Research map / Vision-language and multimodal / Robot action and navigation
LaST-VLA: Thinking in Latent Spatio-Temporal Space for Vision-Language-Action in Autonomous Driving
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Proposes LaST-VLA, a driving VLA that reasons in a latent spatio-temporal CoT supervised by Cosmos world-model and VGGT geometry features, trained with progressive SFT and GRPO, reaching 91.3 PDMS on NAVSIM v1 and 87.1 EPDMS on NAVSIM v2.
Problem
Explicit textual chain-of-thought in driving VLAs creates a semantic-perceptual gap and high latency, while unsupervised latent CoT is physics-agnostic and unstable during training.
Approach
Supervise continuous latent CoT tokens by aligning adapter-projected hidden states to frozen features from a video world model (Cosmos, dynamics) and a 3D foundation model (VGGT, geometry), using a two-phase SFT schedule with structured causal masking, then refine with GRPO while adapters are frozen.
Key results
- LaST-VLA-8B reaches 91.3 PDMS on NAVSIM v1 (RL), above Recogdrive-2B at 90.8 and InternVL3-8B RL at 87.2.
- LaST-VLA-8B reaches 87.1 EPDMS on NAVSIM v2, versus 86.1 for DriveVLA-W0-7B.
- On SURDS, LaST-VLA-8B scores 84.29% average and 81.19% Motion on NuDynamics, versus 76.61% and 73.97% for InternVL3-8B.
Surprising findings
- Textual CoT improves PDMS by only 1.2 over no-text baseline, and unsupervised latent CoT reaches 89.8 PDMS, which is above the textual variant.
Limitations
- Single front-view camera causes failures when trajectories extend beyond the field of view at sharp turns or intersections.
- Unsupervised latent CoT is unstable during RL, and supervision is needed for stability.
- Relies on external frozen teacher models (Cosmos, VGGT) during training.
Experimental setup
Datasets: NAVSIM navtrain navtrain-hard-24k SURDS nuScenes NuDynamics
Benchmarks: NAVSIMv1 NAVSIMv2 SURDS NuDynamics nuScenes
Metrics: PDMS EPDMS accuracy L2 error collision rate
Baselines: DiffusionDrive WoTE DriveVLA-W0-7B AdaThinkDrive-8B Recogdrive-2B InternVL3-8B SURDS-3B Qwen2.5-VL-72B-Instruct HydraMDP++ TransFuser UniAD AutoVLA
Builds on: GRPO InternVL3 VGGT Cosmos NAVSIM
Closest papers by meaning
- OneVL: One-Step Latent Reasoning and Planning with Vision-Language Explanation (NeurIPS 2026 · similarity 0.94)
- Explicit Geometric Chain-of-Thought for Vision-Language-Action in Autonomous Driving (NeurIPS 2026 · similarity 0.93)
- Drive-R1: Bridging Reasoning and Planning in VLMs for Autonomous Driving with Reinforcement Learning (AAAI 2026 · similarity 0.92)
- AutoVLA: A Vision-Language-Action Model for End-to-End Autonomous Driving with Adaptive Reasoning and Reinforcement Fine-Tuning (NeurIPS 2025 · similarity 0.92)
- Less Language, More Latents: Annotation-Efficient VLAs for Driving (NeurIPS 2026 · similarity 0.92)
- DriveSpatial: A Benchmark for Spatiotemporal Intelligence in VLMs for Autonomous Driving (NeurIPS 2026 · similarity 0.92)
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