Integrated longitudinal and lateral guidance of vehicles in critical high speed manoeuvres

Abstract

One of the most important and conventional manoeuvres, that is not easy to even skilled drivers, is the high-speed critical lane change on the highways. The main contribution of this study is the development of an integrated longitudinal and lateral guidance algorithm for these manoeuvres. This algorithm consists of two parts: the trajectory planning and the integrated control. In the first part, taking into account the position of the target vehicle for different accelerations, several trajectories are produced. Next, considering the dynamic capabilities of the vehicle, the most appropriate trajectory is selected. Since the proposed trajectory planning approach works algebraically, its computational cost is negligible, which is very valuable for practical implementations. In the second step, using a robust-integrated longitudinal–lateral controller, the control inputs are calculated and transmitted to the brakes, throttle and steering actuators. It should be noted that the trajectory planning and the integrated controller are based on the seven degrees of freedom model of the vehicle, and the nonlinear dynamics of the tyre and the dynamics of the brakes/throttle actuators are also taken into account. To assess the efficiency of the integrated longitudinal–lateral guidance algorithm, the full vehicle model is used in the CarSim–Simulink software. In order to have conditions closer to real applications, it is assumed that the yaw rate and the longitudinal and lateral accelerations of the vehicle are noisy, and the longitudinal and lateral velocities are predicted using the same signals. Obtained results for the critical collision avoidance manoeuvres confirm the effectiveness of the proposed planned trajectory and the good performance of the combined control method. In addition, the results indicate that the integrated control is robust against the variation of friction coefficient and unmodelled dynamics while maintaining the vehicle stability.