Nonlinear integrated control with friction estimation for automatic lane change on the highways

Abstract

A vehicle is a highly nonlinear dynamical system with high degrees of freedom. There are also very strong couplings between the longitudinal and lateral dynamics. Therefore, the simultaneous longitudinal and lateral motion control in different road conditions is a challenging problem. This paper presents an integrated adaptive control for longitudinal and lateral vehicle guidance on the highways. The contribution of this work is the design of a robust integrated controller that can handle tyre-road friction changes with low computational cost The proposed controller can adapt to the variations of tyre and road specifications. The strength of this method is that without the use of complex models, the nonlinear tyre dynamic is considered in the design of the controller. Therefore, despite the consideration of a comprehensive nonlinear vehicle dynamic model and the ability to adapt to changes in tyre and road specifications, the computational cost of the algorithm is very small. Besides, due to the controller robustness, there are no concerns about uncertainties. To validate the proposed algorithm, a full vehicle model in CarSim software is used. In obtained results, it is assumed that the yaw rate, longitudinal and lateral acceleration signals are available and have noises. The estimation of longitudinal and lateral velocities and other vehicle states has been done using these signals. Results for different road conditions as well as various vehicle movement modes confirm that tracking of longitudinal and lateral positions has been carried out with high precision. Besides, the results show that the proposed integrated control guarantees the stability of the vehicle, it will manage the tyre-road friction changes well, and also it is resistant to unmodeled uncertainties.