Stability-Guaranteed Model Predictive Path Tracking of Autonomous Tractor Semi-Trailers Under Extreme Conditions

Autonomous tractor semi-trailers are expected to improve safety and efficiency for road freight transportation. However, the complex dynamics introduced by the articulated structure of the tractor semi-trailer results in poor yaw and roll stability, which in consequence poses great challenges in path tracking under extreme conditions featuring high lateral acceleration or low tire-road friction. In this work, a stability-guaranteed computationally efficient model predictive path tracking framework is devised. In particular, a comprehensive tractor semi-trailer stability constraint (TSSC) consisting of a three-dimensional (3D) yaw stability envelope and rollover limitation is proposed to guarantee the yaw and roll stability. By linearizing the system model and constraints, the proposed path tracking controller is solved as a set of quadratic programming (QP) problems with the potential for real-time implementation. Simulation results demonstrate that the proposed control framework reduces the maximum tracking deviation by at least 48.5% compared to the existing method and ensures the dynamic stability of the tractor semi-trailer under extreme conditions.