A Dual-Level Lane Departure Avoidance System Based on Differential Torque

This paper presents a lane departure avoidance system which exploits differential torque delivered to the four wheels as actuation. The system is designed to avoid unsafe lane change due to drowsiness (unintentional maneuver) or inattention (intentional maneuver) and is composed by two levels. A high-level supervisor controls closure of a lateral position control loop by means of a 4-conditions switching rule; a low-level controller is in charge of regulating the vehicle lateral position to the reference value. At first, a model of the system is derived, which describes the dynamics from the control input and steering angle, which acts as a disturbance, to the lateral position. Then, the supervisor is presented and the low-level controller is tuned within the H
_∞
framework, with a gain-scheduling term that compensates for speed variations. Finally, the system is shown to be able to stabilize the system without applying excessive control action during typical intentional maneuvers and to keep the vehicle in lane during standard unintentional maneuvers with less than 0.35 m error, during straight highway driving.