Rear Wheel Steering Dynamics Compared to Front Steering

1990 ◽  
Vol 112 (1) ◽  
pp. 88-93 ◽  
Author(s):  
J. C. Whitehead
Keyword(s):  
High Speed ◽  
Rear Wheel ◽  
Front Wheel ◽  
Slip Angle ◽  
Vehicle Speed ◽  
Lateral Dynamics ◽  
High Speeds ◽  
Control Response ◽  
Steady State Responses ◽  
State Responses

The lateral dynamics of rear wheel steering vehicles are examined using low order linear mathematical models. The response to rear steer angle inputs differs significantly from the front wheel steering response at low speeds. However, both the transient and steady state responses become less dependent on which wheels are steered as vehicle speed increases. This fact indicates that the unusual fixed control response does not alone cause rear wheel steering vehicles to be unsafe at high speeds. The free control instability unique to rear wheel steering vehicles is analyzed using a torque input model which treats steer angle as a degree of freedom. The cause of this unstable weave mode and the stable front wheel steering weave mode is a ratio of tire slip angle to steer angle in excess of unity during high speed cornering.

The Effects of Tire Nonlinearity on Vehicle Steering Stability at High Speed

2014 ◽  
Vol 505-506 ◽  
pp. 301-309
Author(s):  
Hua Dong Xu
Keyword(s):  
High Speed ◽  
Necessary Conditions ◽  
Front Wheel ◽  
Vehicle Safety ◽  
Slip Angle ◽  
Vehicle Speed ◽  
Tire Model ◽  
Dynamics Model ◽  
Steering Angle ◽  
Yaw Rate

The steering stability of a vehicle at high speed is the urgent key problem to be solved of automobile independent development. And it is also the premise and one of the necessary conditions of vehicle safety. Considering of the effects of tire nonlinearity, a 4-DOF dynamics model for a vehicle is established. The yaw rate responses, side slip angle, carriage roll angle and front wheel steering angle with different vehicle speeds are calculated. The calculated values are then compared with the values without considering of the effects of tire nonlinearity. The simulations results show that the vehicle responses can be reflected accurately by using nonlinear tire model. With the bigger vehicle speed, the effects of tire nonlinearity on vehicle high-speed steering stability become more obvious.

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.

Test Results: Vehicle Responses to Simulated Drag Caused by Front Tire Tread Detachment — The Effect of Scrub Radius and Speed

2018 ◽  
Author(s):  
Mark W. Arndt ◽  
Stephen M. Arndt
Keyword(s):  
Lateral Displacement ◽  
Rear Wheel ◽  
Lateral Acceleration ◽  
Steering Wheel ◽  
Slip Angle ◽  
Yaw Rate ◽  
Wheel Drive ◽  
Steady State Responses ◽  
Four Wheel Drive ◽  
Left Front

The effects of reduced kingpin offset distance at the ground (scrub radius) and speed were evaluated under controlled test conditions simulating front tire tread detachment drag. While driving in a straight line at target speeds of 50, 60, or 70 mph with the steering wheel locked, the drag of a tire tread detachment was simulated by applying the left front brake with a pneumatic actuator. The test vehicle was a 2001 dual rear wheel four-wheel-drive Ford F350 pickup truck with an 11,500 lb. GVWR. The scrub radius was tested at the OEM distance of 125 mm (Δ = 0) and at reduced distances of 49 mm (Δ = −76) and 11 mm (Δ = −114). The average steady state responses at 70 mph with the OEM scrub radius were: steering torque = −24.5 in-lb; slip angle = −3.8 deg; lateral acceleration = −0.47 g; yaw rate = −8.9 deg/sec; lateral displacement after 0.75 seconds = 3.1 ft and lateral displacement after 1.5 seconds = 13.1 ft. At the OEM scrub radius, responses that increased linearly with speed included: slip angle (R2 = 0.84); lateral acceleration (R2 = 0.93); yaw rate (R2 = 0.73) and lateral displacement (R2 = 0.59 and R2 = 0.87, respectively). At the OEM scrub radius, steer torque decreased linearly with speed (R2 = 0.76) and longitudinal acceleration had no linear relationship with speed (R2 = 0.09). At 60 mph and 70 mph for both scrub radius reductions, statistically significant decreases (CI ≥ 95%) occurred in average responses of steer torque, slip angle, lateral acceleration, yaw rate, and lateral displacement. At 50 mph, reducing the OEM scrub radius to 11 mm resulted in statistically significant decreases (CI ≥ 95%) in average responses of steer torque, lateral acceleration, yaw rate and lateral displacement. At 50 mph the average slip angle response decreased (CI = 87%) when the OEM scrub radius was reduced to 11 mm.

An Active Suspension System Design for the Lateral Dynamics of a High-Speed Wheel-Rail System

1971 ◽  
Vol 93 (4) ◽  
pp. 233-241 ◽  
Author(s):  
G. N. Sarma ◽  
F. Kozin
Keyword(s):  
High Speed ◽  
Optimization Problem ◽  
Active Suspension ◽  
Analog Computer ◽  
Suspension System ◽  
High Speed Rail ◽  
Lateral Dynamics ◽  
High Speeds ◽  
Quadratic Cost ◽  
Quadratic Cost Function

Railroad cars are known to exhibit instabilities in the lateral dynamics at high speeds. To solve some of the problems of stability, an active suspension system is studied for the high-speed rail vehicle and is compared with the passive system. The vehicle control problem is formulated as an optimization problem with an integral quadratic cost function, and the feedback law thus obtained is further simplified. For the case of the truck dynamics, with external controllers, a Lyapunov function approach is taken for considering state constraints. Stability regions are obtained by analog computer simulation.

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.

Implementation of SSM to Lateral Guided Steering Vehicle With Body Fixed High-Speed Camera

2013 ◽  
Author(s):  
Yoshihiro Takita ◽  
Date Hisashi
Keyword(s):  
High Speed ◽  
Rear Wheel ◽  
Front Wheel ◽  
Dump Truck ◽  
Reverse Phase ◽  
Automated Vehicle ◽  
Steering Mechanism ◽  
And Performance ◽  
The Stability ◽  
Rotating Camera

This paper proposes an SSM (Sensor Steering Mechanism) for a lateral guided vehicle with an articulated body. Authors demonstrated a simple lateral guiding method SSM for front wheel steer type, the reverse phase four-wheel steer type and rear wheel steer type vehicles. SSM presents a stable lateral guiding performance for automated vehicle that following a straight and curved path created by a guideway. This paper proposes a simplified SSM to remove the following servo system for a rotating camera. The simplified SSM is applied to 1/25 scale articulated dump truck that was developed and discussed in the previous paper. The stability of the simplified SSM is discussed. Experimental and simulation results show stable movement and performance of the proposed method.

The Control of the Braking Stability of Active Rear Wheel Steering Vehicle Based on LQR

2013 ◽  
Vol 416-417 ◽  
pp. 909-913
Author(s):  
Qi Jia Liu ◽  
Si Zhong Chen
Keyword(s):  
Slip Rate ◽  
Linear Quadratic Regulator ◽  
Rear Wheel ◽  
Front Wheel ◽  
Slip Angle ◽  
Linear Quadratic ◽  
Wheel Slip ◽  
Side Slip Angle ◽  
Braking Distance ◽  
Lock Mode

The aim of this article is to improve the brake stability of active rear wheel steering vehicle. The optimal theory of linear quadratic regulator is used to construct a controller, and the aim of the controller is to maintain the side slip angle is zero, and the control parameter is set according to the change of velocity when braking. An antilock brake model based on the door limit of wheel slip rate is constructed. The analysis is carried on a front wheel steering vehicle, which has two kinds of unti-lock mode. Meanwhile, an active rear wheel steering vehicle with two kinds of unti-lock mode is performed, also. All tests are performed on the bisectional road. The results of analysis show that the active rear wheel steering vehicle using the anti-lock mode of four wheels independent control can give the shortest braking distance, the smaller side slip angle and the smaller deviation from the lane. So it can give more contribution to the braking safety.

Dynamic Interactions of a High-Speed Vehicle and a Distributed Discretely Supported Guideway

2010 ◽  
Vol 26 (1) ◽  
pp. N9-N16
Author(s):  
C.-Y. Hu ◽  
K.-C. Chen ◽  
J.-S. Chen
Keyword(s):  
High Speed ◽  
Integration Method ◽  
Equations Of Motion ◽  
Dynamic Interactions ◽  
Coupled Equations ◽  
Steady State Responses ◽  
Loading Modes ◽  
Rigid Supports ◽  
State Responses ◽  
High Speed Vehicle

AbstractThis study investigates the dynamic interactions between a vehicle and guideway of a high-speed ground transportation system based on maglev vehicles. The guideway is assumed to be made up of identical simply supported beams with single spans and rigid supports. The vehicle is considered to a two-dimensional vehicle model with primary and secondary suspensions. Three kinds of loading modes acting at each beam of guideway are first developed according to the locations of suspensions of vehicle. Coupled equations of motion of both vehicle and guideway in various loading modes are derived and solved by using numerical integration method. The simulations have been performed to investigate the parameters of vehicle/guideway system which may affect the steady-state responses of the vehicle and guideway.

A Sampling Moiré Method to Measure the Dynamic Shape and Strain of Rotating Tires

2013 ◽  
Vol 41 (3) ◽  
pp. 214-225 ◽  
Author(s):  
Ryoji Hanada ◽  
Masashi Miyazawa ◽  
Motoharu Fujigaki ◽  
Kosuke Simo ◽  
Yoshiharu Morimoto
Keyword(s):  
High Speed ◽  
Surface Strain ◽  
Surface Shape ◽  
Slip Angle ◽  
High Definition ◽  
Static State ◽  
High Speeds ◽  
Modeling Analysis ◽  
Moire Method ◽  
Practical Accuracy

ABSTRACT There has long been a strong desire to know the deformation and surface shape of tires rotating at high speeds, both in order to verify finite element modeling analysis results and for the design of tire construction and materials. We used the sampling Moiré method to measure sidewall deformation and surface strain of rotating tires when cornering or braking. This method takes photos simultaneously with two cameras placed at a distance from a tire sidewall with a grid sheet laid over it, allowing precision 3D rendering through analysis of these images. This enables a practical and accurate chronological measurement of deformation and surface strain in tires rotating at high speeds, something that was difficult to do until now. But owing to hardware limitations, this had only previously been done in the static state. By combining the sampling Moiré method with high-speed, high-definition cameras, it is possible to measure the time-based shape and surface strain of tires rotating at high speeds, with practical accuracy. In this paper we have made continuous, time-based measurements of surface strain when a sinusoidal slip angle is applied to the tires and measurements of changes in surface strain when enveloping a cleat.

Vehicle Motion Stability With Two Vehicle Dynamics Models

2011 ◽  
Author(s):  
Jingliang Li ◽  
Jingang Yi
Keyword(s):  
Vehicle Dynamics ◽  
Rear Wheel ◽  
Slip Angle ◽  
State Variables ◽  
Wheel Slip ◽  
Side Slip Angle ◽  
Lateral Dynamics ◽  
Vehicle Maneuver ◽  
The Stability ◽  
Dynamics Models

We present and compare vehicle maneuver stability under two vehicle dynamics models, one with the rear tire slip angle dynamics and the other with the vehicle side slip angle dynamics. Instead of using vehicle mass center side slip angle, we consider to use rear axial slip angle as one of the state variables for studying vehicle lateral dynamics. Using rear wheel slip angle as a state variable for studying vehicle dynamics has been reported in practices in industry but not rigorously studied. We analyze the new vehicle dynamics and compare the stability results with existing reported results. Both analytical and numerical results have shown that the stability region of the vehicle dynamics by using the rear slip angle is less conservative comparing with using the vehicle side slip angle.

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