https://hal.archives-ouvertes.fr/hal-00849264/document

Estimation of vehicle sideslip, tire force and wheel cornering stiffness

The principal concerns in driving safety with standard vehicles or cybercars are understanding and preventing risky situations. A close examination of accident data reveals that losing control of the vehicle is the main reason for most car accidents. To help to prevent such accidents, vehicle-control systems may be used, which require certain input data concerning vehicle-dynamic parameters and vehicle-road interaction. Unfortunately, some fundamental parameters, like tire-road forces and sideslip angle are difficult to measure in a car, for both technical and economic reasons. Therefore, this study presents a dynamic modeling and observation method to estimate these variables. One of the major contributions of this study, with respect to our previous work and to the largest literature in the field of the lateral dynamic estimation, is the fact that lateral tire force at each wheel is discussed in details. To address system nonlinearities and unmodeled dynamics, two observers derived from extended and unscented Kalman filtering techniques are proposed and compared. The estimation process method is based on the dynamic response of a vehicle instrumented with available and potentially integrable sensors. Performances are tested using an experimental car. Experimental results demonstrate the ability of this approach to provide accurate estimations, and show its practical potential as a low-cost solution for calculating lateral tire forces and sideslip angle.

Onboard Real-Time Estimation of Vehicle Lateral Tire–Road Forces and Sideslip Angle

https://hal.archives-ouvertes.fr/hal-00759487/document

Integrated vehicle dynamics control via coordination of active front steering and rear braking

In this paper, the modeling of steer-by-wire (SbW) systems is further studied, and a sliding mode control scheme for the SbW systems with uncertain dynamics is developed. It is shown that an SbW system, from the steering motor to the steered front wheels, is equivalent to a second-order system. A sliding mode controller can then be designed based on the bound information of uncertain system parameters, uncertain self-aligning torque, and uncertain torque pulsation disturbances, in the sense that not only the strong robustness with respect to large and nonlinear system uncertainties can be obtained but also the front-wheel steering angle can converge to the handwheel reference angle asymptotically. Both the simulation and experimental results are presented in support of the excellent performance and effectiveness of the proposed scheme.

Robust sliding mode control for Steer-by-Wire systems with AC motors in road vehicles

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.

/pdf/stabilizing-vehicle-lateral-dynamics-with-considerations-of-3gai8hu58h.pdf

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

The motion of a vehicle is governed by the forces generated between the tyres and the road. Knowledge of these vehicle dynamic variables is important for vehicle control systems that aim to enhance vehicle stability and passenger safety. This study introduces a new estimation process for tyre/road forces. It presents many benefits over the existing state-of-art works, within the dynamic estimation framework. One of these major contributions consists of discussing in detail the vertical and lateral tyre forces at each tyre. The proposed method is based on the dynamic response of a vehicle instrumented with potentially integrated sensors. The estimation process is separated into two principal blocks. The role of the first block is to estimate vertical tyre forces, whereas in the second block two observers are proposed and compared for the estimation of lateral tyre/road forces. The different observers are based on a prediction/estimation Kalman filter. The performance of this concept is tested and compared with real experimental data using a laboratory car. Experimental results show that the proposed approach is a promising technique to provide accurate estimation. Thus, it can be considered as a practical low-cost solution for calculating vertical and lateral tyre/road forces.

Observers for vehicle tyre/road forces estimation: experimental validation

This paper proposes a new estimation process to estimate tire–road forces, sideslip angle and wheel cornering stiffness. This method uses measurements from currently–available standard sensors. The estimation process is separated into two blocks: the first block contains an observer whose principal role is to calculate tire–road forces without a descriptive force model, while in the second block an observer estimates sideslip angle and cornering stiffness with an adaptive tire-force model. The different observers are based on an Extended Kalman Filter method. Concerning the vehicle model, for observability reasons, the rear longitudinal forces are neglected relative to the front longitudinal forces. The estimation process was applied and compared to real experimental data, notably wheel force measurements. Experimental results show the accuracy and potential of the estimation process, and a limitation in the estimation of the cornering stiffness.

Experimental evaluation of observers for tire–road forces, sideslip angle and wheel cornering stiffness

http://www.gipsa-lab.grenoble-inp.fr/~moustapha.doumiati/IFAC08.pdf

An Estimation Process for Vehicle Wheel-Ground Contact Normal Forces

This paper proposes a new process for the estimation of tire-road forces and vehicle sideslip angle. The method strictly uses measurements from sensors potentially integrable or already integrated in recent car (yaw rate, longitudinal/lateral accelerations, steering angle and angular wheel velocities). The estimation process is based on two blocks in series: the first block contains a sliding-mode observer whose principal role is to calculate tire-road forces, while in the second block an extended Kalman filter estimates sideslip angle and cornering stiffness. More specifically, this study proposes an adaptive tire-force model that takes variations in road friction into account. The paper also presents a study of convergence for the sliding-mode observer. The estimation process was applied and compared to real experimental data, in particular wheel force measurements. Experimental results show the accuracy and potential of the estimation process.

Guillaume Baffet

Papers

Estimation of vehicle sideslip, tire force and wheel cornering stiffness

Observers for vehicle tyre/road forces estimation: experimental validation

Experimental evaluation of observers for tire–road forces, sideslip angle and wheel cornering stiffness

An Estimation Process for Vehicle Wheel-Ground Contact Normal Forces

Experimental evaluation of a sliding mode observer for tire-road forces and an extended Kalman filter for vehicle sideslip angle