter tyre model (LPTM) uses a small set of model parameters that can be obtained without recourse to special software and can be easily manipulated to fit the model to available tyre test data. The model has been exercised and compared with two existing tyre models, using a multi-body computer model of a tyre test machine and has been shown to produce improved predictions of the important forces and moments generated in a tyre contact patch when validated against test data. The evaluation at this stage is related to the tyre characteristics needed to simulate vehicle braking and cornering manoeuvres and the validation is against available test data for the lateral force and aligning moment arising due to slip angle.

Asymptotic sideslip angle and yaw rate decoupling control in four-wheel steering vehicles

This paper shows that, for a four-wheel steering vehicle, a proportional-integral (PI) active front steering control and a PI active rear steering control from the yaw rate error together with an additive feedforward reference signal for the vehicle sideslip angle can asymptotically decouple the lateral velocity and the yaw rate dynamics; that is the control can set arbitrary steady state values for lateral speed and yaw rate at any longitudinal speed. Moreover, the PI controls can suppress oscillatory behaviours by assigning real stable eigenvalues to a widely used linearised model of the vehicle steering dynamics for any value of longitudinal speed in understeering vehicles. In particular, the four PI control parameters are explicitly expressed in terms of the three real eigenvalues to be assigned. No lateral acceleration and no lateral speed measurements are required. The controlled system maintains the well-known advantages of both front and rear active steering controls: higher controllability, enlarged bandwidth for the yaw rate dynamics, suppressed resonances, new stable cornering manoeuvres and improved manoeuvrability. In particular, zero lateral speed may be asymptotically achieved while controlling the yaw rate: in this case comfort is improved since the phase lag between lateral acceleration and yaw rate is reduced. Also zero yaw rate can be asymptotically achieved: in this case additional stable manoeuvres are obtained in obstacle avoidance. Several simulations, including step references and moose tests, are carried out on a standard small SUV CarSim model to explore the robustness with respect to unmodelled effects such as combined lateral and longitudinal tyre forces, pitch, roll and driver dynamics. The simulations confirm the decoupling between the lateral velocity and the yaw rate and show the advantages obtained by the proposed control: reduced lateral speed or reduced yaw rate, suppressed oscillations and new stable manoeuvres.