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Reflex: Visually Grounded Reactive Humanoid Control

Trains a three-stage system that enables humanoid robots to visually perceive and reflexively catch thrown boxes using an egocentric RGB-D encoder, a compact latent object-dynamics representation, and a whole-body RL controller; reports 85.7% simulation success and 65%/40% real-world success at 2.5/5 m.

Introduction

Reactive whole-body control from egocentric vision remains a core gap for humanoid robots: anticipating a moving object and coordinating the whole body within a second requires perception tightly coupled to fast, whole-body control. The paper's central insight is that decomposing the problem into (1) a state-based whole-body RL controller, (2) a learned latent representation that encodes object dynamics from delayed and partial measurements, and (3) an egocentric RGB-D encoder that regresses that latent while keeping the controller frozen, yields scalable visual grounding without retraining the expensive controller.

Key Findings
  • Decomposition matters: separating control, dynamics inference, and visual grounding lets each module receive direct training signals and scales visual learning independently of RL. This enables training on egocentric RGB-D while retaining a robust whole-body controller.
  • Empirical performance: in simulation, 85.7% catch success from egocentric RGB-D (vs. 87.9% with privileged box observations). On a real Unitree G1 robot, human-thrown-box success is 65% at 2.5 m and 40% at 5 m (reaching ~76% and ~59% of comparable human success rates at those distances).
  • Temporal visual history and camera ego-motion are critical: removing temporal history drops success by ~35–40 points on key throw distributions; including ego-motion improves visual grounding.
  • Latent representation design: regressing the learned latent that conditions the controller outperforms directly regressing the full privileged box state; the system tolerates observation latency (20–60 ms) and incomplete observations via the dynamics encoder.
Who it's for and trade-offs

Great fit if you research embodied AI, robot perception–control integration, or sim-to-real reactive behaviors for humanoid platforms and can supply RGB-D + ego-motion and access to simulation for RL. Look elsewhere if you need a turnkey solution for non-humanoid platforms, have only monocular vision without reliable ego-motion, or cannot afford the compute and engineering cost of whole-body RL training and real-robot deployment. The method focuses on catching-like reactive behaviors rather than general manipulation or long-horizon planning, and achieving the reported real-world performance requires careful sim-to-real practices and robot-specific tuning.

Where it fits

Positions itself at the intersection of reinforcement learning, embodied perception, and real-time robotics: more targeted than end-effector-only reactive systems and more perception-grounded than controllers relying on motion-capture or instrumented objects. The modular design makes it a useful reference architecture for future work that wants to swap in alternative perception encoders or dynamics representations without retraining the controller.

Information

  • Websitearxiv.org
  • OrganizationsUniversity of Washington, Stanford University, University of Southern California, National University of Singapore, University of North Carolina at Chapel Hill, Allen Institute for AI
  • AuthorsTaoyang Jia, Weikai Huang, Linxin Song, Jared Darlington, Jieyu Zhao, Yue Wang, Jiafei Duan, Zhongzheng Ren, Ranjay Krishna
  • Published date2026/10/08

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