Research map / Reinforcement learning / Imitation learning
Meta-Controller: Few-Shot Imitation of Unseen Embodiments and Tasks in Continuous Control
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Proposes Meta-Controller, a few-shot behavior cloning framework that uses joint-level tokenization, a structure-motion transformer encoder with embodiment/task-specific PEFT parameters, and a matching-based policy network to generalize to unseen embodiments and tasks from five reward-free demonstrations on DeepMind Control.
Problem
Few-shot behavior cloning that generalizes simultaneously to unseen robot embodiments and unseen tasks in continuous control, where prior modular policy methods lack few-shot task adaptation and few-shot IL methods handle only a single embodiment.
Approach
Tokenize states and actions per joint to unify heterogeneous embodiments, encode states with a structure encoder (joint axis) and a causal motion encoder (time axis) that split shared and embodiment/task-specific parameters via PEFT-style adapters, and predict actions with a non-parametric cross-attention matching against demonstration action features, fine-tuning only the adaptive parameters on n
Key results
- 5-shot average normalized score of 71.1 across eight held-out tasks, versus 37.9 for MetaMorph and 35.3 for MT-DT (best baselines).
- On the unseen reacher-four hard task, Meta-Controller scores 50.8 versus 8.5 for HDT and 3.8 for MetaMorph.
- Removing the structure encoder drops the 5-shot average from 71.1 to 31.6 in the architecture ablation.
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| Use Meta-Controller instead of the strongest baseline, MetaMorph | 5-shot DMC control · DMC average | normalized score: 37.9 -> 71.1 | Helped |
| Use Meta-Controller instead of MT-DT | 5-shot behavior cloning · walker walk-bwd. | normalized score: 86.4 -> 84.3 | Hurt |
| Add a structure encoder (ablation) | Meta-Controller without the structure encoder · DMC average | normalized score: 31.6 -> 60.3 | Helped |
| Add a motion encoder (ablation) | Meta-Controller with structure encoder and no matching module · DMC average | normalized score: 44.7 -> 60.3 | Helped |
| Add the matching module (ablation) | Meta-Controller with structure and motion encoders · DMC average | normalized score: 60.3 -> 71.1 | Helped |
| Add adaptive embodiment-specific structure parameters (ablation) | Meta-Controller without adaptive structure parameters · DMC average | normalized score: 49.0 -> 71.1 | Helped |
| Add adaptive embodiment- and task-specific motion parameters (ablation) | Meta-Controller without adaptive motion parameters · DMC average | normalized score: 58.7 -> 71.1 | Mixed |
| Increase demonstrations from 5 to 10 or 20 (ablation) | Meta-Controller · DMC tasks | normalized score | Helped |
| Use Meta-Controller instead of the strongest baseline on each task | 3-shot DMC behavior cloning · DMC average | normalized score: 30.1 -> 57.0 | Helped |
| Add action noise to the transitions | Meta-Controller · DMC tasks | reward | Mixed |
Surprising findings
- Without adaptive embodiment-specific parameters in the structure encoder, the model still performs competitively on many tasks, suggesting joint-level I/O alone gives much compositional generalization.
Limitations
- Evaluated only in simulation (DeepMind Control) with 2D-plane embodiments; no real-world validation.
- Transformer encoders and decoders make inference costly for real-time resource-constrained robots.
- Struggles on tasks requiring reaching an unseen posture before reward appears, as shown in failure cases.
Experimental setup
Datasets: DeepMind Control suite replay-buffer demonstrations from DrQ-v2 expert agents
Benchmarks: DeepMind Control suite
Metrics: normalized score mean with standard error over 20 initial states
Baselines: FS-DT MT-DT PDT PDT+PEFT HDT L2M MetaMorph MTGv2
Builds on: Decision Transformer MetaMorph matching networks Hyper Decision Transformer Prompt Decision Transformer
Closest papers by meaning
- Zero-Shot Robotic Manipulation with Pre-Trained Image-Editing Diffusion Models (ICLR 2024 · similarity 0.88)
- Scaling Proprioceptive-Visual Learning with Heterogeneous Pre-trained Transformers (NeurIPS 2024 · similarity 0.88)
- OSVI-WM: One-Shot Visual Imitation for Unseen Tasks using World-Model-Guided Trajectory Generation (NeurIPS 2025 · similarity 0.87)
- Videos are Sample-Efficient Supervisions: Behavior Cloning from Videos via Latent Representations (NeurIPS 2025 · similarity 0.87)
- Generalizable Domain Adaptation for Sim-and-Real Policy Co-Training (NeurIPS 2025 · similarity 0.87)
- What's the Move? Hybrid Imitation Learning via Salient Points (ICLR 2025 · similarity 0.87)
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