DiscreteRTC: Discrete Diffusion Policies are Natural Asynchronous Executors

TL;DR

DiscreteRTC leverages discrete diffusion policies for asynchronous execution in dynamic tasks, offering improved success rates, reduced latency, and simpler implementation over flow-matching RTC methods.

Contribution

The paper introduces DiscreteRTC, a novel approach that uses native unmasking in discrete diffusion policies for asynchronous execution, overcoming limitations of flow-matching policies.

Findings

Higher success rates on dynamic benchmarks and real-world tasks.

Faster inference with only 0.7x additional computation.

50% higher success rate in real-world pick tasks.

Abstract

Unlike chatbots, physical AI must act while the world keeps evolving. Therefore, the inter-chunk pause of synchronous executors are fatal for dynamic tasks regardless of how fast the inference is. Asynchronous execution -- thinking while acting -- is therefore a structural requirement, and real-time chunking (RTC) makes it viable by recasting chunk transitions as inpainting: freezing committed actions and consistently generating the remainder. However, RTC with flow-matching policy is structurally suboptimal: its inpainting comes from inference-time corrections rather than the base policy, yielding little pre-training benefit, specific fine-tuning, heuristic guidance, and extra computation that inflates the latency. In this work, we observe that discrete diffusion policies, which generate actions by iteratively unmasking, are natural asynchronous executors that resolve all limitations at once: they are fine-tuning free since inpainting is their native operation, while early stopping further provides adaptive guidance and reduces inference cost. We propose DiscreteRTC, which replaces external corrections with native unmasking, and show on dynamic simulated benchmarks and real-world dynamic manipulation tasks that it achieves higher success rates than continuous RTC and other baselines. In summary, DiscreteRTC is simpler to implement with 0 lines of code for async inpainting, faster at inference with only 0.7x computation compared with generating actions from scratch, and better at execution with 50% higher success rate in real-world dynamic pick task compared with flow-matching-based RTC. More visualizations are on https://outsider86.github.io/DiscreteRTCSite/.