Natural Language Can Help Bridge the Sim2Real Gap

TL;DR

This paper introduces a novel approach using natural language descriptions to bridge the visual gap between simulation and real-world images, improving the transfer of robotic policies with less real data.

Contribution

The paper proposes leveraging language descriptions as a unifying signal to create domain-invariant visual representations for sim2real transfer, outperforming existing methods.

Findings

Outperforms prior sim2real methods by 25-40%.

Using language-based pretraining improves domain invariance.

Effective with limited real-world demonstrations.

Abstract

The main challenge in learning image-conditioned robotic policies is acquiring a visual representation conducive to low-level control. Due to the high dimensionality of the image space, learning a good visual representation requires a considerable amount of visual data. However, when learning in the real world, data is expensive. Sim2Real is a promising paradigm for overcoming data scarcity in the real-world target domain by using a simulator to collect large amounts of cheap data closely related to the target task. However, it is difficult to transfer an image-conditioned policy from sim to real when the domains are very visually dissimilar. To bridge the sim2real visual gap, we propose using natural language descriptions of images as a unifying signal across domains that captures the underlying task-relevant semantics. Our key insight is that if two image observations from different domains are labeled with similar language, the policy should predict similar action distributions for both images. We demonstrate that training the image encoder to predict the language description or the distance between descriptions of a sim or real image serves as a useful, data-efficient pretraining step that helps learn a domain-invariant image representation. We can then use this image encoder as the backbone of an IL policy trained simultaneously on a large amount of simulated and a handful of real demonstrations. Our approach outperforms widely used prior sim2real methods and strong vision-language pretraining baselines like CLIP and R3M by 25 to 40%. See additional videos and materials at https://robin-lab.cs.utexas.edu/lang4sim2real/.