Improve Vehicle Handling Research Articles

Nonlinear adaptive sliding mode control for vehicle handling improvement via steer-by-wire

This paper proposes a nonlinear adaptive sliding mode control that aims to improve vehicle handling through a Steer-By-Wire system. The designed sliding mode control, which is insensitive to system uncertainties, offers an adaptive sliding gain to eliminate the precise determination of the bound of uncertainties. The sliding gain value is calculated using a simple adaptation algorithm that does not require extensive computational load. Achieving the improved handling characteristics requires both accurate state estimation and well-controlled steering inputs from the Steer-By-Wire system. A second order sliding mode observer provides accurate estimation of lateral and longitudinal velocities while the driver steering angle and yaw rate are available from the automotive sensors. A complete stability analysis based on Lyapunov theory has been presented to guarantee closed loop stability. The simulation results confirmed that the proposed adaptive robust controller not only improves vehicle handling performance but also reduces the chattering problem in the presence of uncertainties in tire cornering stiffness.

Studies on improving vehicle handling and lane keeping performance of closed-loop driver–vehicle system with integrated chassis control

This study proposes a new integrated robust model matching chassis controller to improve vehicle handling performance and lane keep ability. The design framework of the H ∞ controller is based on linear matrix inequalities (LMIs), which integrates active rear wheel steering control, longitudinal force compensation and active yaw moment control. To comprehensively evaluate the performance of the integrated chassis control system, a closed-loop driver–vehicle system is used. The effectiveness of the integrated controller on handling performance improvement is tested by a vehicle without driver model under a crosswind disturbance. At the same time, both the handling and lane keeping improving performance of the closed-loop driver–vehicle system is evaluated by tracking an S shape winding road. The simulation results reveal that the integrated chassis controller not only achieves preferable handling performance and stability, but also improves the vehicle lane keep ability significantly, and can alleviate the working load of the driver.

Stabilizing Vehicle Lateral Dynamics With Considerations of Parameter Uncertainties and Control Saturation Through Robust Yaw Control

This paper presents a robust yaw-moment controller design for improving vehicle handling and stability with considerations of parameter uncertainties and control saturation. The parameter uncertainties dealt with are the changes of vehicle mass and moment of inertia about the yaw axis and the variations of cornering stiffnesses. The control saturation considered is due to the physical limitations of actuators and tires. Both polytopic and norm-bounded approaches are used to describe parameter uncertainties, and a norm-bounded approach is applied to handle the saturation nonlinearity. The conditions for designing such a controller are derived as linear matrix inequalities (LMIs). A nonlinear vehicle model is utilized to validate the effectiveness of the proposed approach. The simulation results show that the designed controller can improve vehicle handling and stability, regardless of the changes in vehicle mass and moment of inertia and the variations of road surfaces and saturation limitations.

Optimisation of handling and traction in a rear wheel drive vehicle by means of magneto-rheological semi-active differential

This paper presents a semi-active differential, magneto-rheological fluid limited slip differential, which allows us to bias the torque between the driving wheels. It is based on the magneto-rheological fluid employment, by which it is possible to change, in a controlled manner, the internal friction torque and, consequently, the torque bias ratio. This device is an adaptive one and allows us to obtain an asymmetric torque distribution in order to improve vehicle handling. The device modelling and the control algorithm, realised for this activity, are described. The illustrated results highlight the advantages that are attainable regarding directional behaviour, stability, and traction.

Integrated control of wheel drive—brake torque for vehicle-handling enhancement

Wheel torque control is an effective means of improving vehicle handling and stability. Brake-based electronic stability programs which intervene in extreme situations to regulate vehicle behaviour are the most common form of wheel torque control. With the advent of advanced driveline technologies, wheel torque control can also be achieved by the differential distribution of available drive torque to all four wheels. Similarly, in combined cornering and braking manoeuvres, the applied brake input can be differentially distributed to regulate vehicle handling. This paper proposes an integrated scheme for wheel torque control that combines differential drive or brake torque distribution with the emergency braking control to regulate the vehicle yaw rate and side-slip angle. A wheel torque controller was developed using a non-linear predictive control theory, an eight-degrees-of-freedom vehicle model, and non-linear tyre models. The simulated vehicle responses show improved vehicle-handling performance.

Comparing Internal Model Control and Sliding-Mode Approaches for Vehicle Yaw Control

In this paper, the problem of vehicle yaw control using a rear active differential is investigated. The proposed control structure employs a reference generator designed to improve vehicle handling, a feedforward contribution that enhances the transient system response, and a feedback controller. Due to system uncertainties and the wide range of operating situations, which are typical of the automotive context, a robust control technique is needed to guarantee system stability. Two different robust feedback controllers, which are based on internal model control and sliding mode methodologies, respectively, are designed, and their performances are compared by means of extensive simulation tests performed using a realistic 14-degree-of-freedom (DOF) model of the considered vehicle. The obtained results show the effectiveness of the proposed control structure with both feedback controllers and highlight their respective benefits and drawbacks. The presented comparative study is a first step to devise a new mixed control strategy that is able to exploit the benefits of both the considered techniques.

Gain-scheduled integrated active steering and differential control for vehicle handling improvement

This paper presents a gain-scheduled active steering control and active differential design method to preserve vehicle stability in extreme handling situations. A new formulation of the bicycle model in which tyre slip angles, longitudinal slips and vehicle forward speed appear as varying vehicle parameters is introduced. Such a model happens to be useful in the design of vehicle dynamics controllers scheduled by vehicle parameters: after having expressed the parametric bicycle model in the parametric descriptor form, gain-scheduled active steering and differential controllers are designed to improve vehicle handling at ‘large’ driver-commanded steering angles. Simulations reveal the efficiency of the selected modelling and controller design methodology in enhancing vehicle handling capacity during cornering on roads with varying adhesion coefficient and under variable speed operation.

Analysis on Electric Power Steering System to Improve Vehicle Handling and Steering Feeling for Avoidance Maneuver

Analysis on Electric Power Steering System to Improve Vehicle Handling and Steering Feeling for Avoidance Maneuver

Vehicle Yaw Control via Second-Order Sliding-Mode Technique

The problem of vehicle yaw control is addressed in this paper using an active differential and yaw rate feedback. A reference generator, designed to improve vehicle handling, provides the desired yaw rate value to be achieved by the closed loop controller. The latter is designed using the second-order sliding mode (SOSM) methodology to guarantee robust stability in front of disturbances and model uncertainties, which are typical of the automotive context. A feedforward control contribution is also employed to enhance the transient system response. The control derivative is constructed as a discontinuous signal, attaining an SOSM on a suitably selected sliding manifold. Thus, the actual control input results in being continuous, as it is needed in the considered context. Simulations performed using a realistic nonlinear model of the considered vehicle show the effectiveness of the proposed approach.

Integrated vehicle chassis control based on direct yaw moment, active steering and active stabiliser

In order to coordinate steering, braking/traction and active stabiliser, an integrated vehicle chassis controller is proposed. The controller is realised via a main/servo-loop structure: in the main-loop, stabilising forces/moments are first calculated using robust sliding mode controller; then in the servo-loop, the stabilising forces/moments are optimally distributed to tyre control inputs, i.e. active steering and wheel torques. To reduce body roll angle and assist to track the desired yaw rate, active stabilisers are further integrated. Through open-loop and closed-loop simulations using Matlab/Simulink® and MSC CarSim®, it is verified that the controller can significantly improve vehicle handling performances and ride in comfort in the meantime.

Composite bushing having dual damping capability

A composite bushing including an outer sleeve coaxially surrounding an inner sleeve, and including an elastomeric body extending between the outer sleeve and the inner sleeve. The elastomeric body is provided with circumferentially alternating wedge sections having different physical characteristics, so as to provide a bushing having directional differences in resistance to deflection. The resiliency in a first radial direction appreciably differs from the resiliency in a second radial direction, where the second radial direction is at an angle to the first radial direction. The resulting bushing configuration can be used to attenuate vibration and noise in a vehicle, and thereby contribute to improved vehicle handling and ride comfort.

Integrated control of braking and steering for vehicle stability considering the parametric uncertainties and input constraints

A vehicle dynamics controller is designed to improve vehicle handling and stability by coordinating Active Front Steering (AFS) and differential braking with the consideration of input constraints. An uncertain integrated control model is constructed by choosing the tyre cornering stiffness and longitudinal velocity as the uncertainties. A state feedback integrated controller based on Optimal Guaranteed Cost with input Constraints (OGCC) is developed which can not only attenuate the influence of the modelling uncertainties on vehicle dynamics but also reduce the possibility of actuators' saturation. Simulations on an 8-DOF nonlinear vehicle model demonstrate the satisfying performance of the OGCC scheme.

Control and Sensor Fault-Tolerance of Vehicle Lateral Dynamics

In this paper, fault tolerant control (FTC) system is developed for lateral vehicle dynamics by combining static output feedback control and sliding mode observers for improving vehicle handling and stability under sensors faults. The system consists of three blocks: fault detection and isolation (FDI) block, a static output feedback controller block and a switcher block. The nonlinear two degrees of freedom vehicle motion (bicycle model) is described by a Takagi-Sugeno (T-S) fuzzy model. The strategy of the FDI method is based on a bank of observers, each one is constructed using sliding mode design techniques to estimate the system state vector. Thus the diagnostic signal-residuals are generated by the comparison of measured and estimated outputs and the faulty sensor is isolated. Simulations demonstrate that the vehicle maintains acceptable performance after either set of yaw rate sensor and lateral velocity sensor has failed.

On Torque Control of Vehicle Handling and Steering Feel for Avoidance Maneuver with Electric Power Steering

This paper evaluates EPS control strategies for improving vehicle handling and steering feel during high speed avoidance maneuver. Theoretical analysis of frequency response of steering angle and vehicle lateral acceleration relative to steering torque input is performed. Closed-loop simulation studies are also conducted by adopting a driver model to describe the human steering behavior. Based on the study, EPS control strategies of steering torque assistance and damping compensation are investigated. The results show the effectiveness of EPS to improve vehicle responsiveness and stability, to reduce steering effort, and to realize comfortable steering feel for high speed avoidance maneuver.

Vehicle Motion Control Issues Using Micro Electric Vehicle “NOVEL”

This article describes the scope of vehicle dynamics control application on micro-scale electric vehicle for enhancing its active safety. The use of in-wheel-motor control in various control objectives as active safety devices are stated in the paper. In the first half of the paper, the control systems for enhancing vehicle dynamics are described. The active front steering by using steer-by-wire mechanism for improving vehicle handling and stability is mainly presented. The latter half of the paper presents the control system designed for driving assist system. The lane keeping control with torque distribution strategy is described. The theoretical controller design and experimental validation are shown in the paper

Coordination of active steering, driveline, and braking for integrated vehicle dynamics control

An integrated vehicle dynamics control system which aims to improve vehicle handling and stability by coordinating active front steering (AFS) and dynamic stability control (DSC) subsystems is developed in this paper. The DSC subsystem includes driveline-based, brake-based, and driveline plus brake-based DSC subsystems. The influence of varying forward speed and lateral acceleration on the lateral vehicle dynamics is investigated first. The AFS controller, which is used to improve vehicle steerability in the low to mid-range lateral acceleration, and the DSC controller, which manages to maintain vehicle stability during extreme driving situations, are then designed by using the sliding mode control (SMC) technique and phase plane method respectively. Based on the two independently developed controllers, a rule-based integration scheme is proposed to optimize the overall vehicle performance by minimizing interactions between the two subsystems and extending functionalities of individual subsystems. Computer simulation results confirm the effectiveness of the proposed control system and the overall improvements in vehicle handling and stability.

Integrated control of front-wheel steering and front braking forces on the basis of fuzzy logic

This paper presents a free model based fuzzy controller that integrates front steering control and front braking distribution forces to improve vehicle handling and stability. Thus, the yaw rate and the sideslip angle of the vehicle are controlled to follow their target values. The main advantages of fuzzy methods are their simplicity and their good performance in controlling non-linear systems. Simulation results show the effectiveness of the proposed control system during different manoeuvres (J-turn and change lane) and driving conditions (dry pavement and snow).

Development of a new control strategy for a semi-active differential for a high-performance vehicle

Although VDC systems usually operate on the engine torque and on brake pressures [Van Zanten, A.T., Erhardt, R. and Pfaff, G., 1995, VDC, The Vehicle Dynamics Control System of Bosch. SAE Technical Paper Series, no. 950759, Esmailzadeh, E., Goodarzi, A. and Vossoughi, G.R., 2003, Optimal yaw moment control law for improved vehicle handling. Mechatronics 13.] new automotive applications try to use semi-active or active differentials in order to optimize the torque distribution on the wheels for traction maximization, driving comfort, stability, and safety of the vehicle. The system presented in the article comes from the cooperation of Ferrari S.p.A. and Politecnico di Milano in the development of a new semi-active differential. In the article, a description of the vehicle dynamic control strategy, its development, and experimental results are presented.

Fuzzy-logic applied to yaw moment control for vehicle stability

In this paper, we propose a new yaw moment control based on fuzzy logic to improve vehicle handling and stability. The advantages of fuzzy methods are their simplicity and their good performance in controlling non-linear systems. The developed controller generates the 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. The simulation results show the effectiveness of the proposed control method when the vehicle is subjected to different cornering steering manoeuvres such as change line and J-turn under different driving conditions (dry road and snow-covered).

Dynamic normal force control for vehicle stability enhancement

It is well understood that variations in normal force under the contact patch of pneumatic tyres effects the ability of that tyre to generate longitudinal and lateral forces. Normal forces self modulate when the vehicle corners, accelerates, or brakes, and its distribution, left to right and front to rear, can be affected by suspension design, anti-roll, and anti-pitch devices. This paper addresses the effectiveness of active suspension control to enhance vehicle lateral and longitudinal dynamics by modulating the normal force distribution at each corner of a vehicle. Normal force control is proposed for several scenarios including split µ roads and cornering over bumpy roads. It is shown that improved vehicle handling can result if normal force control is incorporated. Actuator and power requirements are assessed.