One Hand to Rule Them All: Canonical Representations for Unified Dexterous Manipulation

Zhenyu Wei, Yunchao Yao, Mingyu Ding

University of North Carolina at Chapel Hill

OHRA Teaser
We introduce a canonical hand representation that unifies diverse dexterous hands into a shared parameter space and canonical URDF format, serving as a condition for cross-embodiment policy learning. It enables dexterous grasping and zero-shot generalization to novel hand morphologies, highlighting its potential for a wide range of dexterous manipulation tasks.

Abstract

Dexterous manipulation policies today largely assume fixed hand designs, severely restricting their generalization to new embodiments with varied kinematic and structural layouts. To overcome this limitation, we introduce a parameterized canonical representation that unifies a broad spectrum of dexterous hand architectures. It comprises a unified parameter space and a canonical URDF format, offering three key advantages. 1) The parameter space captures essential morphological and kinematic variations for effective conditioning in learning algorithms. 2) A structured latent manifold can be learned over our space, where interpolations between embodiments yield smooth and physically meaningful morphology transitions. 3) The canonical URDF standardizes the action space while preserving dynamic and functional properties of the original URDFs, enabling efficient and reliable cross-embodiment policy learning.

We validate these advantages through extensive analysis and experiments, including grasp policy replay, VAE latent encoding, and cross-embodiment zero-shot transfer. Specifically, we train a VAE on the unified representation to obtain a compact, semantically rich latent embedding, and develop a grasping policy conditioned on the canonical representation that generalizes across dexterous hands. We demonstrate, through simulation and real-world tasks on unseen morphologies (e.g., 81.9% zeroshot success rate on 3-finger LEAP Hand), that our framework unifies both the representational and action spaces of structurally diverse hands, providing a scalable foundation for cross-hand learning toward universal dexterous manipulation.

URDF Comparison

Original URDF

Canonical URDF

Real-World

Model Success Rate
Apple Band Aid Coke Cube Football Mayo Orange Pear Sheep Soccer Average
leap_3333 (trained) 8/10 7/10 9/10 7/10 10/10 6/10 8/10 9/10 10/10 9/10 83/100
leap_3033 (trained) 8/10 8/10 2/10 6/10 9/10 6/10 7/10 9/10 10/10 10/10 75/100
leap_3033 (zero-shot) 8/10 10/10 5/10 5/10 7/10 2/10 9/10 7/10 9/10 9/10 71/100
leap_3303 (trained) 7/10 8/10 5/10 3/10 9/10 4/10 9/10 7/10 9/10 9/10 70/100
leap_3303 (zero-shot) 9/10 6/10 4/10 5/10 9/10 5/10 8/10 6/10 9/10 10/10 71/100

leap_3333

leap_3033

leap_3303

More Hand Variants

All videos are played at 1x speed.

Simulation

1. Morphology Latent Space

URDF interpolations
Visualization of latent-space interpolation between two dexterous hands. Canonical URDFs are shown at the ends, with decoded reconstructions and interpolated morphologies in between, demonstrating smooth transitions in DoF, finger arrangement, and overall geometry.

2. URDF Fidelity

Canonical vs. Original URDF Grasping Transfer Performance
Method Success Rate (%)
Allegro Barrett ShadowHand
Ours (Canonical) 84.20 88.10 62.90
Ours (Original) 71.60 (-12.60) 88.70 (+0.60) 62.60 (-0.30)
$\mathcal{D(R,O)}$ (Original) 92.30 87.30 83.00
$\mathcal{D(R,O)}$ (Canonical) 92.38 (+0.08) 87.34 (+0.04) 78.63 (-4.37)
In-hand Reorientation Policies Comparison
Policy Steps-to-Fall ↑ Cumulative Rotation ↑
Shadow (Original) 369.66 9.09
Shadow (Canonical) 390.62 10.92
LEAP (Original) 397.62 5.63
LEAP (Canonical) 326.98 6.31

3. Dexterous Grasping

Cross-Embodiment Grasping Performance
Method Success Rate (%) ↑ Time (Sec.) ↓
Allegro Barrett ShadowHand
DFC 76.2 86.3 58.8 >1800
GenDexGrasp 51.0 67.0 54.2 19.71
$\mathcal{D(R,O)}$ Grasp 92.3 87.3 83.0 0.65
Ours 84.2 88.1 62.9 0.13
Zero-shot Grasping Performance (Underlined)
Model Success Rate (%)
leap_3033 leap_3303 leap_3330
All data 76.1 85.4 43.3
No leap_3033 data 67.8 83.4 31.5
No leap_3303 data 81.5 81.9 46.9
No leap_3330 data 74.7 81.6 36.3

BibTeX

TODO