EMPIRE: Explicit Manipulation Planning as a Learnable Intermediate Representation for Egocentric Hand-Motion Forecasting
Organizations: Key Laboratory of Intelligent Information Processing of Chinese Academy of Sciences (CAS), Institute of Computing Technology, CAS, China · University of Chinese Academy of Sciences, China
Abstract
Forecasting dexterous hand motions from egocentric observations is fundamental to intelligent interactive systems. Existing VLM-based methods typically map observations directly to future motions, overlooking the underlying manipulation process that governs hand-object interactions. Moreover, end-to-end optimization couples manipulation learning with motion synthesis, causing motion-generation gradients to interfere with the pre-learned manipulation-aware representations. To overcome these limitations, we propose EMPIRE, a two-stage framework that introduces Explicit Manipulation Planning as an Intermediate Representation for Egocentric hand-motion forecasting. Stage I: Learn to Plan. EMPIRE first learns explicit manipulation plans from multimodal context to capture the progression of hand-object interactions. Stage II: Learn to Act. A motion generator synthesizes future bimanual hand motions conditioned on frozen planner representations, preventing motion-generation gradients from affecting manipulation planning. To support our method, we further construct EMPIRE-651K, a bimanual hand-motion forecasting dataset comprising 650,910 training windows across 111 tasks, each paired with an explicit per-hand manipulation plan. Under identical training and evaluation protocols, EMPIRE achieves state-of-the-art forecasting accuracy, with an MPJPE of 84.53 mm and a finger-relative error of 38.97mm. We release the code and dataset at https://github.com/wangwen-banban/EMPIRE.
Figures & tables
| Metric | Score |
|---|---|
| Caption quality | |
| Motion-plan quality | |
| Overall quality | |
| Usable pairs |
| Method | Params | MPJPE | Wrist MPJPE | Finger- relative MPJPE | Infer.(s/window) |
|---|---|---|---|---|---|
| VITRA re-impl. ( 23 ) | B | ||||
| Being-H0-1B ( 27 ) | B | ||||
| Being-H0-8B ( 27 ) | B | ||||
| Being-H0-14B ( 27 ) | B | ||||
| EMPIRE (ours) | B |
| Difficulty (baseline MPJPE) | #tasks | Mean | Plan helps |
|---|---|---|---|
| Easy ( ) | |||
| Medium ( – ) | |||
| Hard ( ) | |||
| All |
| Configuration | Overall | Seen | Unseen |
|---|---|---|---|
| VITRA re-impl. (caption only) | |||
| motion plan | |||
| depth (cross-attention) | |||
| depth (concatenation) |
| Setting | VLM grad.? | LM loss | MPJPE |
|---|---|---|---|
| Single-stage | Yes | – | |
| Two-stage, trainable | Yes | ||
| Two-stage, frozen (ours) | No |
| Action head | Params | Overall | Seen | Unseen |
|---|---|---|---|---|
| DiT-M | M | |||
| DiT-B (default) | M | |||
| DiT-L | M |
Appendix figures & tables9 assets
Supplementary material from the paper’s appendix.
Appendix
| Target | Criterion | Definition | Score |
|---|---|---|---|
| Caption | Grounding | Described actions and objects are consistent with the visual evidence in the video. | |
| Caption | Hand attribution | Left/right roles, hand activities, and None assignments are correctly identified. | |
| Plan | Grounding | Described actions, objects, and contact states are supported by the visual evidence. | |
| Plan | Coverage | Key sub-actions and all visibly active hands are covered. | |
| Plan | Temporal coordination | Step order, simultaneous motion, and bimanual coordination are correct. | |
| Plan | Conditioning utility | The plan is specific, non-redundant, complete, and useful for motion generation. |
| Partition | Caption | Plan | Overall | Usable ( ) |
|---|---|---|---|---|
| Part 1 | ||||
| Part 2 | ||||
| Part 3 | ||||
| Part 4 | ||||
| Part 5 | ||||
| Overall |
| Configuration | Stage I: Learn to Plan | Stage II: Learn to Act |
|---|---|---|
| Trainable modules | Gemma-2 decoder, multimodal projector, depth mapper, and FoV encoder; SigLIP and DA3 encoders are frozen | DiT-B and conditioning projectors; the Planner and all condition encoders are frozen |
| Training objective | Autoregressive plan-language cross-entropy | Flow matching with on |
| Training length | epoch ( optimizer steps) | epochs ( optimizer steps) |
| Optimizer | AdamW, , weight decay | Same as Stage I |
| Learning rate | ||
| Schedule / clipping | Constant learning rate, no warmup; gradient-norm clipping at | Same as Stage I |
| Run | Trainable | Epoch | Steps | s/step | Hours |
|---|---|---|---|---|---|
| Baseline (single stage) | VLM DiT | ||||
| Ours Stage-I (plan SFT) | VLM | ||||
| Ours Stage-II (DiT) | DiT | ||||
| Ours total | — | — |
| Model | AR tokens | s / window |
|---|---|---|
| Baseline (no plan) | ||
| EMPIRE (plan depth) | ||
| Being-H0-1B | ||
| Being-H0-8B | ||
| Being-H0-14B |
| Stage-II plan condition | 26-task subset | Train Part 1–5 |
|---|---|---|
| Ground-truth plan | ||
| Stage-I predicted plan (ours) |
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