Integrated Decision and Control: Towards Interpretable and Efficient Driving Intelligence.

Decision and control are two of the core functionalities of high-level automated vehicles. Current mainstream methods, such as functionality decomposition or end-to-end reinforcement learning (RL), either suffer high time complexity or poor interpretability and limited safety performance in real-world complex autonomous driving tasks. In this paper, we present an interpretable and efficient decision and control framework for automated vehicles, which decomposes the driving task into multi-path planning and optimal tracking that are structured hierarchically. First, the multi-path planning is to generate several paths only considering static constraints. Then, the optimal tracking is designed to track the optimal path while considering the dynamic obstacles. To that end, in theory, we formulate a constrained optimal control problem (OCP) for each candidate path, optimize them separately and choose the one with the best tracking performance to follow. More importantly, we propose a model-based reinforcement learning (RL) algorithm, which is served as an approximate constrained OCP solver, to unload the heavy computation by the paradigm of offline training and online application. Specifically, the OCPs for all paths are considered together to construct a multi-task RL problem and then solved offline by our algorithm into value and policy networks, for real-time online path selecting and tracking respectively. We verify our framework in both simulation and the real world. Results show that our method has better online computing efficiency and driving performance including traffic efficiency and safety compared with baseline methods. In addition, it yields great interpretability and adaptability among different driving tasks. The real road test also suggests that it is applicable in complicated traffic scenarios without even tuning.