Measurement of Vehicle Handling by Tethered Testing

1969 ◽  
Vol 184 (1) ◽  
pp. 219-231 ◽  
Author(s):  
N. F. Barter
Keyword(s):  
Steady State ◽  
Front Wheel ◽  
Lateral Acceleration ◽  
Slip Angle ◽  
Vehicle Stability ◽  
Centrifugal Acceleration ◽  
Vehicle Handling ◽  
Centre Of Gravity ◽  
Stability Derivatives ◽  
Method Of Measurement

The technique of tethered testing is introduced as a method of measurement of vehicle steady state handling, where the vehicle under test is attached to a large parent vehicle by means of an arm attached at its centre of gravity, and the tyre forces, which in the normal free vehicle situation produce a centrifugal acceleration, are simply reacted by this arm. The tethered testing rig built at M.I.R.A. is described. It is shown that the concept of tethered testing leads naturally to the idea of describing vehicle steady state handling by means of a quantity which depends only on lateral acceleration, and suitable quantities are shown to be static margin and the slope of a curve of mean front wheel steer angle against vehicle slip angle. These quantities are defined and their derivation in terms of vehicle stability derivatives is outlined in an appendix. Some examples of tethered test measurements are given in the form of plots of static margin against lateral acceleration, and a tentative set of criteria for good steady state handling is given in terms of the behaviour of static margin with lateral acceleration.

Enhanced braking and steering yaw motion controllers with a non-linear observer for improved vehicle stability

2008 ◽  
Vol 222 (3) ◽  
pp. 293-304 ◽  
Author(s):  
Jeonghoon Song
Keyword(s):  
Load Transfer ◽  
Rear Wheel ◽  
Front Wheel ◽  
Driver Model ◽  
Lateral Acceleration ◽  
Slip Angle ◽  
Vehicle Stability ◽  
Motion Controller ◽  
Non Linear ◽  
Linear Observer

This study proposes two enhanced yaw motion controllers that are modified versions of a braking yaw motion controller (BYMC) and a steering yaw motion controller (SYMC). A BYMC uses an inner rear-wheel braking pressure controller, while an SYMC uses a rear-wheel steering controller. However, neither device can entirely ensure the safety of a vehicle because of the load transfer from the rear to front wheels during braking. Therefore, an enhanced braking yaw motion controller (EBYMC) and an enhanced steering yaw motion controller (ESYMC) are developed, which contain additional outer front-wheel controllers. The performances of the EBYMC and ESYMC are evaluated for various road conditions and steering inputs. They reduce the slip angle and eliminate variation in the lateral acceleration, which increase the controllability, stability, and comfort of the vehicle. A non-linear observer and driver model also produce satisfactory results.

Limit Steady State Vehicle Handling

1987 ◽  
Vol 201 (4) ◽  
pp. 281-291 ◽  
Author(s):  
J C Dixon
Keyword(s):  
Steady State ◽  
Load Transfer ◽  
Limit State ◽  
Lateral Acceleration ◽  
Design Parameters ◽  
Centre Of Mass ◽  
Vehicle Handling ◽  
Specific Proposal ◽  
Turning Radius ◽  
Mass Position

Previously, limit steady state handling has always been restricted to the qualitative statement that a vehicle has final understeer or final oversteer; it cannot be analysed by the conventional understeer gradient concept. A specific proposal is made for quantification of final understeer or oversteer. This is called the understeer number, and is defned by Nu = (ArAf)-1, where Af and Ar are the lateral acceleration capabilities of the front and rear axles. Thus Nu is non-dimensional, is zero for a notional final neutral vehicle, positive for final understeer and negative for final oversteer. A typical value is 0.150 (rear drive) or 0.220 (front). The various design parameters that influence the understeer number are investigated, and equations are obtained and quantified, including centre of mass position, lateral load transfer distribution, longitudinal load transfer, traction, the components of aerodynamic forces and moments, the effect of non-free differentials and the effect of load increments. The effect of turning radius and slopes is also investigated. Thus the limit state of handling is subject to a quantitative assessment, showing the degree of a vehicle's commitment to final understeer or oversteer.

Analysis of Vehicle Lateral Response During Regenerative Braking in a Turn

2016 ◽  
Author(s):  
C. S. Nanda Kumar ◽  
Shankar C. Subramanian
Keyword(s):  
Rear Wheel ◽  
Front Wheel ◽  
Lateral Acceleration ◽  
Regenerative Braking ◽  
Steering Wheel ◽  
Slip Angle ◽  
Lateral Response ◽  
Wheel Drive ◽  
Reference Track ◽  
The Impact

Regenerative braking is applied only at the driven wheels in electric and hybrid vehicles. The presence of brake force only at the driven wheels reduces the lateral traction limit of the corresponding tires. This impacts the vehicle lateral response, particularly while applying the regenerative brake in a turn. In this paper, a detailed study was made on the impact of regenerative brake on the vehicle lateral response in front wheel drive and rear wheel drive configurations on dry and wet asphalt road surfaces. Simulations were done considering a typical set of vehicle parameters with the IPG CarMaker® software for different drive conditions and braking configurations along the same reference track. The steering wheel angle, yaw rate, lateral acceleration, vehicle slip angle, and tire forces were obtained. Further, they were compared against the conventional all wheel friction brake configuration. The regenerative braking configuration that had the most impact on vehicle lateral response was analyzed and response variations were quantified.

Sensitivity Analysis of Vehicle Parameters on Dynamic Stability and Vehicle Handling Performance

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
M.M.M. Salem ◽  
Mina. M Ibrahim ◽  
M.A. Mourad ◽  
K.A. Abd El-Gwwad
Keyword(s):  
Dynamic Stability ◽  
Degrees Of Freedom ◽  
Front Wheel ◽  
Lateral Acceleration ◽  
Vehicle Speed ◽  
Vehicle Dynamic ◽  
Vehicle Handling ◽  
Bicycle Model ◽  
State Region ◽  
The Mathematical Model

In this paper, a linear two degrees of freedom linear bicycle model is proposed to investigate the vehicle handling criterion. The study is based on simulation developed using MATLAB / Simulink to predict the vehicle dynamic stability. Steering angle is given as an input to the mathematical model for various vehicular manoeuvres. This model is validated using a step input which is adjusted to give 0.3g lateral acceleration. The system model is simulated under a typical front wheel steering to examine the highway vehicle prediction output within its manoeuvre. This input is also adjusted to keep lateral acceleration value in steady state region. It is found that changing the vehicle center of gravity (CG) position, vehicle mass, tire cornering stiffness and vehicle speed all have a significant influence on the vehicle dynamic stability.

Influence of Front Wheel Alignment Parameters on Handling Stability of Vehicle Based on Joint Simulation

2014 ◽  
Vol 716-717 ◽  
pp. 832-836
Author(s):  
Hui Wang ◽  
Xiao Zhi Wang
Keyword(s):  
Steering System ◽  
Front Wheel ◽  
Front Axle ◽  
Lateral Acceleration ◽  
Steering Wheel ◽  
Initial Alignment ◽  
Vehicle Handling ◽  
Joint Simulation ◽  
Hydraulic Steering ◽  
Lane Change Test

This paper uses AMESim software to establish simulation model of SGA170 mine truck full hydraulic steering system, and validates the correctness of the proposed model. Through the joint simulation, vehicle steady circular test, double lane change test and steering wheel angle input test are verified. By changing the initial alignment parameters of front axle, vehicle handling performance are tested through the same simulation test, and yaw velocity, and the curves of lateral acceleration and vehicle roll angle describing vehicle handling stability are obtained, which provides a reference for the design and improvement of the similar mine truck selection.

Full Vehicle Handling Prediction and Correlation

2014 ◽  
Vol 945-949 ◽  
pp. 53-60
Author(s):  
Xiao Long Zhang ◽  
Rong Guo
Keyword(s):  
Dynamic Performance ◽  
Time History ◽  
Lateral Acceleration ◽  
Steering Wheel ◽  
Slip Angle ◽  
Vehicle Handling ◽  
Full Vehicle ◽  
History Of ◽  
Steering Torque ◽  
Flexible Component

Accurate full vehicle handling prediction can be used to evaluate the vehicle dynamic performance. This paper presents the prediction and correlation of full vehicle handling with ADAMS/Car. After building the initial model, major flexible component, steering friction and damping was introduced to optimize the model that makes the model much more accurate. The model will be used to run four major vehicle handling events; the predicted results are compared with measured data. The correlation includes time history of steering wheel angle, steering torque, lateral acceleration, side slip angle, roll, yaw etc. It also includes the derivates such as understeer gradients, steering gradients, side slip gradients, roll gradients etc. It is shown that good correlations are obtained in handling;

Tire Transient Lateral Force Generation: Characterization and Contribution to Vehicle Handling Performance

2014 ◽  
Vol 42 (4) ◽  
pp. 263-289
Author(s):  
Terence Wei ◽  
Hans R. Dorfi
Keyword(s):  
Steady State ◽  
Measurement Methods ◽  
Force Generation ◽  
Slip Angle ◽  
Small Contribution ◽  
Force Response ◽  
Vehicle Handling ◽  
Handling Performance ◽  
State Force ◽  
Transient Force

ABSTRACT Tire force generation is often described in terms of a steady-state force response, which is considered independent of time and a function of the kinematic roll conditions such as slip angle. In addition to the steady-state response, the tire also exhibits a time-dependent transient force response, which in the lateral direction is a delay in the buildup of the cornering force. This delay is often characterized by the so-called tire relaxation length (RL) (Ly), a tire performance characteristic often thought to have a strong effect on handling performance. The definition and mechanistic interpretation of tire lateral RL is discussed, and different methods for measuring and interpreting lateral RL are compared. The measurement methods include different types of flat belt as well as static stiffness measurements. Because of different levels of measurement uncertainty, the repeatability and benefits of the different measurement methods are demonstrated. To determine the effect of including tire transient response in tire/vehicle system models, a handling study was performed. The study included a series of CarSim handling simulations with tires of different transient force and moment characteristics as well as an analysis of outdoor subjective handling ratings. The results show the relatively small contribution of tire transient characteristics to vehicle handling performance compared with the tire steady-state force response.

Vehicle rollover warning system based on TTR method with Inertial Measurement

2021 ◽  
Author(s):  
Mengmeng Wang ◽  
Jinhao Liu ◽  
Hongye Zhang ◽  
Linjie Gan ◽  
Xiangbo Xu ◽  
...  
Keyword(s):  
Steady State ◽  
Load Transfer ◽  
Warning System ◽  
Front Wheel ◽  
Roll Angle ◽  
Lateral Acceleration ◽  
Vehicle Speed ◽  
Matlab Simulink ◽  
Vehicle Rollover ◽  
Rollover Warning

Abstract This paper presents a theoretical and experimental study conducted on the rollover warning of wheeled off-road operating vehicles. The time to rollover (TTR) warning algorithm was studied with real-time vehicle roll angle and roll angle velocity as the input variables, and lateral load transfer ratio (LTR) was used as the rollover determination index. Subsequently, a vehicle dynamics model was built using CarSim software, and a warning algorithm was established in the MATLAB/Simulink environment. The rollover joint simulation in CarSim and MATLAB/Simulink was conducted under typical working conditions. Finally, combined with inertial measurements, a rollover warning system was independently developed. In addition, the rollover warning system was installed on a light forest firefighting truck to verify the feasibility of the system via a real vehicle experiment, and the law of vehicle rollover motion was also studied. The serpentine experiment and steady-state rotation experiment were conducted. The experimental results showed that at identical front-wheel steering angles, the roll angle and lateral acceleration increased with an increase in the vehicle speed. Furthermore, for identical vehicle speeds, the roll angle and lateral acceleration of the vehicle increased with an increase in the front-wheel steering angle. The dangerous vehicle speed was 50 km/h in the serpentine condition and 40 km/h in the steady-state rotation condition. The risk trend and alarm signal obtained by the rollover warning system were consistent with the actual situation. Thus, this can assist drivers in judging the rollover risk and effectively improve the active safety of special vehicles. Furthermore, it also provides a reference for further research on active rollover control technology of special vehicles.

Paper 5: Vehicle Behaviour in Combined Cornering and Braking

1968 ◽  
Vol 183 (8) ◽  
pp. 19-34 ◽  
Author(s):  
A. J. Harris ◽  
B. S. Riley
Keyword(s):  
Steady State ◽  
Load Transfer ◽  
Equations Of Motion ◽  
Rear Wheel ◽  
Front Wheel ◽  
Slip Angle ◽  
Vehicle Model ◽  
Force Coefficient ◽  
Wheeled Vehicle ◽  
Non Linear

This paper considers first the steady-state motions of a simple two-wheeled vehicle model having non-linear sideway force relationships with respect to tyre slip angle. It is shown that any steady-state conditions may be represented and their solutions found by simple graphical means, using only the non-linear curves. The curves can be modified to take into account the influence of vehicle parameters such as compliance, roll steer, wheel camber, and load transfer. Stability boundaries are discussed and criteria are presented showing that stability of the motion depends only on the slopes of the curves and the speed of the manoeuvre at the cornering acceleration being considered. A more involved four-wheeled vehicle model is then considered when subjected to braking while cornering on a fixed radius path of 45·8 m on a wet Bridport macadam surface. Actual sideway force–slip angle curves for combined braking and cornering, as presented by Holmes and Stone (see reference (6))†, are used with the equations of motion derived for the quasi-steady state conditions of decelerating while cornering. The effects of front wheel steered angle and body slip angle on the forces necessary for the manoeuvre are also considered. An envelope of maximum cornering acceleration at various braking decelerations is presented. This shows that for those particular conditions up to about 70 per cent of maximum deceleration may be obtained before there is more than about 10 per cent loss in maximum cornering ability. Outside the envelope the vehicle fails to maintain the path. At the lower deceleration the car spins, and at higher values it continues tangentially to its original path without spinning. It is also shown that the total sideway force–slip angle curve for a pair of front or rear wheels, when one or both wheels have a high braking force coefficient, can have a sharp peak, such that for small increase in slip angle there is a rapid fall in sideway force. It is suggested that this is why a rear wheel skid which occurs while braking and cornering is more difficult to correct than one which occurs when only cornering.

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