Diversifying Latent Flows for Safety-Critical Scenarios Generation with CARLA Simulator

The likelihood of encountering scenarios that lead to accidents, namely safety-critical scenarios, is minimal compared to long-term safe driving environments. The generation of repeatable and scalable safety-critical scenarios is essential for the advancement of human and autonomous driving capabilities. Compared with the high complexity and low practicality of existing scenario generation methods, in this paper we propose a real-time approach to automatically generate challenging scenarios and instantiate them in a CARLA-based simulator. First, the safety-critical scenario is decomposed into a perturbed and optimized vehicle trajectory and the remaining reusable Unreal Engine assets based on a hierarchical model. Second, a model that is based on a graph conditional variational autoencoder (VAE) is employed to predict future trajectories and head angles based on past information. Third, the safety-critical scene generation model is used to enhance the diversity of the scene by diversifying the latent variables over a pre-trained trajectory representation model. Finally, the trajectories of real-world vehicles are placed into the simulator by adapting them to enable the generation of safety-critical scenes in a three-dimensional environment. The results demonstrate that the proposed approach generates scenarios that are more plausible than those generated by the baselines, with a performance improvement of over 10% in collision metrics for scenario generation. The research facilitates the simplification of the long-tail scenario construction process for autonomous vehicles, which in turn facilitates the optimization of algorithms such as autonomous trajectory planning.