An integrated longitudinal and lateral control strategy for low friction conditions of tractor semi-trailer vehicles

Driving articulated heavy vehicles (AHVs) at high-speeds is complicated due to their unstable motion modes. Accelerated motion trajectory planning is essential for collision avoidance (CA) maneuver in dynamic traffic conditions. This article proposes a new trajectory planning strategy for collision-free and feasible maneuver of a tractor semi-trailer truck in critical conditions in which the truck and the obstacles are moving with non-constant speeds. For this purpose, a convenient optimal practical trajectory for different tire-road frictional conditions, the physical limitation of the tires, and the stability status of the truck is suggested. The main strategy of the trajectory planning is to increase the capability of the control system using the longitudinal and lateral forces of the tires. A robust integrated controller is then proposed to control the longitudinal and lateral directions of the AHV of which the longitudinal controller is configured to track the longitudinal position considering the vehicle stability conditions, and the lateral controller is organized to follow the yaw rate, the lateral position of the tractor, and the articulation angle. The results show that the proposed novel strategy with integrated longitudinal and lateral control has convenient performance in high-speed and low friction conditions as well as normal situations.