Lateral and longitudinal coupling control of autonomous vehicles using adaptive integral terminal super-twisting sliding mode control

Vehicle motion control is one of the key technologies to achieve automatic vehicle driving, including lateral and longitudinal control. However, obtaining an accurate mathematical model of the vehicle is problematic because it is a complex nonlinear system and there are problems of external disturbances, model uncertainty, and parameter perturbations during the motion. For these challenges, this paper proposes an adaptive integral terminal super-twisting sliding mode control strategy based on a nonlinear disturbance observer for the vehicle’s lateral and longitudinal coordinated trajectory tracking system. External disturbances and system modeling errors are considered integrated disturbances, and a nonlinear disturbance observer compensates for their impact on control performance. An integral-type terminal sliding mode surface is designed, and introducing a global term enhances the convergence performance of the system. The controller outputs the front wheel turning angle and the longitudinal drive to control the automatic vehicle steering and regulate the vehicle speed, respectively, ensuring coupled path and speed tracking. Finally, the effectiveness of the designed strategy is validated by the co-simulation platform of Carsim and MATLAB/Simulink.