A humanoid that falls under an obstacle recovers in 88.5 percent of trials, against 18.9 percent without geometric escape guidance
AspireAI community · arXiv (cs.RO)
A fallen humanoid beneath an overhead obstacle faces a coupled problem: it must create clearance while organising support for a stable rise, since standing before making room can worsen the obstruction. The method uses reinforcement learning with contact-supported geometric escape guidance, rewarding incremental reduction of robot-obstacle overlap without prescribing an escape path. A learned motion prior plus posture-dependent support and joint-stall costs shape a single policy that learns when to clear the obstacle, how to establish support and when to complete the rise, using proprioception alone. In simulation it recovers in 88.5 percent of trials beneath plates that can only be lifted, versus 18.9 percent without geometric guidance, and in 98.6 percent of trials beneath free plates with randomised size, mass and placement. Deployed on a Unitree G1, the policy recovered in 95 of 150 attempts across seven real-world obstacle scenes including furniture and multi-object arrangements absent from training.
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Two sparse-autoencoder analyses have resisted scaling: matching semantically similar features across layers, and compressing large feature circuits into interpretable supernodes. This paper argues both are the same underlying problem, estimating semantic distances between SAE features that sit on different activation manifolds. Its representation treats each feature not as a single decoder vector but as an activation-weighted distribution over the hidden states expressing it, projects those distributions into a shared reference space, and compares them with Wasserstein distance. The representation is proved invariant to activation rescaling and stable under perturbation, and recovers true matches under finite-sample margin conditions. Empirically it outperformed decoder-vector and LLM-based baselines and captured subtle functional distinctions between related features, and it compressed large feature circuits into interpretable supernodes automatically. The limitation is that this is interpretability tooling: the paper demonstrates better feature matching and circuit compression, not that downstream interpretability claims become more accurate.