Stability-Aware Reinforcement Learning for Autonomous Driving With Dynamics-Augmented State and Lyapunov Constraints

Autonomous driving in extreme conditions presents substantial challenges in ensuring vehicle stability and safety. Traditional reinforcement learning (RL) methods for decision-making often lack vehicle dynamics modeling and formal stability constraints, leading to dynamically infeasible behaviors and unstable policy training. To overcome these limitations, we present an end-to-end reinforcement learning framework that incorporates a data-driven vehicle dynamics prediction model and Lyapunov-based stability constraints. The dynamics module is constructed using a hybrid Transformer architecture to effectively capture nonlinearities, time-varying parameters, and the coupling between longitudinal and lateral motions. This module captures the nonlinear interaction among vehicle, tire, and road, and provides predicted dynamic states as auxiliary inputs to enhance the RL state representation. Second, a neural network-based Lyapunov candidate function is incorporated into an enhanced Soft Actor–Critic (SAC) framework to impose stability-aware constraints on policy learning. To explicitly characterize lateral instability, the squared sideslip angle at the vehicle's center of gravity is defined as the Lyapunov cost. In addition, a hierarchical reward function is designed to balance multiple objectives during policy learning. The proposed framework is then validated through open-loop prediction experiments using both simulated and real vehicle data, followed by closed-loop evaluation in the CARLA simulator under representative driving scenarios, including low-friction road and dynamic obstacle avoidance. Experimental results show that the proposed method leads to significant improvements in both the stability and safety of the learned policies.