Emergent Neural Automaton Policies:
Learning Symbolic Structure from Visuomotor Trajectories

Robotics Institute, Carnegie Mellon University
* Equal contribution

ENAP enables unsupervised discovery of task structures, improving both interpretability and task performance.

Abstract

Scaling robot learning to long-horizon tasks remains a formidable challenge. While end-to-end policies often lack the structural priors needed for effective long-term reasoning, traditional neuro-symbolic methods rely heavily on hand-crafted symbolic priors. To address the issue, we introduce ENAP (Emergent Neural Automaton Policy), a framework that allows a bi-level neuro-symbolic policy to adaptively emerge from demonstrations. Specifically, we first employ adaptive clustering and an extension of the \(L^*\) algorithm to infer a Mealy state machine from visuomotor data, which serves as an interpretable high-level planner capturing latent task modes. Then, this discrete structure guides a low-level reactive residual network to learn precise continuous control via behavior cloning. By explicitly modeling the task policy with discrete transitions and continuous residuals, ENAP achieves high sample efficiency and interpretability without requiring task-specific labels. Extensive experiments on complex manipulation and long-horizon tasks demonstrate that ENAP outperforms state-of-the-art end-to-end VLA policies by up to 27% in low-data regimes, while offering a structured representation of robotic intent.

Method Overview ▶ Replay

ENAP follows a three-stage pipeline—(i) symbol abstraction, (ii) structure extraction via an extended \(L^*\), and (iii) bi-level control—to learn structured policies from demonstrations.

Inference Pipeline ▶ Replay

ENAP resolves multi-modal decisions by leveraging a learned state machine and observation-conditioned residual control to guide transitions into the correct logical branch.

Comparison with Sota
Complex Manipulation Tasks
Method Param (M) DualStack Peg
Cube (%) Insert (%)
Oracle 2.98 98.3 ±0.4 86.7 ±0.8
Transformer 63.81 38.7 ±6.0 51.8 ±5.5
GMM 46.11 73.6 ±2.3 53.1 ±2.6
Diffusion Policy 114.39 41.2 ±7.2 31.1 ±6.8
OpenVLA 7652.10 69.8 ±2.0 42.3 ±2.8
\(\pi_0\) 3288.52 73.4 ±1.2 51.6 ±1.4
ENAP (Oracle) 2.66 98.8 ±0.3 85.6 ±0.6
ENAP* (DINO) 22.94 76.0 ±2.0 63.2 ±2.4
Long-Horizon TAMP Tasks
Method Seq. (%) Hier. (%)
3/5 5/5 3/5 5/5
FLOWER 91.0 ±0.6 90.6 ±0.5 90.8 ±0.7 15.9 ±0.4
ENAP (FLOWER) 97.0 ±0.4 96.8 ±0.3 95.5 ±0.5 28.2 ±0.6
Real-World Evaluation
Method Param (M) Speed (ms) Stack Pick Hanger
Lego Place Task
\(\pi_{0.5}\) 3403 6841 58.82 76.47 64.71
ENAP* (DINO) 23 281 88.24 94.12 94.12
Qualitative Results
Real-time PMM Transition
Real-time PMM Transition
Real-time PMM Transition
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StackLego is a high-precision assembly task where a blue brick must be placed onto a fixed red brick without force feedback, evaluated by graded stacking success.

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Hanger is a manipulation task requiring the agent to unhook a hanger and transfer it across an obstacle to the opposite side of a rack.

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MultiGoalPickPlace is a sorting task where the agent must match and place multiple colored cans into their corresponding bowls from randomized initial positions.