Improve Vehicle Handling Research Articles

Yaw moment control for vehicle stability in a crosswind

Owing to the effect of wind disturbance on its behaviour, a vehicle may not follow the desired trajectory. This paper presents a new yaw moment control based on fuzzy logic to improve vehicle handling and stability in a crosswind. The main advantages of fuzzy methods are their simplicity and their good performance to control non-linear systems. The developed controller generates a suitable yaw moment, which is obtained from the difference of the brake forces between the front wheels so that the vehicle follows the target values of the yaw rate and the sideslip angle. Simulation results show the effectiveness of the proposed control method when the vehicle is subjected to driving conditions (dry road surface and snow) and wind disturbance.

Multi-objective H ∞ optimal control for four-wheel steering vehicle based on yaw rate tracking

In this paper, a lateral controller is designed for four-wheel steering (4WS) vehicles. The linear lateral dynamics of 4WS vehicles are deduced and then analysed, aided with three-dimensional graphs. To improve vehicle handling and stability at high speed, a multiobjective H ∞ optimal control algorithm is presented, while yaw rate is the only feedback signal. Simulation shows that the sideslip angle, yaw rate, and lateral acceleration of the 4WS vehicle follow and maintain preferable characteristics. The 4WS vehicle is agile and consistent with the steering input and does not understeer excessively.

Active Comfort and Handling Improvement with a "3D" Bicycle Model

In this paper, a "3D" mathematical nonlinear bicycle model is developed, that takes into account the vertical, longitudinal and lateral motions, while neglecting the roll motion. Then, linear control oriented models are obtained by linearizing the previous model and are used to design H∞ controllers to impose ride comfort and handling. Concerning ride comfort, we aim to prove the benefits of controlled active-passive suspension compared to passive ones. With active steering we focus on the vaw disturbance attenuation and vehicle handling improvement; for this purpose, H∞ control design is compared with the well known Ackermann robust decoupling steering control. The proposed controllers are then validated in simulation using the nonlinear model.

Automotive Steering Control in a Split-µ Manoeuvre Using an Observer-Based Sliding Mode Controller

Summary In this paper a sliding mode integral action controller and sliding mode observer are used to enhance vehicle stability in a split- µ manoeuvre. Anti-lock braking systems (ABS) have become an integral part of modern cars, and they have dramatically improved vehicle handling in braking manoeuvres. However, when a vehicle attempts to brake on a surface with uneven friction coefficient such as on wet or icy roads, a so-called split- µ scenario, the yaw moment generated by the asymmetric braking can prove demanding for an inexperienced driver. The controller presented hereworks in conjunction with a conventional ABS system to provide safe and effective braking through steer-by-wire. This paper extends previous state-feedback work by only using certain measurable quantities in the controller, estimating further signals by employing an observer.

221 路面から4輪が受ける動的3軸方向力を用いた車両運動安定化システム(ビークル・ダイナミクス,OS-2:運動と振動のモデリングと制御(1))

This paper proposes a control system using dynamic forces between 4 wheels and road to improve vehicle handling and stability under severe driving conditions using yaw moment generated from the distriution of braking forces of four tyres (DYC). First, we propose a nonlinear 4-wheels vehicle model. And the longitudinal motion, the lateral motion, the yawing motion, and the load shift are taken into consideration in the proposed analysis model. In addition, nonlinear caracteristics of tyre are also taken into consideration by Magic Formula function. Then we design control system using model matching control method. In order to confirm the effectiveness of this system, the computer simulation are conducted.

Development and experimental evaluation of translational semi-active dampers on a high mobility off-road vehicle

This paper describes the further development and experimental evaluation of two-state semi-active translational dampers on a 6×6 high mobility off-road vehicle. As only ride comfort was enhanced during previous work, the low-speed damping characteristics on the semi-active damper was increased in order to improve vehicle handling. The existing passive dampers, as normally fitted to the test vehicle, were modified to the semi-active configuration by adding a bypass assembly and a controllable valve. Experimental work included driving over various repeatable surfaces at different speeds and executing severe lane change manoeuvres. Results indicated that both handling and ride comfort were improved when selecting the semi-active configuration.

Surface Shape Optimization of Tire Pattern by Optimality Criteria

Abstract A new optimization procedure to design the surface shape of tire patterns is proposed in which the optimality criteria is combined with finite element method. The effectiveness of this new procedure to control tread-element contact pressure distribution was verified by building and testing the rubber block samples. The objective function was the pressure uniformity on the block and the constraint was to keep the contact area in the optimization process. The shape of the optimized surface was round at the edges and concave at the center where the pressure was large in the flat surface block. The pressure of the block with the optimized surface became uniform and the friction coefficient increased 10% on dry compared with the flat surface block. Furthermore, this procedure was applied to complicated block shapes such as tire patterns and it was verified that the optimized surface effectively improved vehicle handling, riding comfort and irregular wear.

Robust Fuzzy-Optimal Four Wheels Steering Nonlinear Controller

Nonlinear single track vehicle model is investigated. The nonlinearity in the vehicle model reduces vehicle stability significantly. Four wheel steering nonlinear controller is developed to utilize the responsiveness and relaxed stability of the rear wheel steering in conjunction with front wheel steering using fuzzy logic robust controller based on Sugeno fuzzy model. Results show that four wheel steering improves vehicle handling in negotiating a turn significantly. Comparison between this fuzzy logic controller and continuos gain scheduling shows the similar performance. The resulting controller improves vehicle handling in the presence of noise, steering linkage play, and variation in vehicle parameters.

Optimal yaw moment control law for improved vehicle handling

A new optimal control law for direct yaw moment control, to improve the vehicle handling, is developed. Although, this can be considered as part of a multi-layer system, for the traction control of a motorized wheels electric vehicle, but the results of this study are quite general and can be applied to other types of vehicles. The dynamic model of the vehicle system is initially developed and, using the well-known optimal control theory, an optimal controller is designed. Two different versions of control laws are considered here and the performance of each version of the control law is compared with the other one. The numerical simulation of the vehicle handling with and without the use of the optimal yaw moment controller, and assuming a comprehensive non-linear vehicle dynamic model, has been carried out. Simulation results obtained indicate that considerable improvements in the vehicle handling can be achieved whenever the vehicle is governed by the optimal yaw moment control.

Vehicle Handling Improvement by Active Steering

Summary This paper first analyses some stability aspects of vehicle lateral motion, then a coprime factors and linear fractional transformations (LFT) based feedforward and feedback H 8 control for vehicle handling improvement is presented. The control synthesis procedure uses a linear vehicle model which includes the yaw motion and disturbance input with speed and road adhesion variations. The synthesis procedure allows the separate processing of the driver reference signal and robust stabilization problem or disturbance rejection. The control action is applied as an additional steering angle, by combination of the driver input and feedback of the yaw rate. The synthesized controller is tested for different speeds and road conditions on a nonlinear model in both disturbance rejection and driver imposed yaw reference tracking maneuvers.

Study on integrated control of active front steer angle and direct yaw moment

This study proposes a control system to improve vehicle handling and stability under severe driving conditions by actively controlling the front steering angle and the distribution of braking forces on four tires. With the application of a model-matching control technique, this proposed control system makes the performance of the actual vehicle model follow that of an ideal vehicle model with consideration of nonlinearity of tire characteristics. Finally, this paper investigates the effectiveness of control system during the following conditions: braked cornering, lane change and side wind disturbance.

Feedforward and Feedback Control for Vehicle Handling Improvement by Active Steering

This paper presents coprime factors and linear fractional transformations (LFT) based feedforward and feedback H∞ control for vehicle handling improvement. Control synthesis uses a linear vehicle model which includes the yaw motion and disturbance input with speed and road adhesion variations. The synthesis procedure allows the separate processing of the reference signal and robust stabilization problem or disturbance rejection. The control action is applied as an additional steering angle, by combination of the driver input and feedback of the yaw rate. The synthesized controller is tested for different speeds and road conditions on a nonlinear model in both disturbance rejection and driver imposed yaw reference tracking maneuvers.

Vehicle Stabilization by the Vehicle Dynamics Control System ESP

The problem of the driver losing control of his car will be explained and the goal for the vehicle dynamics control system ESP (Electronic Stability Erogram, alternatively called VDC) will be formulated. It will be shown, that the vehicle slip angle is a crucial indicator for the stability of the automobile. Since the complete vehicle state is not readily available, estimation algorithms are used to supply the control algorithms with sufficient information. The slip angle is controlled by a yaw moment generated by individual wheel slip control. It will be shown, that ESP can significantly improve vehicle handling in extreme maneuvers.

Improvement of Road Vehicle Handling by Mechatronic Systems

Starting with ABS (Antilock Brake System) which was introduced on the automotive market in 1978 the initial step towards mechatronic systems dealing with vehicle dynamics was taken. Other systems like suspension control and four wheel steering control to improve vehicle handling followed in the early part ofthe 1980 decade. These systems were initially designed as open loop controllers for the lateral vehicle motion. A frrst approach towards closed loop control of the lateral vehicle motion was in combination with four wheel steering using a yaw velocity sensor in the frrst halve of the 1990 decade. Other closed loop systems like ESP (Electronic Stability Program) and DYC (Direct Yaw Control) followed in 1995 and 1997 respectively. ESP has become very popular since 1998 because of its low cost and high efficiency in limit handling maneuvers.

The benefits of road friction feed forward control for improved vehicle handling

Vehicle stability augmentation has been refined over many years, and currently there are commercial systems that control right/left braking and throttle to create vehicles that remain controlled when road conditions are very poor. There have also been associated efforts to measure or estimate the road surface condition to provide additional information for the stability augmentation systems. Here, a road surface estimation is used as a feed forward signal in conjunction with a stability enhancement system designed principally to react to steering commands. It is shown that the road surface estimate offers significant improvement over the stability controller without road surface information. It is shown that even with estimate errors and time delays, it is still beneficial to use the road surface estimate.

Application of Aerodynamic Actuators to Improve Vehicle Handling

This exploratory study considers applications of active aerodynamic devices for suppressing parasitic motion and for improving the response of vehicles to steering, within the scope of the linear dynamic behaviour. A three DOF linear model is chosen to describe the side slip, yaw and roll motion of a baseline front-wheel steered vehicle. The improvements in performance of the base-line vehicle that are achievable by the application of direct yaw and roll moments are determined when either an open loop control pre-filter or a state feedback control law based on LQR design is applied. Unlike the former control, the state feedback control is unable to make the body side-slip angle vanish. The feedback control performance of each of the two moment actuators has been examined separately and then jointly. The advantages of combining the open loop and feedback dual actuator configurations are demonstrated using the two-degree of freedom control scheme. It is found that the scheme yields a spectacular performance but demands unreasonably large moments from the actuators in the context of available aerodynamic forces. On the other hand, the demand on direct yaw and roll moment of actuators is modest when the actuators are controlled using the LQR feedback only and if the control design is used to track a desired yaw rate trajectory and simultaneously to reduce the parasitic rolling motion. Significant improvements in handling and dynamic stability of a base-line vehicle can be achieved by aerodynamically generated direct yaw and roll actuator moments provided the target control performance is reasonable. The configurations of aerodynamic actuators considered are feasible for improving vehicle handling in cornering on motorways but more work remains to be done to explore alternative aerodynamic configurations that give rise to less side effects and higher lift coefficients.

Steer-by-Wire-Oriented Steering System Design: Concept and Examination

SUMMARYDiscussions on the steer-by-wire-oriented steering system design are now focused on the methods for determination of a steering system gain and dynamics aimed to improve vehicle handling qualities, the optimum steering system gain, and the effects of artificial steering torque fed to the driver as kinesthetic information through the steering wheel. The results of studying these topics have recently been verified by a series of tests with a fixed-base driving simulator.

Four-Wheel Independent Steering (4WIS) System for Vehicle Handling Improvement by Active Rear Toe Control.

This paper presents the enhancement of vehicle cornering stability through active and independent rear toe control. Because toe change in the rear wheel during high-speed turning maneuvers is an important factor influencing vehicle stability, the active rear toe control vehicle such as four-wheel steering(4WS)vehicle has been developed in past years. Especially, a toe in the rear outer wheel(bump side)plays a dominant role in cornering, hence the four-wheel independent steering(4WIS)system which selectively or simultaneously controls the rear wheels, could be suggested. In the proposed system, there are some advantages not only in energy consumption, but also in control responsiveness. The independent rear steering strategy using rear toe control scheme has been developed and its performances were evaluated with the ADAMS full vehicle model. Also, 4WIS system is compared to the conventional four-wheel steering(4WS)system through the step input and the double lane change test. The simulation results of 4WIS system show the similar handling performance with those of the conventional 4WS system and the total consumed power to control the system in rear wheels was much reduced.

Integrated Robust Control of Active Rear Wheel Steering and Direct Yaw Moment Control

An integrated control system of active rear wheel steering (ARS) and direct yaw moment control (DYC) is presented in this paper. Because of the tire nonlinearity that is mainly due to the saturation of cornering forces, vehicle handling performance is limited to a certain extent only by steering control. The direct yaw moment control using braking and/or driving forces is effective not only in linear but also nonlinear ranges of tire friction circle. The proposed control system based on a model matching controller is verified to improve vehicle handling and stability.

Integrated Robust Control of Active Rear Wheel Steering and Direct Yaw Moment Control

Abstract An integrated control system of active rear wheel steering (ARS) and direct yaw moment control (DYC) is presented in this paper. Because of the tire nonlinearity that is mainly due to the saturation of cornering forces, vehicle handling performance is limited to a certain extent only by steering control. The direct yaw moment control using braking and/or driving forces is effective not only in linear but also nonlinear ranges of tire friction circle. The proposed control system based on a model matching controller is verified to improve vehicle handling and stability.