VisuaLLMPlanner - A Maneuver Planner for Automated Vehicles using Large Language Models

Achieving safe and reliable automated driving in real-world conditions requires the ability to handle rare and unpredictable situations, commonly known as long-tail scenarios. These cases are often underrepresented in training data and remain a major challenge for conventional motion planning systems. In this work, we present VisuaLLMPlanner, a maneuver planning framework that integrates a multimodal large language model (MLLM) into the high-level decisionmaking loop of an automated driving pipeline. The system is triggered when the ego vehicle encounters a situation with an obstacle that cannot be resolved by a standard lane-following planner. At this point, a structured input comprising a bird'seye view image and a textual scene description is generated and passed to the MLLM. Rather than generating plans directly, the model selects from a discrete set of pre-generated and validated maneuver options, allowing for interpretable and structured decision-making. We evaluate our approach on the interPlan benchmark, which focuses explicitly on long-tail scenarios, and demonstrate that VisuaLLMPlanner achieves strong performance in comparison to prior LLM-based planners. The results highlight both the potential and current limitations of foundation models for high-level reasoning in automated vehicle planning.